CA2395312C - Method and system for handling the transcoding of connections handed off between mobile switching centers - Google Patents
Method and system for handling the transcoding of connections handed off between mobile switching centers Download PDFInfo
- Publication number
- CA2395312C CA2395312C CA002395312A CA2395312A CA2395312C CA 2395312 C CA2395312 C CA 2395312C CA 002395312 A CA002395312 A CA 002395312A CA 2395312 A CA2395312 A CA 2395312A CA 2395312 C CA2395312 C CA 2395312C
- Authority
- CA
- Canada
- Prior art keywords
- msc
- codec
- target
- user equipment
- message
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
Links
Classifications
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04W—WIRELESS COMMUNICATION NETWORKS
- H04W36/00—Hand-off or reselection arrangements
- H04W36/12—Reselecting a serving backbone network switching or routing node
Abstract
A communication system supports multiple source coding and/or channel coding schemes. When a handoff is needed that transfers radiocommunication service support responsibility from a base station controlled by one MSC to a base station controlled by another MSC, signaling procedures are employed to handle the transfer as it pertains to the source coding and/or channel coding, i.e., ensuring that the new MSC links in an appropriate codec to support the handed off connection.
Various techniques are described to provide such signaling, both in the direction of the new (target) MSC and in the direction of the user equipment being handed off.
Various techniques are described to provide such signaling, both in the direction of the new (target) MSC and in the direction of the user equipment being handed off.
Description
WO 01!50799 PCT/EPO1I00003 METHOD AND SYSTEM FOR HANDLING THE TRANSCODING OF
CONNECTIONS HANDED OFF BETWEEN MOBILE SWITCHING CENTERS
RELATED APPLICATION
This application is related to, and claims priority from, U.S. Patent 6810256 with the granting date 10/26!2004, the disclosure of which is incorporated here by reference.
BACKGROUND
The present invention generally relates to coding in the f eld of communication systems and, more particularly, to handling the signaling for controlling transcoding when a connection is handed offbetween mobile switching centers (MSCs) in radiocommunication systems.
The growth of commercial communication systems and, in particular, the is explosive growth of cellular radiotelephone systems, have compelled system designers to search for ways to increase system capacity without reducing communication quality beyond consumer tolerance thresholds. One technique to achieve these objectives involved changing from systems wherein analog modulation was used to impress data onto a carrier wave, to systems wherein digital modulation was used to impress the data on carrier waves.
In wireless digital communication systems, standardized sir interfaces specify most of the system parameters, including speech coding type(s), burst format, communication protocol, etc. For example, the European Telecommunication Standard Institute (BTSI) has specified a Global System for Mobile Communications (GSM) standard that uses time division multiple access (TDMA) to communicate control, voice and data information over radio frequency (RF) physical channels or links using a Gaussian Minimum Shift Keying (GMSK) modulation scheme at a symbol rate of 271 ksps. In the U.S., the Telecommunication Industry Association (T1A) has published a number of Interim Standards, such as IS-54 and IS-I36, that define various versions of digital advanced mobile phone service (D-AMPS), a TDMA system that uses a Amended Sheet
CONNECTIONS HANDED OFF BETWEEN MOBILE SWITCHING CENTERS
RELATED APPLICATION
This application is related to, and claims priority from, U.S. Patent 6810256 with the granting date 10/26!2004, the disclosure of which is incorporated here by reference.
BACKGROUND
The present invention generally relates to coding in the f eld of communication systems and, more particularly, to handling the signaling for controlling transcoding when a connection is handed offbetween mobile switching centers (MSCs) in radiocommunication systems.
The growth of commercial communication systems and, in particular, the is explosive growth of cellular radiotelephone systems, have compelled system designers to search for ways to increase system capacity without reducing communication quality beyond consumer tolerance thresholds. One technique to achieve these objectives involved changing from systems wherein analog modulation was used to impress data onto a carrier wave, to systems wherein digital modulation was used to impress the data on carrier waves.
In wireless digital communication systems, standardized sir interfaces specify most of the system parameters, including speech coding type(s), burst format, communication protocol, etc. For example, the European Telecommunication Standard Institute (BTSI) has specified a Global System for Mobile Communications (GSM) standard that uses time division multiple access (TDMA) to communicate control, voice and data information over radio frequency (RF) physical channels or links using a Gaussian Minimum Shift Keying (GMSK) modulation scheme at a symbol rate of 271 ksps. In the U.S., the Telecommunication Industry Association (T1A) has published a number of Interim Standards, such as IS-54 and IS-I36, that define various versions of digital advanced mobile phone service (D-AMPS), a TDMA system that uses a Amended Sheet
-2-differential quadrature phase shift keying (DQPSK) modulation scheme for communicating data over RF links.
TDMA systems subdivide the available frequency into one or more RF channels.
The RF channels are further divided into a number of physical channels corresponding to time slots in TDMA frames. Logical channels are formed of one or several physical channels where modulation and coding is specified. In these systems, the mobile stations communicate with a plurality of scattered base stations by transmitting and receiving bursts of digital information over uplink and downlink RF channels.
The growing number of mobile stations in use today has generated the need for more voice and data channels within cellular telecommunication systems. As a result, base stations have become more closely spaced, with an increase in interference between mobile stations operating on the same frequency in neighboring or closely spaced cells.
In fact, some systems now employ code division multiple access (CDMA), using a form of spread spectrum modulation wherein signals intentionally share the same time and frequency. Although digital techniques provide a greater number of useful channels from a given frequency spectrum, there still remains a need to maintain interference at acceptable levels, or more specifically to monitor and control the ratio of the carrier signal strength to interference, (i.e., carrier-to-interference (C/I) ratio).
Another factor which is increasingly important in providing various communication services is the desired/required user bit rate for data to be transmitted over a particular connection. For example, for voice and/or data services, user bit rate corresponds to voice quality and/or data throughput, with a higher user bit rate producing better voice quality and/or higher data throughput. The total user bit rate is determined by a selected combination of techniques for speech coding, channel coding, modulation, and resource allocation, e.g., for a TDMA system, this latter technique may refer to the number of assignable time slots per connection, for a CDMA
system, this latter parameter may refer to the number of assignable codes per connection.
Speech coding (or more generally "source coding") techniques are used to compress the input information into a format which uses an acceptable amount of bandwidth but from which an intelligible output signal can be reproduced. Many
TDMA systems subdivide the available frequency into one or more RF channels.
The RF channels are further divided into a number of physical channels corresponding to time slots in TDMA frames. Logical channels are formed of one or several physical channels where modulation and coding is specified. In these systems, the mobile stations communicate with a plurality of scattered base stations by transmitting and receiving bursts of digital information over uplink and downlink RF channels.
The growing number of mobile stations in use today has generated the need for more voice and data channels within cellular telecommunication systems. As a result, base stations have become more closely spaced, with an increase in interference between mobile stations operating on the same frequency in neighboring or closely spaced cells.
In fact, some systems now employ code division multiple access (CDMA), using a form of spread spectrum modulation wherein signals intentionally share the same time and frequency. Although digital techniques provide a greater number of useful channels from a given frequency spectrum, there still remains a need to maintain interference at acceptable levels, or more specifically to monitor and control the ratio of the carrier signal strength to interference, (i.e., carrier-to-interference (C/I) ratio).
Another factor which is increasingly important in providing various communication services is the desired/required user bit rate for data to be transmitted over a particular connection. For example, for voice and/or data services, user bit rate corresponds to voice quality and/or data throughput, with a higher user bit rate producing better voice quality and/or higher data throughput. The total user bit rate is determined by a selected combination of techniques for speech coding, channel coding, modulation, and resource allocation, e.g., for a TDMA system, this latter technique may refer to the number of assignable time slots per connection, for a CDMA
system, this latter parameter may refer to the number of assignable codes per connection.
Speech coding (or more generally "source coding") techniques are used to compress the input information into a format which uses an acceptable amount of bandwidth but from which an intelligible output signal can be reproduced. Many
-3-different types of speech coding algorithms exist, e.g., residual excited linear predictive (RELP), regular-pulse excitation (RPE), etc., the details of which are not particularly relevant to this invention. More significant in this context is the fact that various speech coders have various output bit rates and that, as one would expect, speech coders having a higher output bit rate tend to provide greater consumer acceptance of their reproduced voice quality than those having a lower output bit rate. As an example, consider that more traditional, wire-based telephone systems use PCM speech coding at 64 kbps, while GSM systems employ an RPE speech coding scheme operating at 13 kbps.
In addition to speech coding, digital communication systems also employ various techniques to handle erroneously received information. Generally speaking, these techniques include those which aid a receiver to correct the erroneously received information, e.g., forward error correction (FEC) techniques, and those which enable the erroneously received information to be retransmitted to the receiver, e.g., automatic retransmission request (ARQ) techniques. FEC techniques include, for example, convolutional or block coding (collectively referred to herein as "channel coding") of the data prior to modulation. Channel coding involves representing a certain number of data bits using a certain number of code bits. Thus, for example, it is common to refer to convolutional codes by their code rates, e.g., 1/2 and 1/3, wherein the lower code rates provide greater error protection but lower user bit rates for a given channel bit rate.
Conventionally, each of the techniques which impacted the user bit rate were fixed for any given radiocommunication system, or at least for the duration of a connection established by a radiocommunication system. That is, each system established connections that operated with one type of speech coding, one type of channel coding, one type of modulation and one resource allocation. More recently, however, dynamic adaptation of these techniques has become a popular method for optimizing system performance in the face of the numerous parameters which may vary rapidly over time, e.g., the radio propagation characteristics of radiocommunication channels, the loading of the system, the user's bit rate requirements, etc.
This type of dynamic adaptation of coding techniques has been referred to in the GSM
standard as _4_ adaptive multirate (AMR) communications. AMR techniques and the like are likely to be used in next generation radiocommunication systems, e.g., Universal Mobile Telecommunication Systems (UMTS).
In GSM systems, AMR techniques have been traditionally been coordinated by the base station controller (BSC). For context, consider Figure l, which depicts various nodes in a hybrid UMTS/GSM communication system 10. This Figure will also be referred to below in describing aspects of the present invention. The system 10 is designed as a hierarchical network with multiple levels for managing calls.
Using a set of uplink and downlink frequencies, mobile stations 12 operating within the system 10 participate in calls using time slots allocated to them on these frequencies.
At an upper hierarchical level, a group of Mobile Switching Centers (MSCs) 14a-14c are responsible for the routing of calls from an originator to a destination. In particular, these entities are responsible for setup, control and termination of calls. One of the MSCs 14a, known as the gateway MSC, handles communication with a Public Switched Telephone Network (PSTN) 18, or other public and private networks.
At a lower hierarchical level, each of the MSCs 14a-14c are connected to a group of BSCs 16a-b (although the BSCs are only depicted for MSC 14b to simplify the figure) using, for example, PCM (pulse code modulated) links. Under the GSM
standard, the BSCs 16a-16b communicate with MSCs 14a-14c under a standard interface known as the A-interface, which is based on the Mobile Application Part (MAP) of CCITT Signaling System No. 7. Under the UMTS standard, the BSCs are referred to as radio network controllers (RNCs) and communicate with the MSCs 14a-14c over a standard interface known as the Iu interface.
At a still lower hierarchical level, each of the BSCs (RNCs) 16 controls a group of base transceiver stations (BTSs) 20. Each BTS 20 includes a number of TRXs (not shown) that use the uplink and downlink RF channels to serve a particular common geographical area, such as one or more communication cells 21. The BTSs 20 primarily provide the RF links for the transmission and reception of data bursts to and from the mobile stations 12 within their designated cell. As mentioned earlier, the information transmitted on these RF links may be speech coded in various ways to enhance various aspects of communication over the air interface, which coding is controlled in conventional GSM systems by the responsible BSC.
However, in next generation systems (e.g., UMTS) it has been proposed that the coding of this information be controlled by the MSC rather than the radio network controller (RNC), which is the nomenclature for the node corresponding to the BSC in third generation systems. This shifting of responsibility leads to a number of problems regarding management of coding, particularly during handoffs of connections between MSCs. For example, it will be necessary to know which MSC, i.e., the serving (anchor) MSC or the target MSC, will control the transcoder. Additionally, it will be useful to define where the radio access network protocol is terminated and the format for signaling between the MSCs involved in the handoff to control coding parameters.
Accordingly, it will be desirable to provide methods and systems for handling the transcoding of connections being handed off between MSCs which take into account these various aspects of emerging, next generation communication systems.
SUMMARY
These and other drawbacks, problems and limitations of conventional radiocommunication systems are overcome according to the present invention, wherein various signaling techniques and protocols are described for handling codec issues during inter-MSC handoff. For example, exemplary embodiments of the present invention handle codec issues associated with inter-MSC handoff by determining at least one codec that is available in a target MSC, selecting, by an anchor MSC, one of the available codecs for handling the connection, signaling the target MSC with an indication of the selected codec, and informing the user equipment of the selected codec.
Various exemplary embodiments perform these signaling steps in different ways.
For example, the determination of available codecs in the target MSC may (or may not) require signaling to ascertain the target MSC's codec capabilities. If such signaling is performed, mobile application part (MAP) protocol messages may be used.
According to another aspect of the present invention, the signaling used to inform the target MSC of the selected codec may take any of a plurality of different forms. For example, the selected codec information may be forwarded to the target MSC as a MAP message which is independent of another message wherein the radio access bearer (RAB) assignment is forwarded. Alternatively, the selected codec information can be passed to the target MSC using the same message by which the RAB
is assigned. Different protocols, e.g., radio access network application protocol (RANAP) or base station system management application part (BSSMAP) can be used to as the signaling protocol for these messages.
Likewise, signals informing the user's equipment of the selected codec can be provided in different forms. For example, a call control message can be sent to the user's equipment identifying the selected codec so that it is prepared to properly process messages for transmission and reception after the inter-MSC handoff.
Alternatively, an RANAP message identifying the RAB can also be used to convey selected codec information to the user equipment.
BRIEF DESCRIPTION OF THE DRAWINGS
These and other objects, features and advantages of the present invention will become more apparent upon reading from the following detailed description, taken in conjunction with the accompanying drawings, wherein:
FIG. 1 is a block diagram of an exemplary GSM communication system which advantageously uses the present invention;
FIG. 2 is a flow chart depicting a general set of steps for handling inter-MSC
handoff according to exemplary embodiments of the present invention;
FIG.3 is a signaling/block diagram which depicts inter-MSC handoff signaling according to an exemplary embodiment of the present invention;
FIG.4 is a signaling/block diagram which depicts inter-MSC handoff signaling according to another exemplary embodiment of the present invention;
FIG. 5 is a signaling/block diagram which depicts inter-MSC handoff signaling according to yet another exemplary embodiment of the present invention;
FIGS. 6(a) and 6(b) depict protocol stacks for the control plane and user plane, respectively, for the exemplary embodiments of FIG. S;
WO 01150799 PCTlEP01100003 _7_ FIG. 7 is a signaling/block diagram which depicts inter-MSC handoffsignaling according to still another exemplary embodiment of the present invention;
FIGS. 8(a) and 8(b) depict protocol stacks for the control plane and user plane, respectively, for the exemplary embodiment of FIG. 7; and FIG. 9 is a signaling/block diagram which depicts inter-MSC handoff signaling according to still another exemplary embodiment of the present invention.
DETAILED DESCRIPTION
The various features of the invention will now be described with reference to the to figures, in which like parts are identified with the same reference characters. In the following description, for purposes of explanation and not limitation, specific details are set forth, such as particular circuits, circuit components, techniques, ete. in order to provide a thorough understanding of the present invention. However, it will be apparent to one skilled in the art that the present invention may be practiced in other t5 embodiments that depart from these specific details. In other instances, detailed descriptions of well-known methods, device~, and circuits are omitted so as not to obscure the description of the present invention.
The following exemplary embodiments are provided in the context of TDMA
radiocommunication systems. However, those skilled in the art will appreciate that this 2d access methodology is merely used for the purposes of illustration and.
that the present invention is readily applicable to all types of access methodologies including frequency division multiple access (FDMA), TDMA, code division multiple access (CDMA) and hybrids thereof.
Moreover, operation in accordance with GSM communication systems is z5 described in, for example, European Telecommunication Standard Institute (ETSI) documents ETS 300 573, ETS 300 574 and ETS 300 578. Therefore, the operation of the GSM system is only described herein to the extent necessary for understanding the present invention. Similar standards related documents are also available for UMTS.
Although, the present invention is described in terms of exemplary embodiments in a 30 UMTS/GSM~system, Amended Sheet _g_ those skilled in the art will appreciate that the present invention may be applicable to digital communication systems.
When user equipment (UE), e.g., a mobile phone or personal digital assistant, moves to a location wherein its wireless connection with a fixed network has deteriorated to a point where a new connection is desirable, a handoff procedure is initiated to provide the UE with continued service via a different portion of the fixed network. In some cases, the best candidate base station for providing this continued service is controlled by a different (target) MSC than that which is currently controlling the UE's service, i.e., the anchor MSC, in which case the handoff can be referred to as an "inter-MSC" handoff. Various control signaling is performed in order to accomplish inter-MSC handoffs.
In general, the handling of codec control during inter-MSC handoff according to the present invention follows a number of steps as illustrated in Figure 2.
Therein, at step 100, the codecs available in the target MSC are determined. Those skilled in the art will appreciate that not all MSCs will contain the same type and number of codecs and, therefore, it is useful to determine the target MSCs codec capabilities before making a codec selection. This determination may be rather straightforward if the codecs supported by the target MSC are administered by the anchor MSC.
Alternatively, a message can be transmitted from the anchor MSC to the target MSC to request a supported codec list therefrom. These messages may be formatted as, for example, MAP messages since MAP messages will terminate in the target MSC.
In any event, once the anchor MSC has determined the codecs available in the target MSC, a codec selection is made to determine which codec in the target MSC shall be linked in to handle the connection once it has been handed off (step 102).
This selection can be based on a comparison between the codec list associated with the target MSC and the codecs supported by the UE, the latter of which can be identified to the anchor MSC during call set-up. For example, the call setup message (or call confirmation message) transmitted from the UE to the anchor MSC may include a GSM
codec list and a UMTS codec list. Separate lists may be provided for each system in order to ensure unique codec identification, e.g., since AMR for GSM and AMR
for UMTS may differ in rate adaptation and discontinuous transmission (DTX) modes.
Additionally, the UE may transmit a separate intersystem code handoff list which may include preferences for the codec selected during inter-MSC handoff described below.
If the target MSC and the UE support more than one of the same codecs, then a selection from among the common codecs can be made based on preferences, e.g., either network preferences, UE preferences or some combination thereof. The particular mechanism by which a particular codec is selected for handling the connection after the handoff is beyond the scope of this discussion.
After a codec is selected for use in the target MSC, the target MSC needs to be informed of that selection in step 104 so that it can link in the selected codec to handle the connection once it is handed off. Likewise, at step 106, the UE needs to be informed of the codec selection so that it can employ the appropriate codec post-handoff.
Those skilled in the art will appreciate that steps 104 and 106 can be performed in any temporal order including simultaneously.
Those skilled in the art will also appreciate that steps 100-106 illustrated in Figure 2 can be implemented in many different ways depending, for example, upon network topologies and which systems, e.g., GSM and/or UMTS, are involved in the inter-MSC handoff process. Several examples will now be provided to illustrate these variations.
Consider the example of Figure 3 for a handoff between two MSCs which operate in accordance with the UMTS standard. Therein, a UE 300 needs a handoff (relocation required by RNC) due to, for example, a change in position relative to a serving RNC 302 or base station (not shown) associated therewith. A relocation request is communicated through to the anchor MSC 304 which then begins, among other tasks, to coordinate the codec transition to the new (target) MSC 306. In this particular example, the anchor MSC 304 administers the codecs in the target MSC 306, such that no signaling needs to be performed between the two MSCs to establish the codec capability of the target MSC 306 prior to a selection being made. The anchor can, therefore, make its codec selection based upon its a priori knowledge of the codecs available in the target MSC 306, UE 300 and preferences.
Once a codes Selection is made, the anchor MSC 304 informs the target MSC
306 and UE 300 of the selection using different mechanisms. According to this exemplary embodiment, the anchor MSC 304 sends a BSSMAP Prepare HandoverRequest Message which includes, as a parameter, the preferred speech version over a synchronous transfer mode (STM) link 308. The preferred speech version indicates which type of codes is to be seized by the target MSC 306 for this handoff Those skilled in the art will recognize that BSSMAP is the acronym for Base Station System Management Application Part which identifies a protocol which is used over the A-interface. Those interested readers desiring more information regarding BSSMAP
l0 protocols are directed to the published standard GSM 08.08: "Digital cellular telecommunications system (Phase 2+); Mobile Switching Centre - Base Station System (MSC-BSS) interface Layer 3 specification,". The BSSMAP message may also inform the target MSC 306 which radio access bearer (RA.B) is requested for the new connection. The target MSC 306, in tum, provides the relevant RNC 310 with a 5 Relocation Request over the Iu interface to alert it to its responsibilities for the handoff of UE 300 thereto. The target MSC 306 also acknowledges the PrepareHandover Request message to the anchor MSC 304. In the UE direction, the anchor MS 304 sends a call control {CC) message informing the UE 300 of the selected codes.
According to another embodiment of the present invention illustrated in Figure
In addition to speech coding, digital communication systems also employ various techniques to handle erroneously received information. Generally speaking, these techniques include those which aid a receiver to correct the erroneously received information, e.g., forward error correction (FEC) techniques, and those which enable the erroneously received information to be retransmitted to the receiver, e.g., automatic retransmission request (ARQ) techniques. FEC techniques include, for example, convolutional or block coding (collectively referred to herein as "channel coding") of the data prior to modulation. Channel coding involves representing a certain number of data bits using a certain number of code bits. Thus, for example, it is common to refer to convolutional codes by their code rates, e.g., 1/2 and 1/3, wherein the lower code rates provide greater error protection but lower user bit rates for a given channel bit rate.
Conventionally, each of the techniques which impacted the user bit rate were fixed for any given radiocommunication system, or at least for the duration of a connection established by a radiocommunication system. That is, each system established connections that operated with one type of speech coding, one type of channel coding, one type of modulation and one resource allocation. More recently, however, dynamic adaptation of these techniques has become a popular method for optimizing system performance in the face of the numerous parameters which may vary rapidly over time, e.g., the radio propagation characteristics of radiocommunication channels, the loading of the system, the user's bit rate requirements, etc.
This type of dynamic adaptation of coding techniques has been referred to in the GSM
standard as _4_ adaptive multirate (AMR) communications. AMR techniques and the like are likely to be used in next generation radiocommunication systems, e.g., Universal Mobile Telecommunication Systems (UMTS).
In GSM systems, AMR techniques have been traditionally been coordinated by the base station controller (BSC). For context, consider Figure l, which depicts various nodes in a hybrid UMTS/GSM communication system 10. This Figure will also be referred to below in describing aspects of the present invention. The system 10 is designed as a hierarchical network with multiple levels for managing calls.
Using a set of uplink and downlink frequencies, mobile stations 12 operating within the system 10 participate in calls using time slots allocated to them on these frequencies.
At an upper hierarchical level, a group of Mobile Switching Centers (MSCs) 14a-14c are responsible for the routing of calls from an originator to a destination. In particular, these entities are responsible for setup, control and termination of calls. One of the MSCs 14a, known as the gateway MSC, handles communication with a Public Switched Telephone Network (PSTN) 18, or other public and private networks.
At a lower hierarchical level, each of the MSCs 14a-14c are connected to a group of BSCs 16a-b (although the BSCs are only depicted for MSC 14b to simplify the figure) using, for example, PCM (pulse code modulated) links. Under the GSM
standard, the BSCs 16a-16b communicate with MSCs 14a-14c under a standard interface known as the A-interface, which is based on the Mobile Application Part (MAP) of CCITT Signaling System No. 7. Under the UMTS standard, the BSCs are referred to as radio network controllers (RNCs) and communicate with the MSCs 14a-14c over a standard interface known as the Iu interface.
At a still lower hierarchical level, each of the BSCs (RNCs) 16 controls a group of base transceiver stations (BTSs) 20. Each BTS 20 includes a number of TRXs (not shown) that use the uplink and downlink RF channels to serve a particular common geographical area, such as one or more communication cells 21. The BTSs 20 primarily provide the RF links for the transmission and reception of data bursts to and from the mobile stations 12 within their designated cell. As mentioned earlier, the information transmitted on these RF links may be speech coded in various ways to enhance various aspects of communication over the air interface, which coding is controlled in conventional GSM systems by the responsible BSC.
However, in next generation systems (e.g., UMTS) it has been proposed that the coding of this information be controlled by the MSC rather than the radio network controller (RNC), which is the nomenclature for the node corresponding to the BSC in third generation systems. This shifting of responsibility leads to a number of problems regarding management of coding, particularly during handoffs of connections between MSCs. For example, it will be necessary to know which MSC, i.e., the serving (anchor) MSC or the target MSC, will control the transcoder. Additionally, it will be useful to define where the radio access network protocol is terminated and the format for signaling between the MSCs involved in the handoff to control coding parameters.
Accordingly, it will be desirable to provide methods and systems for handling the transcoding of connections being handed off between MSCs which take into account these various aspects of emerging, next generation communication systems.
SUMMARY
These and other drawbacks, problems and limitations of conventional radiocommunication systems are overcome according to the present invention, wherein various signaling techniques and protocols are described for handling codec issues during inter-MSC handoff. For example, exemplary embodiments of the present invention handle codec issues associated with inter-MSC handoff by determining at least one codec that is available in a target MSC, selecting, by an anchor MSC, one of the available codecs for handling the connection, signaling the target MSC with an indication of the selected codec, and informing the user equipment of the selected codec.
Various exemplary embodiments perform these signaling steps in different ways.
For example, the determination of available codecs in the target MSC may (or may not) require signaling to ascertain the target MSC's codec capabilities. If such signaling is performed, mobile application part (MAP) protocol messages may be used.
According to another aspect of the present invention, the signaling used to inform the target MSC of the selected codec may take any of a plurality of different forms. For example, the selected codec information may be forwarded to the target MSC as a MAP message which is independent of another message wherein the radio access bearer (RAB) assignment is forwarded. Alternatively, the selected codec information can be passed to the target MSC using the same message by which the RAB
is assigned. Different protocols, e.g., radio access network application protocol (RANAP) or base station system management application part (BSSMAP) can be used to as the signaling protocol for these messages.
Likewise, signals informing the user's equipment of the selected codec can be provided in different forms. For example, a call control message can be sent to the user's equipment identifying the selected codec so that it is prepared to properly process messages for transmission and reception after the inter-MSC handoff.
Alternatively, an RANAP message identifying the RAB can also be used to convey selected codec information to the user equipment.
BRIEF DESCRIPTION OF THE DRAWINGS
These and other objects, features and advantages of the present invention will become more apparent upon reading from the following detailed description, taken in conjunction with the accompanying drawings, wherein:
FIG. 1 is a block diagram of an exemplary GSM communication system which advantageously uses the present invention;
FIG. 2 is a flow chart depicting a general set of steps for handling inter-MSC
handoff according to exemplary embodiments of the present invention;
FIG.3 is a signaling/block diagram which depicts inter-MSC handoff signaling according to an exemplary embodiment of the present invention;
FIG.4 is a signaling/block diagram which depicts inter-MSC handoff signaling according to another exemplary embodiment of the present invention;
FIG. 5 is a signaling/block diagram which depicts inter-MSC handoff signaling according to yet another exemplary embodiment of the present invention;
FIGS. 6(a) and 6(b) depict protocol stacks for the control plane and user plane, respectively, for the exemplary embodiments of FIG. S;
WO 01150799 PCTlEP01100003 _7_ FIG. 7 is a signaling/block diagram which depicts inter-MSC handoffsignaling according to still another exemplary embodiment of the present invention;
FIGS. 8(a) and 8(b) depict protocol stacks for the control plane and user plane, respectively, for the exemplary embodiment of FIG. 7; and FIG. 9 is a signaling/block diagram which depicts inter-MSC handoff signaling according to still another exemplary embodiment of the present invention.
DETAILED DESCRIPTION
The various features of the invention will now be described with reference to the to figures, in which like parts are identified with the same reference characters. In the following description, for purposes of explanation and not limitation, specific details are set forth, such as particular circuits, circuit components, techniques, ete. in order to provide a thorough understanding of the present invention. However, it will be apparent to one skilled in the art that the present invention may be practiced in other t5 embodiments that depart from these specific details. In other instances, detailed descriptions of well-known methods, device~, and circuits are omitted so as not to obscure the description of the present invention.
The following exemplary embodiments are provided in the context of TDMA
radiocommunication systems. However, those skilled in the art will appreciate that this 2d access methodology is merely used for the purposes of illustration and.
that the present invention is readily applicable to all types of access methodologies including frequency division multiple access (FDMA), TDMA, code division multiple access (CDMA) and hybrids thereof.
Moreover, operation in accordance with GSM communication systems is z5 described in, for example, European Telecommunication Standard Institute (ETSI) documents ETS 300 573, ETS 300 574 and ETS 300 578. Therefore, the operation of the GSM system is only described herein to the extent necessary for understanding the present invention. Similar standards related documents are also available for UMTS.
Although, the present invention is described in terms of exemplary embodiments in a 30 UMTS/GSM~system, Amended Sheet _g_ those skilled in the art will appreciate that the present invention may be applicable to digital communication systems.
When user equipment (UE), e.g., a mobile phone or personal digital assistant, moves to a location wherein its wireless connection with a fixed network has deteriorated to a point where a new connection is desirable, a handoff procedure is initiated to provide the UE with continued service via a different portion of the fixed network. In some cases, the best candidate base station for providing this continued service is controlled by a different (target) MSC than that which is currently controlling the UE's service, i.e., the anchor MSC, in which case the handoff can be referred to as an "inter-MSC" handoff. Various control signaling is performed in order to accomplish inter-MSC handoffs.
In general, the handling of codec control during inter-MSC handoff according to the present invention follows a number of steps as illustrated in Figure 2.
Therein, at step 100, the codecs available in the target MSC are determined. Those skilled in the art will appreciate that not all MSCs will contain the same type and number of codecs and, therefore, it is useful to determine the target MSCs codec capabilities before making a codec selection. This determination may be rather straightforward if the codecs supported by the target MSC are administered by the anchor MSC.
Alternatively, a message can be transmitted from the anchor MSC to the target MSC to request a supported codec list therefrom. These messages may be formatted as, for example, MAP messages since MAP messages will terminate in the target MSC.
In any event, once the anchor MSC has determined the codecs available in the target MSC, a codec selection is made to determine which codec in the target MSC shall be linked in to handle the connection once it has been handed off (step 102).
This selection can be based on a comparison between the codec list associated with the target MSC and the codecs supported by the UE, the latter of which can be identified to the anchor MSC during call set-up. For example, the call setup message (or call confirmation message) transmitted from the UE to the anchor MSC may include a GSM
codec list and a UMTS codec list. Separate lists may be provided for each system in order to ensure unique codec identification, e.g., since AMR for GSM and AMR
for UMTS may differ in rate adaptation and discontinuous transmission (DTX) modes.
Additionally, the UE may transmit a separate intersystem code handoff list which may include preferences for the codec selected during inter-MSC handoff described below.
If the target MSC and the UE support more than one of the same codecs, then a selection from among the common codecs can be made based on preferences, e.g., either network preferences, UE preferences or some combination thereof. The particular mechanism by which a particular codec is selected for handling the connection after the handoff is beyond the scope of this discussion.
After a codec is selected for use in the target MSC, the target MSC needs to be informed of that selection in step 104 so that it can link in the selected codec to handle the connection once it is handed off. Likewise, at step 106, the UE needs to be informed of the codec selection so that it can employ the appropriate codec post-handoff.
Those skilled in the art will appreciate that steps 104 and 106 can be performed in any temporal order including simultaneously.
Those skilled in the art will also appreciate that steps 100-106 illustrated in Figure 2 can be implemented in many different ways depending, for example, upon network topologies and which systems, e.g., GSM and/or UMTS, are involved in the inter-MSC handoff process. Several examples will now be provided to illustrate these variations.
Consider the example of Figure 3 for a handoff between two MSCs which operate in accordance with the UMTS standard. Therein, a UE 300 needs a handoff (relocation required by RNC) due to, for example, a change in position relative to a serving RNC 302 or base station (not shown) associated therewith. A relocation request is communicated through to the anchor MSC 304 which then begins, among other tasks, to coordinate the codec transition to the new (target) MSC 306. In this particular example, the anchor MSC 304 administers the codecs in the target MSC 306, such that no signaling needs to be performed between the two MSCs to establish the codec capability of the target MSC 306 prior to a selection being made. The anchor can, therefore, make its codec selection based upon its a priori knowledge of the codecs available in the target MSC 306, UE 300 and preferences.
Once a codes Selection is made, the anchor MSC 304 informs the target MSC
306 and UE 300 of the selection using different mechanisms. According to this exemplary embodiment, the anchor MSC 304 sends a BSSMAP Prepare HandoverRequest Message which includes, as a parameter, the preferred speech version over a synchronous transfer mode (STM) link 308. The preferred speech version indicates which type of codes is to be seized by the target MSC 306 for this handoff Those skilled in the art will recognize that BSSMAP is the acronym for Base Station System Management Application Part which identifies a protocol which is used over the A-interface. Those interested readers desiring more information regarding BSSMAP
l0 protocols are directed to the published standard GSM 08.08: "Digital cellular telecommunications system (Phase 2+); Mobile Switching Centre - Base Station System (MSC-BSS) interface Layer 3 specification,". The BSSMAP message may also inform the target MSC 306 which radio access bearer (RA.B) is requested for the new connection. The target MSC 306, in tum, provides the relevant RNC 310 with a 5 Relocation Request over the Iu interface to alert it to its responsibilities for the handoff of UE 300 thereto. The target MSC 306 also acknowledges the PrepareHandover Request message to the anchor MSC 304. In the UE direction, the anchor MS 304 sends a call control {CC) message informing the UE 300 of the selected codes.
According to another embodiment of the present invention illustrated in Figure
4, 2o the inter-MSC handoff occurs from a UMTS network to a GSM network. Therein, similar reference numerals are used to refer to similar functional units as set forth above with respect to Figure 3. Morever, to avoid redundancy, those similarities between the two embodiments are not repeated here and reference is made to the foregoing for the description of similar signaling. Unlike the embodiment of Figtue 3, however, the target 25 MSC 306 coordinates with a target BSC 400 which contains the transcoder unit ('TRAIT) to be used to support the UE 300 after the handoff. Thus, in this embodiment, the selected codes information is passed from the target MSC 306 to the BSC 400 over the A-interface via a Handover Request message. Also note that the link 308 between Amended Sheet the (GSM) target MSC 306 and the~(iJMTS) anchor MSC 304 can either be an STM
link or an asynchronous transfer mode (ATM) link.
Another variation of a UMTS MSC to UMTS MSC handofl;'is depicted in the exemplary embodiment of Figure 5. Again, similar reference numerals are used to refer to similar functional units as set forth above with respect to Figure 3 and differences are discussed with respect thereto. Therein, the anchor MSC 304 is not responsible for administering the codecs supported by the target MSC 306. Accordingly, step 100 of Figure 2 is performed by sending a MAP message requesting that the supported codecs be identified over the STM link 308 and receiving a MAP response indi~ing those to supported codecs so that the anchor MSC 304 can then select a codes, e.g., by comparison to a list supplied by UE 300 and preferences, for the handoff.
Once a codes is selected, the anchor MSC 304 sends a MAP message indicating the selected codes to the target MSC 306. Unlike the embodiment of Figure 3, the signaling associated with the selected codes in this embodiment is separate from the is signaling relocation request sig~taling, which permits the relocation request signaling to be codes independent. This, in tuna, provides for a clear separation of functionality as MAP signalling is used in both GSM and UMTS systems and terminates in the target MSC. Additionally, the embodiment of Figure S employs the RANAP protocol for , transmitting the relocation request message, as opposed to the BSSMAP protocol 2o employed in the exemplary embodiment of Figure 3. Those skilled in the art will recognize that RANAP is the acronym for Radio Access Network Application Protocol which identifies the protocol defined for use over the Iu interface between UMTS MSCs and RNCs to maintain links there between. For more information regarding RANAP
signaling in general, the interested reader is directed to the published standard 3GPP
25 25.413: "Iu interface RANAP signaling,".
'The embodiments of Figures 3-5 are depicted using signaling diagrams and functional block units. However, as will be appreciated .by those skilled in the art, the choice of sigtaling protocols used to perform codes handling during inter-MSC
handoff according to the present invention can also be described using protocol stacks. The Amended Sheet resulting protocol stacks after handoff from the anchor MSC 304 to the target (with an STM link there between) are illustrated in Figures 6(a) and 6(b) for the control plane and user plane, respectively. A non-access stratum (NAS) container can be used to covey the chosen codec information from the MSC to the UE.
If ATM links are used between the MSCs involved in the handoff, then ATM
need not be terminated in the target MSC 306 and compressed speech, for example, can be passed transparently through the target MSC 306 to the anchor MSC 304. This means, in turn, that transcoding need not necessarily be performed in the target MSC
306 and, instead, can be performed in the anchor MSC 304. One exemplary embodiment which illustrates an inter-MSC handoff using an ATM link is provided as Figure 7. Therein, it will be noted that the signaling used to perform the inter-MSC
handoff is similar as that described above and illustrated in Figure 5, with the exception that there is no need to inform the target MSC 306 of the selected codec, since the same codec in the anchor MSC 304 is used both pre- and post-handoff. Thus, from the protocol stack perspective (see Figures 8(a) and 8(b)), the target MSC 306 is transparent on the user plane and is used only for performing RANAP control signaling.
Those skilled in the art will appreciate that although the embodiment of Figures 7, 8(a) and 8(b) provides certain advantages, e.g., compressed speech through to anchor MSC and continued use of the same codec after handoff, that the techniques described above with respect to Figures 3-5 can also be used in circumstances where ATM links exist between the relevant MSCs.
Figure 9 depicts yet another example of signaling between various units associated with inter-MSC handoff according to the present invention. Therein, the UE
300's codec lists are forwarded to the system during call setup. The target MSC is interrogated via MAP signaling for its list of supported/available codecs, after which the anchor selects a codec for the handoff. The UE and the target MSC are informed of the selection via various MAP and/or RANAP signaling as shown.
Although the invention has been described in detail with reference only to a few exemplary embodiments, those skilled in the art will appreciate that various modifications can be made without departing from the invention. Accordingly, the invention is defined only by the following claims which are intended to embrace all equivalents thereof.
link or an asynchronous transfer mode (ATM) link.
Another variation of a UMTS MSC to UMTS MSC handofl;'is depicted in the exemplary embodiment of Figure 5. Again, similar reference numerals are used to refer to similar functional units as set forth above with respect to Figure 3 and differences are discussed with respect thereto. Therein, the anchor MSC 304 is not responsible for administering the codecs supported by the target MSC 306. Accordingly, step 100 of Figure 2 is performed by sending a MAP message requesting that the supported codecs be identified over the STM link 308 and receiving a MAP response indi~ing those to supported codecs so that the anchor MSC 304 can then select a codes, e.g., by comparison to a list supplied by UE 300 and preferences, for the handoff.
Once a codes is selected, the anchor MSC 304 sends a MAP message indicating the selected codes to the target MSC 306. Unlike the embodiment of Figure 3, the signaling associated with the selected codes in this embodiment is separate from the is signaling relocation request sig~taling, which permits the relocation request signaling to be codes independent. This, in tuna, provides for a clear separation of functionality as MAP signalling is used in both GSM and UMTS systems and terminates in the target MSC. Additionally, the embodiment of Figure S employs the RANAP protocol for , transmitting the relocation request message, as opposed to the BSSMAP protocol 2o employed in the exemplary embodiment of Figure 3. Those skilled in the art will recognize that RANAP is the acronym for Radio Access Network Application Protocol which identifies the protocol defined for use over the Iu interface between UMTS MSCs and RNCs to maintain links there between. For more information regarding RANAP
signaling in general, the interested reader is directed to the published standard 3GPP
25 25.413: "Iu interface RANAP signaling,".
'The embodiments of Figures 3-5 are depicted using signaling diagrams and functional block units. However, as will be appreciated .by those skilled in the art, the choice of sigtaling protocols used to perform codes handling during inter-MSC
handoff according to the present invention can also be described using protocol stacks. The Amended Sheet resulting protocol stacks after handoff from the anchor MSC 304 to the target (with an STM link there between) are illustrated in Figures 6(a) and 6(b) for the control plane and user plane, respectively. A non-access stratum (NAS) container can be used to covey the chosen codec information from the MSC to the UE.
If ATM links are used between the MSCs involved in the handoff, then ATM
need not be terminated in the target MSC 306 and compressed speech, for example, can be passed transparently through the target MSC 306 to the anchor MSC 304. This means, in turn, that transcoding need not necessarily be performed in the target MSC
306 and, instead, can be performed in the anchor MSC 304. One exemplary embodiment which illustrates an inter-MSC handoff using an ATM link is provided as Figure 7. Therein, it will be noted that the signaling used to perform the inter-MSC
handoff is similar as that described above and illustrated in Figure 5, with the exception that there is no need to inform the target MSC 306 of the selected codec, since the same codec in the anchor MSC 304 is used both pre- and post-handoff. Thus, from the protocol stack perspective (see Figures 8(a) and 8(b)), the target MSC 306 is transparent on the user plane and is used only for performing RANAP control signaling.
Those skilled in the art will appreciate that although the embodiment of Figures 7, 8(a) and 8(b) provides certain advantages, e.g., compressed speech through to anchor MSC and continued use of the same codec after handoff, that the techniques described above with respect to Figures 3-5 can also be used in circumstances where ATM links exist between the relevant MSCs.
Figure 9 depicts yet another example of signaling between various units associated with inter-MSC handoff according to the present invention. Therein, the UE
300's codec lists are forwarded to the system during call setup. The target MSC is interrogated via MAP signaling for its list of supported/available codecs, after which the anchor selects a codec for the handoff. The UE and the target MSC are informed of the selection via various MAP and/or RANAP signaling as shown.
Although the invention has been described in detail with reference only to a few exemplary embodiments, those skilled in the art will appreciate that various modifications can be made without departing from the invention. Accordingly, the invention is defined only by the following claims which are intended to embrace all equivalents thereof.
Claims (24)
1. A method for handing off a connection supporting radiocommunications with user equipment from an anchor mobile switching center (MSC) to a target MSC
comprising the steps of:
determining at least one codec that is available in said target MSC;
selecting, by said anchor MSC, one of said at least one available codecs for handling said connection;
signaling said target MSC with an indication of said selected one of said at least one available codecs; and informing said user equipment of said selected one of said at least one available codecs.
comprising the steps of:
determining at least one codec that is available in said target MSC;
selecting, by said anchor MSC, one of said at least one available codecs for handling said connection;
signaling said target MSC with an indication of said selected one of said at least one available codecs; and informing said user equipment of said selected one of said at least one available codecs.
2. The method of claim 1, wherein said step of determining further comprises the step of:
signaling said target MSC to request identification of said at least one available codec.
signaling said target MSC to request identification of said at least one available codec.
3. The method of claim 2, wherein said step of determining further comprises the steps of:
sending a mobile application part (MAP) protocol message requesting said identification of said at least one available codec; and receiving a MAP protocol message with said identification of said at least one available codec.
sending a mobile application part (MAP) protocol message requesting said identification of said at least one available codec; and receiving a MAP protocol message with said identification of said at least one available codec.
4. The method of claim 1, further comprising the step of:
administering a list of available codecs for said target MSC in said anchor MSC.
administering a list of available codecs for said target MSC in said anchor MSC.
5. The method of claim 1, further comprising the step of:
receiving, at said anchor MSC from said user equipment, an indication of at least one codec supported by said user equipment.
receiving, at said anchor MSC from said user equipment, an indication of at least one codec supported by said user equipment.
6. The method of claim 5, wherein separate lists of available codecs are received from said user equipment for different types of accesses.
7. The method of claim 5, wherein said indication is transmitted as part of a call setup message.
8. The method of claim 5, wherein said indication is transmitted as part of a call confirmation message.
9. The method of claim 5, wherein said step of selecting further comprises the steps of:
comparing said at least one available codec associated with said target MSC to said indication of said at least one codec supported by said user equipment; and selecting said one of said at least one available codecs based on said comparing step.
comparing said at least one available codec associated with said target MSC to said indication of said at least one codec supported by said user equipment; and selecting said one of said at least one available codecs based on said comparing step.
10. The method of claim 6, wherein said step of selecting further comprises the steps of:
comparing said at least one available codec associated with said target MSC to said indication of said at least one codec in said list received from said user equipment for a corresponding target radio access; and.
selecting said one of said at least one available codecs based on said comparing step.
comparing said at least one available codec associated with said target MSC to said indication of said at least one codec in said list received from said user equipment for a corresponding target radio access; and.
selecting said one of said at least one available codecs based on said comparing step.
11. The method of claim 1, wherein said step of signaling said target MSC
further comprises the step of:
transmitting a mobile application part (MAP) message which includes said indication of said selected one of said at least one available codec to said target MSC
from said anchor MSC.
further comprises the step of:
transmitting a mobile application part (MAP) message which includes said indication of said selected one of said at least one available codec to said target MSC
from said anchor MSC.
12. The method of claim 11, further comprising the step of:
transmitting, as a message which is independent of said MAP message, a radio access bearer (RAB) assignment message from said anchor MSC to said target MSC.
transmitting, as a message which is independent of said MAP message, a radio access bearer (RAB) assignment message from said anchor MSC to said target MSC.
13. The method of claim 11, wherein step of signaling said target MSC
further comprises the step of:
transmitting a radio access network application protocol (RANAP) message which includes said indication of said selected one of said at least one available codec to said target MSC from said anchor MSC.
further comprises the step of:
transmitting a radio access network application protocol (RANAP) message which includes said indication of said selected one of said at least one available codec to said target MSC from said anchor MSC.
14. The method of claim 11, wherein said step of signaling said target MSC
further comprises the step of:
transmitting a base station system management application part (BSSMAP) message which includes said indication of said selected one of said at least one available codec to said target MSC from said anchor MSC.
further comprises the step of:
transmitting a base station system management application part (BSSMAP) message which includes said indication of said selected one of said at least one available codec to said target MSC from said anchor MSC.
15. The method of claim 1, wherein said step of informing said user equipment further comprises the step of:
transmitting a control channel message to said user equipment including an indication of said selected one of said at least one available codecs.
transmitting a control channel message to said user equipment including an indication of said selected one of said at least one available codecs.
16. The method of claim 1, wherein said step of informing said user equipment further comprises the step of:
forwarding an indication of said selected one of said at least one available codecs to said user equipment as part of a radio access network application protocol (RANAP) message which includes a radio access bearer (RAB) assignment.
forwarding an indication of said selected one of said at least one available codecs to said user equipment as part of a radio access network application protocol (RANAP) message which includes a radio access bearer (RAB) assignment.
17. The method of claim 1, wherein an asynchronous transfer mode (ATM) link is used to convey signals between said target MSC and said anchor MSC, said method further comprising the step of:
continuing to use a codec in said anchor MSC to handle said connection after handoff to said target MSC.
continuing to use a codec in said anchor MSC to handle said connection after handoff to said target MSC.
18. The method of claim 13, further comprising the step of:
terminating said RANAP message in said anchor MSC and forwarding said indication to said user equipment as part of an RRC setup message.
terminating said RANAP message in said anchor MSC and forwarding said indication to said user equipment as part of an RRC setup message.
19. The method of claim 11, wherein said step of informing said user equipment further comprises the step of:
transmitting a control channel message to said user equipment including an indication of said selected one of said at least one available codecs.
transmitting a control channel message to said user equipment including an indication of said selected one of said at least one available codecs.
20. A method for handing off a connection supporting radiocommunications with user equipment from an anchor mobile switching center (MSC) to a target MSC
comprising the steps of:
signalling control information, associated with handing off said connection, between said anchor MSC and said target MSC using a protocol stack which includes radio access network application protocol (RANAP) and mobile application part (MAP) protocol;
signalling said control information between said target MSC and a target radio network controller (RNC) using said RANAP protocol;
terminating said RANAP protocol in said target RNC; and conveying said control information to said user equipment as part of a radio bearer setup message.
comprising the steps of:
signalling control information, associated with handing off said connection, between said anchor MSC and said target MSC using a protocol stack which includes radio access network application protocol (RANAP) and mobile application part (MAP) protocol;
signalling said control information between said target MSC and a target radio network controller (RNC) using said RANAP protocol;
terminating said RANAP protocol in said target RNC; and conveying said control information to said user equipment as part of a radio bearer setup message.
21. The method of claim 20, wherein an asynchronous transfer mode (ATM) link is used to convey signals between said target MSC and said anchor MSC, said method further comprising the step of:
continuing to use a codec in said anchor MSC to handle said connection after handoff to said target MSC.
continuing to use a codec in said anchor MSC to handle said connection after handoff to said target MSC.
22. The method of claim 20, wherein said control information is codec information.
23. The method of claim 22, wherein a non-access stratum (NAS) container delivers said codec information from said target MSC to said user equipment via said RANAP protocol and said radio bearer setup message.
24. The method of claim 20, wherein a link between said target MSC and said anchor MSC is an STM link.
Applications Claiming Priority (5)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US17416500P | 2000-01-03 | 2000-01-03 | |
| US60/174,165 | 2000-01-03 | ||
| US09/742,396 US6810256B2 (en) | 2000-01-03 | 2000-12-22 | Method and system for handling the transcoding of connections handed off between mobile switching centers |
| US09/742,396 | 2000-12-22 | ||
| PCT/EP2001/000003 WO2001050799A2 (en) | 2000-01-03 | 2001-01-02 | Method and system for handling the transcoding of connections handed off between mobile switching centers |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CA2395312A1 CA2395312A1 (en) | 2001-07-12 |
| CA2395312C true CA2395312C (en) | 2005-12-27 |
Family
ID=26869937
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002395312A Expired - Lifetime CA2395312C (en) | 2000-01-03 | 2001-01-02 | Method and system for handling the transcoding of connections handed off between mobile switching centers |
Country Status (7)
| Country | Link |
|---|---|
| US (2) | US6810256B2 (en) |
| EP (1) | EP1245128B1 (en) |
| CN (2) | CN1328927C (en) |
| AT (1) | ATE550895T1 (en) |
| AU (1) | AU3538801A (en) |
| CA (1) | CA2395312C (en) |
| WO (1) | WO2001050799A2 (en) |
Families Citing this family (34)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6832088B1 (en) * | 1999-07-19 | 2004-12-14 | Telefonaktiebolaget Lm Ericsson | Implementation of basic call setup transporting layer address and logical point in backward direction in cellular networks with separation of call control and bearer control |
| JP4421187B2 (en) * | 2000-08-21 | 2010-02-24 | 富士通株式会社 | Communications system |
| TW532040B (en) * | 2000-10-20 | 2003-05-11 | Koninkl Philips Electronics Nv | Method and system for transferring a communication session |
| WO2002065796A1 (en) * | 2001-02-15 | 2002-08-22 | Nokia Corporation | Method and system for managing a connection of a mobile element to a network |
| US7526572B2 (en) * | 2001-07-12 | 2009-04-28 | Research In Motion Limited | System and method for providing remote data access for a mobile communication device |
| US7623865B2 (en) * | 2002-07-31 | 2009-11-24 | Telefonaktiebolaget Lm Ericsson (Publ) | Forced registration in concurrent services mobile station handoff |
| US20040037312A1 (en) * | 2002-08-23 | 2004-02-26 | Spear Stephen L. | Method and communication network for operating a cross coding element |
| ATE455225T1 (en) * | 2003-06-16 | 2010-01-15 | Secuman B V | METHODS CONCERNING SENSOR ARRANGEMENTS, SYSTEMS AND AUTOMATIC DOOR OPENER |
| US20050009523A1 (en) * | 2003-07-07 | 2005-01-13 | Nokia Corporation | Protocol using forward error correction to improve handover |
| GB0321423D0 (en) * | 2003-09-12 | 2003-10-15 | Ericsson Telefon Ab L M | Method and apparatus for providing a multimedia service |
| US7319871B2 (en) * | 2004-03-08 | 2008-01-15 | Lucent Technologies Inc. | Method and apparatus for repeatable handback attempt after inter-MSC handoff |
| KR100810333B1 (en) * | 2004-06-15 | 2008-03-04 | 삼성전자주식회사 | Apparatus and method for supporting soft handover in a broadband wireless access communication system |
| KR100965694B1 (en) * | 2004-06-15 | 2010-06-24 | 삼성전자주식회사 | System and method for supporting soft handover in a broadband wireless access communication system |
| JP4427415B2 (en) * | 2004-08-05 | 2010-03-10 | 株式会社日立コミュニケーションテクノロジー | Handoff control method, radio control station, and radio base station |
| ES2433475T3 (en) * | 2005-08-16 | 2013-12-11 | Telefonaktiebolaget Lm Ericsson (Publ) | Individual codec path degradation indicator for use in a communication system |
| JP4782847B2 (en) * | 2006-03-02 | 2011-09-28 | テレフオンアクチーボラゲット エル エム エリクソン（パブル） | Wideband codec negotiation |
| US20070282613A1 (en) * | 2006-05-31 | 2007-12-06 | Avaya Technology Llc | Audio buddy lists for speech communication |
| US8057545B2 (en) * | 2006-08-25 | 2011-11-15 | Warsaw Orthopedic, Inc. | Revision spacer |
| CN100551127C (en) * | 2006-09-05 | 2009-10-14 | 华为技术有限公司 | Realize the method and system of load migration in the district of pond |
| CN101163318B (en) * | 2006-10-13 | 2010-09-22 | 大唐移动通信设备有限公司 | Switch method and apparatus in subscriber terminal access process |
| WO2008076073A1 (en) * | 2006-12-19 | 2008-06-26 | Telefonaktiebolaget Lm Ericsson (Publ) | Transfer of buffered data from a source base station to a target base station |
| CN101316385B (en) * | 2007-05-30 | 2011-12-21 | 华为技术有限公司 | Conversation description protocol negotiation method and correlated equipment |
| CN101309500B (en) | 2007-05-15 | 2011-07-20 | 华为技术有限公司 | Security negotiation method and apparatus when switching between different wireless access technologies |
| CN101316382B (en) * | 2007-05-31 | 2012-07-11 | 华为技术有限公司 | Code switching method based on notice, communication system and mobile switching centre |
| CN105635172B (en) * | 2007-08-14 | 2019-11-05 | 爱立信电话股份有限公司 | Method, module and system for codec negotiation |
| CN101400091B (en) * | 2007-09-30 | 2012-02-15 | 华为技术有限公司 | Method, system and device for conversion of session control signaling |
| CN101222690B (en) * | 2008-02-01 | 2012-12-12 | 华为技术有限公司 | Code switching method, system and device |
| GB2461684A (en) * | 2008-06-27 | 2010-01-13 | Vodafone Plc | Transmitting communication mode information between network elements |
| JP5001983B2 (en) * | 2009-07-21 | 2012-08-15 | 株式会社エヌ・ティ・ティ・ドコモ | Communication control system and communication control method |
| WO2012025666A1 (en) * | 2010-08-23 | 2012-03-01 | Nokia Corporation | Method and apparatus for implementing communications session continuity |
| US9712891B2 (en) * | 2011-11-01 | 2017-07-18 | Nokia Technologies Oy | Method and apparatus for selecting an access method for delivery of media |
| CN102448135A (en) * | 2011-11-17 | 2012-05-09 | 中兴通讯股份有限公司 | Method and system for continuously switching single wireless voice |
| CN103650627B (en) * | 2013-06-28 | 2017-09-29 | 华为技术有限公司 | Voice communication method, apparatus and system |
| JP6917390B2 (en) * | 2016-04-01 | 2021-08-11 | テレフオンアクチーボラゲット エルエム エリクソン（パブル） | Methods and devices for resource configuration in handover |
Family Cites Families (23)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5732359A (en) * | 1994-05-13 | 1998-03-24 | Westinghouse Electric Corporation | Mobile terminal apparatus and method having network inter-operability |
| KR100407426B1 (en) * | 1994-05-27 | 2004-03-24 | 브리티쉬 텔리커뮤니케이션즈 파블릭 리미티드 캄퍼니 | Communication system and how it works |
| US5608779A (en) * | 1994-11-08 | 1997-03-04 | Motorola, Inc. | Method for communications between mobile units using single and multiple switching center configurations |
| FI100079B (en) * | 1994-11-09 | 1997-09-15 | Nokia Telecommunications Oy | A method for implementing coding in a cellular radio network |
| US5682380A (en) * | 1994-11-30 | 1997-10-28 | Electronics And Telecommunications Research Institute | Hard-handoff control method for a CDMA (Code Division Multiple Access) mobile switching center |
| US5577029A (en) * | 1995-05-04 | 1996-11-19 | Interwave Communications | Cellular communication network having intelligent switching nodes |
| US5826188A (en) * | 1995-12-07 | 1998-10-20 | Motorola, Inc. | Method and apparatus for handing off calls between differing radio telecommunication networks |
| FI101924B (en) * | 1995-12-18 | 1998-09-15 | Nokia Telecommunications Oy | Handover between mobile exchanges for high speed data transmission |
| US6349204B1 (en) * | 1996-02-12 | 2002-02-19 | British Telecommunications Public Limited Company | Provision of telecommunications control program data pursuant to preliminary data exchange between system elements |
| US6097951A (en) * | 1997-08-06 | 2000-08-01 | Northern Telecom Limited | Method and apparatus for wireless network architecture based on subscriber distribution |
| USH1941H1 (en) * | 1997-09-26 | 2001-02-06 | Dsc/Celcore, Inc. | Agent interworking protocol and call processing architecture for a communications system |
| US6108560A (en) * | 1997-09-26 | 2000-08-22 | Nortel Networks Corporation | Wireless communications system |
| FI106172B (en) | 1998-01-29 | 2000-11-30 | Nokia Networks Oy | A method for reconfiguring a connection in a cellular radio network |
| WO1999039258A1 (en) * | 1998-02-02 | 1999-08-05 | Seiko Epson Corporation | Portable data processing device |
| JP4354641B2 (en) * | 1998-04-03 | 2009-10-28 | テレフオンアクチーボラゲット エル エム エリクソン（パブル） | Flexible radio access and resource allocation in Universal Mobile Telephone System (UMTS) |
| FI106905B (en) * | 1998-05-12 | 2001-04-30 | Ericsson Telefon Ab L M | Method and device in a telecommunication system |
| US6490284B1 (en) * | 1998-09-08 | 2002-12-03 | Telefonaktiebolaget Lm Ericcson | Use of CIC to identify calls when using ISUP in conjunction with AAL type 2 signaling protocol |
| US6546253B1 (en) * | 1998-12-30 | 2003-04-08 | At&T Corp. | Neighborhood cordless service call handoff |
| US6725038B1 (en) * | 1999-01-26 | 2004-04-20 | Nokia Corporation | Method and apparatus for speeding up AAL2 connection setup during handover in advanced cellular networks |
| US7072656B2 (en) * | 1999-03-16 | 2006-07-04 | Telefonaktiebolaget Lm Ericsson (Publ) | Handover in a shared radio access network environment using subscriber-dependent neighbor cell lists |
| US6466556B1 (en) * | 1999-07-23 | 2002-10-15 | Nortel Networks Limited | Method of accomplishing handover of packet data flows in a wireless telecommunications system |
| CA2383366C (en) * | 1999-08-23 | 2006-12-19 | Motorola, Inc. | Domain selecting system and method |
| EP1102511A1 (en) * | 1999-11-15 | 2001-05-23 | TELEFONAKTIEBOLAGET LM ERICSSON (publ) | Method for a handover between different nodes in a mobile communication system |
-
2000
- 2000-12-22 US US09/742,396 patent/US6810256B2/en not_active Expired - Lifetime
-
2001
- 2001-01-02 AT AT01907398T patent/ATE550895T1/en active
- 2001-01-02 AU AU35388/01A patent/AU3538801A/en not_active Abandoned
- 2001-01-02 WO PCT/EP2001/000003 patent/WO2001050799A2/en active Application Filing
- 2001-01-02 CN CNB2004100789837A patent/CN1328927C/en not_active Expired - Fee Related
- 2001-01-02 CA CA002395312A patent/CA2395312C/en not_active Expired - Lifetime
- 2001-01-02 CN CNB018034403A patent/CN1196375C/en not_active Expired - Fee Related
- 2001-01-02 EP EP01907398A patent/EP1245128B1/en not_active Expired - Lifetime
-
2004
- 2004-09-14 US US10/940,102 patent/US7558573B2/en not_active Expired - Lifetime
Also Published As
| Publication number | Publication date |
|---|---|
| CN1196375C (en) | 2005-04-06 |
| US20050030923A1 (en) | 2005-02-10 |
| CN1592486A (en) | 2005-03-09 |
| WO2001050799A3 (en) | 2002-04-18 |
| EP1245128B1 (en) | 2012-03-21 |
| CN1328927C (en) | 2007-07-25 |
| CN1394455A (en) | 2003-01-29 |
| US20020009997A1 (en) | 2002-01-24 |
| AU3538801A (en) | 2001-07-16 |
| CA2395312A1 (en) | 2001-07-12 |
| EP1245128A2 (en) | 2002-10-02 |
| ATE550895T1 (en) | 2012-04-15 |
| US6810256B2 (en) | 2004-10-26 |
| WO2001050799A2 (en) | 2001-07-12 |
| US7558573B2 (en) | 2009-07-07 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CA2395312C (en) | Method and system for handling the transcoding of connections handed off between mobile switching centers | |
| EP0976282B1 (en) | Automatic data transfer mode control | |
| US6301242B1 (en) | Communication system with fast control traffic | |
| EP0868826B1 (en) | Inter-msc handover in high-speed data transmission | |
| US5857153A (en) | Cellular telecommunications network having seamless interoperability between exchanges while providing voice, asynchronous data and facsimile services in multiple frequency hyperbands | |
| US8428593B2 (en) | Method and apparatus for soft handoff between base stations using different frame formats | |
| US5940762A (en) | Inter-system calling supporting inter-system soft handoff | |
| US7392052B2 (en) | Hard handover method and controller | |
| FI114424B (en) | A method and apparatus for performing a handover of a communications system in a communication system | |
| JP4460173B2 (en) | Asymmetric data transmission for use in multi-modulation environments | |
| JP2002510915A (en) | Method of transferring a data signal in a wireless communication system | |
| WO1997014263A1 (en) | Cellular telecommunications network having seamless interoperability between exchanges while supporting operation in multiple frequency hyperbands | |
| US7953075B2 (en) | Methods and apparatus for implementing a protocol format capable of handling shared and dedicated radio resources | |
| JP2002543719A5 (en) | ||
| WO2003073773A2 (en) | Mobile handoff between hybrid networks |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| EEER | Examination request | ||
| MKEX | Expiry |
Effective date: 20210104 |