US20080026691A1

US20080026691A1 - Increasing wireless network capabilities via broadcast control-signaling channel usage

Info

Publication number: US20080026691A1
Application number: US11/716,923
Authority: US
Inventors: Mingshen Gao
Original assignee: Lucent Technologies Inc
Current assignee: Alcatel Lucent SAS
Priority date: 2006-07-31
Filing date: 2007-03-12
Publication date: 2008-01-31
Also published as: US20080026715A1; KR101073621B1; ATE516690T1; JP2009545269A; CN101496438B; KR20090023736A; WO2008016556A3; US8005471B2; CN101496438A; EP2050298A2; EP2050298B1; JP4977757B2; WO2008016556A2

Abstract

An access network of an apparatus in one example is configured to provide a wireless communication service over a coverage area and is configured to support a broadcast multicast system (BCMCS). The access network is configured to broadcast at least one broadcast control-signaling channel (BCC) over the coverage area via at least one BCMCS flow. The BCC is utilized by the access network to transmit control and signaling messages to the access terminals, either independent of or in conjunction with a standard control message channel.

Description

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation-in-part of application Ser. No. 11/496,942 filed Jul. 31, 2006 by M. Gao entitled, “ACCESS NETWORK BROADCAST CONTROL-SIGNALING CHANNEL”.

TECHNICAL FIELD

The invention relates generally to wireless signaling in an access network and more particularly to signaling using a broadcast control-signaling channel to improve network performance in communicating with access terminals (mobiles).

BACKGROUND

Wireless service providers that offer voice over internet protocol (VoIP) and push-to-talk (PTT) services are starting to move these and other real-time applications and services to a converged evolution-data optimized (EV-DO) based radio access network (RAN) from their current 1× based radio access network. All the signaling messages for an idle access terminal (AT) in an EV-DO based RAN go through a ControlChannel (CC) and are transmitted across many sectors. For example, a RouteUpdateRequest message sent by the access network (AN) to the entire radio network controller's ( ) coverage area for finding an AT's current location which may be followed by the AN sending another message such a DOS (data over signaling) message to several sectors in which the AT has good pilot signal strength. The DOS message may carry call-setup related information or an instance short message, once the access terminal returns the requested RouteUpdate message. Traditional paging strategy sends a page message to a last seen active-set in a first attempt to contact the access terminal, escalates to an entire RNC's coverage area in the next attempt, and is followed with a page to an RNC group that combines a few adjacent RNCs. For RNCs with about 50-cells/150-sectors, nearly 50 sectors on average may be involved in transmitting page messages for each call, assuming a 70%-75% success rate for the first attempt and 24%-29% for the second attempt within RNC, and just 1% for the third attempt to the RNC group. The success rate of the attempts to page the access terminal is a good indication of overall average response time for call setup within the RAN. One way to improve the success rate for the first page (it is only about 60%-80% for this traditional page strategy) is to page the entire 150 sectors in the RNC in the first attempt. However, this may use too large of an amount of network resources during a busy hour for an EVDO based RAN since it does not have a dedicated paging channel which is the case for the 1× based RAN.
It is desirable to reduce a response time for real-time applications (e.g., using data over signaling, DOS). However, in the EVDO RAN, the CC can transmit no more than 16 bytes of physical layer data in each time-slots at its highest rate of 76.8 kbps. Accordingly, a 100 byte general ‘compressed SIP invite’ (call-setup message) will take 7 times-slots for the CC to transmit. Since an EVDO based RAN delivers high-speed service based on its high-speed traffic/broadcast channels, time-slots used by the slower control channels will degrade the overall system performance.
At 1.2 K busy hour call attempts (BHCA) per sector (35 Erlang with 100 seconds hold time) for EVDO based RAN, a RNC with 50-cells/150-sectors will transmit more than 5 page messages per ControlChannelCycle (CCcycle) from every sector, assuming the traditional paging strategy is performed. It will be approximately 20-25 page messages per CCcycle if the entire RNC coverage area is paged at the first attempt for better result as it is often the customary way for 1× based RAN. With this rate, the system simply cannot afford to convert some of the page messages to DOS messages (data over signaling) for passing the call-setup information directly to the users as the real-time applications (such as PTT services) would like to do.
Using a zone base method for tracking users (e.g., using the RouteUpdateTriggerCode for zones as small as one or a few sectors) will limit the number of sectors participating for transmitting signaling messages so that some CC cycles can be saved from air interface resources. But for small zones, access terminals that are approximately stationary near the zone boundaries could often “ping-pong” between the zones as they are toggling between sectors that belong to different zones. In this case, while some CC cycles have been saved, it places an additional load on the Access Channels (AC), which could be very heavy such that the overall system's accessing ability will be impacted.
(A1) Multiple carriers in one access network. Currently, an EV-DO access network will typically utilize only a single carrier. As used in this context, a carrier in an EVDO deployment means a CDMA channel with band class and channel number. However, there will be more carriers in a service provider's access network as its usage grows, especially when new versions of VoIP and other real-time applications become available. In the current practice, the AT's will be hashed, i.e. assigned, to one of the carriers. Utilizing the current standard, a signaling message is sent to an idle AT through the control channel in the carrier to which the AT is assigned. The assignment may be made by hashing, i.e. a forced distribution that could be pseudo-random. However such signaling messages will be transmitted at a relatively low data rate over the normal control channel. With multiple carrier configurations, each individual carrier would have to waste the valuable air interface bandwidth for this type of signaling to ATs. This gives rise to a need for improved signaling efficiency and bandwidth utilization.
(A2) Need for flexible configuration for signaling zones with high-performance signaling channels. Transmitting signaling messages to the ATs can be accomplished using conventional techniques over the normal control channel. However, it is desirable to minimize the use of system resources and to speed up signaling performance. U.S. application Ser. No. 11/496,942 has proposed the use of broadcast signaling zones with high-performance channels. However, it is desirable to have more flexible ways of configuring the signaling zones and channels in achieving better performance for the AN.
(A3) Additional signaling channel selection method. In systems in which an AT can receive signaling messages from more than one channel, questions arise as to how to determine the channel to be utilized and how to coordinate the selection of the signaling channel between the AT and system infrastructure. Although U.S. application Ser. No. 11/496,942 discloses a method for channel selection and coordination between the AT and AN, there exists a need for additional methods for resolving these issues in a way that further enhances system performance.
(A4) Informing an AT on availability of signaling channels and configuration of signaling zones. In systems in which an AT can receive signaling messages from more than one channel in a plurality of communication zones, coordination between the system infrastructure and the AT is required so that both agree on the same signaling channel and communication zone. Improvements in communications between the infrastructure and AT with regard to achieving synchronization of the signaling channel and zone to be utilized for the AT can result an improved system efficiencies.
Thus, a need exists for improved system performance and efficient use of air interface resources.

SUMMARY

The invention in one implementation encompasses a method that supports wireless communication services, including broadcast multicast system (BCMCS), by an access network configured to provide coverage for a plurality of access terminals. Access terminals are capable of being served by two or more carriers of the access network. The access terminals are assigned among the two or more carriers for wireless communication service. The access network transmits only a single broadcast control-signaling channel (BCC) on only one of the two or more carriers to all of the access terminals. Each of the access terminals receives the single BCC regardless of which of the two or more carriers each access terminal is assigned. The BCC carries control and signaling messages that are received by all of the access terminals. This saves bandwidth for other carriers since the other carriers do not have to employ individual BCCs and do not have to use extra bandwidth for its normal Control Channel to carry signaling messages for ATs.
In another implementation, a method provides wireless communication service over a coverage area by an access network that supports BCMCS. The access network broadcasts at least one BCC over the coverage area via at least one BCMCS flow. Each of the at least one BCMCS flow is identified by a flow identifier. First and second coverage areas associated with first and second radio network controllers, respectively, are used to provide wireless service to access terminals. The first and second coverage areas share an adjacent boundary. First and second wireless transmission sectors are disposed in the first coverage area. The first sector serves access terminals in a location that includes the adjacent boundary and the second sector serves access terminals in a location that does not include the adjacent boundary. The first sector transmits control messages to access terminals using both the BCC and another control channel so that access terminals in the area served by the first sector can receive control messages via either the BCC or the another control channel, and transmitting control messages to access terminals in the area served by the second sector using only the BCC.
In a further implementation, a method provides a wireless communication service by an access network over a coverage area to a plurality of access terminals, where the access network supports BCMCS. The access network is divided into a plurality of sectors that support communications with access terminals within the respective sectors. At least one BCC is transmitted by the access network for reception by the access terminals in each sector. An access terminal could perform BCMCS flow registration to all the BCCs for the sector in which the access terminal is located at the time of the registration. The access network identifies the sector in which the access terminal is located and the access network transmits to the access terminal a response message that defines one BCC to which the access terminal is to monitor for the receipt of control messages.
In another implementation, a method a wireless communication service is provided by an access network over a coverage area to a plurality of access terminals, where the access network supports BCMCS. The access network transmits a broadcast overhead message (BOM) on a carrier directed to the access terminals, wherein the BOM includes at least one bit that serves as a flag indicating whether an associated portion of the BOM identifies a corresponding BCC. In one embodiment, the listed order of BCCs could be used to identify the preferred or destined BCC for the signaling zone that serves the sector. The access terminals select the identified BCC in response to receiving the BOM that includes the at least one bit indicating an associated portion of the BOM identifies the BCC. The access terminals monitor the identified BCC for receipt of control messages transmitted over the identified BCC from the access network.
Embodiments of the present invention also include apparatus that performs the methods described above in this section.

DESCRIPTION OF THE DRAWINGS

Features of example implementations of the invention will become apparent from the description, the claims, and the accompanying drawings in which:

FIG. 1 is a representation of one implementation of an apparatus that comprises an access network and an access terminal.

FIG. 2 is a representation of one implementation of a plurality of cells of the access network of FIG. 1 and illustrates assigned broadcast signaling zones and coverage broadcast signaling zones.

FIG. 3 is a representation of another implementation of the assigned broadcast signaling zones and coverage broadcast signaling zones of FIG. 2.

FIG. 4 is a one-dimensional representation of yet another implementation of the assigned broadcast signaling zones and coverage broadcast signaling zones of the apparatus of FIG. 2.

FIG. 5 is an illustrative example of multiple carriers utilized in accordance with an embodiment of the present invention.

FIG. 6 is an example of multiple radio network controllers and representative carriers of each in accordance with an embodiment of the present invention.

FIG. 7 is an exemplary flow diagram of steps in accordance with an embodiment of the present invention in which the access network selects the broadcast control-signaling channel to be monitored by an access terminal.

FIG. 8 of exemplary flow diagram of steps in accordance with an embodiment of the present invention in which a broadcast overhead message contains information enabling an access terminal to determine the broadcast control-signaling channel to be monitored.

DETAILED DESCRIPTION

Turning to FIG. 1, an apparatus 100 in one embodiment comprises an access network 102 and an access terminal (AT) 104. The access network 102 in one example comprises an evolution data optimized (EVDO) wireless communication network. The standard specification for an EVDO network is described in “CDMA2000 High Rate Packet Data Air Interface Specification” (3GPP2 document C.S0024). The access network 102 in one example comprises a radio network controller 106 and a plurality of base transceiver stations (BTS) 108, 110, 112, and 114. The access network 102 provides a wireless communication service to the access terminal 104 over a coverage area 116. The access network 102 in one example provides a broadcast multicast service (BCMCS) or enhanced BCMCS (EBCMCS) to the access terminal 104 in the coverage area 116. The standard specification for a BCMCS air interface is described in “CDMA2000 High Rate Broadcast-Multicast Packet Data Air Interface Specification” (3GPP2 document C.S0054).
The coverage area 116 in one example comprises a plurality of cells 118, 120, and 122 that subdivide the coverage area 116. In a further example, the cells 118, 120, and 122 are further subdivided into a plurality of sectors, for example, three or six sectors per cell. In the example of FIG. 1: cell 118 comprises sectors 124, 126, and 128; cell 120 comprises sectors 130, 132, and 134; and cell 122 comprises sectors 136, 138, and 140. The BTSs in one example cooperate to provide the wireless communication service over the plurality of cells. For example, BTS 108 communicates over sector 124, BTS 110 communicates over sector 128, and BTS 112 communicates over sector 126 to provide service to the cell 118.
Turning to FIG. 2, another implementation of a coverage area 201 serviced by the access network 102 in one example is divided into a plurality of sectors, where each sector is represented by a hexagon. For example, the coverage area 201 comprises sectors 202 through 252 (additional sectors shown are not numbered for clarity). The sectors of the coverage area 201 are organized into coverage broadcast signaling zones (CBSZs) and assigned broadcast signaling zones (ABSZs). Each zone comprises an associated pair, ABSZ and CBSZ, that is identified by a unique zone identifier. Each ABSZ is also assigned with a BCMCS flow identified by a BCMCS flow identifier available to the coverage area, as described herein. The ABSZs in one example do not overlap and each ABSZ is covered by a CBSZ. The CBSZ in one example comprises the ABSZ and the sectors that surround the ABSZ. In a further example, the CBSZ comprises the ABSZ and at least one “layer” of sectors that surround the ABSZ.
Referring to FIG. 2, the coverage area 201 in one example is divided into a plurality of ABSZs where each ABSZ is a sector. Each ABSZ is associated with a CBSZ, but only CBSZ 254 and CBSZ 256 are shown for clarity. The CBSZ 254 comprises sectors 202, 204, 206, 208, 210, 212, and 214 where sector 202 is its associated ABSZ. The sectors 204, 206, 208, 210, 212, and 214 comprise a first layer of sectors that surround the ABSZ 202. A second layer of sectors that surrounds the zone 202 comprises sectors 216, 218, 220, 222, 224, 226, 228, 230, 232, 234, 236, and 238. In an alternative example, the CBSZ may comprise the ABSZ, the first layer of sectors that surround the ABSZ, and the second layer of sectors that surround the ABSZ. CBSZ 256 in one example comprises sectors 240, 242, 244, 246, 248, 250, and 252 where sector 240 is the associated ABSZ.
The ABSZs completely cover the coverage area 201 with no overlap among ABSZs and the CBSZs comprise the first layer of sectors that surround the corresponding ABSZ. The first layer of sectors that surround the ABSZ 202 comprises sectors 204, 206, 208, 210, 212, and 214. The first layer of sectors that surround the ABSZ 206 comprises sectors 218, 220, 222, 208, 202, and 204. In this example, a CBSZ for zone 202 partially overlaps a CBSZ for zone 206. In this configuration, the overlapped areas for the CBSZs comprise soft zone boundaries, which will create a single frequency network (SFN) effect for ATs in the zone for achieving high data rate signaling and which will be used to protect access channel from toggling by stationary ATs near the zone boundary.
The access network 102 in one example is configured to broadcast at least one broadcast control-signaling channel (BCC) to the coverage area 201. In one example, the access network 102 is configured to broadcast one BCC per ABSZ. Each ABSZ in one example is assigned with a completely independent and localized broadcasting-multicasting (BCMCS) flow. The access network employs the BCCs for passing control-signaling messages to an access terminal in or just slightly outside the ABSZ so that it appears to be or behaves like a broadcasting channel carrying the control-signaling messages. The access network 102 in one example comprises a BCMCS program (e.g., named as BCCs-over-BSZs) for creation of the BCC BCMCS flows, where all the available BCMCS flow identifiers to the coverage area are considered as a BCMCS flow under the BCMCS program.
The current BCMCS standard specification allows for up to 64 BCMCS flows for each BCMCS program and the air interface allows only up to 64 BCMCS physical channels. In one example for this apparatus, each BCC will be directly associated with one of the possible BCMCS physical channel. In this way, we can use a 6-bit flow discriminator, which is the lowest 6 bits in the standard format for BCMCSFlowID structure, to uniquely identify each and every possible BCCs (each BCC in one example is an independent localized BCMCS flow, such that it has a complete BCMCS flow identifier, the assigned BCMCSFlowID structure. But for our purpose, only enough of bits for the flow discriminator in BCMCSFlowID will be used to identify a BCC). If the coverage area 201 comprises more than 64 zones or if it is desirable to use fewer than 64 flows, the access network 102 will have to reuse the BCMCS flow identifiers since each BCMCS flow identifier here specifies an actual BCMCS physical channel and maps to a fixed time-slot with the fundamental ControlChannelCycle. The access network 102 in one example assigns a BCMCS flow identifier to each ABSZ, but it also reuses the BCMCS flow identifiers for ABSZs that are distant enough from each other when the cross-interference between the BCCs can be ignored. Referring to FIG. 2, the access network 102 in one example reuses a same flow identifier for the zone 202 (the ABSZ for CBSZ 254) and zone 240 (the ABSZ for CBSZ 256).
The access network 102 in one example employs the BCCs for sending signaling messages to the access terminal 104. The BCC in one example comprises a supplementary signaling route to the access terminal 104, in addition to a standard signaling route using the control channel. In an EVDO based network, the control channel (CC) comprises limited bandwidth, for example, it can transmit no more than 16 bytes of physical layer data in each time-slot at its highest rate of 76.8 kilobits per second (kbps). A BCMCS flow in one example allows for data packets of up to 2 k bits and transfer speeds up to 1.2 megabits per second (Mbps). Where the access network 102 employs the BCC over the BCMCS flow for sending signaling messages, a much higher data rate (e.g., 16 or 24 times) may be achieved as compared to the standard EVDO control channel based signaling.
Since the BCMCS flow allows for higher bandwidth, the access network 102 in one example can more efficiently employ the data over signaling (DOS) protocol to send messages to the access terminal. The access network 102 in one example sends a ‘compressed SIP invite’ type of call-setup message to the access terminal for real-time applications such as voice over internet protocol (VoIP) or push-to-talk (PTT) to speed up a session setup process for the application as it bypasses the paging process entirely. The access network 102 in one example use the DOS protocol for sending call-setup related information to the access terminal 104 to speed up information (small in size) delivery. In one example, the access network 102 comprises a multi-carrier configuration, for example, the access network comprises at least a first and a second carrier. In this configuration, the access network 102 may use the BCC to send many or all of the best effort (BE) messages for each of the carriers (e.g., the first and second carriers). Examples of best effort messages comprise RouteUpdateRequest messages, DOS (data over signaling) messages, and page messages.
In one example, the access network 102 puts a plurality of signaling messages for a plurality of access terminals such as 104 in the data packet since the data packet is 16 to 24 times larger than the 128 bits transferred by the normal control channel in each time slot. The access network 102 in another example employs an R-S coding (described by the BCMCS specification) to the data packets of the BCC to add error correction capability to improve the bit-error rate for transmission. If the entire data packet of the BCMCS flow for a time-slot is not utilized for signaling messages to the access terminals such as 104, the access network 102 in yet another example duplicates the signaling messages for redundancy in consecutive cycles. Although the example of FIG. 2 shows that each zone (the ABSZ) comprises a sector, in practice, a zone (the ABSZ) can comprise any of: one sector; a plurality of sectors; one cell; a plurality of cells; or one radio access network (more practically, all the sectors within the RNC that are one sector deep inside make up the ABSZ so that the CBSZ itself is the entire RNC).
Turning to FIG. 3, another implementation of a coverage area 302 serviced by the access network 102 is shown. In FIG. 3, the hexagons represent individual sectors, similar to sectors 202 through 252 of FIG. 2, but are not numbered for clarity. Coverage area 302 in one example comprises ABSZs 304, 306, 308, 310, 312, 314, 316, 318, and 320, each comprising four sectors and represented by a parallelogram that passes through the four sectors. The CBSZ for each ABSZ of FIG. 3 comprises the ABSZ and a first layer of sectors that surround the ABSZ. The ABSZ 304 corresponds to the CBSZ 256, represented by a parallelogram that passes through twelve sectors of the first layer of sectors that surround the ABSZ 304.
Referring to FIG. 3, the coverage area 302 comprises nine ABSZs 304 through 320. The access network 102 in one example assigns nine different flow identifiers to the nine ABSZs 304 through 320, for example, BCC1, BCC2, BCC3, BCC4, BCC5, BCC6, BCC7, BCC8, and BCC9. The coverage area 302 in a further example comprises additional instances of the nine ABSZs 304 through 320 to fully cover the coverage area 302. In this example, each additional instance of the nine ABSZs structure reuses the flow identifiers BCC1 through BCC9. The ABSZs 306, 308, 310, 312, 314, 318, and 318 provide a buffer area to separate multiple instances of the ABSZ 304 that use the same BCC1 from interfering with other ABSZs that are also using the same BCC1 BCMCS flow identifier, as will be appreciated by those skilled in the art.
An illustrative description of operation of the apparatus 100 is presented, for explanatory purposes. Turning to FIG. 4, the apparatus 100 in another embodiment comprises an access network 402, an access terminal 404, and an access terminal 406 that moves from a position 408, to a position 410, and then to a position 412. The access network 402 comprises base transceiver towers (BTSS) 414, 416, 418, 420, 422, 424, 426, 428, 430, and 432. The access network 402 in one example comprises a coverage area 434 that is divided into cells, where each BTS serves one cell. The coverage area 434 in one example comprises a plurality of ABSZs, for example, ABSZs 436, 438, 440, 442 and 444 that correspond to a plurality of CBSZs 446, 448, 450, 452, and 454, respectively.
Referring to FIG. 4: ABSZ 436 comprises the cells served by BTSs 414 and 416 and is identified by a zone identifier ABSZ1 and a BCMCS flow identifier BCC1; ABSZ 438 comprises the cells served by BTSs 418 and 420 and is identified by a zone identifier ABSZ2 and a BCMCS flow identifier BCC2; ABSZ 440 comprises the cells served by BTSs 422 and 424 and is identified by a zone identifier ABSZ3 and a BCMCS flow identifier BCC3; ABSZ 442 comprises the cells served by BTSs 426 and 428 and is identified by a zone identifier ABSZ4 and the reused BCMCS flow identifier BCC1; ABSZ 444 comprises the cells served by BTSs 430 and 432 and is identified by a zone identifier ABSZ5 and the reused BCMCS flow identifier BCC2. The access network 402 broadcasts a BCMCS flow with flow identifier BCC1 over CBSZ 446, which comprises cells 414, 416, and 418. CBSZ 448 comprises cells 416, 418, 420, and 422. CBSZ 450 comprises cells 420, 422, 424, and 426. CBSZ 452 comprises cells 424, 426, 428, and 430. CBSZ 454 comprises cells 428, 430, and 432.
The cells 414 through 432, ABSZs 436 through 444, unique zone identifiers (Zone ID), CBSZ 446 through 454, and BCMCS flow identifiers (Flow ID) of a broadcast overhead message (BOM) in one example are configured as:


Cell	ABSZ	Zone ID	CBSZ	Flow ID

Cell
414	ABSZ 436	ABSZ1	CBSZ1	BCC1
Cell
416	ABSZ 436	ABSZ1	CBSZ1, CBSZ2	BCC1, BCC2
Cell
418	ABSZ 438	ABSZ2	CBSZ1, CBSZ2	BCC2, BCC1
Cell
420	ABSZ 438	ABSZ2	CBSZ2, CBSZ3	BCC2, BCC3
Cell
422	ABSZ 440	ABSZ3	CBSZ2, CBSZ3	BCC3, BCC2
Cell
424	ABSZ 440	ABSZ3	CBSZ3, CBSZ4	BCC3, BCC1
Cell
426	ABSZ 442	ABSZ4	CBSZ3, CBSZ4	BCC1, BCC3
Cell
428	ABSZ 442	ABSZ4	CBSZ4, CBSZ5	BCC1, BCC2
Cell
430	ABSZ 444	ABSZ5	CBSZ4, CBSZ5	BCC2, BCC1
Cell
432	ABSZ 444	ABSZ5	CBSZ5	BCC2

For example, the access network 402 broadcasts a BCC for ABSZ1 over cells 414, 416, and 418 via the BCMCS flow identified by BCC1. The access terminals 404 and 406 in one example perform a registration with the access network 402 to receive a BCMCS flow. The access terminals 404 and 406 receive a broadcast overhead message (BOM) that comprises the BCMCS flow identifiers of available BCMCS flows for the serving sectors. The broadcast overhead message in one example is described in the 3GPP2 BCMCS standard. For example, the access terminal 404 is located near cell 416 and receives a BOM that comprises flow identifiers BCC1 and BCC2. The access terminal 404 in one example selects the BCC1 or BCC2 based on which cell provides service first. In another example, the access terminal 404 selects the BCC based on the ordering of the BCMCS flow identifiers in the BOM message under the BCMCS program.
Once the access terminal 404 has selected a BCMCS flow identifier, the access terminal 404 in one example registers the BCMCS flow identifier with the access network 402 employing a standard BCMCS flow registration procedure. The access network 402 stores the flow identifier registered by the access terminal 404. The access network 402 also determines and stores the zone identifier that corresponds to the CBSZ from which the BCMCS registration message from the access terminal 404 is received. The access network 402 determines the CBSZ based on the sector that receives the registration message in combination with the BCMCS flow identifier being registered, as shown by the configuration table. Upon registration of the BCMCS flow identifier, the access terminal 404 begins listening to the BCC over the corresponding BCMCS flow. In one example, the access terminal 404 selects the BCC1 flow identifier and registers with the access network 402. In this example, the access terminal 404 may toggle between cells 416 and 418 which belong to two different ABSZs (ABSZ1 and ABSZ2). However, the access terminal 404 can continue to receive the BCC1 for signaling messages no matter which cell becomes the serving cell. The access terminal 404 will only monitor one cell at a time and it may toggle or “ping-pong” between the two cells if the pilot strength for the two is about the same. Since the BCC1 is available from both cell 416 and 418, the access terminal 404 does not need to perform another BCMCS registration when crossing soft zone boundaries, which substantially reduces or eliminates the “ping-pong” effect, as will be appreciated by those skilled in the art.
The access terminal 406 in one example is powered up in position 408, e.g., within cell 418. The access terminal 406 in one example receives a BOM message that comprises the flow identifiers BCC2 followed by the flow identifier BCC1. In this example, the access terminal 406 registers the flow identifier BCC2 since it is first in the flow identifier list. If the access terminal 406 moves to position 410, it is then between cells 420 and 422. While the access terminal 406 may “ping-pong” between the cells 420 and 422, for example, due to changes in signal strength, the access terminal 406 may continue to listen to the signaling messages from BCC2 without notifying the access network 402 that it has moved. In addition, since cell 420 and 422 both broadcast the BCC over the BCMCS flow BCC2, the access terminal 406 in one example can add or soft combine a signal for the BCC2 received from the cell 420 with a signal for the BCC2 received from the cell 422. This allows the access terminal to receive signaling messages at very high data rate relative to the standard control channel. The soft combine capability is described in the BCMCS standard. The signal from the cells 416, 418, 420 and 422, which make up the coverage area of CBSZ2, comprise a single frequency network (SFN) for the BCMCS flow BCC2, so that it can achieve a higher data rate for broadcasting the signaling messages anywhere within the CBSZ2, as will be appreciated by those skilled in the art.
If the access terminal 406 moves to position 412, it is then past the cell 422 and close to cell 424. The access terminal 406 in one example switches to the BCC3 upon any of: receiving a notification from the access network 402; determining that the BCC2 is no longer available (i.e., the BCC2 flow identifier is not found in the more recently received broadcast overhead messages transmitted by cell 424); or the access terminal 406 determines that an error-rate for the BCC over BCC2 is over a predetermined threshold. The access terminal 406 in one example will not switch back to the BCC2 flow until it has moved to cell 418, as it is now near the center of CBSZ3 and CBSZ3 should have good SFN coverage for BCC3 at this point.
An access terminal near a zone boundary (including cases where the access terminal has passed its current ABSZ and has entered another ABSZ slightly) in one example will be able to continuously receive signaling from its current selected BCC as the BCC is still available in the current CBSZ. This is the soft zone boundary effect which helps to maintain the SFN effect for inside the coverage area of the zone and which helps to protect the access channels at zone boundaries without suffering “ping-pong” effect by stationary mobiles right near the boundaries. In one example if the access terminal is stationary or in slow mobility, then there is no need for it to change to the new BCC that is assigned to the new zone, until it is directed by the access network to switch to the new BCC or it has moved deeply into the new zone. This later case is similar to that of a fast moving access terminal, e.g., it will find from the normal BroadcastOverheadMessage carried by the normal EVDO control channel that the old BCC is no longer carried by the new sectors. The access terminal will then pick a new BCC for signaling as directed by the BroadcastOverheadMessage from the normal control channels.
The access network 402 in one example will begin to broadcast signaling messages to the access terminals 404 and 406 upon registration of the flow identifiers. The access terminals 404 and 406 in one example use a Default Signaling Application (with Signaling Network Protocol or SNP) for receiving the signaling messages. The access terminal 404 or 406 listens to the BCC for the signaling messages and they will be routed to the right protocol layer for processing through the Default Signaling Application on the access terminal as specified by the SNP header.
The access network 402 in one example is able to track the access terminals 404 and 406 to the zones within the access network 402. In one example, this allows the access network 402 to limit the participating zones for transmitting signaling messages. Otherwise, these signaling messages are often escalated ‘squarely’ for the next retry in terms of a number of cells or sectors to be used. The access network 402 can then reach an access terminal and even notify the access terminal using DOS protocol quickly with the BCC by broadcasting to the entire CBSZ in the first attempt (rather than going through traditional escalation procedure from the last seen active-set, to the radio network controller, to the radio network controller group). In addition, this zone tracking property can be used actually to tune the sizes for zones based on the bandwidth required for signaling messages (e.g., a large zone can be used in early release when the number of capable access terminals are limited and the zones will be reduce in sizes as more mobiles starting to use the BCC).
The access network 402 in one example is configured to select, based at least in part on the flow identifier registration by the access terminal 406, a selected BCC of the at least one BCC or another control channel (e.g., the standard EVDO control channel) for sending a signaling message to the access terminal. The access network 402 in one example is configured to send the signaling message to the access terminal over the selected BCC if the flow identifier registered by the access terminal comprises a valid flow identifier (e.g., BCC1, BCC2, etc.). The access network 402 in a further example is configured to send the signaling message to the access terminal over the other control channel if the flow identifier comprises a blank flow identifier, such as BCC0. In one example, the access network 402 employs the blank flow identifier for access terminals that do not support signaling over the BCCs.
Numerous alternative implementations of the present invention exist. The ABSZs and/or CBSZs in alternative examples may comprise different numbers of zones than those shown in FIGS. 2 and 3. Additionally, The ABSZs and/or CBSZs may be different sizes and/or shapes within the same access network 102 or 402. In one example, the access network 102 or 402 (or an operator thereof) may resize or reconfigure the ABSZs and/or CBSZs. For example, early deployments with a low number of compatible access terminals may use larger zones since there would be less signaling over the BCCs. The signaling messages sent over the BCC in one example comprise an incrementing transaction ID, so that access terminals listening to the BCC will know whether they have missed any signaling messages, which may reflect a poor quality of reception. The steps performed by the access network 102 and/or 402 in one example are performed by a radio network controller (e.g., RNC 106), a base transceiver station (e.g., BTSs 108, 110, 112, or 114), or combinations thereof.
The access networks 102 and 402 in one example speed up the signaling for real-time applications/services provided by the access networks 102 and 402 by using the BCMCS flow over a CBSZ to achieve a single frequency network (SFN) effect, which reduces interference and allows soft combining of signals from different sectors. Soft combining the signals in one example allows the access terminals to receive signaling messages at very high data rates The access networks 102 and 402 in one example use fewer resources for signaling by using the ABSZ and CBSZ zones to track down an access terminal's location. For example, upon receipt of the flow identifier registration, the access network 402 can determine which zone the access terminal is located in based on which sector or cell that the registration message came from. This reduces the number of sectors that a signaling message must be sent to for contacting an idle access terminal.
The access networks 102 and 402 in one example solve the “ping-pong” effect that is associated with normal zone based networks: while the access terminals near boundaries of zones will toggle between sectors that belong to different zones, the overlapped signaling area of the CBSZs which completely cover the actual zone will allow the “stationary or slow moving” access terminals to stay with their currently monitored BCC BCMCS flow and to receive signaling message without interruption, even though the access terminals may have passed the zone's boundary and moved into another zone.
The access networks 102 and 402 in one example allow the co-existence of the broadcast control-signaling channel with normal control channel so that from each access terminal's point of view, the AN is completely backward compatible. This is not just for access terminals that are not capable of BCC (e.g., old access terminals or access terminals without the mobile client software). It is also for BCC capable access terminals, especially access terminals that are near the edge of the BCCs coverage areas or simply in uncovered areas. Therefore the access terminal may choose to receive signaling messages from either channel. This allows the access terminal to receive signaling messages in areas that are less useful for broadcasting channels (e.g., very rural areas or coverage edges for RNCs or the access network). For access terminals near coverage area boundaries, the access network in one example uses the normal CC based signaling. Additionally, the BCC capable access terminals may choose to use the normal control channel based signaling when it cannot get good reception for the BCC (for example, by error-rate detection). In another example, the access network uses the normal control channel to send a signaling message to the access terminal's last active set and then follow it with a broadcast to the zone that the access terminal is located in. In this example, there will be no escalation or flooding over the entire coverage area.
The access networks 102 and 402 in one example continue to send messages to the access terminals through the normal control channels, for example: the basic overhead message and other sector-specific messages (e.g., SectorParameter, AccessParameter, etc.) Therefore, the access terminal will continue to monitor the normal control channel for these messages.
The apparatus 100 in one example comprises a plurality of components such as one or more of electronic components, hardware components, and computer software components. A number of such components can be combined or divided in the apparatus 100. An example component of the apparatus 100 employs and/or comprises a set and/or series of computer instructions written in or implemented with any of a number of programming languages, as will be appreciated by those skilled in the art.
(A1) FIG. 5 illustrates a carrier configuration in which three carriers 502, 504 and 506 are utilized in the same access network. In accordance with one aspect of the present invention, when an access network utilizes a plurality of carriers, only one of the carriers is selected to carry a BCC that is to be utilized by all ATs in the access network. In this example, BCC 508 of carrier 502 will be utilized by all ATs, including ATs that may have been assigned to be generally served by carrier 504 or 506. The bandwidth allocations 510 and 512 in carriers 504 and 506, respectively, are shown in dashed lines indicating that this bandwidth may be utilized for other purposes since only BCC 508 of carrier 502 is utilized for the entire access network. This dashed line bandwidth would have otherwise been used for transmitting control and signaling messages to ATs either through the normal Control-Channel or through the BCC if it is deployed in the carrier. Although an AT may for example have been assigned to carrier 504 and receive normal system overhead messages from the normal control channel of this carrier, the AT will also monitor BCC 508 of carrier 502 for other messages. Thus, such an AT will be required to tune to and receive information from both carriers 502 and 504. This requirement can be met either by concurrent reception by the receiver or receivers of the AT, or by periodic sequential scanning of the carriers required to be received. Alternatively, in an access system containing a substantial number of carriers, a small number of the carriers may be selected to contain an active BCC to be utilized by ATs. For example, all of the ATs within a predetermined zone may be directed to monitor a single BCC regardless of a carrier assignment of the ATs. The general technique described in conjunction with FIG. 5 is advantageous in that substantial air-interface resources have been saved and additional bandwidth resources made available to the system since the bandwidth that would have been utilized by a normal Control-Channel for transmitting signaling messages to ATs or a BCC not implemented in a carrier can be reallocated for other needs. Due to the higher capacity of the BCC, a single BCC from one carrier is capable of supporting all of the signaling messages for ATs from multiple carriers. As used herein a control and signaling message and/or a signaling message includes the control/signaling messages generated within the access network, e.g. paging messages transmitted to ATs by the AN, as well as signaling messages that are generated by applications on AT or by applications on the core network, e.g. a call notification in a SIP invite message to targets by a PTT server on the core network. Short length data messages, e.g. text messages, could also be treated as signaling messages and passed to ATs, e.g. the Data-Over-Signaling protocol, via the BCC.
(A2) FIG. 6 shows a representation of an alternate embodiment with regard to radio network controller coverage areas and corresponding signaling channels utilized. Each of the hexagonal elements represents a different RNC coverage area. In this example, RNC coverage area 602 as a plurality of sectors for providing coverage within the area and at its edges. It is surrounded by adjacent RNC coverage areas 604, 606, 608, 610, 612 and 614. In accordance with this embodiment, the entire RNC associated with coverage area 602 will be designated as a single broadcast signaling zone (BSZ) and will utilize a single BCC to broadcast signaling messages to ATs located within coverage area 602. A broadcast carrier stream 620 represents a carrier utilized within the sectors of the RNC of coverage area 602. This stream contains BCC 626 to be utilized by all ATs within this coverage area.
However, ATs in sectors of RNC of coverage area 602 near the edge boundaries might experience difficulties in receiving the high-speed broadcast messages conveyed via the BCC since such ATs will not be able to perform a soft combine because sectors outside of the RNC will not be broadcasting the signaling messages via a BCC. Thus, in accordance with this embodiment, sectors which define the boundary of the RNC with coverage area 602 also transmit the same signaling messages over a standard control channel. Broadcast carrier streams 622 and 624 are illustrative of boundary sectors and include, in addition to a BCC, standard control channels 628 and 630, respectively. This permits ATs inside an RNC to be able to receive signaling messages from the BCC in order to speed up signaling performance and save system resources. ATs located near the edges of the RNC served by the boundary sectors of the subject RNC can either receive the signaling messages by the BCC or by the normal control channel when reception by the BCC is not available.
In this way, more flexibility is given to the possible deployment of a proposed BCC. The entire natural geographic shape of a coverage area for the access network, e.g. the coverage area for a RNC, can be initially used when the number of ATs is not too large. The signaling zones configured for the AN can be refined, i.e. reduced in geographic area, gradually to accommodate more and more BCC capable ATs as these become active in the region, e.g. more ATs will be migrated from CDMA 1× network to DO network as QoS or VoIP service become the norm.
(A3) FIG. 7 is a flow diagram of illustrative steps in accordance with an alternative embodiment of the present invention. In accordance with the embodiment described with regard to FIG. 1, it was the responsibility of the AT to select a BCC to be utilized for receiving signaling messages. Beginning at START 702, the AT can accomplish this by checking the order of the BCMCS flow that makes up the available BCCs at a particular location. In accordance with this embodiment, the AN specifies the BCC to be used by an AT in a particular location. The AT will perform a BCMCSFlowRegistration, as indicated by step 704, for all BCCs available from the serving sector or to the BCMCS program corresponding to all of the BCCs, e.g. the BCC over BSZ program discussed in U.S. application Ser. No. 11/496,942. A BCC is a BCMCS flow under a specific BCMCS Program that is designed to carry local signaling messages to ATs. The BCMCS registration can list all of the BCCs or it could only register to the BCMCS program itself, when the AT needs to pick a new BCC. Based on this registration by the AT and the identified location of the sector that receives the registration message at step 706, the AN selects a BCC to be used by the AT and notifies the AT such as by using BCMCS control protocol of the identity of the BCC that the AT will monitor for the reception of future signaling messages in step 708. For example, the AN could reply with a BroadcastReject message, which is part of the BCMCS control protocol, to reject all other possible BCCs other than the one BCC selected to be utilized by the AT. Following this process, the AT will monitor the specified BCC for as long as the reception of the BCC is available from the AN. The process is thus concluded per step 710.
(A4) FIG. 8 is a flow diagram of a further alternative embodiment of the present invention. Based on a currently available BCMCS standard, an AT has to first be provisioned in order to receive one or more BCMCS flows. The AT must at least have the program name or other information so that the AT can contact a corresponding BCMCS controller to obtain information for a BCMCS flow associated with the program. In accordance with the embodiment of the present invention as described with regard to FIG. 8, the AT will learn the locally supported BCC(s) from a modified BroadcastOverheadMessage (BOM), thereby illuminating the need to provision the AT as explained above.
The process begins at START 802 and continues with the AT receiving a modified BOM from the access network as indicated at step 804. When the existing BCMCSFlowFormat bit field in the BOM is set to “1”, this indicates the use of a program ID-flow discriminator format. A new bit field, e.g. “FlowForBCC”, in the BOM is set to “1” to indicate that it is the BCMCS program that carries BCMCS flows for the BCCs, i.e. each flow listed under the program is a BCC. If the BCMCSFlowFormat bit field in the BOM is set to “0”, the BOM will list all BCMCS flows carried by the sector. If none of the programs or flows in the BOM has the new bit field set to “1”, this will indicate that the system does not support BCC at the subject sector. In step 806 a determination is made by the AT of whether a FlowForBCC bit is set in a received BOM. A NO determination in step 806 results in the AT processing the BOM and acquisition of a BCC as a normal BCMCS flow. A YES determination by step 806 results in the AT selecting the one BCC indicated in the BOM to be monitored by the AT for the reception of future messages at step 810.
In this embodiment, all neighboring sectors that carry the same BCC define a CBSZ. Neighboring sectors that carry a different BCC define the boundaries of the CBSZ. It will be noted that the BOM is sent out by each sector. If the sector is part of several CBSZs, the BOM transmitted by the sector will list all of the BCMCS flows corresponding to the BCCs carried for all of the CBSZs (except specific BCCs that may be purposely omitted from the BOM for a better SFN effect). It is preferably assumed by the AT that the first BCMCS flow listed in a BOM with the FlowForBCC set to “1” is the designated BCC for the ABSZ, where the sector can belong to only one ABSZ. Thus, the AT can readily discern the BCC to be utilized and the ABSZ and CBSZ(s) to which the AT belongs based on information available from the BOM in accordance with this embodiment. In this way, the AN has communicated to the ATs the signaling zones (ABSZs and CBSZs) and their associated BCCs to be used.
The steps or operations described herein are just for example. There may be many variations to these steps or operations without departing from the spirit of the invention. For instance, the steps may be performed in a differing order, or steps may be added, deleted, or modified.
Although example implementations of the invention have been depicted and described in detail herein, it will be apparent to those skilled in the relevant art that various modifications, additions, substitutions, and the like can be made without departing from the spirit of the invention and these are therefore considered to be within the scope of the invention as defined in the following claims.

Claims

1. An apparatus, comprising:

an access network configured to provide a wireless communication service over a coverage area to a plurality of access terminals, where the access network is configured to support a broadcast multicast system (BCMCS);

wherein the access network is configured to broadcast information on two or more carriers;

the access terminals being assigned among the two or more carriers for wireless communication service;

wherein the access network transmits only a single broadcast control-signaling channel (BCC) on only one of the two or more carriers to be accessed by all of the access terminals, the single BCC being received by all the access terminals regardless of which carrier of the two or more carriers each access terminal is assigned, the BCC carrying control and signaling messages including short data messages that are received by all of the access terminals.

2. The apparatus of claim 1, wherein the access network comprises the one and others of the two or more carriers, wherein a first BCC in the one of the two or more carriers supports the transmission of all signaling messages for all ATs over the single BCC, whereby bandwidth in the others of the two or more carriers that could have been used to carry the signaling messages to ATs is now free to be used to support general communication services.

3. A method comprising the steps of:

supporting wireless communication services by an access network configured to provide coverage for a plurality of access terminals, where the supporting step comprises supporting a broadcast multicast system (BCMCS);

broadcasting information from the access network to the access terminals on two or more carriers, where the access terminals are assigned among the two or more carriers for wireless communication service;

transmitting by the access network only a single broadcast control-signaling channel (BCC) on only one of the two or more carriers to all of the access terminals;

each of the access terminals receiving the single BCC regardless of which of the two or more carriers each access terminal is assigned;

the BCC carrying control and signaling messages that are received by all of the access terminals.

4. The method of claim 3, wherein the two or more carriers are divided into the one and others of the two or more carriers, wherein a first BCC in the one of the two or more carriers supports the transmission of all signaling messages for all ATs over the single BCC, whereby bandwidth in the others of the two or more carriers that could have been used to carry the signaling messages to ATs is now free to be used to support general communication services.

5. An apparatus, comprising:

an access network configured to provide a wireless communication service over a coverage area and is configured to support a broadcast multicast system (BCMCS);

wherein the access network is configured to broadcast at least one broadcast control-signaling channel (BCC) over the coverage area via at least one BCMCS flow, wherein each of the at least one BCMCS flow is identified by a flow identifier;

first and second radio network controllers support first and second coverage areas, respectively, where the first and second coverage areas share an adjacent boundary;

first and second wireless transmission sectors are disposed in the first coverage area, where the first sector serves access terminals in a location that includes the adjacent boundary and the second sector serves access terminals in a location that does not include the adjacent boundary;

wherein the access network causes the first sector to transmit control and signaling messages to access terminals using both the BCC and another control channel so that access terminals in the area served by the first sector can receive control messages via either the BCC or the another control channel, the access network causing the second sector to transmit control and signaling messages to access terminals using only the BCC.

6. A method comprising the steps of:

providing a wireless communication service over a coverage area by an access network that supports a broadcast multicast system (BCMCS);

broadcasting by the access network at least one broadcast control-signaling channel (BCC) over the coverage area via at least one BCMCS flow, wherein each of the at least one BCMCS flow is identified by a flow identifier;

using first and second coverage areas associated with first and second radio network controllers, respectively, to provide wireless service to access terminals, where the first and second coverage areas share an adjacent boundary;

employing first and second wireless transmission sectors disposed in the first coverage area, where the first sector serves access terminals in a location that includes the adjacent boundary and the second sector serves access terminals in a location that does not include the adjacent boundary;

transmitting by the first sector control messages to access terminals using both the BCC and another control channel so that access terminals in the area served by the first sector can receive control messages via either the BCC or the another control channel, transmitting control messages to access terminals by the second sector using only the BCC.

7. An apparatus, comprising:

the access network being divided into a plurality of sectors that support communications with access terminals within the respective sectors;

each sector having at least one broadcast control-signaling channel (BCC) that is accessed by at least the access terminals in the sector;

each access terminal performing a BCMCS flow registration for all BCCs either by listing flows for BCCs or by listing a program for BCCs at the sector in which the access terminal is located at the time of the registration;

the access network identifying the sector in which the access terminal is located at the time of the registration;

the access network transmits to the access terminal as part of the response to the registration a message that defines one BCC to which the access terminal is to monitor for the receipt of its control and signaling messages.

8. A method comprising the steps of:

providing by an access network a wireless communication service over a coverage area to a plurality of access terminals, where the access network supports a broadcast multicast system (BCMCS), the access network being divided into a plurality of sectors that support communications with access terminals within the respective sectors;

at least one broadcast control-signaling channel (BCC) is transmitted by the access network for reception by the access terminals in each sector;

conducting a BCMCS flow registration to all the BCCs carried by the AN for the sector in which the access terminal is located at the time of the registration between each access terminal and the access network;

identifying by the access network the sector in which the access terminal is located at the time of the initial registration session;

transmitting by the access network to the access terminal as response to the registration a message that defines one BCC to which the access terminal is to monitor for the receipt of control messages.

9. An apparatus, comprising:

the access network transmitting a broadcast overhead message (BOM) on a carrier directed to the access terminals, wherein the BOM includes at least one bit that serves as a flag indicating whether an associated portion of the BOM identifies a corresponding broadcast control-signaling channel (BCC);

the access terminals, upon receiving the BOM that includes the at least one bit indicating an associated portion of the BOM identifies the BCC, selects one of the at least one identified BCCs and performs registration to the selected one BCC;

the access terminals monitoring their respective selected one BCC for receipt of control and signaling messages transmitted over the one BCC by the access network.

10. A method comprising the steps of:

providing a wireless communication service by an access network over a coverage area to a plurality of access terminals, where the access network supports a broadcast multicast system (BCMCS);

transmitting by the access network a broadcast overhead message (BOM) on a carrier directed to the access terminals, wherein the BOM includes at least one bit that serves as a flag indicating whether an associated portion of the BOM identifies a corresponding broadcast control-signaling channel (BCC);

selecting one BCC based on said flag and performing registration to the selected one BCC by the access terminals;

monitoring by the access terminals the selected one BCC for receipt of control and signaling messages generated by the access network or by applications in the core network for the AT that are transmitted over the selected one BCC from the access network.

11. The method of claim 10 wherein the BOM includes identification of a plurality of BCCs, and the AT receiving the BOM selects the one BCC to use based on order of listed BCCs in the BOM.

12. The method of claim 10 wherein the AT selects a first listed BCC in the BOM that identifies a destined BCC associated with an assigned signaling zone to which the AT belongs.