WO2000072611A1

WO2000072611A1 - Originating a call in a communication system

Info

Publication number: WO2000072611A1
Application number: PCT/US2000/006027
Authority: WO
Inventors: Thomas K. Appiah
Original assignee: Motorola Inc.
Priority date: 1999-05-20
Filing date: 2000-03-08
Publication date: 2000-11-30

Abstract

Base stations (101-102) within a communication system (100) broadcast an overhead message over a paging channel to all mobile stations (113) within the communication system (100). In the preferred embodiment of the present invention the overhead message comprises those capabilities supported by the base stations (101-102). When originating a call, a mobile station (113) analyzes the overhead message and selects a service configuration supported by the base station. The mobile station (113) then originates a call with the service configuration supported by the base station.

Description

METHOD AND APPARATUS FOR ORIGINATING A CALL IN A COMMUNICATION

SYSTEM

Field ofthe Invention

The present invention relates generally to communication systems and, in particular, to a method and apparatus for originating a call in a communication system.

Background ofthe Invention

Oftentimes devices on each end of a communication link have differing capabilities. For example, a mobile station within a Code-Division, Multiple- Access (CDMA) communication system may be capable of supporting a first set operating parameters for a set of attributes (e.g., encoding/decoding frame formats, data rate, service options such as data services, . . . , etc.) while a base station within the cellular communication system supports a second set of operating parameters for the attributes. In order to establish a communication link between the base station and the mobile station, a service must be negotiated between the two to establish a link utilizing those operating parameters that are shared among them. Such a prior-art service negotiation is described in US Pat. No. 5.638,412 METHOD FOR PROVIDING SERVICE AND RATE NEGOTIATION IN A MOBILE COMMUNICATION SYSTEM, by Blakeney, II et al.

As described in US Pat. No. 5,638,412, during service negotiation between a base station and a mobile station, a base station sends out a page message over a paging channel, which identifies a single service configuration (i.e., a single operating parameter for each attribute in the set of attributes). In other words, the base station sends out a page message identifying a single encoding/decoding frame format, a single data rate, . . . , etc. supported by the base station. The mobile station then provides a page response message over an access channel that acknowledges the page, and either accepts the service configuration or suggests a second service configuration. The base station can reject the proposed service configuration or propose an alternative service configuration. If the base station proposes an alternative service configuration, the mobile station can accept or reject the service configuration proposed by the base station, or propose yet another service configuration. The service negotiation ends when the mobile

5 station and the base station find a mutually acceptable service configuration, or after a predetermined time period.

The prior-art method for service negotiation can be time consuming and needlessly contribute to overall system interference. More particularly, the process of sending multiple messages can delay channel assignment.

1 o Additionally, since in a CDMA communication system all mobile station and base station transmissions occur simultaneously within the same frequency band, transmitting messages contributes to overall system interference. Furthermore, transmitting unnecessary messages wastes mobile station battery life. Therefore a need exists for a method and apparatus for originating a call within a

15 communication system that is not time consuming, does not needlessly contribute to overall system interference, and does not waste mobile station battery life.

Brief Description ofthe Drawings

20

FIG. 1 is a block diagram of a communication system in accordance with the preferred embodiment ofthe present invention.

FIG. 2 is a block diagram of a base station of FIG. 1 in accordance with the preferred embodiment ofthe present invention. 25 FIG. 3 is a flow chart showing operation of the communication system of

FIG. 1 in accordance with the preferred embodiment ofthe present invention.

Detailed Description ofthe Drawings

J 0

To address the above-described need, a method and apparatus for originating a call within a communication system is provided herein. In accordance with the preferred embodiment of the present invention, base stations within a communication system broadcast an overhead message over a paging channel to all mobile stations within the communication system. In the preferred embodiment of the present invention the overhead message comprises those capabilities supported by the base stations. When originating a call, a mobile station analyzes the overhead message and selects a service configuration supported by the base station. The mobile station then originates a call with the service configuration supported by the base station. By broadcasting those capabilities supported by a base station, a mobile station within communication system 100 can originate a call without the time-consuming process of negotiating for a mutually acceptable service configuration. Additionally, overall system interference and battery consumption is reduced since the amount of messaging needed to establish a call is greatly reduced.

The present invention encompasses a method within a communication system. The method comprises the steps of identifying a set of attributes supported by a base station and transmitting a message over a channel to facilitate call origination within the communication system, where the message comprises the set of attributes. In the preferred embodiment of the present invention the set of attributes supported by the base station comprises multiple operating parameters for a single attribute within the set of attributes.

The present invention additionally encompasses a method for call origination within a communication system. The method comprises the steps of monitoring a paging channel by a mobile station and receiving a message transmitted over the paging channel. In the preferred embodiment of the present invention the message comprises multiple operating parameters supported by a base station for an attribute. An operating parameter supported by the mobile station for the attribute is identified and an operating parameter supported by the base station for the attribute is identified from the message. Finally, a call is originated with an operating parameter for the attribute, shared by both the mobile station and the base station.

Finally, the present invention encompasses an apparatus comprising paging channel circuitry having an output comprising a message. In the preferred embodiment of the present invention the message comprises multiple operating parameters supported by a base station for an attribute.

Turning now to the drawings, where like numerals designate like components, FIG. 1 is a block diagram of communication system 100 in accordance with the preferred embodiment of the present invention. In the preferred embodiment of the present invention, communication system 100 utilizes a Code Division Multiple Access (CDMA) system protocol as described in Cellular System Mobile Station-Base Station Compatibility Standard of the Electronic Industry Association/Telecommunications Industry Association Interim Standard 95B (TIA/EIA-95-B), which is incorporated by reference herein. (EIA/TIA can be contacted at 2001 Pennsylvania Ave. NW Washington DC 20006). In alternate embodiments communication system 100 may utilize other analog or digital cellular communication system protocols such as, but not limited to, the Narrowband Advanced Mobile Phone Service (NAMPS) protocol, the Advanced Mobile Phone Service (AMPS) protocol, the Global System for Mobile Communications (GSM) protocol, the Personal Digital Cellular (PDC) protocol, or the United States Digital Cellular (USDC) protocol. Communication system 100 includes a number of network elements such as base station 101, base station 102, mobile station 113, Centralized Base Station Controller (CBSC) 103, and Mobile Switching Center (MSC) 104. In the preferred embodiment of the present invention, all network elements are available from Motorola, Inc. (Motorola Inc. is located at 1301 East Algonquin Road, Schaumburg, IL 60196). It is contemplated that network elements within communication system 100 are configured in well known manners with processors, memories, instruction sets, and the like, which function in any suitable manner to perform the function set forth herein.

As shown, mobile station 113 is communicating with base stations 101 and 102 via uplink communication signals 119 and base stations 101 and 102 are communicating with mobile station 113 via downlink communication signals 116. In the preferred embodiment of the present invention, base stations 101 and 102 are suitably coupled to CBSC 103, and CBSC is suitably coupled to MSC 104.

Operation of communication system 100 in accordance with the preferred embodiment of the present invention occurs as follows: Base stations 101-102 within communication system 100 broadcast an overhead message over a paging channel to all mobile stations 1 13 within communication system 100 via downlink communication signal 116. In the preferred embodiment of the present invention the overhead message comprises those operating parameters supported by the base station. In alternate embodiments of the present invention the overhead message may be transmitted on other channels. When originating a call, mobile station 113 analyzes the overhead message and selects a service configuration supported by the base station. Mobile station 1 13 then originates a call with the service configuration supported by the base station. As described above, by broadcasting those capabilities supported by a base station, a mobile station within communication system 100 can originate a call without the time-consuming process of negotiating for a mutually acceptable service configuration. Additionally, overall system interference and battery consumption is reduced since the amount of messaging needed to establish a call is greatly reduced.

FIG. 2 is a block diagram of base station 101 in accordance with the preferred embodiment of the present invention. As shown, base station 101 comprises traffic channel circuitry 203, paging channel circuitry 205, and other channel circuitry 206. In the preferred embodiment of the present invention there are three separate channels over which information is communicated between base stations and mobile stations. A traffic channel is for one or two way communication of information between a mobile station and a base station and is uniquely allocated for communications to and from the mobile station. The information includes primary traffic, secondary traffic, and signaling traffic. Primary and secondary traffic communicate digital information data such as speech, modem, or facsimile data, and signaling data communicates information to initiate and maintain a link in the communication system such as power control or service negotiation information.

When using the traffic channel, a mobile station and base station communicate through the exchange of forward and reverse traffic channel frames.

Forward traffic channel frames refer to those frames of information transmitted from the base station to the mobile station. Conversely, reverse traffic channel frames refer to those frames of information transmitted from the mobile station to the base station. The mobile station and base station use a common set of attributes for building and interpreting traffic channel frames. This set of attributes, referred to as a service configuration, consists ofthe following:

1. Forward and Reverse Multiplex Attributes: These control the way in which the information bits of the forward and reverse traffic channel frames, respectively, are divided into various types of traffic, such as signaling traffic, primary traffic and secondary traffic. Associated with each multiplex attribute is a rate set parameter which specifies the frame structures and transmission rates supported by the base station. The multiplex attributes used for the forward traffic channel can be the same as that used for the reverse traffic channel, or it can be different.

2. Forward and Reverse Traffic Channel Transmission Rate Attribute: These are the transmission rates actually used for the forward and reverse traffic channels respectively. The transmission rate operating parameters for the forward traffic channel can include all of the transmission rates supported by the rate set associated with the forward traffic channel multiplex option, or a subset of the supported rates. Similarly, the transmission rates used for the reverse traffic channel can include all rates supported by the rate set associated with the reverse traffic channel multiplex option, or a subset of the supported rates. The transmission rates used for the forward traffic channel can be the same as those used for the reverse traffic channel, or they can be different.

3. Service Option Connection Attributes: These are the services in use on the traffic channel. It is possible that there is no service option connection, in which case the mobile station and base station use the forward and reverse traffic channels to send only signaling traffic; or there can be one or multiple service option connections.

Associated with each service option connection are attributes such as a service option, a forward traffic channel traffic type, a reverse traffic channel traffic type and a service option connection reference. The associated service option formally defines the way in which traffic bits are processed by the mobile station and base station. For example a service option may specify the speech encoding or decoding format attribute to be used or the data service protocol attribute to be employed. The associated forward and reverse traffic channel traffic types specify the types of traffic used to support the service option. A service option can require the use of a particular type of traffic, such as primary or secondary, or it can accept more than one traffic type. Likewise, a service option can be one-way, in which case it can be supported on the forward traffic channel only, the reverse traffic channel only, or on either the forward or reverse traffic channel; or the service option can be two-way, in which case it can be supported on the forward and reverse traffic channels simultaneously. The associated service option connection reference provides a means for uniquely identifying the service option connection. The reference serves to resolve ambiguity when there are multiple service option connections in use.

The remaining channels are the paging channel and the access channel. These channels are common to all mobile stations communicating with a base station or set of base stations. Because of the commonality of these channels, capacity is a significant issue and messages transmitted over them must be restricted to a minimum. The paging channel is for one way communication of messages between a base station and a mobile station. The access channel (not shown) is a channel utilized by the mobile station and is for one way communication of messages between a mobile station and a base station. FIG. 3 is a flow chart showing operation communication system 100 in accordance with the preferred embodiment of the present invention. The logic flow begins at step 301 where mobile station 113 is in an idle state (i.e., not involved in a traffic channel call). While mobile station 113 is in an idle state mobile station 113 monitors a paging channel for an Extended System Parameters Message. In the preferred embodiment of the present invention the Extended System Parameters Message is a similar to the Extended System Parameters Message described in TIA/EIA-95-B section 3.7.2.3.2.13 except modified to include a total list of those operating parameters for each attribute that the base station can support. Additionally, the Extended System Parameters Message contains the operating parameters for each attribute in a prioritized order so that for each attribute, the operating parameters that are more preferred by a base station are listed in the message before the operating parameters which are less preferred.

Unlike prior-art methods for call origination, in the preferred embodiment of the present invention the Extended System Parameters Message contains multiple operating parameters, rank ordered, for a single attribute. For example, considering a vocoding attribute, if base station 101 supports both Enhanced Variable Rate Coder (EVRC) described in IS- 127 and 13 Kilobit vocoding parameters, but favors EVRC, base station 101 will send the Extended System Parameters Message with both EVRC and 13 Kilobit listed as operating parameters for the vocoding attribute, however EVRC will be designated as the preferred operating parameter associated with the vocoding attribute. Similarly, if base station 101 supports EVRC, 13 Kilobit vocoding , and 8 Kilobit QCELP vocoding, and EVRC is the most preferred vocoder and 8 Kilobit QCELP is the least preferred vocoder, then EVRC is listed first in the prioritized list in the Extended System Parameters Message, while 13 Kilobit is listed second in the prioritized list and 8 Kilobit QCELP is listed third in the prioritized list.

Continuing, at step 303 mobile station 113 determines if a call should be initiated, and if not, the logic flow returns to step 301 where the paging channel is monitored. If, at step 303, it is decided that mobile station 1 13 should initiate a call, then the logic flow continues to step 305 where mobile station 1 13 analyzes the Extended System Parameters Message to determine the attributes and operating parameters for the attributes for base station 101. Mobile station 113 then determines its own capabilities (step 307) and an Origination Message is transmitted to base station 101 (step 309). In the preferred embodiment of the present invention the Origination Message is similar to the Origination Message described in TIA/EIA-95-B section 6.7.1.3.2. When mobile station 113 determines the contents of the prioritized service option list in the Extended System Parameters Message, it chooses the operating parameters most preferred by base station 101 if it is supported by mobile station 113. If, however, mobile station 113 does not support the service option that is most preferred by base station 101, then another service option may be chosen from the prioritized list in the Extended System Parameters Message instead. The mobile station proposes the service option by setting the SPECIAL_SERVICE field in the Origination Message to T and including the SERVICE_OPTION field in the Origination Message and setting it to the chosen service option number (for example, 0x0003 for EVRC).

Once the Origination Message has been transmitted to base station 101, a traffic channel is originated with a service configuration proposed by mobile station 1 13 in the Origination Message (step 311), the base station accepts the service configuration from the mobile station without further hand shaking or negotiation. By broadcasting those capabilities supported by a base station in an Extended System Parameters Message, a mobile station within communication system 100 can originate a call without the time-consuming process of negotiating for a mutually acceptable service configuration. Additionally, overall system interference is reduced since the amount of messaging needed to establish a call is greatly reduced.

Table 1 shows an Extended System Parameters Message in accordance with the preferred embodiment of the present invention. When a base station sends an Extended System Parameters Message, it uses the following variable- length message format:

Table 1 : Extended System Parameters Message

In the preferred embodiment of the present invention the fields of the

Extended System Parameters Message are similar to those described in TIA/EIA- 95-B section 3.7.2.3.2.13, except for the addition of the NUM_PREF_SERVICE OPTION field and one or more occurrences of the SERVICE_OPTION field. The occurrences of the SERVICE_OPTION field are used to convey the prioritized list of those operating parameters supported by the base station as described above. To represent CDMA vocoder service options, EVRC is 0x0003; 13K is 0x8000; 8K QCELP is 0x0001, where 'Ox' represents a hexadecimal number. For example, base station 101 supports EVRC, 13 Kilobit vocoding, and 8 Kilobit QCELP vocoding. EVRC is the most preferred vocoder and 8 Kilobit QCELP is the least preferred vocoder. 13 Kilobit is less preferred than EVRC, but more preferred than 8 Kilobit QCELP. The NUM_PREF_SERVICE_OPTION field will be set to 3. The first occurrence of the SERVICE_OPTION field will be set to 0x0003. The second occurrence of the SERVICE_OPTION field will be set to 0x8000. The third occurrence ofthe SERVICE_OPTION field will be set to 0x0001.

The descriptions of the invention, the specific details, and the drawings mentioned above, are not meant to limit the scope of the present invention. For example, although base station capabilities are transmitted out over a paging channel in an Extended System Parameters Message, base station capabilities may be transmitted out over another channel (e.g., BS Channel Assignment Message, Dedicated Broadcast Control Channel, . . . , etc.). It is the intent of the inventor that various modifications can be made to the present invention without varying from the spirit and scope of the invention, and it is intended that all such modifications come within the scope ofthe following claims and their equivalents.

Claims

1. A method within a communication system, the method comprising the steps of: identifying a set of attributes supported by a base station, wherein the set of attributes supported by the base station comprises multiple operating parameters for a single attribute within the set of attributes; and transmitting a message over a channel to facilitate call origination within the communication system, wherein the message comprises the set of attributes.

2. The method of claim 1 further comprising the steps of: prioritizing the multiple operating parameters for the single attribute supported by the base station to produce a set of prioritized operating parameters for the single attribute; and the step of transmitting comprises the step of transmitting a message over a paging channel to facilitate call origination within the communication system, wherein the message comprises the set of prioritized operating parameters for the single attribute.

3. The method of claim 1 wherein: the step of identifying the set of attributes supported by a base station comprises the step of identifying a set of attributes comprising vocoding parameters supported by the base station; and the step of transmitting the message over the paging channel comprises the step of transmitting over the paging channel, the vocoding parameters supported by the base station.

4. The method of claim 3 further comprising the steps of: prioritizing the vocoding parameters supported by the base station to produce a prioritized set of vocoding parameters; and the step of transmitting over the paging channel, the vocoding parameters supported by the base station, comprises the step of transmitting over the paging channel, the prioritized set of vocoding parameters.

5. The method of claim 1 further comprising the steps of: monitoring the paging channel by a mobile station; receiving the message transmitted over the paging channel; identifying an operating parameter supported by the mobile station; identifying, from the message, an operating parameter supported by the base station; and originating a call with an operating parameter shared by both the mobile station and the base station.

6. An apparatus comprising paging channel circuitry having an output comprising a message wherein the message comprises multiple operating parameters supported by a base station for an attribute.

7. The method of claim 6 wherein the message is a page message.

8. The method of claim 6 wherein the multiple operating parameters comprise multiple vocoding parameters and the attribute is a vocoding function.

9. The apparatus of claim 6 wherein the multiple operating parameters are in a prioritized order.