Method and apparatus for providing packet data communications to a communication unit in a radio communication system

We claim:

1. In a mobile radio communication system that includes a system controller, a packet data router, a communication unit, and a plurality of base sites, the plurality of base sites serving respective service coverage areas, the service coverage areas being grouped into a plurality of location areas, and each location area of the plurality of location areas including at least one service coverage area, a method for the packet data router to provide packet data communications to the communication unit, the method comprising the steps of:

receiving a first data packet intended for the communication unit;

processing a transport protocol layer of the first data packet;

determining whether the communication unit is presently involved in a packet data communication session based at least on information contained in the transport protocol layer of the first data packet;

when the communication unit is presently involved in a packet data communication session, providing the first data packet to the communication unit via a first base site serving a service coverage area containing the communication unit; and

when the communication unit is not presently involved in a packet data communication session, instructing the system controller to transmit a page to the communication unit via each base site serving a service coverage area of a location area containing the communication unit.

2. The method of claim 1, further comprising the steps of:

receiving, from the system controller, an identification of a second base site serving a service coverage area containing the communication unit, the second base site being a base site that received an acknowledgment of the page from the communication unit; and

providing the first data packet to the communication unit via the second base site.

3. The method of claim 1, wherein the step of processing the transport protocol layer comprises the step of determining a session type of a first packet data communication session that includes the first data packet, the session type being indicated within the transport protocol layer of the first data packet, and wherein the step of determining whether the communication unit is presently involved in a packet data communication session comprises the steps of:

determining whether the first packet data communication session has terminated based on the session type of the first packet data communication session; and

determining whether every other packet data communication session involving the communication unit has terminated;

the method further comprising the step of:

when the first packet data communication session and every other packet data communication session involving the communication unit have terminated, changing a current mobility status of the communication unit at the packet data router to produce an updated mobility status, wherein the updated mobility status indicates that the communication unit is to be paged prior to transmission of a subsequently received data packet.

4. The method of claim 3, wherein the session type is a transport control protocol, a user datagram protocol, or an Appletalk transaction protocol.

5. The method of claim 1, further comprising the steps of:

determining an application type of a packet data communication session that includes the first data packet, the application type being indicated within a header of the transport protocol layer of the first data packet;

determining whether at least a second data packet is to be received based on the application type; and

when at least a second data packet is to be received, maintaining a current mobility status of the communication unit at the packet data router, such that the current mobility status indicates that the at least a second packet, when received by the packet data router, is to be transmitted directly to the communication unit via a base site that received a most recent registration from the communication unit.

6. The method of claim 5, further comprising the step of:

when the at least a second data packet is received, transmitting the at least a second data packet to the communication unit via the base site that received the most recent registration from the communication unit.

7. The method of claim 5, wherein the step of determining whether at least a second data packet is to be received further comprises the steps of:

determining whether the at least a second data packet is received within a predetermined period of time after receipt of the first data packet; and

when the at least a second data packet is not received within the predetermined period of time, changing the current mobility status of the communication unit to produce an updated mobility status, wherein the updated mobility status indicates that the communication unit is to be paged prior to transmission of the at least a second data packet.

8. The method of claim 5, wherein the application type is a file transfer protocol, a trivial file transfer protocol, or a simple mail transfer protocol.

9. In a mobile radio communication system that includes a packet data router, a communication unit, a system controller, and a plurality of base sites, the plurality of base sites serving respective service coverage areas, wherein the service coverage areas are grouped into a plurality of location areas, each location area of the plurality of location areas including at least one service coverage area, a method for the communication unit to participate in packet data communications, the method comprising the steps of:

receiving, via a first base site, a first data packet from the packet data router during a first packet data communication session;

processing a transport protocol layer of the first data packet;

determining whether the communication unit is to remain involved in the first packet data communication session based at least on information contained in the transport protocol layer of the first data packet;

when the communication unit is to remain involved in the first packet data communication session, transmitting a registration message to the system controller upon entering a new service coverage area;

when the communication unit is not to remain involved in the first packet data communication session,

determining whether the communication unit is to remain involved in at least a second packet data communication session;

when the communication unit is to remain involved in the at least a second packet data communication session transmitting a registration message to the system controller upon entering a new service coverage area;

when the communication unit is not to remain involved in the at least a second packet data communication session,

monitoring a control channel to determine whether the communication unit is being paged to begin a third packet data communication session; and

transmitting a registration message to the system controller upon entering a new location area.

10. In a mobile radio communication system that includes a packet data router, a communication unit, a system controller, and a plurality of base sites, the plurality of base sites serving respective service coverage areas, a method for the communication unit to participate in packet data communications, the method comprising the steps of:

receiving, via a first base site, a first data packet from the packet data router during a first packet data communication session;

processing a transport protocol layer of the first data packet, wherein the step of processing the transport protocol layer comprises the step of determining a session type of the first packet data communication session, the session type being indicated within the transport protocol layer of the first data packet;

determining whether the communication unit is to remain involved in the first packet data communication session based at least on information contained in the transport protocol layer of the first data packet, wherein the step of determining whether the communication unit is to remain involved in the first packet data communication session comprises the step of determining, based on the session type of the first packet data communication session, whether the first packet data communication session includes additional data packets; and

when the communication unit is to remain involved in the first packet data communication session, transmitting a registration message to the system controller upon entering a new service coverage area.

11. The method of claim 10 wherein the session type is a transport control protocol, a user datagram protocol, or an Appletalk transaction protocol.

12. In a mobile radio communication system that includes a packet data router a communication unit a system controller, and a plurality of base sites, the plurality of base sites serving respective service coverage areas, a method for the communication unit to participate in packet data communications, the method comprising the steps of:

receiving via a first base site, a first data packet from the packet data router during a first packet data communication session;

processing a transport protocol layer of the first data packet;

determining whether the communication unit is to remain involved in the first packet data communication session based at least on information contained in the transport protocol layer of the first data packet;

when the communication unit is to remain involved in the first packet data communication session, transmitting a registration message to the system controller upon entering a new service coverage area;

determining an application type of the first packet data communication session, the application type being indicated within a header of the transport protocol layer of the first data packet;

determining whether at least a second data packet is to be received based on the application type; and

when the at least a second data packet is to be received, transmitting a registration message to the system controller upon entering a new service coverage area.

13. The method of claim 12, wherein the application type is a file transfer protocol, a trivial file transfer protocol, or a simple mail transfer protocol.

14. A packet data router for use in a mobile radio communication system that includes the packet data router, a system controller, a communication unit, and a plurality of base sites, the plurality of base sites serving respective service coverage areas, the service coverage areas being grouped into a plurality of location areas, each location area of the plurality of location areas including at least one service coverage area, the packet data router comprising:

a mobility database that identifies a mobility status of the communication unit;

a network protocol layer analyzer, coupled to each base site, that receives a first data packet intended for the communication unit, processes a network protocol layer of the first data packet, and determines a routing address of the communication unit based on information contained in the network protocol layer; and

a transport protocol layer analyzer, coupled to the mobility database, the network protocol layer analyzer, and the system controller, that receives the first data packet, processes a transport protocol layer of the first data packet, determines whether the communication unit is presently involved in a packet data communication session based on information contained in the transport protocol layer, instructs the network protocol layer analyzer to route the first data packet to a first base site identified in the mobility database when the communication unit is presently involved in a packet data communication session, the first base site serving a service coverage area containing the communication unit, and instructs the system controller to page the communication unit via each base site serving a service coverage area of a location area containing the communication unit when the communication unit is not presently involved in a packet data communication session.

Description Submit all comments and votes

FIELD OF THE INVENTION

The present invention relates generally to radio communication systems and, in particular, to providing packet data communications to a communication unit in a radio communication system.

BACKGROUND OF THE INVENTION

Radio communication systems, such as trunked radio systems or cellular systems, are known to include a system controller, a plurality of base sites, and a plurality of communication units, such as mobile radios, portable radios, or radiotelephones. Each base site serves a corresponding service coverage area and typically provides at least one traffic channel and a control channel to the communication units that are located within the base site's service coverage area. The traffic channels are utilized to convey information between communication units or between communication units and public switched telephone network (PSTN) subscribers. The control channel is used to convey system information between the communication units and a particular base site.

During a typical communication, a communication unit moves throughout service coverage areas of the system. The movement of the communication unit requires the system controller to track the location of the communication unit within the system to enable the system controller to alert the communication unit when a call involving the communication unit is received at the system controller. That is, the system controller must know approximately where the communication unit is located in order to assign an appropriate base site to support a communication for the communication unit.

One known approach to tracking communication unit movement is known as the coverage area update approach. The coverage area update approach requires a communication unit to report, or register, each time the communication unit enters a different service coverage area. The communication unit monitors the system control channel to obtain the identification of the base site serving the coverage area containing the communication unit. Upon observing a change in the base site identification on the control channel, the communication unit transmits an inbound message on the control channel to register with the system controller in the new service coverage area. Therefore, when a communication arrives at the system controller for a particular communication unit, the system controller simply transmits the communication to the communication unit via the base site serving the service coverage area containing the communication unit. Although this approach facilitates expedient call set-up because the system controller always knows the service coverage area within which a particular communication unit is located, the approach requires substantial inbound signaling on the control channel to maintain location reporting accuracy to within a base site's service coverage area. Excessive inbound control channel activity results in inefficient use of both the control channel and system controller resources that are necessary to process the abundance of registration messages. Due to its excessive inbound control channel activity, coverage area tracking is generally used only when tracking a communication unit that is actively participating in a communication.

Another known approach to tracking communication unit movement is known as the location area update approach. The location area update approach requires a communication unit to report, or register, each time the communication unit enters a different so-called location area. A location area typically comprises multiple base site service coverage areas and, accordingly, is serviced by multiple base sites. With this approach, the communication unit monitors the system control channel to obtain the identification of the location area containing the communication unit. Upon observing a change in the location area identification on the control channel, the communication unit transmits an inbound message on the control channel to register with the system controller in the new location area. Since the number of location areas is generally less than the number of service coverage areas, the communication unit registers proportionately less with the location area update approach than with the coverage area update approach. Thus, the location area update approach involves substantially less inbound control channel activity than does the coverage area update approach.

With location area tracking, when a communication arrives at the system controller for a particular communication unit, the system controller pages the communication unit from all the base sites serving the location area containing the communication unit. Upon receiving an acknowledgment of the page from the communication unit, the system controller transmits the communication to the communication unit via the base site that received the page acknowledgment. Thus, although the location area update approach reduces the amount of inbound control channel activity as compared with the coverage area update approach, the location area update approach increases the amount of outbound control channel activity (i.e., pages). Due to its excessive amount of outbound control channel activity, location area tracking is generally used only when tracking a communication unit that is not actively participating in a communication.

Packet data communications are becoming more popular in trunked radio communication systems. The nature of packet data communications is such that a single communication is comprised of multiple data packets. In such systems, the system controller is divided into two entities, the controller and a packet data router. The controller performs registration, paging, and other system control functions. The packet data router extracts a destination address (e.g., Internet protocol (IP) address) for each received data packet from a network layer (layer 3) of the packet and, in response to signaling from the controller, directs the received data packets to the appropriate base sites for subsequent transmission to the appropriate target communication units. In addition, the various data protocols utilized in the wireline packet routing network (e.g., the Internet) to convey the data packets often causes groups of packets of the communication to arrive at the packet data router/controller at different times. Thus, in many circumstances, the router/controller must contact the communication unit more than one time to provide the complete packet data communication to the communication unit.

In a packet data communication, a communication unit is considered to be actively participating in a communication only during the time when either the data packets are being delivered to the communication unit or the communication unit is transmitting its data packets. When the communication unit is awaiting additional packets to complete the communication, the communication unit is not considered to be actively participating in the communication. Therefore, when the system controller or packet data router is transmitting data packets to the communication unit, the communication unit utilizes coverage area tracking; whereas, when the system controller or packet data router is awaiting more data packets to the complete the communication, the communication unit utilizes location area tracking. Consequently, the system controller must page the communication unit on more than one occasion to deliver a single packet data communication. The subsequent number of pages undesirably increases the amount of outbound control channel activity per communication.

Therefore, a need exists for a method and apparatus of providing packet data communications to a communication unit in a radio communication system that efficiently utilizes inbound and outbound control channel resources.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a block diagram of an exemplary radio communication system that may beneficially employ the present invention.

FIG. 2 illustrates initial entries in a mobility database in accordance with the present invention.

FIG. 3 illustrates updated entries in a mobility database in accordance with the present invention.

FIG. 4 illustrates a block diagram depiction of a packet data router in accordance with a preferred embodiment of the present invention.

FIG. 5 illustrates a logic flow diagram of steps executed by a packet data router to provide a packet data communication to a communication unit in accordance with a preferred embodiment of the present invention.

FIG. 6 illustrates a logic flow diagram of steps executed by a communication unit to participate in a packet data communication in accordance with a preferred embodiment of the present invention.

DESCRIPTION OF A PREFERRED EMBODIMENT

Generally, the present invention provides a method and apparatus for providing packet data communications to a communication unit in a radio communication system. The radio communication system includes a system controller and a packet data router, both of which are coupled to a plurality of base sites. Each base site serves a respective service coverage area and the service coverage areas a grouped into a plurality of location areas. The packet data router receives a first data packet intended for the communication unit and processes a transport protocol layer (e.g., layer 4 in the well-known Open Systems Interconnection (OSI) model) of the first packet. The packet data router then determines whether the communication unit is presently involved in a packet data communication session based at least on information contained in the transport protocol layer of the first packet. When the communication unit is presently involved in such a communication session, the packet data router provides the first data packet directly to the communication unit via a base site serving a service coverage area containing the communication unit.

However, when the communication unit is not presently involved in a packet data communication session, the packet data router instructs the system controller to page the communication unit from the base sites serving the location area containing the communication unit. By providing a packet data communication to the communication unit in this manner, the present invention substantially reduces the amount of control channel activity (paging or registering) normally associated with delivering such a communication by examining the transport protocol layer (layer 4), as opposed to only the network protocol layer (layer 3), of the received packet to determine whether the communication unit is already involved in a packet data communication session and, thereby, locatable for direct transmission of the received packet without the need to page.

The present invention can be more fully understood with reference to FIGS. 1-6. FIG. 1 illustrates a block diagram of an exemplary radio communication system 100 that may beneficially employ the present invention. The radio communication system 100 includes a packet data router 101, a system controller 102, a plurality of base sites 103-109, and a plurality of communication units 120-122. Each base site 103-109 provides communication service to (i.e., serves) a corresponding service coverage area 133-139. The base site service coverage areas 133-139 are grouped into one or more location areas 150-151 (two shown). Thus, each location area 150-151 includes one or more of the base site service coverage areas 133-139 and, accordingly, one or more of the base sites 103-109. The base sites 103-109 are coupled to the packet data router 101 and the system controller 102 via communication links, such as T1 wireline, fiber optic, or microwave links.

In a preferred embodiment, the radio communication system comprises a trunked radio communication system, such as the "iDEN" platform that is commercially available from Motorola, Inc. The packet data router 101 preferably comprises a Motorola Data Gateway and the system controller 102 preferably comprises an "iDEN" Dispatch Application Processor. Although shown as two separate entities in FIG. 1, the packet data router 101 and the system controller 102 may be two parts of the same entity in an alternative embodiment.

The base sites 103-109 preferably support one or more trunking communication platforms, such as frequency division multiple access (FDMA), time division multiple access (TDMA), or code division multiple access (CDMA). In the preferred embodiment, the base sites 103-109 comprise "iDEN" Enhanced Base Transceiver Sites. The communication units 120-122 preferably comprise any wireless devices, such as wireless data terminals, radios, or radiotelephones, that are capable of receiving and transmitting (transceiving) data packets. In alternative embodiments, one or more of the communication units 120-122 may comprise a data terminal coupled to a wireless communication device.

Operation of the radio communication system 100 occurs substantially as follows in accordance with the present invention. When each communication unit 120-122 is initially activated, it registers with the system controller 102 by first identifying a serving base site from control channel transmissions of all the base sites 103-110, as is well-known in the art, and then transmitting a registration message to the system controller 102 via the identified serving base site. Upon receiving the registrations, the system controller 102 affiliates each communication unit 120-122 with its serving base site and the location area that includes the service coverage area of the serving base site. The system controller 102 then stores the registrations in a lookup table (not shown) located in the system controller's random access memory (RAM).

The registrations are also stored in a mobility database located in the packet data router 101. The mobility database provides a means for the packet data router 101 to determine the mobility status of a particular communication unit (i.e., whether the communication unit can receive a data packet directly or whether the communication unit must first be paged by the system controller 102). An exemplary, initial mobility database 200 is illustrated in FIG. 2. For the purposes of this discussion, it is assumed that communication unit 120 registers initially via base site 104, communication unit 121 registers initially via base site 107, and communication unit 122 registers initially via base site 108. The mobility status of each initially registered communication unit 120-122 is set to require paging of the communication unit in the event that the packet data router 101 receives a data packet data for the respective communication unit. The association of each communication unit 120-122 with its respective mobility status, number of open or ongoing communication sessions, and serving base site is provided by the entries 201-203 in the initial mobility database 200.

When the packet data router 101 receives a data packet for one of the communication units (e.g., 120) from some other entity, such as another one of the communication units (e.g., 121) or a subscriber to the Internet Protocol (IP) network 158 (e.g., via an integrated services digital network (ISDN) 154, an asynchronous transfer mode (ATM) network 155, or a public switched telephone network (PSTN) 156), the packet data router 101 processes a transport protocol layer (e.g., OSI layer 4) of the data packet. As is known, the transport protocol layer is typically used by a host (e.g., a computer coupled to the IP network) and an end user (e.g., communication unit 120) to open (set-up) and close (terminate) a communication session therebetween. By examining the transport protocol layer of the data packet, the packet data router 101 can determine whether the received data packet is opening, closing, or continuing a present packet data communication session.

For example, a header of the transport protocol layer typically indicates the session type and application type of the communication session containing the received data packet. When the session type is a transport control protocol (TCP), the end user automatically knows that multiple packets will be, or are being, conveyed and that the transport protocol layer indicates explicitly (e.g., via TCP header code bits) whether the data packet is opening or closing the communication session. When the session type is a user datagram protocol (UDP) or Appletalk transaction protocol, the end user does not know how many packets are involved (one or more) and must determine the application type of the communication session. For example, when the application type is a trivial file transfer protocol (TFTP) in UDP, multiple packets will be, or are being conveyed; whereas, when the application type is a control message protocol, only the received packet comprises the complete communication session. As is known, the end or termination of a multi-packet TFTP session in UDP is indicated by a packet containing less than 512 bytes.

When the transport protocol layer of the received packet indicates that the received packet is part of an ongoing communication session (i.e., is either continuing or ending the communication session), the packet data router 101 consults the mobility database 200 and provides the received data packet directly to the base site 104 indicated in the mobility database 200 as serving the target communication unit 120 (i.e., the communication unit 120 for which the data packet is intended). The base site 104 then transmits the data packet to the communication unit 120.

When the transport protocol layer of the received packet indicates that the received packet is opening a communication session, the packet data router 101 consults the mobility database 200 to determine whether the target communication unit 120 is presently involved in any other open communication sessions. When the target communication unit 120 is not presently involved in any other communication sessions (as shown in the target unit's entry 201 in the initial mobility database 200), the packet data router 101 instructs the system controller 102 to page the target communication unit 120 from each base site 103-106 serving a service coverage area 133-136 that is located in a location area 150 containing the communication unit 120. Accordingly, the system controller 102 pages the communication unit 120 from the base sites 103-106 over a paging control channel 162.

Upon receiving a page, the target communication unit 120 transmits an acknowledgment of the page over the paging control channel 162 to the system controller 102 via the base site (e.g., 104) servin