Optimization of transmission parameters of a wireless interface based on communication type

Optimization of transmission parameters of a wireless interface based on communication type

BACKGROUND OF THE INVENTION Field of the Invention [0002] The present invention relates generally to wireless communication systems, and more particularly to optimization of a wireless interface within such communication systems based on the type of communication.

Wireless communication systems are known in the art. In conventional wireless communication systems, real-time services are typically implemented using a circuit switched infrastructure associated with at least one dedicated radio resource. However, a current trend in the industry is the use of so-called packet switched infrastructures to support wireless communication systems. In particular, the use of Internet Protocol (IP) may become an industry standard.

Although it can be expected that packet-switched technology be capable of supporting real-time services such as voice and/or video communications, a basic design constraint in any such system is the efficiency of the air interface. To this end, it has long been understood that the additional switching overhead used in packet switching techniques cannot be transmitted over the air interface. To improve efficiency, headers may be erased or compressed together when data represented in packet switched format is transmitted over the air. Moreover, it is known in the art that different types of source encoders result in encoded information having varying levels of error resistance. As a result, certain portions of the output of the encoder may be less precisely error protected than other portions, thereby providing an opportunity to improve the overall efficiency of the air interface.

In current communication systems, wireless subscribers or communication units communicate with a radio or radio access network (RAN), which typically communicates with a packet switched network forming part of the infrastructure. Often, the target of a communication unit is a client coupled to the packet network, typically via an intermediate packet switched network such as the Internet or the World Wide Web. In order to take advantage of the above-mentioned opportunities to optimize the air interface, the radio access network needs to have knowledge of the specific types of data being transmitted and received for a given communication. In this way, the radio access network knows how to best optimize the air interface using the radio communication units. However, in current systems, the radio access network does not have this knowledge because it is "hard-coded" invariably within the operation of the radio access network. In order to maintain maximum flexibility and still obtain the advantages of an optimized air interface, it would be useful to provide a technique for notifying the radio access network of communication types for separate radio communications between the communication units and the infrastructure.

1 is a block diagram of a wireless communication system according to the present invention;

2 is a flowchart illustrating the operation of a wireless communication system in accordance with an embodiment of the present invention;

3 is a block diagram of a wireless communication system according to the invention and based on a so-called universal mobile communication system;

4-6 are diagrams of protocol stacks and frame formats according to the prior art;

7 is a diagram of an exemplary protocol stack in accordance with the present invention;

8 is a diagram of an exemplary frame format in accordance with the present invention;

<u>DETAILED DESCRIPTION OF THE INVENTION</u>

The present invention provides a technique for notifying a radio access network about the type of communication between a communication unit and a network-based client. Based on this information, the radio access network can optimize the air interface between the radio access network and the communication unit. To this end, one endpoint of the communication may notify the radio access network of the type of communication. In a preferred embodiment, the notifying endpoint may include the communication unit itself or the client. Alternatively, the notifying endpoint may comprise a proxy acting on behalf of the communication unit or a call server acting on behalf of the client. Additionally, the type of communication may be embodied by information about the source encoder to be used during the communication. Preferably, the optimization of the air interface may be implemented through selection of an optimal error correction method or through compression and decompression of headers associated with a plurality of packet switching units constituting the communication. Network elements disposed within the radio access network are used to optimize the air interface based on the type of communication.

The present invention may be described in more detail below with reference to FIGS. 1 to 8 . Referring to FIG. 1 , a wireless communication system 100 is shown. In particular, the wireless communication system 100 includes a plurality of portable subscribers or communication units 102 in wireless communication with a wireless access network 104 . The radio access network 104 is in turn coupled to a packet switched network 106 , which itself is coupled to an Internet Protocol (IP) based network 108 . A plurality of clients 110 are coupled to an IP network 108 . The radio access network 104 may optionally be coupled to a circuit switched network 116 as shown.

Communication units 102 may include portable or portable devices (such as in-vehicle or portable radios or cordless telephones) capable of communicating with wireless access network 104 via one or more wireless channels 112 . desirable. Preferably, the wireless channels 112 are such as code division multiple access (CDMA), frequency division multiple access (FDMA), or time division multiple access (TDMA). one or more radio frequency (RF) channels implementing one of a variety of known protocols or access methods. As described in detail with reference to FIG. 3 , the radio access network 104 includes these elements of an infrastructure that manages wireless communications using communication units. As schematically shown in FIG. 1 , a radio access network 104 includes one or more network elements 114 that contribute to the operation of the radio access network. With respect to the communication units 102 , the radio access network 104 implements a radio interface via radio channels 112 , whereby the communication units 102 connect to the radio access network 104 as well as FIG. 1 . It is possible to communicate with the various packet switched networks and IP networks shown in Fig.

Packet switched network 106 is described in more detail below with reference to FIG. 3 , but features the use of headers to effect routing of data across the packet network. As is known in the art, such packet switched networks provide an efficient use of available resources compared to conventional circuit switched networks because the resources are not dedicated to specific communications for the duration of these communications. Likewise, IP network 108 is a packet-switched based network of the type commonly used on the Internet and the World Wide Web. Consequently, clients 110 may include computer devices capable of terminating the IP protocol as is known in the art.

When the communication unit 102 communicates and engages with the client 110 , either the communication unit or the client may be considered an endpoint of the communication. In conventional first and second generation communication systems, encoder/decoder (codec) devices are typically hard coded within the endpoints of the communication. For example, in many terrestrial portable wireless communication systems, voice compression codecs are used to maximize the spectral efficiency of voice data transmitted over an air interface. In these systems, since a single voice codec is provided, the air interface between the communication units and the radio access network is precisely optimized for that single source codec type. However, with the advent of real-time services such as voice over IP (VoIP), any one of a variety of source encoders may be used for a given communication. As such, the air interface provided by the radio access network may not be optimized for the source encoder selected for a particular communication.

To this end, the present invention provides a technique for notifying a radio access network of a communication type for a given communication so that the radio access network can continuously optimize the air interface. Referring now to Fig. 2, there is shown a flow diagram illustrating a process in accordance with the present invention. Preferably, the process depicted in Figure 2 is implemented using stored computer-executable instructions executed by a suitable processor in a suitable platform or platforms. Techniques for such implementation are known in the art. Accordingly, at block 202, the endpoint of the communication determines a communication type for the communication. In general, the type of communication may include any information sufficient to determine how the network element optimizes the air interface. In this preferred embodiment, the communication type is indicated by the type of source encoder to be used during communication. Typically, the type of source encoder to be used during communication is determined by the type of service and is explicitly (or implicitly) requested during call setup. For example, in voice-only communication by means of a specific class of communication units, a specific voice encoder may be used, for example the GSM full rate codec in GSM networks. Conversely, if the communication involves only video data, a suitable video encoder may be used, for example H.263 or MPEG 2.0 codecs. It is possible that a combination of multiple encoders may be used as in the case of communications involving voice and video data. It is also possible to change the selected source coder during a call. Regardless, the present invention can handle each of these scenarios. Endpoints may also include communication units or various entities acting on behalf of clients. As further described below with reference to FIG. 3 , devices such as wireless proxies and call servers may be used in place of the communication unit and/or client.

Regardless, in block 204, the endpoint for which the communication type for communication has been determined notifies the radio access network of the communication type. This may be accomplished through the use of explicit or implicit messaging methods. In the case of an explicit messaging method, a new message is created, or existing messages are modified to contain information indicating the type of communication to the radio access network, for example through the addition of an additional protocol layer or augmentation of an existing protocol layer. do. Thus, for example, if the communication unit is an endpoint that notifies the radio access network of the communication type, a new message may be created in the protocol used by the communication unit to communicate with the radio access network, the message being specific to the communication type. include information about In some situations, the communication unit essentially acts as a wireless modem for a device attached to the communication unit, which is the actual endpoint for the communication. In this case, the communication unit notifies the communication type by the attached device as necessary. Alternatively, if the client or a call server acting on behalf of the client acts as an endpoint that notifies the radio access network of the type of communication, an appropriate connection between the client (or the call server) and the radio access network (or an agent on its behalf) An explicit message specified in the protocol may be added. As will be described in more detail below with respect to FIG. 3 , packet switched network 106 may include a wireless agent acting on behalf of wireless access network 104 , which agent may include this specification from a client or call server. It is designed to receive incoming messages and continuously notify the radio access network of the type of communication.

In an alternative embodiment, instead of an explicit message sent by the endpoint to the radio access network, this indication is implicitly included in the information sent to the radio access network via the endpoint. Specific examples of this alternative are described below with respect to FIGS. 4 to 8 . In general, these implicit methods are characterized by the presence of sufficient information in each packet of data to indicate the appropriate techniques to be used to optimize the air interface.

Once the radio access network is notified of the communication type, in block 206 it optimizes the air interface between the radio access network and the particular communication unit involved in the communication based on the communication type information. In this preferred embodiment, this optimization is achieved by one or both of the two methods. In the first, an optimal error correction method is selected for the air interface based on the communication type. As is known in the art, data output by certain source encoders has varying degrees of sensitivity to errors induced during transmission of the data. For example, certain speech codecs provide output parameters that are relatively less sensitive to channel errors, while other parameters are very sensitive to channel errors. In order to maximize spectral efficiency when transmitting these parameters over the air interface, it provides a greater degree of error protection for these bits with a greater degree of sensitivity to channel errors, while providing a greater degree of error protection against channel errors. It is known that parameters with relatively insignificant sensitivities are either protected to a lesser extent or left unprotected together. Since this type of selective error encoding depends on the source encoder used, the present invention allows the radio access network to select an optimal error encoding method based on knowledge of its communication type. This knowledge may be predetermined, in which case the radio access network knows to apply a predetermined error correction method based on the type of communication provided to it by one of the endpoints. However, in a more generalized way, the radio access network may only have knowledge of various levels of error protection that it freely applies to data as needed. Thus, an appropriate level of error protection is based solely on knowledge of the different quantities of parameters within a given packet that can be provided to those within each class of error sensitivity. Specific examples of the concepts described above with respect to FIG. 2 are further described with reference to FIGS. 3 to 8 .

In the second optimization method, packet header compression/decompression is used. Such techniques, including Van Jacobson's header compression, are known in the art. Alternatively, again using known techniques, the headers are discarded together on the transmitting side and reproduced on the receiving side of the communication. Disposal and reproduction of headers is further described in pending US patent application Ser. No. 09/887,831, the teachings of which are incorporated herein by reference. Regardless, compression/decompression or erasure/reproduction techniques minimize the amount of data to be transmitted over the air interface, improving output and bandwidth usage efficiency.

Referring now to FIG. 3 , a wireless communication system 330 based on the Universal Mobile Telecommunications System (UMTS) model is shown. The wireless communication system 300 includes base station systems 302 , 308 , wireless network subsystems 304 , 306 , and a core network 310 . The core network 310 is coupled to an IP network 312 , which in turn may be coupled to one or more clients 314 and one or more call servers 316 . A plurality of communication units 328 may communicate with base station systems 302 , 308 and/or wireless network subsystems 304 , 306 . Each of the elements shown in Figure 3 is known in the art and has a well-defined functionality. Moreover, for purposes of the present invention, each element shown in Figure 3 includes processors and storage devices suitable for implementing software algorithms as is known in the art.

As shown, each base station system 302 , 308 includes a base station controller 320 coupled to one or more base transceiver systems 322 . As is known in the art, base station controller 320 controls the operation of base transceiver systems 322 including one or more radio transceivers used to implement a radio interface in accordance with the present invention. In a similar manner, each radio network subsystem 304 , 306 includes a radio network controller 324 coupled to one or more nodes 326 . Each node 326 is essentially a logical representation of a facility responsible for wireless transmission and reception within one or more coverage areas. The radio network controller 324 then controls the use and integrity of radio resources represented by the corresponding nodes.

The core network 310 preferably includes a packet switching unit (PS) shown on the right and a circuit switching unit (CS) shown on the left. As shown in FIG. 3 , the base station systems 302 , 308 may be coupled to the packet switching part of the core network 310 or the circuit switching part of the core network 310 . Conversely, each of the wireless network subsystems 304 , 306 may be coupled to both the packet switched and circuit switched portions of the core network 310 . As is known in the art, the packet switching portion of the core network 310 typically includes a plurality of support nodes. In particular, as shown in FIG. 3 , a serving support node 330 ( SGSN) is provided and coupled to a gateway support node (GGSN) 332 . The SGSN stores subscription information and location information necessary to implement packet-switched services for each communication unit registered with the SGSN. The GGSN 332 stores subscription information and routing information necessary for routing packet data traffic received from the IP network and destined for one of the communication units 328 . In the circuit switching section of the core network 310 , a portable switching center 334 performs functions to handle circuit switched services to and from the communication units 328 . Note that the present invention does not affect, nor is it affected by, the operation of the circuit switch of the core network.

In the inventive concept, the base station systems 302 , 308 or radio network subsystems 304 , 306 constitute the radio access network portion of the system 300 . Moreover, base station controllers 324 and base transceiver systems 322, or radio network controllers 324 and nodes 236, may implement functionality pertaining to a radio access network as described above with respect to FIG. Includes network elements suitable for The SGSN 330 may also function as a radio agent acting on behalf of the radio access network. As discussed above, using an explicit messaging method, an endpoint, such as communication unit 328 or wireless proxy 336, 318 acting on behalf of communication unit 328, may be a base station system 302, 308 or wireless network. An indication of the type of communication may be sent directly to the subsystems 304 and 306 . Alternatively, the client 314 or the call server 316 acting on behalf of the client 314 may be the serving support node 330 on behalf of the appropriate base station system 302,308 or wireless network subsystem 304,306. ) can also be sent an explicit message. As shown in FIG. 3 , wireless proxy 336 may be coupled to SGSN 330 or IP network 312 . In a typical application of a wireless proxy and call server, a communication unit may communicate with a wireless proxy to establish communications with a given client. The wireless proxy may then communicate with a call server acting on behalf of the client to establish communication. Once communication is established by the wireless proxy and call server, the communication unit and client may take control of the communication. Regardless of the mechanism used to establish communications between the communication unit and the client, implicit or explicit messaging methods may be used to advertise the RAN as described above. An example of an implicit messaging method based on modifications to existing protocols is further described with reference to FIGS. 4 to 8 .

Referring now to FIG. 4 , a protocol stack according to the prior art is shown. The illustration of Figures 4, 5 and 7 is based on the Open Systems Interconnect (OSI) model in which each protocol layer uses the layer below it and provides services to the layer above it. . The protocol stack shown in FIG. 4 can be exchanged between a radio network controller and a codec, typically located within the core network, and thus forms part of the so-called Iu interface. The codec protocol 402, which contains data frames generated by the codec, occupies the highest level in the protocol stack. In practice, the codec protocol 402 is passed explicitly through the radio network controller and terminated by the codec within the communication unit. The frame protocol 404 generates data packets according to the frame format and supports communication between the radio network controller and the codec within the core network. The lower protocol layers 406 and 408 corresponding to the data link layer and the physical layer, respectively, as specified in the OSI model are provided as known in the art.

On the other side of the packet switching section of the core network, from the core network 310 to the IP network 312 via the GGSN 332, a protocol stack similar to that shown in FIG. 5 may be used. As above, the codec protocol 502 occupies the highest level in the protocol stack. In this case, the codec protocol 502 constitutes data frames originating by a codec within the communication unit and terminated by a client residing on a packet switched network. Frames generated by the codec are encapsulated by a real-time protocol (RTP)/user datagram protocol (UDP)/IP encapsulation layer 504 . RTP/UDP/IP encapsulation allows data to be properly routed when transmitted over an IP network. As in FIG. 4 , the lower protocol layers 506 and 508 are provided again as needed.

A typical prior art codec frame format is further described with reference to FIG. 6 . In particular, the frame format shown in Figure 6 is typical of those found in conventional circuit switched systems. For the purposes of the present invention, the frame format of Figure 6 illustrates the concept of sub-flows corresponding to a given communication. In this case, the user plane protocol header 602, which forms part of the Iu interface, specifies which communication belongs to a particular set of sub-flows 604 to 608, i.e. which communication unit is established for this communication. do. Each sub-flow preferably corresponds to a different level of error sensitivity, and therefore a different level of required error protection. For example, in an Adaptive Multirate (AMR) codec used to encode speech, there are three different layers of error protection. The concept of sub-flows is developed by the present invention as a means of providing an implicit indication of the type of communication to the radio access network.

Referring now to Figure 7, a protocol stack in accordance with the present invention is shown. In particular, like the protocol stack shown in FIG. 5 , the protocol stack of FIG. 7 supports communication between the core network and the IP network. Accordingly, the codec protocol layer 702 is encapsulated again in the RTP/UDP/IP header information by the RTP/UDP/IP layer 704 . However, a so-called enhancement frame protocol layer 706 is inserted between the RTP/UDP/IP layer 704 and lower layers 708 , 710 . The enhancement frame protocol layer 706 , also shown in FIG. 8 , communicates information specific to RTP/UDP/IP encapsulation 802 on a packet-to-packet basis as an additional sub-flow to the frame format. Additionally, sub-flows descriptors 804 - 808 are also included that illustrate the nature of the data contained within each sub-flow forming part of the codec protocol 702 . With this knowledge, the radio access network can optimize error correction for data transmitted over the air interface when receiving the enhancement frame protocol layer. In this way, the radio access network can be informed of the communication type and thereby optimize the air interface. It is understood that the method shown in Figures 7 and 8 is merely one of many possible implementations of the implicit messaging method in accordance with the present invention, and is provided by way of example rather than limitation, as will be appreciated by those skilled in the art. note that

The present invention provides a technique whereby endpoints of a communication, or other entities on their behalf, notify the wireless access network of the type of communication between the endpoints, thereby allowing the radio access network to optimize the air interface. Compared to conventional systems, the present invention allows for considerable flexibility as to the types of services that can be provided, while ensuring that each such service is supported on the air interface in an optimal manner.

In the above description, the present invention has been described with reference to specific embodiments. However, it will be understood by those skilled in the art that various modifications and changes may be made without departing from the scope of the invention as set forth in the claims below. Accordingly, the specification and drawings are to be regarded in an illustrative rather than a restrictive sense, and all such modifications are intended to be included within the scope of the present invention.

Benefits, other advantages, and solutions to problems have been described above in connection with specific embodiments. However, the benefits, advantages, solutions of problems, and any element(s) that give rise to or further manifest any benefit, advantage, or solution are crucial, required, or essential of any or all claims. should not be considered as features or elements of As used herein, the terms "comprises", "comprising", or any other derivative thereof means that a process, method, article, or apparatus that includes a list of elements does not merely include these elements, but is such a process. It is intended to cover the non-exclusive inclusion in a manner that may include other elements unique to, or not expressly listed in, a method, article, or apparatus.