KR100927321B1 - Radio access communication systems and devices, and methods and protocols for use therein - Google Patents

Abstract

The wireless communication system 100, 200, 300 includes a wireless local area network (WLAN) operably connected to the cell-based wireless communication system 160. The wireless local area network (WLAN) is adapted to support the use of the control channel 360 for communication to or from the cell-based communication system 160. The dual-mode wireless communication unit 112, 116 is configured as being capable of communicating with a wireless local area network (WLAN) and cell-based wireless communication system 160 mode, so that a specific multicast address (MCCH-mcast) and port number (MCCH-port) is used on the control channel 360 for control channel communication by the dual-mode wireless communication unit 112,116. In this way, control channel communication is supported over the WLAN, providing a wide range of new additional performance and advantages to end users of WLAN compatible units.

Wireless communication system, cell-based wireless communication system, wireless local area network, dual-mode wireless communication unit, multicast address

Description

WIRELESS COMMUNICATION SYSTEMS AND APPARATUS AND METHODS AND PROTOCOLS FOR USE THEREIN

The present invention relates to a wireless communication system and apparatus and a method for use therein. In particular, the present invention relates to the use of control channels over a wireless local area network (WLAN). The present invention may be applied to, but is not limited to, facilitating and supporting control channel features such as group calls over a WLAN.

Over the years, the development of wireless communications has been dramatic. Many wireless communications have been standardized so that not only all communication units provide the same level of performance in a particular communication field, but also facilitate the interoperability of communication between different manufacturers. One technique for undergoing this rapid development and standardization is a wireless local area network (WLAN). The purpose of a WLAN is to provide wireless connectivity at bit rates faster than 100 Mbps. WLANs also provide improved security, improved mobility management, inter-operation with cellular networks, and the like. Thus, WLAN technology is expected to play a key role in the wireless data market for years to come.

Moreover, WLANs are currently being enhanced to provide guaranteed quality of service (QoS), which is an IEEE standard 802.11e / D8.0, “Part II: Wireless Media Access Control (MAC) and Physical Layer (PHY) Specification. : MAC QoS Enhancement "(February 2004). This is an additional reason why WLAN solutions for voice and video are quickly created in the data market.

A wireless communication system (e.g., cellular telephony or private mobile wireless communication system) includes a system infrastructure comprising a plurality of base transceiver stations and a plurality of subscriber units or terminals (often a mobile station (MS)). Provide a wireless communication link that is prepared between. An example of a zone / cell-base wireless communication system is the TETRA system, which operates according to the TETRA standards and protocols defined by the European Telecommunications Standards Institute (ETSI). The main focus on TETRA devices is that they are emergency services because TETRA provides dispatch and control services. The system infrastructure of the TETRA system is referred to generically as the Switching and Management Infrastructure (SwMI), which includes substantially all of the communication components away from the MS. Likewise, cellular systems such as global system for mobile communications (GSM) are also based on cell-based methods.

Communication through such a wireless communication system is typically performed through two types of logical channels, which are one or more traffic channels that carry data to / from the MS, and signaling information, available frequency information. One or more control channels for conveying information about the use of the communication system, such as timing information. Different channels can be used for communication of different types of information.

In particular, the information may represent speech, sound, data, picture or video information. Data information is primarily digital information (ie, the type of user information processed on a personal computer) representing handwritten words, numbers, and the like. In addition, signaling messages are delivered. These are messages related to the communication system itself, for example for controlling how user information is conveyed in accordance with selected industrial protocols such as TETRA.

A communication terminal processing protocol is required so that data is transmitted over a communication network through a data communication channel. In general, an address is assigned to a communication unit, which is read by a communication bridge, gateway and / or router to determine how data is to be sent to an addressed destination communication unit. Such data transmission needs to be provided efficiently and efficiently to optimize the use of limited communication resources. Currently, the most popular protocol used to transmit data in communication systems is the Internet Protocol (IP).

IP adds a data header to the information conveyed from the transport layer. The resulting data packet is known as an internet diagram. The header of the diagram contains information such as the destination and source IP address and the version number of the IP protocol. Each data exchange typically includes transmitting one or more data packets on an uplink channel and transmitting one or more data packets on a downlink channel. A Packet Data CHannel (PDCH) in a TETRA network can serve several MSs at the same time. In this regard, the resources of the PDCH are shared between MSs on a channel on a statistical multicast basis. This allows air interface resources to be used in an optimal manner.

As an example, the TETRA known signaling procedure used to access the PDCH first requires the MS to request access to the PDCH via a main control channel (MCCH), which primarily transmits a control signaling message. Following an access grant by SwMI and sending the appropriate signaling message to the MS, the MS can then be moved to the PDCH where data packets are exchanged by the receipt of the signaling message.

In TETRA packet data communication, the physical data channel carries both system control signaling and data payload (user delivery information). The two types of traffic can be given different attributes along with control signaling, which is primarily assigned higher priority. TETRA packet data communication is now at up to 28.8kbits / sec, which is considerably slower than some other wireless communication technologies such as WLAN.

Cell-based technologies, such as private mobile radio systems or cellular systems, do not operate over a WLAN. One reason for this is that WLAN systems do not support control channels.

The inventors thus recognize that there is a need for improved mechanisms and associated apparatus, methods and communication protocols to facilitate cell-based communication across WLAN systems (where the disadvantages / limitations described above can be mitigated).

According to a first aspect of the invention, a wireless communication system is provided. The wireless communication system includes a wireless local area network (WLAN) operatively coupled to a cell-based communication system and configured to support the use of one or more control channels by a WLAN.

According to a second, third and fourth aspect of the present invention, a wireless local area network (WLAN) access gateway configured to facilitate control channel communication via a cell-based communication system, such as a wireless cellular communication system or a private mobile wireless system. WAG), InterWorking Function (IWF), and wireless terminal, respectively.

According to a fifth aspect of the present invention, a method is provided for communicating using a control channel between a wireless cell-based system such as a private mobile wireless system or a cellular telephone system and a wireless local area network (WLAN).

According to a sixth aspect of the present invention, a protocol is provided for facilitating the aforementioned communication between a wireless local area network (WLAN) and a private mobile wireless system.

Further features of the invention are defined in the dependent claims.

Embodiments of the present invention will now be described by way of example only, with reference to the accompanying drawings.

1 is a schematic diagram of a WLAN inter-operating with a TETRA switching and management infrastructure (SwMI) constructed in accordance with a preferred embodiment of the present invention.

2 is an additional schematic diagram of a WLAN inter-operating with TETRA switching and management infrastructure (SwMI) including various logical interfaces.

3 illustrates a mechanism for supporting a primary control channel (MCCH) in a WLAN in accordance with a preferred embodiment of the present invention.

4 illustrates a protocol architecture of a ToW terminal according to a preferred embodiment of the present invention.

5 illustrates a preferred packet structure for use within TETRA over WLAN architecture,

6 illustrates a preferred packet structure of a control-plane packet transmitted by the IWF, including a D-SETUP message.

7 and 8 illustrate an exemplary signaling flow of TETRA across a WLAN system, in accordance with a preferred embodiment of the present invention.

In summary, the preferred embodiment of the present invention proposes to integrate WLAN technology and radio cell-based communication systems and to use control channels to control communication between them. A preferred embodiment of the present invention is described with reference to the use of a control channel between a WLAN and a private mobile radio system, such as a TErrestrial Trunked RAdio (TETRA) system defined by the European Telecommunication Standards Institute (ETSI). The proposed system architecture of both WLANs interoperating with TETRA switching and management infrastructure (SwMI) is shown in the schematic diagram of FIG. Those skilled in the art will recognize that the inventive concept of the present invention can equally apply to any radio cell-based system capable of using a control channel such as a cellular communication system.

A preferred embodiment of the present invention proposes a dual-mode wireless communication unit. Dual-mode operation uses a first private (or public) mobile radio technology such as TETRA and a second WLAN technology. A wireless communication terminal, hereinafter referred to as a TETRA over WLAN (TOW) terminal 116, interfaces with a TETRA switching and management infrastructure (SwMI) 160 via a WLAN air interface 115. This is in contrast to a conventional TETRA terminal 132 that interfaces with the TETRA SwMI 160 via a conventional TETRA enhanced base transceiver station (EBTS) 135 over a conventional TETRA air interface and communication link 135. Thus, dual Mode TETRA and WLAN supported terminals are described.

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In the context of the present invention, ToW terminals 112 and 116 are any WLAN terminals that can interface with TETRA SwMI 160 and are configured to use TETRA services by the protocols and functions described herein. ToW terminals 112 and 116 are preferably associated with a WLAN by using a specific service set identifier (SSID). Preferred examples of SSIDs are described in IEEE Standard 802.11, 1999, entitled "Wireless LAN Media Access Control (MAC) and Physical Layer (PHY) Specification". By this particular SSID, the WLAN can distinguish between ToW terminals and non-ToW terminals to apply different routing and / or access control policies.

WLAN 110 preferably implements a specific routing enforcement policy for ToW terminals 112,116. That is, WLAN tunnels uplink packets from all ToW terminals 116 to the Interworking Function (IWF) 150 via the Ft tunnel. Thus, the Ft interface operates between WAG 142 and IWF 150 and implements a tunneling scheme that tunnels IP packets over IP network 140 between WAG 142 and IWF 150. It is preferred to be used.

While the preferred embodiment uses 'Ft tunnels', it is understood that any possible tunneling scheme could be used, for example IP encapsulation, GRE, and the like. If IWF 150 is interconnected with WAG 142 via a leased line, tunneling may be eliminated. Thus, packets originating from any ToW terminals 112 and 116 are routed to the IWF 150 via the Ft tunnel.

All ToW terminals preferably implement the protocol architecture and procedures described below to support TETRA services on the WLAN. Physically, the ToWs 112 and 116 may be any kind of wireless communication device (ie, personal computer (PC), laptop, PDA, dual-mode WLAN / TETRA terminal, etc.) having a WLAN interface. It is figured out.

From the SwMI point of view, ToW terminals 112 and 116 can be considered as any TETRA terminal. That is, it is preferable that the ToW terminals 112 and 116 be assigned a TETRA ISSI (Individual Short Subscriber Identity). Accordingly, the ToW terminals 112 and 116 can initiate and participate in a group call and the Short Data Service. Message may be received / transmitted, and in general, all authenticated services provided by TETRA SwMI 160 may be used. Thus, ToW terminals 112 and 116 may communicate with other ToW terminals, conventional TETRA terminals, dispatchers, PSTN users, and other TETRA entities in accordance with subscriber profiles in SwMI 160.

ToW terminals 112 and 116 preferably use all known TETRA services, including group calls, SDS messaging, packet services, and the like. In terms of SwMI, ToW terminals 112 and 116 are no different from any other conventional TETRA terminals 132.

Advantageously, the characteristics of the WLAN air interface 115 include high speed data services, simultaneous voice and data, improved voice quality, reduced call setup and voice transmission delays, simultaneous reception of multiple group calls, voice and / or data It enables expanded capabilities and new features, such as monitoring primary control channel (MCCH) traffic. Thus, TETRA terminals (eg, ToW terminals 112, 116) benefit from the advantages of known WLAN technologies.

ToW terminals 112 and 116 operate at a WLAN site, which may be considered a geographic area where WLAN coverage is provided and controlled by a single WLAN access gateway 142. WLAN sites typically include one or more APs. ToW terminals 112 and 116 have a wireless interface to the WLAN access point 114. The WLAN access point 114 interfaces with the WLAN terminal via any kind of WLAN interface, for example using IEEE 802.11 WLAN technology, which is a " wireless LAN media access control (MAC) and physical layer (PHY) specification. Is published by the IEEE in the IEEE Standard 802.11, 1999 edition. The WLAN access point has an interface 115 to one or more WLAN access gateways 142 to the Internet Protocol (IP) network 140. IP network 140 is operatively connected to TETRA SwMI 160 via key components of the proposed system (ie, Interoperability Function (IWF) 150).

IWF 150 is configured to interface 155 with SwMI in a manner similar to conventional TETRA base station 134. IWF 150 also interfaces with one or more WLAN access gateways (WAGs) 142. In effect, the WAG 142 controls a single WLAN site as a router, or a combination of routers and Ethernet switches. The WAG typically interfaces with one or more APs 114 over an Ethernet 100BaseT medium. Preferably, one WAG is assigned to each WLAN site. When there are ToW terminals in a WLAN site, the WAG 142 preferably creates an Ft tunnel with the IWF 150. It is understood that any known tunnel establishment protocol may be used, for example PPTP, L2TP, IPsec. WAG 142 then applies the appropriate routing enforcement policy. In addition, if there are no ToW terminals in the WLAN site, the WAG 142 preferably releases the Ft tunnel to free up capacity. It is also understood that there may be fixed Ft tunnels that are created / unresolved dynamically.

Obviously, both WAGs and APs are off-the-shelf devices, and their configuration is typical for known WAGs and APs, with the exception of signal processing functions that support TETRA SSIDs and are configured to route such TETRA communications as determined by the SSID. It is

IWF 150 uses known IP multicasting techniques to send control packet data units (PDUs) and voice packets to ToW terminals 112,116.

Thus, in this manner, the mobile or fixed ToW terminals 112, 116, as will be apparent to those skilled in the art, are responsible for the typical services provided by the TETRA SwMI 160 by the corresponding software driver and application and the WLAN network interface 115. Can be accessed. ToW terminals 112 and 116 reuse multiple TETRA air interface protocols, which are described in ETSI document-EN 300 392-2 v2.3.10, "TETRA; Voice + Data (V + D); Part 2: Air Interface ( AI) ", ETSI (June 2003). Clearly, ToW terminals 112 and 116 reuse multiple TETRA air interface protocols on top of the WLAN air interface. TETRA SwMI 160 is preferably built with IP multicast and Voice-over-IP (VoIP) technology, so interfacing with IWF 150 is relatively concise, which will also be apparent to those skilled in the art.

Interaction function (IWF) 150 is a key functional component that interfaces with TETRA SwMI 160 via any suitable interface, such as a proprietary interface, and also interfaces with one or more WAGs 142 via an Ft interface. Clearly, one function of the IWF 150 is to hide the characteristics of the WLAN from the SwMI 160 so that they are easily integrated with the SwMI 160.

As mentioned above, a preferred embodiment of the present invention proposes to integrate a WLAN technology with a radio cell-based communication system (eg, a PMR system such as TETRA) and to use a control channel to control communication between them. . The use of control channels between WLAN and TETRA systems is described in more detail below.

Referring now to FIG. 2, a further schematic diagram of a WLAN interoperating with TETRA switching and management infrastructure (SwMI) is shown, which includes the logical interface of the system of FIG. 1. As can be seen, many system / infrastructure components are similar to those described with reference to FIG. 1. Therefore, they will not be explained any more here.

Again, the WLAN preferably implements a specific routing enforcement policy for the ToW terminal by tunneling uplink packets from all ToW terminals to the Interaction Function (IWF) 150 via the Ft tunnel. Thus, the Ft interface preferably operates between the WAGs 142, 225 and the IWF 150. The private interface 155 is shown between TETRA SwMI 160 and IWF 150. It is understood that IWF 150 may also use logical links to ToW terminals 112 and 116 via Ut interfaces 210 and 215. In this regard, the Ut interfaces 210 and 215 support protocols and procedures for managing communication between the ToWs 112 and 116 and the IWF 150. As described below, the new protocol operates on these logical interfaces 210,215.

In addition, the logical interface Wt is applied to the communication link between the WAGs 142 and 225 and the ToW terminals. The Wt interface supports protocols and procedures for managing communication between (fixed or mobile) ToW terminals and APs. This interface preferably conforms to the IEEE 802.11 basic specification.

Referring now to FIG. 3, the use of a control channel between a WLAN and a cell-based communication system is shown in more detail. As shown in FIG. 3, there is one main control channel (MCCH) 360 in all conventional TETRA sites 340, and control signaling is associated with the conventional TETRA terminal 350 and its associated serving based transceiver (EBTS). 330). In particular, it is desirable to use MCCH 360 to convey some of mobility management signaling, authentication and key management signaling, call control signaling, short message signaling and packet data control signaling. It also broadcasts cell specific and network specific information to help the wireless terminal identify identification of the serving cell 330, identification of neighboring cells such as WLAN site 110, service levels provided by the serving and neighboring cells, and the like. It is preferred to be used to.

Thus, to enable TETRA services on a WLAN, it is necessary to provide a standard mechanism for transmitting all types of messages typically transmitted on conventional MCCH. For this purpose, a specific multicast address and port number (indicated by MCCH-mcast and MCCH-port, respectively) is used in communication 310, 320, which is predefined and pre-defined for all ToW terminals 112,116. Known.

Interworking function (IWF) 150 ensures that all information typically transmitted on downlink MCCH 310 is multicast on this predefined (MCCH-mcast, MCCH-port) socket. Once the ToW terminals 112 and 116 are associated with an access point (AP) 114 and assigned an IP address, it receives multicast traffic sent on this socket defined by the (MCCH-mcast, MCCH-port) pair. And process. This process is performed by a new protocol layer, referred to as the adaptation layer. In this manner, ToW terminals 112 and 116 typically receive information broadcast on the downlink of conventional MCCH channel 360.

This information helps to recognize the identification of the WLAN site 110 providing the cell-based service and determines whether it should register with this service. This information also helps ToW terminals 112 and 116 identify potential neighboring sites (implemented with WLAN or conventional TETRA technology) and monitor these sites in the context of its standard cell reselection processing.

The same (MCCH-mcast, MCCH-port) is used to send signaling using a conventional uplink MCCH at a conventional TETRA site. In particular, all ToW terminals 112 and 116 wishing to transmit uplink MCCH traffic 320 (e.g., a request for a new group call or a request for a new short message) are predefined (MCCH-mcast, MCCH). -port) Send a specific message to the socket. This message (similar to all uplink TETRA specific messages) will be routed to the IWF 150 by the WLAN infrastructure 114, 142, 140. IWF 150 also listens for (MCCH-mcast, MCCH-port) sockets and handles incoming traffic on these sockets. Accordingly, with IP multicasting and predefined multicast sockets, the functionality of the conventional MCCH channel is supported over the WLAN network.

Note that for the example of TETRA MCCH, the MCCH is implemented as a fixed TDMA channel. Accordingly, its performance is limited (the overall bit rate is 7.2 kbps). In order to provide increased control channel performance in a TETRA cell, an additional TDMA channel may be configured as a Secondary Control Channel (SCCH) to assist the operation of the MCCH. However, in a WLAN environment, the performance supported by the multicast channel (MCCH-mcast, MCCH-port) used to carry conventional MCCH traffic is very high, so there is no need to provide a secondary multicast channel.

Referring now to FIG. 4, an overview of a communication layer associated with TETRA communication via a WLAN system is shown. The preferred communication architecture is similar to the ETSI EN 300 392-2 TETRA specification. That is, the control panel 410 information includes the SNDCP 415, mobility management (MM) 420, and call management control entity (CMCE) 425. Mobile link entity (MLE) 430 and logical link control (LLC) layer 435 are also supported.

In the user edition 440, using a real-time protocol (RTP) or compressed RTP protocol 450, a TETRA ACELP (Adaptive Code Excited Linear Predicted) encoded speech block 445 according to ETS 300 395 is placed between the ToW and IWF. send. Typically, one voice block is generated every 30 msec. At the control panel, all TETRA air interface protocols are reused except TETRA MAC and physical layer protocols, which are not applicable to WLAN radio access. The LLC layer supports both basic link services and advanced link services, which are described in ETTSI, EN 300 392-2 v2.3.10, "TETRA; Voice + Data (V + D); Part 2: Air Interface (AI)", ETSI (June 2003). The LLC layer operates within ToW and IWF (partially within SwMI).

Clearly, a new layer of communication, namely the adaptation layer 460, is specific to the ToW system. The adaptation layer 460 provides the adaptation functionality required to require the TETRA air interface protocol to operate over the WLAN. The adaptation layer 460 is implemented in ToW and IWF and provides a service that includes a subset of the services provided by the TETRA MAC layer. In particular, TETRA SSIs are used to support TETRA-compliant encryption and addressing.

The adaptation layer interfaces with the UDP layer via a control-panel-service access point (CP-SAP) 465 and one or more user-panel-service access point (UP-SAP) 470. CP-SAP 465 carries control-panel traffic that is always present and not associated with an ongoing call, ie, control traffic typically delivered on a TETRA MCCH or SCCH.

According to a preferred embodiment of the present invention, this kind of traffic is transmitted using the application of the multicast IP address and port number, referred to as MCCH - multicast and MCCH - port , respectively, and described above with respect to FIG.

In contrast, user plane traffic is carried on the UP-DSP 470. At the start of a new call, a new UP-SAP 470 instance is created to support that particular call. The UP-SAP 470 instance uses a dynamically assigned multicast IP address and port number. As discussed below, this multicast IP address and port number are assigned by the IWF and passed to the ToW in a packet signaling the start of a new call. The UP-SAP 470 is dynamically generated to support user data, traffic and call association control traffic. Obviously, the UP-SAP 470 also supports control-panel traffic 410 associated with an ongoing call (eg, D-TX-CEASED PDU). The adaptation layer is used to distinguish between user- edition traffic and call-associated control traffic on the same UP-SAP.

The adaptation layer 460 in the ToW analyzes every received packet and identifies whether it should be further processed or dropped (based on the indicated SSI). If required to be processed further, the adaptation layer indicates whether or not decryption should be applied (ie, if the received message is encrypted), and if the received packet was received via UP-SAP, then it receives the received packet from the LLC. Forward to entity or RTP entity.

4 shows a further aspect of the protocol architecture of a ToW terminal. The WLAN physical layer 490 and the WLAN MAC layer 485 are used to establish a broadband wireless connection with the AP. These layers are preferably in accordance with the IEEE 802.11 specification described in the document published in IEEE Standard 802.11, 1999, entitled "Wireless LAN Media Access Control (MAC) and Physical Layer (PHY) Specification". However, it is understood that any WLAN can be used.

These layers are also described in IEEE Standard 802.11e / D8.0, "Part II: Wireless Media Access Control (MAC) and Physical Layer (PHY) Specification: Media Access Control (MAC) and Quality of Service (QoS) Enhancements" (2 2004) Follow a specific quality of service (QoS) improvement within a month).

These layers are also referred to as IEEE, "Port-Based Network Access Control", IEEE Standard 802.1x, 2001 Edition, and IEEE Standard 802.11i / D10.0, "Part II: Wireless Media Access Control (MAC) and Physical Layer ( PHY) specification: media access control (MAC) and security enhancements "(April 2004).

Connection to the IWF is provided by the IP layer by service routing and addressing, as shown in a paper by J. Postel entitled "Internet Protocol" published in RFC 791 in September 1981. The UDP layer provides error detection and multiplexing services, as shown in a paper by J. Postel entitled "User Datagram Protocol" published in RFC 0768 in 1980.

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The IP layer is implemented in ToW terminals, IWF and intermediate IP networks (see FIG. 1). The IP layer ensures that all IP datagrams from / to ToW are routed to / from IWF. If necessary, it can also enable different quality of service (QoS) routing to different kinds of IP datagrams, depending on the type of service (ToS) in their respective IP header. Such QoS services may be required to provide a preferred transport service for IP datagrams carrying voice packets.

Referring now to FIG. 5, there is shown a preferred packet structure 500 for use in a ToW architecture. In FIG. 5, the general format of the control-panel 510 and user-panel 550 packets exchanged over the Ut interface (ie, transmitted between the IWF and ToW terminals) is shown.

Control-panel packets 510 carry conventional TETRA LLC PDUs 530 encapsulated in IP / UDP. The structure of the adaptation layer header is a key component of the inventive concept described herein. The structure of all other protocol fields (e.g., IP 515, UDP 520, RTP, LLC, CMCE, MLE, MM, SNDCP 535) is designed to conform to known protocol specifications.

That is, the LLC, CMCE, MLE, MM, and SNDCP protocol fields are described in document ETSI, EN 300 392-2 v2.3.10, "TETRA; Voice + Data (V + D); Part 2: Air Interface (AI)", ETSI ( June 2003). The IP protocol field is further described in J. Postel's article, "Internet Protocol", RFC 791 (September 1981). The UDP protocol field is further described in J. Postel's article, "User Diagram Protocol", RFC 0768 (1980).

It is understood that other kinds of TETRA PDUs may also be encapsulated in control-panel packets to broadcast security related information such as, for example, Common Cipher Key (CCK) identifiers or Static Cipher Key (SCK) version numbers. .

Adaptation layer headers 525 and 565 are populated with the critical information typically contained in the TETRA MAC header. In particular, the adaptation layer headers 525, 565 preferably include an encryption mode field and a TETRA SSI field indicating whether the included LLC or RTP PDU is encrypted. In the downlink direction, the TETRA SSI identifies the TETRA address of the packet receiver (s), and in the uplink direction, the TETRA address of the packet originator.

In addition, the adaptation layers 525 and 565 preferably include additional information in the packet that signals the occurrence of a new call (of any kind). In this case, the adaptation layers 525 and 565 also preferably include the multicast address and port number used to transmit the voice packet of the upcoming call. Finally, the adaptation layer headers 525 and 565 preferably include an information field indicating whether there is an LLC PDU or RTP PDU encapsulated in the packet.

Referring now to FIG. 6, an example of how the various headers are populated in a packet 600 carrying a known TETRA D-SETUP message is shown.

The packet 610 is transmitted by the IWF, for example. Packet 610 indicates that a terminal with SSID = 46 635 creates a group call to GSSI = 8388888. The IP address 615 of the IWF is xyzw, and the multicast address and port corresponding to the well-known MCCH address and MCCH port 620 are designated MCCH-mcast and MCCH-port , respectively. This packet is sent by the IWF to all WAGs that have previously established Ft tunnels or only to WAGs that are known to have members of group GSSI = 8388888. Thus, the packet will ultimately be broadcast to all WLAN sites controlled by this IWF. Thus, all ToW terminals in these sites will receive and decode the packets. Thus, the ToW terminal belonging to GSSI = 8388888 will be configured to receive this user-version information for this group call by creating a new UP-SAP instance. The new UP-SAP 620 of the adaptation layer header is bound to the multicast address g1.g2.g3.g4 and port Gp.

In addition, the packet 650 is transmitted by ToW, for example. Packet 650 indicates that the ToW terminal has SSI = 46 to belong to GSSI = 8388888 group. ToW's IP address 655 is designated as a.b.c.d. In this packet 650, it should be noted that the adaptation layer 665 does not include a multicast IP address and port pair, since the packet does not generate a new call.

Referring now to FIGS. 7 and 8, an exemplary signaling flow of a ToW system in accordance with a preferred embodiment of the present invention is shown. In particular, FIG. 7 illustrates a signaling flow 700 that includes WLAN association and location update.

7 shows a typical signaling flow 700 occurring between the ToW terminal 710, the AP and WAG of the WLAN 715, and the IWF 720. The message in step 725 is sent when the WLAN terminal requests association with the WLAN using SSID = "TETRA". This preferably occurs when the WLAN terminal is powered up, ie when it chooses to change the radio access technology to leave the TETRA site and join to the WLAN site.

In step 730, the WLAN preferably acknowledges the request.

At point 1 735, if there is no existing Ft tunnel with a predefined address of IWF 720, WAG 715 creates such a tunnel. The WAG 715 also sets up a forwarding function to forward the next packet from the ToW 710 to the IWF 720 via the Ft tunnel. Next, as shown in steps 740 and 745, ToW 710 initiates a DCHP procedure and obtains an IP address. This IP address is typically assigned by the IWF 720 in step 745 using an internal DCHP server or possibly an external DHCP server.

At point 2 750, ToW 710 begins to receive a packet with a destination IP equal to MCCP-multicast and a UPD port equal to MCCP-port . The values of MCCH-multicast and MCCF-port are assumed to be preconfigured in ToW 710. However, it is appreciated that other means for transmitting these parameters to ToW 710 may also be developed if necessary.

After point 2 750, the adaptation layer in ToW 710 typically begins to receive and transmit packets 755, 760, 765, 770, 772, 775 containing TETRA traffic transmitted on the MCCH channel.

All packets received by the ToW terminal 710 on the socket (MCCH-mcast, MCCH-port) are sent by the IWF 720 (i.e. IPsrc = xyzw) and are typically sent on the TETRA downlink MCCH group call initiation message. Includes information such as system information messages, short messages, and more. In addition, all these packets contain a TETRA SSI (short subscriber identity) of the intended recipient or recipients, as well as a flag indicating whether the included LLC PDU is encrypted. As such, any packet received by IWF 720 on a socket (MCCH-mcast, MCCH-port) is sent by a separate ToW 710 and is typically a location registration request, call control message sent on a TETRA uplink MCCH. It includes information such as.

In FIG. 7, after the ToW 710 receives the first D-MLE-SYSINFO message 755, the ToW 710 determines identification information of the TETRA network and cell identification information corresponding to the WLAN 715. You decide to register in this cell. As a result, the ToW 710 sends the U-LOCATION-UPDATE-DEMAND PDU 760 to the IWF 720 to request that SwMI register / update its new location and renew its subscription to a particular TETRA talkgroup. Send to). As discussed above, this PDU 760 is sent to the same destination IP address as the MCCH-mcast and to the same destination UDP port as the MCCH-port. IWF 720 examines the SSI field to determine TETRA identification of ToW 710.

Next Messages D-AUTHENTICATION-DEMAND (765), U-AUTHENTICATION-RESPONSE (770), and D-AUTHENTICATION-RESULT (772) are used to authenticate the ToW (710) and create a dynamic encryption key in a way that follows the TETRA security specification. Serve Assuming authentication is successful, all messages following U-AUTHENTICATION-RESPONSE 770 are sent with enabled encryption.

Finally, in message 775, IWF 720 acknowledges receipt of a request prior to ToW 710 to update its location and subscription to a particular TETRA talkgroup 760. After this point, the SwMI network will send all other traffic for this ToW 710 through the IWF 720 to the WLAN 715. This traffic includes both control-panel messages, such as requests for personal or group calls, requests for short messages, as well as user-panel messages such as voice blocks.

Note that the message sequence is in accordance with the message sequence specified in the TETRA specification for authentication and location management. However, the message sequence is used by a cellular communication system or a cell-based communication system such as another PMR network (Project 25 (TIA.EIA-102.BAAA, "Project 25 FDMA Common Air Interface, May 1998)). It can be adapted to any message sequence.

Those skilled in the art will appreciate that FIG. 7 shows only simple examples of association request and location update messages, and is not intended to show all possible communications.

Referring now to FIG. 8, a signaling flow 800 is illustrated that includes a message sequence for group call initiation and participation. The signaling flow 800 illustrates communication between the ToW terminal 805, the AP and WAG of the WLAN 810, and the IWF 815.

An indication of a new group call 820 for ToW terminals belonging to group '8388888' is received at IWF 815. The destination multicast address and destination UDP port of the packet 825 are well known MCCH-mcast and MCCH-port, respectively. The adaptation layer header in this packet indicates that the new group call will use the IP multicast address g1.g2.g3.g4 and UDP port Gp. This is illustrated in the MCCH D-SETUP message 825 sent from the IWF 815 to the ToW terminal 805. All ToW terminals in the WLAN area of the IWF receive this packet whether or not they are involved in the call. ToW terminals belonging to group '8388888' and wishing to participate in this group call will create a new UP-SAP instance and bind it to the specified multicast address and UDP port (ie g1.g2.g3.g4 / Gp). . ToW terminal 805 with SSI = '90 'receives this group call.

After receiving the MCCH D-SETUP message 825, a series of IP multicast diagrams are sent from the IWF 815 to the ToW 805. Each diagram 830, 835 carries a voice packet from the generator. Diagrams 830 and 835, and possibly subsequent diagrams, indicate in the adaptation layer header that they carry encrypted RTP PDUs for groups with GSSI = 8388888.

Diagram message 840 is a call-associated control packet carrying a D-TX end PDU. The adaptation layer in ToW 805 understands that it carries an LLC PDU (unlike RTP PDUs) and thus forwards it to the LLC layer indicated in the information field. After the diagram message 840, the ToW 805 under consideration decides to control the group call and accordingly transmits an uplink call-associated control packet 845. The uplink call-associated control packet 845 carries a U-TX request PDU requesting permission for transmission from SwMI.

In response, SwMI grants permission to transmit to ToW 805 with a D-TX grant message 850. Accordingly, starting from message 855, ToW 805 transmits a series of user-version packets containing encrypted RTP PDUs.

In an improved embodiment of the present invention, security and authentication procedures can be easily integrated into TETRA on a ToW system. The authentication procedure can be easily supported by exchanging appropriate layer-3 messages, such as D-AUTHENTICATION DEMAND and U- / D-ANTHENTICATION RESPONSE, between the ToW and the IWF, which are described in ETSI, EN 300 392-7 v2. 1.1, "TETRA; Voice + Data (V + D); Part 7: Security" (February 2001).

During this procedure, the adaptation layer in the ToW is responsible for running the appropriate security algorithms and generating a Derived Ciphering Key (DCK). This key is then used by the adaptation layer to encrypt and decrypt all LLCs and PDUs over the Ut instance. Support for SCK and CCK is also possible. The CCK is generated by SwMI, which not only protects SSI identification, but also protects group addressed signaling and traffic.

In addition, another improved embodiment of the present invention will support individual and telephone interconnect calls in a manner similar to the signaling flow for group calls described above. Those skilled in the art will appreciate that other procedures and corresponding MCCH signaling flows (eg, for SDS and packet data transmission / reception) can be readily adapted and integrated using the principles and protocols described above. In particular, for packet data transmission, a specific set of multicast IP addresses and port numbers (specified as PDCH-mcast and PDCH-port, respectively) are assigned by the IWF and control channels when ToW requests access to the packet data channel. Can be delivered through.

Accordingly, the concept of the present invention proposes a mechanism for using a control channel when communicating between a cell-based communication system such as a WLAN and a TETRA network.

The foregoing architectures, devices, functional components, protocols and signaling flows that implement the inventive concepts described above tend to provide at least one or more of the following advantages:

(Iv) The integration of WLAN with cell-based networks offers a wide range of new capabilities and benefits that will create differences and competitive advantages.

(Ii) Office clerks and other business users may use dual-mode cell-based / WLAN terminals not only within an office environment but also locally and / or via a private WLAN.

(Iii) With WLAN, enhanced services are provided to end users. E.g:

(a) an enhanced voice encoding scheme (ie, no need for the limited performance constraints provided by cell-based traffic channels) to provide much improved voice quality;

(b) broadband data services may be supported;

(c) voice and data services may be provided simultaneously;

(Iii) Control traffic typically sent on cell-based MCCH may now be received while voice and / or data sessions are active. In conventional cell-based communication, the terminal of the voice session is also unable to receive control traffic on the main control channel (MCCH) because voice and MCCH traffic are sent on different channels. However, according to a preferred embodiment of the invention with cell-based communication over WLAN, this is now possible.

(Iii) Those skilled in the art will recognize that by IP multicast, multiple group calls can be monitored simultaneously by one user, and the like.

(Iii) WLAN features can extend the air interface performance and thus support multiple simultaneous cell-based voice / data calls in an efficient and cost effective manner.

(Iii) Those skilled in the art will also recognize that call setup delay and voice transmission delay can be significantly reduced. Thus, as WLANs support higher bit rates, control messages and voice datagrams are transmitted faster.

(Iii) the ability to support seamless roaming between WLAN access and conventional cell-based access: that is, mobiles use the conventional cell-based mobility management procedure to update SwMI to their new location. Incoming mobiles are handled in a similar way as they enter a new cellular location area.

(Iii) supplementary cell-based features (e.g. Late Entry, dynamic regrouping, etc.) can easily support some of them with SwMI processing or intervention (e.g. priority monitoring) Less.

(Iii) Cell-based terminals may simultaneously participate in group call (s), data session (s), and also typically receive information transmitted on the MCCH. This creates new capabilities not possible with conventional cell-based wireless systems.

(Iii) The preferred architecture has minimal impact on TETRA SwMI. IWF can be considered as a particular kind of cell-based base station that can easily interface with an SwMI core.

(Iii) Local Site Trunking (or fallback mode) in the WLAN area can be easily supported by appropriate IWF engineering (ie control channel and call processing without connecting to SwMI). ).

(Iii) Full compatibility between ToW terminals and conventional cell-based terminals is maintained.

While specific implementations of the invention have been described, those skilled in the art clearly recognize that variations and modifications of those implementations falling within the scope of the appended claims may also be readily applied.

Thus, a wireless terminal adapted to facilitate a wireless communication system, a wireless local area network (WLAN) access gateway (WAG), an interworking function (IWF), and control channel communication between a cell-based communication system and a wireless local area network (WLAN). Is described. Also described is a method of communicating between a wireless local area network (WLAN), a cell-based communication system, and a protocol therefor.

Claims (10)

A wireless communication system (100, 200, 300) comprising a wireless local area network (WLAN) operatively connected to a cell-based wireless communication system 160, The WLAN uses multicast control channels 310, 320 for communication to or from the cell-based wireless communication system 160 using IP multicast addressing. And configured to The wireless communication system (100, 200, 300) has a specific multicast address (MCCH-mcast) and port number (MCCH-port) is a dual-mode wireless communication unit (dual-) on the multicast control channel (310, 320) the dual-mode wireless communication unit 112, 116 configured to communicate with both the WLAN and the cell-based wireless communication system 160 to be used for control channel communication by mode wireless communication unit 112, 116. Characterized in that it comprises a, The dual-mode wireless communication unit 112, 116 can communicate with the cell-based wireless communication system via a WLAN and a terminal 116 through which the WLAN can communicate with the cell-based wireless communication system via a WLAN. Wireless communication system (100, 200, 300) associated with the WLAN by using a specific Service Set Identifier (SSID) to distinguish between missing terminals. delete delete The method of claim 1, The WLAN includes or is operatively connected to a WLAN Access Gateway (WAG) 142 and an Interworking Function (IWF) 150 configured to interface communication between the WLAN and the cell-based communication system 160. Wireless communication system (100, 200, 300). The method of claim 1, The plurality of dual-mode wireless communication units 112, 116 (Iii) set up group calls; (Ii) location registration procedures; (Iii) cell re-selection operation; (Iii) support call control messages; (Iii) mobility management signaling delivery; (Iii) authentication and key management signaling support; (Iii) short message signaling support; And (Iii) cell-specific or network-specific information brocasting; Configured to use the multicast control channel (310, 320) to perform one or more of the following. In a method of communicating between the WLAN and the cell-based communication system 160 by dual-mode terminals 112, 116 capable of operating via a wireless local area network (WLAN) and a cell-based communication system 160. In Providing a multicast control channel to facilitate control channel communications between the WLAN and the cell-based communication system 160 using IP multicast addressing, wherein the multicast control channel 310, 320 is provided. Providing the multicast control channel, characterized in that performed by an adaptation layer in a protocol used by the cell-based communication system (160); Assigning a WLAN association identifier to the dual-mode terminal (112, 116); And The dual-mode terminal transmits a specific multicast address (MCCH-mcast) and a port number (MCCH-port) on the multicast control channels 310 and 320 for control channel communication with the cell-based communication system 160. And using by (112, 116). delete delete The method of claim 6, Using the identifier to further distinguish by the WLAN between a terminal 112, 116 capable of cell-based communication via WLAN and a terminal not capable of cell-based communication via WLAN. A communication method characterized by the above. The method of claim 6, Further comprising authenticating the dual-mode terminals 112, 116 before allowing the dual-mode terminals 112, 116 to use the multicast control channels 310, 320. Communication method.

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