Packet switched handover in a mobile communication system, during which a mobile node receives packets from a source node and a target node

[0001] The invention relates to mobile communication systems. In particular, the invention relates to performing packet switched switching in a mobile communication system.

Description of the state of the art:

[0002] The introduction of conversation and streaming services in a global mobile communication system (GSM) has created a demand for efficient switching from the user's point of view in a GSM radio access network (GERAN). The packet data transmission service (GPRS) and the IP multimedia system (IMS) support streaming and conversation services from its side and impose requirements on the GERAN side. This is necessary to be able to carry out packet switched (PS) switching relatively often and to be able to minimize interruptions in the fixed packet stream to the mobile terminal. These gaps should preferably be short enough to allow the packet buffering mechanism in the mobile terminal to hide the gaps. Earlier in GPRS it was sufficient to provide a link-layer service without loss for interactive applications such as browsing (WAP, Wireless Application Protocol). In browsing applications, moderate additional delays caused by switching are acceptable. However, in streaming or conversational services, gaps in a packet class stream with an allegedly constant stream are immediately noticeable, provided, of course, they can be hidden by means of sufficiently large buffers at the ends of the receive links. However, always such buffering introduces a delay in the multimedia streams provided to the user. For voice conversation services, significant delays are unacceptable, especially considering other factors that introduce delay in the audio path, such as noise filtering and speech coding.

[0003] Reference will now be made to Figure 1, which is a block diagram illustrating the architecture and protocol stacks in the GPRS system in combination with GERAN. The GPRS system is described, for example, in 3GPP 23.060. Stacks of protocols are presented from the perspective of the aircraft user. Fig. 1 has a GPRS gateway support node (GGSN) 106. GGSN 106 is connected to an external network (not shown) via a Gi interface. The external network can be any IP network, for example the internet or intranet. Fig. 1 also has a GPRS service supporting node (SGSN) 104. GGSN 106 communicates with SGSN 104, which routes packets to and from mobile station (MS) 100 via the base station subsystem (BSC). SGSN 104 takes care of mobility-related tasks, such as having information about the location of mobile station 100, network registrations, updating location and routing area, activating and deactivating packet data (PDP), switching and paging of mobile station 100. Some of the above activities are of course performed from other elements of the network with which SGSN 104 communicates. GGSN is responsible for routing and tunneling packets to and from many SGSN 104 and other SGSN nodes. Routing is based on SGSN address information contained in the PDP information content contained in GGSN 106 for each network address active for MS 100, for example IP address or X.25 address or PPP connections.

[0004] In Figure 1, the uppermost protocol layer in MS 100 is the application layer (APPL). The application layer can be any protocol, for example WAP or Transmission Control Protocol (TCP) or Universal Packet Protocol (UDP). For example, http (Hypertext Transfer Protocol) can be sent via TCP / IP. Communication of the application layer takes place with the expected host, which can be located behind the Gi interface, for example on the Internet. Below the application layer is the IP layer, or alternatively the X.25 layer, which in GPRS is supported by both MS 100 and GGSN 106. The IP address for packets addressed to MS 100 indicates GGSN 106. The packet IP 114 is transferred to MS 100 from using GPRS user layer protocols below the IP layer. The IP 114 packet is transferred between GGSN 106 and SGSN 104 using the GPRS tunneling protocol (GTP). The GTP packet is carried forward to UDP / IP.

[0005] In the SGSN IP 114 packet, data is routed based on information about the location of MS 100 and forwarded to the layer of subnet-dependent convergence protocol (SNDCP, Sub-Network Dependent Convergence Protocol). SNDCP is specified in 3GPP specification 44.065. The SNDCP layer maps the characteristics of the network layer to the characteristics of the basic network. For example, SNDCP watches over the transmission and reception of the network protocol data unit (N-PDU) layer carrying IP packets. For example, the IP packet 114 is carried in the N-PDU 112. SNDCP multiplexes several packets of packet data transmission protocol for the same MS. Segments the IP 114 packet into LLC frames, for example the LLC 110 frame. It also merges packets from LLC frames. Header compression and packet usable area compression is also performed at the SNDCP layer. SNDCP negotiates parameters between MS 100 and SGSN 104. SNDCP caches N-PDU for services with confirmed mode.

[0006] Logical Link Control (LLC) provides a reliable connection between MS 100 and SGSN 104. LLC is specified in 3GPP specifications 44.064 and 04.64. The LLC layer is independent of the lower radio protocols and hides the BSS interface tasks and radio associated with LLC layer users. LLC supports variable length information frames. LLC supports both confirmed and unconfirmed data transfer, which is' confirmed and unconfirmed modes of operation. LLC offers services typical for the link layer containing parameter negotiation, flow control in Asynchronous Balanced (ABM) mode, sequence control to maintain the order of LLC frames, accelerated delivery for high priority data, error detection, error correction and indication. LLC performs data confidentiality by encrypting the contents of the LLC frame. LLC also supports user identity confidentiality by using a temporary logical link identity (TLLI) instead of International Mobile Subscriber Identity (IMSI).

[0007] Relay Layer LLC PDU relays between UM and GB interfaces in BSS. Base station of the GPRS system. The protocol (BSSGP) layer defined in the 3GPP specification 08.18 forwards routes and QoS information between BSS and SGSN. For example, it conducts SGSN-related radio resource requests to BSS 102. It also carries LLC frames between BSS and SGSN. In addition to LLC, he also runs PDU signaling frames related to GRPS mobility management. The network (NS) layer transports the BSSGP PDU between BSS and SGSN. NS can be based on Frame Relay (FR). RLC sub - layer in the RLC / MAC layer provides radio technology dependent link between MS 100 and BSS 102. MAC sublayer performs requests and reservations of radio resources and LLC map frames on GSM physical channels. The task of the MAC layer is to ensure effective sharing of a common radio resource of many mobile stations. The RLC / MAC layer is specified in the 3GPP GSM 04.60 specification.

[0008] The Organization Standardization Partnership Project 3G (3GPP) currently defines

Commutation of packages for GERAN / GB mode. One of the most important aspects in packet switched transmission is duplicate packet forwarding to both the source BSS and destination BSS during the forwarding, which has not yet been fully covered by the specifications.

[0009] We now refer to Figure 2, which is a block diagram illustrating GPRS architecture problems associated with the state of the art of forwarding duplicate packets. Pursuant to the applicable GPRS rules, the LLC unit in the new SGSN can be started only so that the LLC connection is established at the request of the SNDCP entity or mutual entity LLC. An LLC unit can only be created in its initial state in which the connection has LLC variables of their initial values. In Figure 2 is MS 100, base stations (BTS) 224-228 and base controller stations (BSC) 210-214 in BSS 216. It is GGSN 200, which is connected to the IP 201 network. A downstream packet stream 246 is received from the IP 201 network for which real-time service is required. Initially, the +246 link packet stream is the tunnel to SGSN +202 as the 240 packet stream. Initially, the SGSN packet stream: 202 routes +240 to MS 100. via BSC and BTS 222. 212. in the form of a packet stream 242. using the terminating connection in LLC 230. LLC; which is PC 100. BSC 212 and BTS 222 are referred to as BSS 262 source. MS 100 communicates with BSC 212 via BTS 222. The handing over of BSC 212 performs tasks related to this transfer of determination and decision algorithms. In the forwarding of associated SGSN signaling, BSC is forwarded within BSS. Similarly, in forwarding related MS signaling communicates with BSC within BSS. Signaling between MS and BSC goes through BTS.

[0010] However, when the MS 100 receives a report indicating that a cell operated by BTS 224 has better radio quality it must start performing cell handover administered by BTS 224. The new cell is in the area of ​​the new SGSN 204.. After forwarding, the packet stream 246 should be directed to MS 100 from GGSN 200 via SGSN 214 204, BSC and BTS 224. BSC 214 and BTS 224 are also referred to as BSS 264 target. When the transfer is not completely complete, SGSN 202 should forward packets to both BSC 212 and SGSN 204. To be able to process packets from packet stream 240 SGSN 204 must receive them as GTTP tunnel packet stream 241 with SGSN 202. Packets from the GTP tunnel 241 packet stream are forwarded in SGSN 204 to its 254 original unit. The LLC unit starts from the initial state of the initial LLC of variable connections. GTP tunnel packet stream +241 is routed from SGSN 204. as packet stream 244. LLC connections transferred. The problem in transmitting packets duplicated mechanism described above is that the entity LLC 254 in the new SGSN, namely SGSN 204, has a different state relative to the entity, LLC 252 and unit 230 original. This means that LLC 230 MS 100 receives packets from two different independent LLCs. Corresponds to LLC entity 230 pairs in SM 100 is not able to receive packets simultaneously from two different entities, LLC, if the states of LLC units containing LLC variables are not synchronized. Individual states generally lead to rejection of LLC stream frame transfer 244 packets or receiving duplicate frames LLC in an uncontrolled manner.

[0011] This attenuation is caused by the fact that unit 252 sends LLC LLC frames by sequential numbers that coincide with the sequence numbers transmitted by unit 254, LLC, even if they are different LLC frames. Frames dismissed in unit 230 original also due to the fact that unit 254 sends LLC LLC frames using various encryption parameters. Because the encryption parameters are different, the 230 LLC unit is able to decrypt LLC frames and rejects them due to lack of Frame Check Sequence (FCS) verification. Another problem is that SGSN 204 is unaware of LLC frame sizes negotiated between MS 100 and SGSN 202. If SGSN 204 uses values ​​that exceed the maximum values ​​supported by MS 100, it discards all LLC frames. This in turn can lead to release from context

PDP transfer packets streams 240, 241, 242 and 244. MS 100 can additionally also perform a reset.

[0012] As explained in the 3GPP specification 44.064, the encryption parameters for LLC frames include IOV LFN, OC and SX. IOV is an Input Offset Value that is a 32-bit value randomly generated by SGSN. LFN is the number of the LLC frame (LFN) in the header of the LLC frame. OC is the overflow that the meter is calculated and maintained independently in sending and receiving pages. OC for recognized work must be set to 0 when work in asynchronous mode is balanced restored to the appropriate Data Link Connection Identifier (DLCI). Connection Layer LLC is identified by DLCI, which consists of the Service Access Point (SAPI) and TLLI ID associated with MS 100. OC, is increased by 512 each time the corresponding LFN rolls over. Therefore, the OC is not sent directly to the LLC frame. The purpose of OC is to add changes to the encryption process to make it more durable. XOR SXmasks were calculated from the LLC entity identifier. There are two IOV values, one for numbered information frames related to recognized work and the other for unconfirmed information frames related to unconfirmed work. There are also two long name values, one for recognized work and the other for unconfirmed work. There are four OC counters associated with each DLCI. There is one OC meter per operating mode which is either unconfirmed or confirmed and the direction of transmission which is either uplink or downlink.

[0013] Naturally, the session key Kc used in the encryption algorithm is one of the encryption parameters.

[0014] The following description refers to Fig. 3, which is a signaling diagram illustrating signaling during handover of switched packet calls in accordance with current 3GPP proposals. Current proposals are described in document TSG GP032710 "switched packet forwarding for GERAN / GB, Stage 2 mode" version 0.2.0, 2004-01. Signaling architecture has as shown in Figure 2. The MS 100 sends radio quality information related to measuring neighbor cells to acquire BSS 262 via 301 message. Based on the measurement of the information source, BSS 262 determines that a transfer is needed. At T0, BSS 262 specifies that the handover is done in a new cell that is "in the area of ​​the new SGSN, which is SGSN 204. BSS 262 sends a PS message forwarding required 302 to the old SGSN 202. The message contains, for example, the source cell, target cell, TLLI, cause and transparent container SGSN 202 determines based on the target cell whether the transfer is a transfer within or between SGSN. SGSN 202 identifies the identity of the new SGSN and sends Prepare a PS 303 Handover Request message from SGSN 204:. SGSN 204 sends a PS Required 304 transfer message that returns target BSS 264 reserving radio resources for MS 100 in the target cell. When radio resources have been allocated successfully, the target sends BSS 264 Forwarding PS Request confirmation message 305 indicating successful allocation. SGSN sends Prepare 204 PS Handover reply message 306 to SGSN 202, which informs, among other things, that SGSN 202 can to MS 100 to complete the handover command to the new cell. SGSN 202 receives message 306 at t1.

[0015] At the same time, however, the packet from the GTP packet stream 307. will receive 202. SGSN. 202 SGSN forwards packets one after the other from the packet stream to SGSN GTP 307 204 308 as the packet stream. SGSN 204 forwards packets from packet stream 308 to BSS 264 as packet stream 309. The BSS target sends packets from 308 to the MS 100 packet stream as the packet stream 310. There is a delay MS 100 is able to receive packets with the target SGSN 204 through BSS 264. SGSN 202 sends a PS 311 transfer message to BSS 262. The BSS source sends another PS transfer message to MS 100. Then, MS 100 tunes to the radio channel and the time slot allocated to the target BSS 264 target cell. As shown by arrow 312. Target BSS 264 sends information to MS 100 Physical for MS 100 for synchronization. After MS 100 is synchronized, it sends a PS Forwarding End message to target BSS 314 264 at time t2. Only after time t2 MS 100 is ready to receive packets by the target BSS 264 Normally, from which it follows that the delay is unacceptable, unless MS 100 receives packets through both BSS 264 and BSS 262 sources. Purpose BSS 264 sends a PS 315 Transfer Completion message to SGSN 204. Then, SGSN 204 performs PDP context update messages represented by arrows, 316 and 317 of GGSN 200. The PDP context change indicates GGSN 200 address of the current SGSN 204. After receiving PDP context update at time t3, GGSN 200 is able to start routing GTP 318 packet stream to SGSN right, which is now SGSN 204. Then, MS 100 receives the destination BSS 320 of 264 packet stream that it received from SGSN: 204 as the 319 packet stream.

[0016] The following description refers to Fig. 4, which is able to diagram illustrating the delay associated with a solution that simply forwards packets from the source node to the destination node during switching processing. This solution is similar to the solution used in the UMTS system in connection with the Serving Radio Network server SRNS transfer. SRNS transfer is explained in 3GPP 23,060. In fig. 4 source node 452 receives the packet stream 401 sent by the upper node 450, which is connected to the IP 451 network. At t0, the top node sends a specific packet 460 in packet stream 401. The source node also sends the packet stream 402 to MS 100 via access network 456. At the time t1, MS 100 will decide to start using destination node 454 instead of source node 452 to receive packet streams. At time t1, MS 100 acknowledges the source 452 received by the last frame using message 403. Package 460 was not received, for example the last frame from package 460 may be in progress. MS 100 sends a request message 403 to the source node 452 indicating cancellation of the source node 452 to the traffic MS 100. After receiving the 403 message, the source node 452 begins forwarding all packets addressed to MS 100 via the destination node as packet stream 454 405. The packet stream 405 is forwarded by the destination node 454 to MS 100 as the packet stream 406. At time t2, MS 100 receives the first packet from MS 100 receiving the last frame via source node 452 at time t1. The time difference between t1 and t2 means a packet receiving gap in MS 100, and the time difference between t0 and t2 means a delay in receiving packet 460 from the upper node 450 to MS 100. The delays explained above are not acceptable for real-time services.

[0017] As illustrated in connection with Figs. 2, 3 and 4, there are problems with the implementation of the handover package switched using the current GPRS architecture and solutions proposed in the prior art. On the one hand, it must be possible for MS to simultaneously receive packets with the source node and the destination node in signaling switching. On the other hand, it is not possible in the current GPRS specifications and leads to the rejection of the sent frames on the MS website.

[0018] WO 01/35586 discloses a method and apparatus for facilitating network forwarding in a wireless network that uses packet switching and the use of common means such as slots and provides a network element for switching the mobile unit through a base station system by providing packet routing to many mobile units to facilitate the transfer of at least one mobile unit. The base station system uses memory containing the data requirement stored radio resources, for example, PDP context information, per mobile unit. By routing packets, storing and maintaining data of shared radio resources, a fixed requirement at the base station system level in the network, it is possible to perform network controlled switching without the control of a packet switched network that provides the base station system packages. The base station, for example, includes a transfer controller, a packet that communicates with a shared radio resource controller, adopted to provide packet routes of received data packets to many mobile devices. The memory is connected to a packet switching controller, containing stored radio resource requirements data, which contains PDP context information. The packet forwarding driver is used to determine the appropriate target cell for at least one mobile unit based on stored radio resource requirements data and attached PDP context information.

[0019] Reference US 6137783 discloses a system and method to reduce or eliminate mobile terminal portability of mobility management information caused by temporarily blocking interference of communications signals. When the distance of the mobile terminal from the base station serving the first network system exceeds the distance threshold, the mobile terminal is from the other base stations (supporting other network systems) are so determined, and the shortest distance corresponding to the second network system is selected and the control passed. Mobility management information on the mobile terminal, but living in the first network system, remains in the first network layout after the transfer of control information is available through the second network system by switching packets with each other first and second network systems.

[0020] US 2003/091011 discloses a communication network that is able to efficiently and effectively support the mobility of user wireless terminals between access point nodes in a packet switched network with minimal load and packet loss. The communication network uses a core network with packet switching and multiple access points in combination with a core network. Each access point is adapted to provide any user terminal with access to wireless core network communication when that user terminal becomes associated with that access point. The system and method furthermore apply ad-hoc routing techniques when switching the wireless user terminal between point nodes backbone access to enable networks to maintain multiple data transmission paths, by which packets are delivered to the user terminal during switching to substantially eliminate the packet loss during switching. US 2003/091011 relates to IP layer mobility based on address resolution cache.

[0021] Reference US 2002/066011 discloses a method in which, when setting up a connection from a first radio access network, a multi-mode mobile station sends an initial unsecured signaling message that contains information about these encryption algorithms that a multi-mode mobile station serving during communication in the second radio access network. The first radio access network stores some or all of the information. Then, it creates and sends a protected integrity message that contains information about the encryption algorithms supported by the multi-mode mobile station in the second radio access network. [0022] Reference US 2002/115460 discloses a method in which, in a radio access network of a cellular communication system, the radio network controller determines a nominal power level to be used by the base station in transmitting a common transport channel through a radio interface in the cell for a connection comprising a unit of equipment user . The nominal power level is set by the radio network controller, regardless of whether the base purification supports a differentiated power control system. A varied power control system allows the base station to selectively regulate the nominal power level, according to whether the cell served by the base station is the primary cell or primary cell to connect to the user equipment unit. When the cell is a primary cell, the base station adapts the nominal power level by subtracting the offset value from the nominal power level to determine the power level used to transmit the actual data on the common transport channel via the radio interface. In other embodiments, the correction value is obtained either by the radio network controller or locally configured to the base station.

[0023] Reference EP 0 978 958 is known for determining a control channel in a mobile communication system in which a mobile station treats multiple connections using a set of wireless communication resource sets in which a control channel is free formed between the mobile station and a network for transferring information controlling between them in such a way that the control channel is formed by one of sets of wireless communication resources, which are used for many calls through a mobile station.

Summary of the invention:

[0024] The invention relates to a method of making packet switched connections in a mobile communication network, comprising a mobile node, a first and a second packet switching node, the method comprising: detecting the switching state associated with said mobile node at the first packet switching node, a request for preparing a transfer , by said first packet switching node from the second packet switching node. This method is characterized in that it further includes: receiving at least one parameter for encryption from said first packet switching node, said second packet switching node, when said first node switch request packet, generating a switch from said second packet switching node, receiving logical link state information from said first packet switching node said second packet switching node, setting the logical link layer entity at said second packet switching node based on said logical layer layer binding information, and sends the logical binding frame from said layers of the first and second switching packet nodes to said mobile node in handover. [0025] The invention also relates to a method of making packet switched connections in a mobile communication network, comprising a mobile node, a first and a second packet switching node, the method comprising: detecting the switching state associated with said mobile node in the first packet switching node, a request for preparing the transfer, by said first packet switching node from the second packet switching node. This method is characterized in that the method further includes: receiving at least one parameter for encryption from said first packet switching node said second packet switching node, when said first node switch request packet generating switching from said second packet switching node, receiving a packet in said first packet switching node, forming a logical link layer unit protocol data (PDU) with data in said package, sending the first frame containing said Data Unit (PDU) logical link layer protocol to said mobile node from said first node packet switching; sending said protocol data link logic (PDU) device from the first node for packet switching said second packet switching node, and sending a second frame comprising said logical link data unit (PDU) logic layer to said mobile node from said second packet switching node.

[0025] The invention also relates to a method of making packet switched connections in a mobile communication network, comprising a mobile node, a first and a second packet switching node, the method comprising: detecting the switching state associated with said mobile node in the first packet switching node, a request for preparing the transfer, by said first packet switching node from the second packet switching node. This method is characterized in that the method further includes: receiving at least one parameter for encryption from said first packet switching node said second packet switching node, when said first node switch request packet generating switching from said second packet switching node, receiving a packet in said first packet switching node, forming a logical link layer unit protocol data (PDU) with data in said package, sending the first frame containing said Data Unit (PDU) logical link layer protocol to said mobile node from said first node packet switching; sending said protocol data link logic (PDU) device from the first node for packet switching said second packet switching node, and sending a second frame comprising said logical link data unit (PDU) logic layer to said mobile node from said second packet switching node.

[0026] The invention also relates to a method of making packet switched connections in a mobile communication network, comprising a mobile node, a first and a second packet switching node, the method comprising: detecting the switching state associated with said mobile node at the first packet switching node and requesting the preparation of transfer by said first packet switching node from the second packet switching node. The method is further characterized in that the method further includes: receiving at least one parameter from said first for encrypting node packet switching to said second packet switching node when said first node switch request packet producing switching with said second node packet switching; performing logical link parameters exchange between said mobile node and first packet switching node, and sending a logical link layer frame from said first and second node packet switching of said mobile node during handover.

[0027] The invention also relates to a method of making switched packet connections in a mobile communication network, comprising a mobile node, a first and a second packet switching node, the method comprising: forming a first logical link layer unit at said mobile node and hand-detecting the condition of said mobile node. This method is characterized in that the method further includes: receiving at least one encryption parameter from said first packet switching node said second packet switching node, when said first node switch request packet, generating a switch from said second packet switching node, creating a second logical connection unit layer, said mobile node, sending logical link layer frames from said first and second switching node packages to said mobile node during handover; detecting completion of the transfer, and re-negotiating the parameters of the logical link layer between said mobile node and said second packet switching node upon said detection of said handing when the logical termination parameters of the link layer are not appropriate.

[0028] The invention also relates to a system in which packet switched communication is performed between the first switched node packet and the second packet switching node. The system is characterized in that the system includes: a mobile logical node configured to receive a link layer frame with said first and second packet switching nodes in forwarding, a first packet switching node configured to detect the switching state associated with said mobile node, in order to prepare a switch request from said second packet switching node, for sending at least one parameter to encrypt said second packet switching, when the transfer preparation request node, from the second packet switching node, to send logical layer status information to the connection with said second packet switching node, and the second packet switching node configured to set the state in the logical link layer unit based on the logical state information said link layers.

[0029] The invention also relates to a system in which packet switched handover is performed between the first switched node packet and the second packet switching node. The system is characterized in that the system includes: a mobile node configured to receive the logical link layer of the protocol data unit (PDU) from the first packet switching node and the second switching node, the first packet switched node is configured to detect the switching state associated with said node mobile, requests to prepare a switch from said second packet switching node for sending at least one parameter, for encrypting said second packet switching, when the node requesting preparation of the switch from said second packet switching node to receive the packet, creating a logical link layer of the protocol data unit (PDU) with the data of said packet for transmitting the first frame containing said layer, the logical relationship of the data unit (PDU) ) to said mobile node, to send said logical data unit (PDU) logic to the second node switching packet and a second switching node configured to send packets a second frame comprising said logical layer data connection (PDU) unit to said mobile node from said second packet switching node.

[0030] The invention also relates to a system in which packet switched communication is performed between the first switched node packet and the second packet switching node. The system is characterized in that the system includes: a mobile logical node configured to receive a link layer frame from said first and second node packet switching during forwarding, the first node switching packet, configured to detect the switching state associated with said mobile node, requesting a switch preparation from said second packet switching node, to send every at least one parameter to encrypt said second packet switching, when the request node is prepared for switching from said second packet switching node to perform a logical parameter exchange connection between said mobile node and the first packet switching node and sending a logical link layer frame to said mobile node during handover, and the second node switching packet configured to send logical link layer frame to said mobile node during handover.

[0031] The invention also relates to a system in which packet switched handover is performed between the first switched node packet and the second packet switching node. The system is characterized by the fact that the system includes: a mobile node adapted to produce the first link layer logic device to detect the switching state to create a second link layer logical unit for detecting the completion of the transfer, to obtain the logical link layer of frames from the first packet switching node, and the second packet switching node in forwarding, the first packet switching node, configured to send at least one parameter to encrypt said second packet switching when the request node is prepared to switch from said second packet switching node and to send a logical layer frame element with said mobile node at the time of switching, second node switching packet configured to renegotiate logical link layer parameters between said mobile node and second node switching packet after said detection of said handover implementation when the logic parameters of the link layer are not appropriate. [0032] In one embodiment of the invention, the mobile node mobile terminal is, for example, a terminal UMTS GSM network terminal, GPRS terminal, WLAN terminal or terminal within any cellular radiocommunication system. [0033] In one embodiment of the invention, the mobile node is mobile a computer, such as a laptop, PDA or personal computer digital assistant (PDA).

[0034] In one embodiment of the invention, the cellular communication system is a General Packet Radio Service (GPRS), the first and second packet switching nodes are nodes supporting the GPRS service (SGSN) and the logical link layer is GPRS Logical Link Control (LLC) and the logical link parameter is Exchange Logical link Control (LLC) Exchange Identification (XID) negotiations. In one embodiment of the invention, the second packet switching node is a base station subsystem (BSS), a node, for example, a base station controller or base station. In one embodiment of the invention, the first or second packet switching node is a node that performs the forwarding and switching of data packets at the link layer. The invention is not limited to packet switching nodes that switch packets at the network layer level in a manner e.g. IP routers. The packets here have in this disclosure data packets pertaining to each protocol layer, e.g., network layer packets, link layer frames, Asynchronous Transfer Mode (ATM) cells.

[0035] In one embodiment of the invention, the exchange logic parameter cell is performed in response to detecting the forwarding condition at the first packet switching node.

[0036] In one embodiment of the invention, the first logical unit of the link layer at the cell node is removed after detection of switching completion. [0037] In one embodiment of the invention, at least one encryption parameter is received from the first packet switch node switching to the second packet switching node, when the first packet transfer node transfer request packet, from the second packet switching node. This means that at least one encryption parameter is transmitted from the first packet switching to the second packet switching in the specimen switch request message.

[0038] In one embodiment of the invention, the logical link layer information received from the first packet switching node to the second packet switching node, when the first switching node of the packet switching application specifying the second packet switching node. This means that the logical link layer information is sent from the first packet switching node to the second packet switching in the message requesting to switch the specimen.

[0039] In one embodiment of the invention, the cell exchange logic parameter is performed in response to a state in which the mobile node receives the LLC frame which has a duplicate flag. A duplicate flag indicates duplication of the LLC frame for forwarding purposes. In one embodiment of the invention, a duplicate flag accepted by the mobile node during handover is performed. Otherwise, the receiving flag results in an error indication to the mutual LLC-entity.

[0040] In one embodiment of the invention, the logical link layers are designated to the mobile node, in the first and second packet switching nodes they are represented by one or more Logical Link Control (LLC), logical link units Management Units (LLMEs) and multiplex unit with them related. On transmission, the multiplexing unit generates and inserts FCS, performs the function of an encryption frame and provides logical link control, layer resolution, SAPI-based rivalry between different logical link units. The functions implemented by the multiplexing unit and LLME are described in 3GPP 23.060.

[0041] In one embodiment of the invention, the control means in the first and second packet switching nodes comprise higher protocol layers above the link layer logical unit. For example, in SGSN, control means may include relay layer units, layer SNDCP units, and GTP layer units.

[0042] In one embodiment of the invention, the control means for the mobile node include higher layer entities of the user protocol relating to the GPRS plane.

[0043] In one embodiment of the invention, the signaling means for a mobile node include signaling protocols for communicating with the first and second packet switching nodes. The GPRS mobile terminal includes signaling means for signaling the control plane of GPRS protocol stack units. In one embodiment of the invention, the.actual mobility management and radio application of control logic are performed in control means or in separate control elements in connection with the signaling means. In this embodiment, the exchange of signaling messages is handled by separate means for this task.

[0044] In one embodiment of the invention, the signaling means in the first and second packet switching nodes include signaling protocols for communicating with a mobile node. In SGSN, the signaling means include a signal stack, the GPRS entities control protocol stack.

[0045] In one embodiment of the invention, the logical sending of link layer frames and other messages between the mobile node and the switching node packet takes place via a radio access network, so that frames and messages are transmitted through one or more networks, such intermediate elements as base station controllers, radio network controllers and base transceiver stations. In one embodiment of the invention, the first and second packet switching nodes are directly connected to base transceiver stations and directly direct radio network control procedures.

[0046] The benefits of the invention are associated with better quality of service. With the invention it is possible to provide a continuous packet stream to a mobile station during its forwarding.

Brief Description of the Drawings [0047] The attached drawings, which are attached to provide additional understanding of the invention and form part of the present description, illustrate embodiments of the invention and together with the description to explain the principles of the invention. In the drawings:

Lynx. . 1 is a block diagram illustrating the state of the art structure and stacks of protocols of the General Packet Radio Service (GPRS) system in connection with GSM / EDGE, radio access networks (GERAN);

Lynx. . 2 is a block diagram illustrating the General Packet Radio Service (GPRS) network architecture and problems in the prior art associated with forwarding duplicate packets;

Lynx. . 3 is a signaling diagram showing signaling during the forwarding of connections of switched packets from the prior art;

Lynx. . 4 is a signaling diagram illustrating the delays associated with a solution that simply forwards packets from the source node to the destination node during switching processing;

Lynx. . 5 is a signaling diagram illustrating one embodiment of packet switched using a transfer method, a state transfer in accordance with the invention; . Fig. 6 is a block diagram illustrating one embodiment of packet switched mode transfer using frames forwarding by a GPRS Serving support node (SGSN) in accordance with the invention;

Lynx. . 6 is a block diagram illustrating one embodiment of a packet switched mode of transfer, using a redirection frame directly to the target base station subsystem, according to the invention;

Lynx. . 7 is a signaling diagram illustrating one embodiment of a packet switched mode of transferring, using a logical cell parameter reset according to the present invention;

Lynx. . 8 is a block diagram illustrating one embodiment of a packet switched mode of transfer, using logical duplication of control units in accordance with the invention;

Lynx. . 9 is a signaling diagram illustrating one embodiment of a packet-switched transfer method using the duplicate frame indicator of the present invention;

Lynx. . 10 is a block diagram illustrating one packet switched embodiment using a context transfer forwarding method according to the invention; Lynx. . 11 is a block diagram illustrating one embodiment of packet switched using the frame transfer switching method according to the invention;

Lynx. . 12 is a block diagram showing one embodiment of a transfer method, packet switched using a logical delete link, according to the present invention; .

Lynx. . 13 is a block diagram illustrating one embodiment of packet switched using a transfer method, logical duplication of a link control unit according to the invention;

Lynx. . 14 is a block diagram illustrating one packet switched embodiment using the duplicate frame indicator switching method of the present invention;

Lynx. . 15 illustrates GPRS Serving Supporting Node (SGSN) in one embodiment of the invention;

Lynx. . 16 depicts a mobile node in one embodiment of the invention.

Detailed description of embodiments [0048] Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings.

[0049] Figure 10 is a block diagram illustrating one embodiment of packet switched transmission in which it uses state transfer using the signaling shown in Fig. 5. Signaling is performed by the GPRS system architecturn, as illustrated in Figure 2. At step 1000, it is checked if the transfer occurs. In the event that the MS 100 is forwarded, it sends quality measurements of the radio information transmitted to neighboring cells to the BSS 262 source via message 301. Based on the measurement of the information source, BSS 262 determines that a transfer is needed. The determination is performed using an algorithm that is performed in the base station controller (BSC) in the source string BSS 262. At T0, BSS 262 specifies that the handover is done in a new cell that is in the area of ​​the new SGSN, which is SGSN 204. The BSS 262 source sends the PS message Forwarding required 302 to the old SGSN 202. The message contains, for example, the source cell, target cell, TLLI, cause and transparent container. SGSN 202 determines based on the target cell when a transfer is made within or between SGSN. SGSN 202 identifies the new SGSN and sends Prepare a PS 303 204 Transfer Request message to SGSN.

[0050] In step 1002, related to the logical state of the link, LLC-204 units in SGSN are obtained. This is accomplished so that PS Forward Requests to prepare an LLC message carriers of item 500 status information. LLC items of 500 state information contains information that is used to synchronize LLC units in SGSN 202 and 204. SGSN. The information element 500 contains at least the session key Kc, the IOV values ​​of both modes of operation, both the IFN values ​​and the four OC values. The SGSN 204 information element stores 500 until SGSN 202 sends packets to it. Signaling of switching between network elements still as explained in connection with Fig. 3.

[0051] In step 1004, when the forwarded packet is first received from the SGSN 202, the LLC unit is initialized in SGSN 204. During initialization, SGSN 204 uses information element 500. Via information element 500 and LLC, status information in that SGSN is possible 204 constructing an LLC unit, which is a replica in an LLC-entity, in SGSN 202 from an MS 100 point of view. Then, the MS 100 is able to receive LLC frames of both LLC units without a noticeable difference. In one embodiment of the invention, the LLC unit in SGSN 204 is initialized and started after SGSN 204 received a 303 message and no packets are to be forwarded were still received by SGSN 204. In step 1006 SGSN 204 starts forwarding packets received by SGSN 202 using an LLC entity constructed and initiated in step 1006.

[0052] Figure 11 is a block diagram illustrating one embodiment of packet switched relaying, which utilizes frame relaying in a system as shown in Figs. 6a and 6b. At step 1100, SGSN 202 is waiting for messages from BSS 262 source indicating that the forwarding. In one embodiment of the invention, the handover indication can also be obtained from MS 100. After receiving the message, the method continues at step 1102. At 1102, SGSN 202 waits for an event in which the SGSN 202 receives packets from GGSN 610 200, which is the first user plane packet after the forwarding has started. In this case, the first LLC 614 frame that carries data from packet 610 is to be sent by SGSN 202. When an event occurs, packet 610 is received by the SNDCP unit 600 in SGSN 202 via GTP and a relay layer as IL-illustrated in Fig. 1.

[0053] The packet 610 is received by SGSN 202 through tunnel 240. The SNDCP 600 performs packet segmentation for packet 610 and other SNDCP-level tasks and sends a request to the 252-LLC to send the first frame LLC 614. The application is issued in the form of LLC data unit services (SDUs). In step 1104 LLC, unit 252 prepares an LLC-PDU using information contained in LLC-SDU and LLC units of 252 state variables. In step 1106 LLC, unit 252 sends the prepared LLC-PDU in the first LLC frame 614 to 262 and BSS BSC 212 sources in it.

[0054] In step 1108 LLC, unit 252 passes LLC-PDU in second LLC of frame 616 to frame forwarding unit 604 in connection with SNDCP of entity 600. Note that the second LLC 616 frame is a duplicate of LLC 614 frame. The 604 frame forwarding unit sends a second LLC SGSN 204 616 frame to use connection 241, which the original frame tunnels LLC - prepared by units 252 to SGSN 204. Connection 241 is, for example, a GTP tunnel established between SGSN 202 and SGSN 204 for transparent transmission of LLC frames. The second frame LLC 616 original will receive units 606 - 204 in SGSN. LLC - unit 606 is configured to receive an LLC frame via connection 241 and forwards it transparently to destination BSS 264. Transparent forwarding means in this case that the LLC entity does not change the field specifying the LLC framework of LLC 252 state. In one embodiment of the invention, the LLC PDU LLC relay formed from the frame 616 is not forwarded by the SNDCP protocol unit in SGSN 204. In another embodiment of the invention LLC-PDU from the frame

LLC 616 is forwarded via the GTP protocol of the SNDCP - LLC BSSGP entity chain for sending to target BSS 264.

[0055] In one embodiment of the invention shown in Fig. 6b, SGSN 202 passes the second LLC of frame 616 to direct BSS 264 directly. This is accomplished so that the connection 241B formed between SGSN 202 and 264 of the target BSS. This is achieved so that in step 1108 the method is omitted. Instead, in step 1110 LLC, entity 252 will pass the LLC-PDU in the second LLC of frame 616 to forward the frame of entity 604b in connection with SNDCP Entity 600. The frame forwarding unit 604b sends a second LLC BSS 616 264 frame to the target via connection 241B. Purpose BSS 264 is configured to receive LLC 616 frames and other duplicate LLC frames for forwarding and preparing them for transmission to MS 100.

[0056] Figure 12 is a block diagram illustrating one embodiment of packet switched relaying, in which it uses logic deletion achieved by means of the signaling link shown in Fig. 7. Signaling is performed via the GPRS system architecture, as illustrated in Figure 2. At step 1200, there is a check for a handover. In the event that the MS 100 is forwarded, it sends quality measurements of the radio information transmitted to neighboring cells to the BSS 262 source via message 301. Based on the measurement of the information source, BSS 262 determines that a transfer is needed. The determination is performed using an algorithm that is performed at the base station controller (BSC) in the source string BSS 262. At the time, this BSS 262 source specifies that the handover is to be made from a new cell that is in the area of ​​the new SGSN, which is SGSN 204. The BSS 262 source sends the PS 302 Forwarding Required message to SGSN 202. The message contains, for example, the source cell, target cell, TLLI, cause and transparent container. SGSN 202 determines based on the target cell when the handover is within or "between SGSN switching. SGSN 202 determines the identity of the new SGSN, which in this case is SGSN 204 and sends Prepare a PS 303 204 Transfer Request message to SGSN.

[0057] In step 1202, the encrypting parameters relating to the logical link are obtained in LLC-entity, in SGSN 204. This is done so that Prepare PS The request carries a message Transmission of information about the parameters of the element cipher 700. The information element 700 contains, for example, the session key Kc and any other parameters not again during the XID negotiation procedure in reset. At step 1204, SGSN 202 XID starts the reset procedure so that LLC LLC 202 252 in SGSN sends an XID 701 command message to MS 100 via the source BSS 262. XID command message 701 contains information about LLC parameters, such as, for example, LLC version number, IOV values, retransmission timeout, maximum number of retransmissions, maximum lengths of information fields in two confirmation modes, frame buffer size in uplink and downlink direction, windows sizes in uplink and downlink directions and Layer-3 parameters. The XID command message 701 proposes LLC parameter values ​​that correspond to the initial values ​​specified LLC LLC SGSN initiates its LLC entity. In the receipt of the XID message of the command 701, MS 100 sets the LLC parameters to the values ​​and problems posed. The XID 702 response message recognizes the proposed power parameters. In one embodiment of the invention, the MS 100 is configured to receive the parameters proposed by SGSN 202 automatically when it is aware that the switching process is in progress. In one embodiment of the invention, MS 100 adopts SGSN 204 automatic descending slat if it is marked accordingly and if it is received during handover.

[0058] At step 1206, SGSN 204 begins receiving packets forwarded from SGSN

202. In Figure 7, these packets are carried in packet stream 308. SGSN 204 initializes its LLC-254 to get the LLC entity's initial parameter values. The initial values ​​correspond to the values ​​of the LLC parameters negotiated SGSN 202 and MS 100 during the XID-reset procedure in step 1204. Then, SGSN 204 will start sending forwarded packets to MS 100. Then SGSN 204 and MS 100 can negotiate the more optimal LLC parameters. Typical renegotiation of LLC parameters is performed after area routing updates.

[0059] Figure 13 is a block diagram illustrating one embodiment of packet switched relaying, which uses the one shown in Figure 8. At step 1300, MS 800 has only one entity, LLC, which is the first entity of LLC 802. The first LLC is an entity of 802 original pairs - an entity in 252 in SGSN 202. There is an LLC 842 connection between LLC 252 and 802. The 842 LLC connection carries a stream of packets from GGSN 200 to MS 800. The MS 800 is waiting in conditions where switching is required. This is determined based on, for example, Handover commands received from BSS 262. When the state is detected by the Contin -lania method in step 1302. At 1302 MS: 100 constructs the second LLC entity, 804, which exists simultaneously with the first LLC- entity 802. at least during the handover. The second entity LLC is the entity 804 original pairs - entity in 254 in SGSN 204. At step 1304, MS 800 initiates a second LLC entity 804. The LLC parameters are initialized values ​​that match the values ​​to which SGSN 204 initializes the LLC parameters during initialization of LLC entity 254 in step 1306. At 1306, SGSN 204 receives packets forwarded from SGSN 202 via tunnel connection 241. The tunnel drilling connection 241 is, for example, a GTP tunnel. SGSN 204 sends forwarded packets to MS 800 via a 844 LLC connection, which is set up between LLC 254 and 804. At step 1308, it checks if the MS 800 handover is completed. If the handover has not been completed, the method continues at step 1308.

[0060] After the connection is completed, the transfer of LLC 842 between LLC entities 252 and 802 is no longer used to transport LLC frames. In one embodiment of the invention, in step 1310, MS 800 checks if the parameters relating to compound 844 of the original LLC are appropriate, taking into account, for example, the radio conditions in the cell served by BTS 224. The MS 800 can also correct parameters depending on the memory available and the data transmission speed in combination 844 original. In one embodiment, the parameters in LLC- entity 254 of the Invention LLC are initiated with a first moderate value that is made suitable for most mobile stations under various radio conditions. Mobile stations can also have different memory sizes and software versions. Sizes e.g. information field lengths, frame buffer and windows can first be set to lower values ​​than would otherwise be negotiated between peering LLC entities. If MS 800 specifies that the LLC parameters are not suitable, it tunes them to different values ​​in step 1312. Parameters are corrected, for example using an XID reset procedure involving an XID command exchange and XID LLC response between 804 and 254 units. If the parameter values ​​are correct, no readjustment is needed.

[0061] In one embodiment of the invention, MS 800 removes the first LLC unit that was used prior to handover after the switch was completed. At step 1314, MS 800 performs the necessary procedures to remove LLC entity 802 that is already in use. MS 800 can also remove LLC entity 802 immediately after step 1308 before checking if the LLC parameters are transmitting. Deleting an LLC-entity includes, for example, releasing memory reserved for the use of LLC-entity 802 and connecting the original 842 800 MS. Similarly, information on LLC-802 and 842 units. Good connections can be removed from memory tables maintained in MS 800.

[0062] Figure 14 is a block diagram illustrating one embodiment of a packet switched method that uses a duplicate frame indicator transported and processed using signaling is shown in Figure 9.

Signaling is performed by the GPRS system architecture, as illustrated in

Figure 2. In step 1400, it is checked if the transfer occurs. When forwarding occurs, MS 100 sends quality radio information related to measuring adjacent cells to acquire BSS 262 using 301 message. Based on the measurement, the BSS 262 source determines that forwarding is required. The determination is performed using an algorithm that is performed in the base station controller (BSC) in the source string BSS 262. At T0, BSS 262 specifies that the handover is done in a new cell that is in the area of ​​the new SGSN, which is SGSN 204. Source. BSS 262 sends a PS 302 Forwarding Required message to SGSN 202. The message contains, for example, the source cell, target cell, TLLI, cause and transparent container. SGSN 202 determines, based on the target cell, the switch reader between SGSN switching. SGSN 202 de - determines the identity of the new SGSN, which in this case is SGSN 204 and sends Prepare a PS 303 204 Handover Request message to SGSN.

[0063] In step 1402, the encrypting parameters relating to the logical link are obtained at LLC-entity, SGSN 204. This is done so that Prepare PS The request carries a message Transfer of information about the parameters of the cipher of element 700. The information element 700 includes, for example , session key Kc and any other parameters were not re-entered during the XID reset procedure.

[0064] In step 1404, SGSN 204 waits for packets forwarded from SGSN 202 to it. When such a packet is received in message 308, the method continues at step 1406. At step 1406, the SNDCP unit in SGSN 204 indicates the LLC- entity in SGSN 204, while the interest is to send the LLC-SDU thatLLC-SDU is the first LLC SDU containing data from packets transferred from SGSN 202 to SGSN 204. The LLC PDU is therefore a copy of another LLC -PDU sent from SGSN 202. LLC, entity in 204 sets SGSN duplicate for forward flag in LLC header - PDU to send. The flag can be made, for example, in one of the reserved bits in the address field or the original in one of the bits of the UI control field. Therefore, no additional bits are needed in the LLC - PDU header. The LLC parameters are set to the default forwarding values. Default values ​​can be normalized so that optimization is maximized or normal default values ​​are used. When the MS 100 receives an LLC - PDU in the LLC frame, it turns out that for duplicate forwarding the bit is set. At step 1408, MS performs implicit XID reset on LLC- entity in it. In implicit XID - MS 100 reset automatically sets the LLC parameters to values ​​that are consistent with the values ​​set by LLC- entity in SGSN 204 when it is created and initialized. Implicite XID -reset is required in MS 100 before it can process any LLC frames with SGSN 204. For example, it is due to various encrypting parameters, e.g., transfer number, which were not received in step 1402.

[0065] Figure 15 shows a Serving GPRS Supporting Node (SGSN) in one embodiment of the invention. SGSN 1500 includes a signaling unit 1504 that communicates with the logical link layer unit 1506. Signaling entity 1504 aircraft performs GPRS control signaling. Link layer logic unit 1506 carries both the control plane and the user plane messages as specified in 3GPP 23,060 regarding LLC. In the embodiment of the invention illustrated in connection with the description of Figs. 6 and 11, logical link layer units 1506 are again responsible for forming the logical link layer "Protocol Data Units (PDUs) and sending the logical link data layer layer (PDU) to the new SGSN. In one embodiment of the invention for sending the logical link layer PDUs to the new SGSN is achieved so that the Information layer logic unit 1506 passes to the PDU to control 1502, which sends it via, for example, the new SGSN GTP 1510 unit. In one embodiment of the invention, the signaling unit 1504 is responsible for detecting forwarding conditions, requesting switchover from other preparation SGSN nodes, receiving handover preparation requests from other SGSN nodes, sending layer state information, logical layer encryption parameter binding, and other information for other SGSN nodes. In one embodiment of the invention, the actual mobility management and radio application procedures related to signaling messages received for signaling unit 1504 are performed by control unit 1502 or by a separate thrust control unit 1504. In one embodiment of the control unit, the invention 1502 corresponds, for example, to setting the logical link layer entity 1506 based on logical link layer information received from another SGSN node and sending the logical link layer frame to the mobile node during handover. The transfer of logical link layer frames is done through the lower layers of 1508 protocols. The arrows in Figure 15 show the directions of information flow between entities within SGSN 1500.

[0066] Figure 16 shows a mobile node in one embodiment of the invention. In Fig. 16, the mobile node is more specifically a GPRS mobile terminal. Mobile node 1600 includes a signaling unit 1604 that communicates with link layer logic unit 1606. The link layer logic unit 1606 carries both the control plane and the user plane messages as defined in 3GPP 23,060. In one embodiment of the invention, the signaling unit 1604 is responsible for receiving signaling messages with the base station subsystem and detects handover conditions and completing handover based on received signaling messages. Link layer logic unit 1606 performs logical link control (LLC) protocol related tasks. From the embodiment of the invention shown in connection with the description of fig. 12 the logical link layers of the 1606 unit are adapted to negotiate the logical link layer parameters of the new SGSN after switching. Mobile station 1600 also includes a control unit 1602 that performs tasks associated with higher protocol layers and overall communication coordination. In one embodiment of the invention, the control unit 1602 is adapted to produce a first link layer logic device during the connection establishment procedure and a second logical link layer unit in response to the switching state. The arrows in Fig. 16 illustrate the directions of information flow between units in a mobile node 1600.

[0067] It is obvious to a person skilled in the art that, as technology advances, the basic idea of ​​the invention can be implemented in various ways. The invention and its embodiments are therefore not limited to the embodiments described above, as they may vary within the scope of the claims