Method and arrangement for transferring real time data in a packet radio network

ES 2 209 584 B2

DESCRIPTION

Telecommunications method and system to transfer information in a packet radio service and the corresponding mobile station.

The invention relates generally to a method and an arrangement for transferring information in a packet radio service. Especially the invention applies to the transfer of delay sensitive data, such as voice and video data, in a mobile telecommunications system.

The designation "mobile telecommunications system" refers generally to any telecommunications system that allows a wireless communication connection between a mobile station (MS) and the fixed parts of the system when the user of the mobile station moves within the service area. of the system. A typical mobile telecommunications system is a Public Land Mobile Network (PLMN). Most of the mobile telecommunications systems used at the time of filing this patent application belong to the second generation of such systems, a well-known example being the GSM system (Global System for Mobile telecommunications). However, the invention also applies to the next or third generation of mobile telecommunications systems, such as a system known as UMTS (Universal Mobile Telecommunications System) that is currently in the process of standardization.

Real-time Internet services have grown in popularity in recent years. IP (Internet Protocol) telephony and different pipeline applications are already known on the Internet. In addition, the demand for wireless access to these real-time services is expected to increase further. Wireless packet-switched networks, such as GPRS (General Packet Radio Service), are designed to provide data services, for example Internet services, at low cost. In GPRS, channels are not continuously dedicated to a single user, but are shared among multiple users. This facilitates efficient multiplexing of the data. However, GPRS was not originally designed to transfer delay-sensitive real-time data, for example IP telephony sessions. For this reason, GPRS contains several technical solutions that do not meet the requirements established by real-time traffic. In the following text, a designation "delay sensitive data" is used for data flows that should be transferred on a real-time basis and which may have passive periods during which the data flow is suspended.

In order to better understand the problems of the prior art solutions and the idea of ​​the present invention, the structure of a third generation digital cellular radio system is first briefly described, and GPRS is further described below. detail.

Figure 1a shows a version of a future cellular radio system, which is not completely new, compared to the known GSM system, but which includes both known elements and completely new elements. The terminals are connected to the radio access network RAN, which includes the base stations and the base station controllers. The core network of a cellular radio system comprises mobile services switching centers (MSCs), other network elements (in GSM, for example SGSN and GGSN, i.e. GPRS Support Node in Service and GPRS Support Node Gateway, where GPRS stands for General Packet Radio Service) and other associated transmission systems. For example, according to the GSM + specifications developed from GSM, the core network can also provide new services.

In Figure 1a, the core network of a cellular radio system 10 comprises a GSM + core network 11 having three radio access networks linked in parallel thereto. Of these, networks 12 and 13 are UMTS radio access networks and network 14 is a GSM + radio access network. The upper UMTS radio access network 12 is, for example, a commercial radio access network, owned by a telecommunications operator offering mobile services, which equally serves all subscribers of said telecommunications operator. The lower UMTS radio access network 13 is, for example, private and is, for example, owned by a company, in whose premises said radio access network operates. Typically, the cells of the private radio access network 13 are nanocells and / or picocells, in which only terminals of the employees of said company can operate. These three radio access networks can have cells of different sizes that offer different types of services. Additionally, the cells of the three radio access networks 12, 13 and 14 may totally or partially overlap each other. The bit rate used at a given moment of time depends, among other things, on the conditions of the radio path, the characteristics of the services used, the general regional capacity of the cellular system and the capacity needs of other users. The new types of radio access networks mentioned above are called Generic Radio Access Networks (GRAN). Such a network can co-operate with different types of fixed core networks CN and especially with the GPRS network of the GSM system. The generic radio access network (GRAN) can be defined as a set of base stations (BS) and radio network controllers (RNC), which are capable of communicating with each other using signaling messages.

Figure 1b shows an architecture of a general packet radio service (GPRS). GPRS is a new service that is currently based on the GSM system, but is expected to become generic in the future. GPRS is one of the objects of the GSM phase 2+ and UMTS standardization work at ETSI (European Telecommunications Standards Institute). The GPRS operating environment comprises one or more subnet service areas, which are interconnected by a GPRS core network. A sub-network comprises a number of packet data service nodes (SN) which, in this application, will be referred to as serving GPRS support nodes (SGSN).

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153, each of which is connected to the mobile telecommunications system (typically to a base station through an interconnect station), such that it can provide packet service for mobile data terminals 151 through various base stations 152, ie, cells. The intermediate mobile communication network provides packet-switched data transmission between a support node and mobile data terminals 151. Different sub-networks are interconnected, in turn, to an external data network, for example, to a public data network (PDN) 155, through GPRS gateway support nodes, GGSN

154. Therefore, the GPRS service enables the provision of packet data transmission between mobile data terminals and external data networks when suitable parts of a mobile communication system function as an access network.

To access GPRS services, a mobile station must first make its presence known to the network by making a GPRS connection. This operation establishes a logical link between the mobile station and the SGSNs, and makes the mobile station available for SMS (Short Message Services) 158, 159, through GPRS, for pager calls through SGSN and for GPRS data notification starters. More particularly, when the mobile station connects to the GPRS network, ie in a GPRS connection procedure, the SGSN creates a mobility management context (MM context). Furthermore, user authentication is performed by the SGSN during the GPRS connection procedure. To send and receive GPRS data, the MS must activate the packet data address to be used, requesting a PDP (Packet Data Protocol) activation procedure. This operation makes the mobile station known to the corresponding GGSN and interconnection with external data networks can begin. More particularly, a PDP context is created at the mobile station and the GGSN and SGSN. The context of the packet data protocol defines different data transmission parameters, such as the PDP type (for example, X.25 or IP), the PDP address (for example, the X.121 address), the quality of the QoS service) and the NSAPI (Network Service Access Point Identifier). The MS activates the PDP context with a specific message, Activate PDP Context Request, in which it gives information about the TLLI, the PDP type, the PDP address, the requested QoS and the NSAPI, as well as optionally the point name access (APN).

Figure 1 also shows the following GSM functional blocks: Mobile Switching Center (MSC) / Visitor Location Register (VLR) 160, Internal Location Register (HLR) 157 and Equipment Identity Register (EIR) 161. The system GPRS is normally also connected to other Public Land Mobile Networks (PLMN) 156.

The functions that apply to digital data transmission protocols are normally described as a stack according to the OSI (Open Systems Interface) model, where the tasks of the various layers of the stack are precisely defined, as well as the transmission of data between strata. In the GSM phase 2+ system, which is seen in this patent application as an example of a wireless digital data transmission system, five operational layers are defined.

The relationships between the protocol layers are illustrated in Figure 2. The lowest protocol layer between the mobile station MS and the base station subsystem is layer 1 (L1) 200,201, which corresponds to a physical radio connection. . Above them is located an entity that corresponds to layers 2 and 3 of a regular OSI model, where the lowest layer is a radio link control / medium access control (RLC / MAC) layer 202, 203; above it is a logical link control (LLC) layer 204, 205; and at the top is a radio resource control layer (RRC) 206, 207. Between the UTRA BSS base station subsystem of the generic radio access network and an interconnection / core network unit IWU / CN located in the core network, it is assumed that a so-called Iu interface is applied, where the layers corresponding to the strata described above from L1 to LLC are the L1 and L2 strata of the OSI model (blocks 208 and 209 in the drawing), and the stratum that corresponds to the RRC stratum described above is the L3 stratum of the OSI model (blocks 210 and 211 in the drawing).

The mobile station MS must include a higher level control protocol 212 and a protocol 213 to serve higher level applications, the former of which communicates with the RRC stratum 206 in order to perform control functions related to data transmission connections, and the latter communicates directly with the LLC layer 204 in order to transmit those data that directly serve the user (eg, digitally encoded voice). In a mobile station of the GSM system, blocks 212 and 213 are included in the MM layer mentioned above.

In GPRS, a Temporal Block Flow (TBF) is created to transfer data packets on a packet data channel. The TBF is a physical connection used by two equal Radio Resource (RR) entities to support the unidirectional transfer of Logical Link Control (LLC) packet data Units (PDUs) on physical packet data channels. The TBF is normally always released when there is no data to transmit. This is a problem in voice services, because there are periods of silence between active periods.

During these silent or “passive” periods, no data is transferred and therefore the TBF is released. The TBF establishment procedure is likely to be too long to be established quickly enough when the active period continues.

An example of resource allocation in GPRS of the current GSM Phase 2+ specification is described in more detail below.

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In GSM Phase 2+, the uplink resource allocation is currently specified as follows. The Mobile Station (MS) requests uplink radio resources by sending a PACKET CHANNEL REQUEST message to the network. Various access type values ​​are specified for this request message. For data transfer, values ​​of the access type "one-phase access", "two-phase access" and "short access" are defined. Using the access type value "short access", the MS can request that the radio resources be transferred only to some RLC data blocks and therefore it is not applicable for transferring continuous data streams.

When a network receives a PACKET CHANNEL REQUEST message indicating access in one phase, it can assign radio resources to one or more packet data channels (PDCH). The assignment is based on the information included in the request message. The following table shows an example of the content of an 11-bit message in a PACKET CHANNEL REQUEST message:

<img file="ES2209584B2_D0001.tif" />

An 11-bit PACKET CHANNEL REQUEST message, indicating a one-phase access, has a 5-bit field that describes the class of multiple time division (multislot) of the mobile station, a two-bit field that indicates the priority of the request and a three-bit field describing the random reference (random mobile station identification information).

The following table shows an example of the 8-bit message content of a PACKET CHANNEL REQUEST message:

<td>Bits</td><td></td>

<td> 87654321</td><td>Channel access by packages</td>

<td>1 mmmmm rr</td><td>One-Phase Access Request</td>

<td>OOnnnrrr</td><td>Short Access Request</td>

<td>OlOOOrrr</td><td>Two-Phase Access Request</td>

<td>OlOOlrrr</td><td>Pager Response</td>

<td>OlOlOrrr</td><td>Cells Update</td>

<td>OlOllrrr</td><td>Mobility Management Procedure</td>

<td>OllOOrrr</td><td>Measurement Report</td>

<td>Everyone else</td><td>Reserved</td>

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An 8-bit Packet Channel Request message indicating one-phase access has a 5-bit field describing the mobile station's multislot class and a two-bit field describing a reference random. Information about the assigned radio resources is sent to the Mobile Station with a PACKET UPLINK ASSIGNMENT message.

When a network receives a PACKET CHANNEL REQUEST message, indicating two-phase access, it can allocate limited radio resources on the packet data channel. The assigned radio resources are transmitted to the mobile station with a PACKET UPLINK ASSIGNMENT message. After this, the mobile station transmits a PACKET RESOURSE REQUEST message to the network using the assigned radio resources. The message more precisely defines the requested radio resources, eg, requested bandwidth and priority, and the radio capacity of the mobile station. From the information received in the PACKET RESOURCE REQUEST message, the network can assign one or more packet data channels to the TBF and informs the radio resources assigned to the mobile station with a PACKET UPLINK ASSIGNMENT message.

Previously, the request for resources was made using the GPRS control channel as an example. There are also other ways to request resources in case the cell does not include a GPRS control channel (even if it supports GPRS). In this case, the request for resources can be made using a GSM control channel.

In prior art uplink radio resource allocation, the following problems arise:

If the priority field included in the PACKET CHANNEL REQUEST and PACKET RESOURCE REQUEST request messages do not unequivocally define delay-sensitive real-time traffic, the network may not be able to provide the necessary radio resources for the MS. Therefore, for example, voice transmission using GPRS may not reach a sufficient quality.

The default RLC mode is an acknowledgment mode in a one-phase access. Since real-time traffic would be transferred using unacknowledged RLC mode, a two-phase access should be used. Using two-phase access, additional information about the request for radio resources can be given to the network. However, two-phase access causes additional delay to the channel allocation procedure, because the mobile station has to send two request messages to the network instead of one. Despite the additional radio resource request information, it is not guaranteed that the network will be able to provide the necessary radio resources for the mobile station transferring the delay-sensitive real-time traffic.

When uplink radio resources are allocated for handover, downlink radio resources cannot be allocated simultaneously, because the downlink temporary flow block cannot be created without downlink packets. Consequently, it is possible that, when the mobile station then receives a downlink packet, the network will not be able to allocate radio resources for the transfer of the packet.

The downlink radio resource allocation is currently specified as follows: When the network receives data for a mobile station that has no radio resources allocated and whose cell location is unknown, the network allocates radio resources on one or more channels data packet by transmitting a PACKET DOWNLINK ASSIGNMENT message to the mobile station. When the mobile station receives the allocation message, it begins to read the allocated packet data channels for Radio Link Control (RLC) data blocks.

In downlink radio resource allocation, the following problems may arise:

If the information attached to the data (from the SGSN) does not unequivocally define the delay-sensitive real-time traffic, the network may not be able to provide the necessary downlink radio resources for the MS.

Furthermore, if there is a need to transmit delay-sensitive real-time traffic in both the downlink and uplink directions, the mobile station may only request uplink radio resources when the network assigns broadcast permission to the mobile station. This can cause a delay of varying length, such as several seconds.

When downlink radio resources are allocated for handover, the uplink radio resources cannot be allocated simultaneously because the temporary flow of uplink blocks cannot be created without uplink packets. Therefore, it is possible that the mobile station requests uplink radio resources, but the network is not able to allocate the requested radio resources.

Uplink radio resource deallocation is currently specified as follows: Each uplink RLC data block includes a down count value (CV) field. It is specified in [1] that the CV should be 15 when the mobile station has more than BS_CV_MAX (broadcast parameter) RLC data blocks that are left to be transmitted to the network. Otherwise, the mobile station indicates to the network with the CV field the number of remaining RLC data blocks. The last block of RLC data must be sent to the network with the CV value set to "O". Specification [1] also defines that once the mobile station has sent a CV value other than "15", it must not queue new RLC data blocks, implying that the new blocks

ES 2 209 584 B2 of RLC data should not be sent during the current TBF. Once the network receives an RLC data block with the CV field set to "O", the TBF release procedures are initiated.

In uplink radio resource deallocation, the following problems may arise:

If delay sensitive real-time data is transferred on the radio interface according to current GPRS rules, the mobile station will have to establish several TBFs per session, because during passive periods the mobile station does not have RLC data blocks that send to the network and therefore the CV value "0" terminates the uplink TBF. Because the TBF establishment procedure is time consuming, delay sensitive traffic cannot be transmitted with good quality. Furthermore, there is no guarantee that free radio resources are available whenever the mobile station requests uplink radio resources.

Downlink radio resource deallocation is currently specified as follows: Each downlink RLC data block includes a Final Block Indicator (FBI) field in the RLC header. Specification [1] defines that the network indicates to the mobile station the release of the downlink TBF by setting the FBI field to "1". The network sets the FBI field to "1" when there are no more RCL data blocks to send to the mobile station.

After receiving an RLC data block with the FBI field set to "1", the mobile station must acknowledge to the network that it has received the FBI information. When the network receives the acknowledgment message, the TBF is released.

In downlink radio resource deallocation, the following problems may arise.

If delay-sensitive real-time traffic is transmitted on the radio interface according to current GPRS rules, the network will have to establish several TBFs per session, because during passive periods the network does not have RLC data blocks that send to the mobile station and therefore the FBI value "1" terminates the downlink TBF. Furthermore, there is no guarantee that free radio resources will be available whenever the network tries to allocate downlink radio resources.

Problems can also arise in assigning uplink and downlink broadcast permits: If delay-sensitive data traffic is transferred in real time on packet data channel / channels (PDCH), it is not guaranteed that permissions will be granted appropriate broadcast data to transfer the data, because the current network may not have unequivocal knowledge about the delay-sensitive data being transferred.

Another problem with the prior art specification concerns the feature that the network assigns transmission permissions for uplink and downlink addresses independently, i.e. it controls which mobile station receives data next and which mobile station can send. data below. However, delay sensitive data, such as speech, has strict delay requirements. Therefore, whenever a user of delay sensitive data has something to transmit, they must be able to do so in order to maintain an acceptable level of service. If more than one user is assigned to the same packet data channel, it is likely that at some point two or more users will need to transmit simultaneously, and only one can be served by the channel. In voice conversations, a large proportion of the connection time is silence. Therefore, it would be possible to statistically multiplex more than one voice user for a packet data channel. However, the GPRS channel reservation system is not sufficiently developed to support this need. Consequently, only one delay sensitive data transfer user can be assigned for a packet data channel, which means that the channel capacity utilization is not optimized.

When the network notices that a mobile station wishes to send delay sensitive data in the uplink direction, the network reserves as many uplink resources as necessary for the mobile station. This naturally requires that the network have the requested resources available. This may mean that the packet data channel is temporarily dedicated for a single mobile station in the uplink direction. During passive periods in the transmission of uplink delay sensitive data, the network may assign uplink broadcast permissions of the allocated channels to other mobile stations. Since the mobile station transmitting delay sensitive data retains the uplink capacity of the packet data channel, it cannot be assigned to other mobile stations, which are assigned to the same packet data channel, permission to detect whether they have data. to send in the uplink direction. Furthermore, if more than one mobile station assigned to the same packet data channel needed to send delay sensitive data at the same time, only one could be served. Consequently, the network is forced to restrict the number of mobile stations transmitting delay sensitive data in accordance with the number of packet data channels in order to provide an acceptable quality of service.

Therefore, an object of this invention is to provide a method and an arrangement that offers solutions to the problems of the prior art. Especially, an object of this invention is to provide a solution, in which the physical connection of a packet radio service is kept reserved also during passive periods of a session, but the same physical resource can still be shared by multiple users.

The objects of the invention are fulfilled by providing a method, in which a TBF can be maintained

ES 2 209 584 B2 functional also when there is a passive transmission period between the mobile station and the network. The procedure supports delay sensitive traffic, while using radio resources efficiently.

One idea of ​​the invention is that the network is informed at the end of an active period, whether the active period is followed by a passive period or whether the connection can be released. The network can also be informed as to whether the packet data channel can be assigned to other temporary block streams. Information can be transferred, for example, on the packet data channel during an active period or at any time through a control channel. The information can be transferred in the packet data channel, for example, in the MAC header field of a data block. Alternatively, a separate signaling message can be used. With this information it is possible to keep the temporary flow of blocks created available, even when no data should be transmitted. When an active period starts after a passive period, the connection is started using the created TBF again, and possibly other users of the packet data channel can be assigned to other channels.

In addition to transferring information between the mobile station and the network about whether the active period is followed by a passive period or whether the connection can be released, there is also an alternative method. The network can use a timer function to determine if the active period is followed by a passive period or if the connection can be released. In this alternative, when a predetermined idle data transfer period has elapsed, the TBF is released.

Furthermore, an object of the invention is fulfilled with the idea of ​​assigning several delay-sensitive data streams to the same packet data channel. On an uplink channel, after a mobile station begins to transmit, the other mobile stations can be reassigned to other channels immediately or a transmission permission can be assigned periodically to the mobile stations, so that the mobile stations can indicate their willingness to transfer. On a downlink channel, after one mobile station starts transmitting, the other mobile stations can also reassign to other channels immediately or the data cannot be transferred until another mobile station starts receiving data on the same channel.

An object of the invention is further fulfilled with the idea of ​​informing the network about a need to assign a TBF also in the opposite data transmission direction. For example, when an uplink TBF is assigned, the downlink TBF is also assigned even if there is no downlink data to transfer at that time. This information can be transferred in a signaling message as a separate information element or in an information element for another purpose. When the data is delay sensitive, temporary data streams can also be allocated automatically in both directions of data transmission (eg during a connection establishment phase).

An object of the invention is further fulfilled with the idea of ​​informing the network about whether the data to be transferred is delay sensitive or not. This information can be provided to the network, for example, in a priority field included in an information element of the system quality profile.

The present invention offers significant advantages over prior art methods. With the present invention it is possible to use the packet channel resources very efficiently. On the other hand, if the total capacity of the network is sufficient, it is possible to avoid the risk that no channel is available when the passive period of data transfer ends.

A characteristic of a method according to the present invention for transferring a data stream by creating a connection in a packet radio service of a telecommunications system, where the data stream comprises at least one active period of data transmission, It consists in that between the mobile station and the network, information is transferred as to whether after an active period of data transfer a passive period begins or whether a connection release is allowed.

The invention also applies to a telecommunications system for transferring a data stream by creating a connection in a packet radio service, where the data stream comprises at least one active data transfer period, having characteristic means for receiving information about whether after an active period of data transfer starts a passive period or if a connection release is allowed.

The invention also applies to a mobile station to transfer a data stream by creating a connection in a packet radio service for a cellular telecommunications system, where the data stream comprises at least one active data transfer period, comprising means to transfer information about whether after the active data transfer period a passive period starts or whether the connection release is allowed.

Preferred embodiments of the invention have been presented in the dependent claims.

The invention is described in more detail below by means of the accompanying drawings, in which:

Figure 1 illustrates a prior art cellular communication system.

Figure 2 illustrates protocol levels of a prior art cellular communication system.

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Figure 3 illustrates a prior art MAC header of an uplink RLC data block.

Figure 4a illustrates a MAC header of an uplink RLC data block with no TBF release indication.

Figure 4b illustrates a MAC header of an uplink RLC data block with TBF release indication.

Figure 5 illustrates a flow chart for uplink RLC block transmission.

Figure 6 illustrates a flow chart for uplink RLC block reception.

Figure 7 illustrates a flow chart for downlink RLC block transmission.

Figure 8 illustrates a flow chart for receiving downlink RLC blocks.

Figure 9 illustrates TDMA frames of active and passive periods of a delay sensitive data stream, and Figure 10 illustrates a block diagram of a mobile station in accordance with the invention.

Figures 1 and 2 were previously described in the description of the prior art. Next, the principles of delay sensitive data indication and resource allocation are first described using an embodiment in a GPRS system as an example. Next, an example of placing release information in the MAC header will be described with reference to Figures 3, 4a and 4b. Next, the phases of the method of the invention are described with reference to Figures 5 to 9. Finally, a mobile station and a cellular system according to the invention are briefly described with reference to Figure 10.

During an uplink resource allocation, a mobile station indicates to the network that it requires radio resources for delay sensitive data transfer. The network needs the information to allocate sufficient radio resources for the mobile station to provide the required level of service. The information may be provided to the network in one of the following ways, where some system specific message names are used as an example without the intention of limiting the applicability of the invention:

- The mobile station sends a PACKET CHANNEL REQUEST message to the network, and the message has a specific type of delay sensitive data transfer;

- The CHANNEL REQUEST DESCRIPTION information element or other corresponding information element is included in a PACKET RESOURCE REQUEST message and the information element includes information indicating the delay-sensitive data to transfer; or

- A priority field or another field is included in the radio resource request message, such as a PACKET CHANNEL REQUEST message or a PACKET RESOURCE REQUEST message, which is transmitted to the network by the mobile station, identifying the field unequivocally the delay sensitive data to be transferred.

In addition to the information on the radio resources that are required to transfer the delay sensitive data, the radio request information may also include the following additional parameters that specify exactly the required resources;

- The number of required packet data channels;

- Information about whether the communication is one-way or two-way. This allows the network to determine if the mobile station also requires downlink resources. By reserving downlink resources simultaneously with the uplink radio resources it is possible to avoid a situation where the mobile station would receive downlink data, but at that time the network would not be able to reserve downlink radio resources.

- Information on the number (N) of passive block periods. If the mobile station has no data to transmit to the network, the network can issue the following N uplink broadcast permits to some other mobile station (s). The mobile station or the network may define the value of this parameter or it may have a default value.

Since the length of the PACKET CHANNEL REQUEST message is only 11 or 8 bits, it can be difficult to include the above parameters in the message. Therefore, if when requesting radio resources to transfer delay sensitive data, a more exact description of the requested radio resources is required, it may be preferable to use a two-phase access.

There are also default values ​​for the channel request when using one-phase access. For example,

ES 2 209 584 B2 when requesting radio resources to transfer delay sensitive data, a packet data channel and only uplink radio resources could be reserved by default. If there is a need to reserve several packet data channels, the modification of the radio resources can then take place through an additional signaling procedure.

During a downlink resource allocation, the procedure starts when the network needs to transmit data to the mobile station, which has no downlink radio resources allocated or when the mobile station requests the establishment of a downlink TBF during an uplink TBF establishment procedure. The network allocates sufficient radio resources from the information that is attached to the packet data. The information includes an indication that radio resources are required to transfer delay sensitive data, so that the network can allocate sufficient radio resources in order to provide the required level of service. For example, the delay sensitivity of the data can be indicated in an information element included in the quality of service (QoS) profile. The delay sensitivity of the data transfer can also be indicated in a new field in the QoS profile or in a new information element accompanying the data transmitted from the network, for example from an SGSN, to the BSS.

Furthermore, in order to more accurately describe the radio resources required in the information that is received from the SGSN, the following parameters may be included:

- The required number of packet data channels;

- Information about whether the communication is one-way or two-way. This allows the network to determine if the mobile station also requires uplink resources. By reserving downlink resources simultaneously with the uplink radio resources it is possible to avoid a situation where the mobile station would have to broadcast uplink data, but at that time the network would not be able to reserve uplink radio resources.

- Information on the number (N) of passive block periods. If the mobile station has no data to transmit to the network, the network may issue the following N uplink broadcast permits to some) other mobile station (s). The mobile station or the network may define the value of this parameter or it may have a default value.

Figure 3 depicts a prior art MAC header in the uplink RLC data block currently specified in [1]. In the header, the Payload Type field indicates the type of data contained in the rest of the RLC / MAC block. The CV Down Count Value field is sent by the mobile station to allow the network to calculate the number of RLC data blocks remaining for the current uplink TBF. This has already been described above.

The Stop Indicator (YES) bit indicates if the mobile station's RLC transmission window can advance, that is, if the RLC transmission window is not stopped, or if it cannot advance, that is, the RLC transmission window is stop. The mobile station sets the SI bit in all uplink RLC data blocks. In RLC unacknowledged mode, SI should always be set to “0”.

The Retry bit (R) indicates whether the mobile station has transmitted the PACKET CHANNEL REQUEST message once or more than once during its most recent access to the channel.

When transmitting delay sensitive data from the mobile station to the network according to the invention, the RLC / MAC data block may include a field indicating whether the RLC block is the last of the connection or not. This field is referred to in this text as TBF Release (TR). If the RLC block is the last, the TR field is set to a value "1", and the TBF is considered to have been released. Otherwise, the TR field is set to "0" and the network then considers the TBF to be open. The TR field can replace, for example, the SI stop indicator field, because when the RLC operates in unacknowledged mode, the SI field is not used. The TR field can also be included in the CV field by substituting part of it.

When transmitting delay sensitive data to the network, the RLC / MAC data block includes information about whether the mobile station has to transmit more RLC data blocks or whether the network can give the following N uplink transmission permissions to other mobile stations. This information can be provided to the network in the RLC / MAC header and in this text the field is called "CV '". The CV 'field may replace all or part of the CV field in the prior art specification.

When the mobile station transfers delay sensitive data and CV '+ 0 to the network, the network interprets it to mean that the mobile station has more blocks of data to transmit and in this way the network is able to assign the following as well uplink transmission permissions for the same mobile station. When the CV 'value is set to "0", the network interprets it in the sense that the first mobile station no longer has more RLC data blocks to transmit at that moment and, therefore, the network can give the following N uplink transmission permissions to some other mobile station (s). However, in order to ensure that the first mobile station to transfer delay sensitive data does not have to wait too long to get a permit

ES 2 209 584 B2 uplink transmission period, the network gives in every N block periods an uplink transmission period for the first mobile station. If the mobile station then has to transmit RLC data blocks, the mobile station includes TR and CV 'fields in the RLC data blocks, as described above. If the mobile station does not have to transmit data, to the network at this time, the mobile station may bypass the uplink transmission permission or it may transmit a Packet Dummy Control Block message or a Packet Dummy Control Block message. signaling.

If the temporary flow of uplink blocks is preserved also when there is no data to transfer to the mobile station and if the network is unable to determine when to release the downlink TBF, the mobile station should tell the network when it can be released the downlink TBF. This can be done by introducing in the RLC / MAC data block header a bit that indicates to the network whether or not to release both uplink and downlink block time streams. The mobile station may also transmit to the network an RLC / MAC control signaling message indicating the release of the temporary downlink block flow prior to the release of the temporary uplink block flow. It is also possible to have a timing function that would release the temporary flow of downlink blocks after a predetermined period of time has elapsed since the last downlink data transfer. The network may contain a logical entity that is capable of determining when the TBF should be released.

Figure 4a describes an example MAC header of the uplink RLC data block according to the invention without including a downlink TBF release indication. TBF Release (TR) indicates whether the mobile station transferring delay sensitive data requests release of the uplink TBF or not.

Figure 4b depicts an example MAC header in the uplink RLC data block according to the invention, including a DTR downlink TBR release indication in bit 6 of the header. Downlink TBF release indicates whether the mobile station transferring delay sensitive data requests release of the downlink TBF or not. The DTR field, if used, may be present in all uplink RLC data blocks occupying, for example, one bit of the CV 'count value field. The DTR field can only really be included in the MAC header when the CV 'field is set to “0” (actually three LBS) and the TR field is set to “1”, thus leaving 4 bits for the CV' field during normal operation.

The parameters according to the invention can be included in the current uplink RLC / MAC data block, as described above, or a new RLC / MAC data block can be defined. If a new data block is defined, the Payload Type can be used to identify the type of the block.

Figure 5 shows a flow chart of the steps for transmitting an RLC block from a mobile station 500 to the network. The following parameters of a MAC header field are given as examples; many others may apply. ways of transmitting information. In step 502, the mobile station checks if the RLC block to be transmitted is the last in a TBF data block. If so, the mobile station sets the parameters CV '= 0 and TR = 1 of the MAC header, step 504, and transmits the block. The parameter TR = 1 means that the TBF can be released, step 506.

If in step 502, the RLC block is not the last in the TBF, the mobile station checks in step 510, if the RLC block is the last in the buffer. If so, in step 512 the mobile station sets the parameters CV '= 0 and TR = 0 and transmits the block. This means that the data flow starts a passive period, but the TBF is not released. If the TLC block is not the last one in the mobile station's buffer, in step 520 the parameters CV '= non-zero and TR = 0 are set, and the block is transmitted. The CV 'value can be the number of blocks remaining in the buffer, if the number is small enough to be expressed in CV'. For example, CV 'can be used as the CV parameter of the current specification (ETSI GSM 06.60).

After the block has been transmitted in any of the previous stages, operation continues at 530, from stage 500, when there is a block of data to be transmitted in memory.

Figure 6 shows a flow chart of the steps for reception by the network, at 600, of an RLC block from a mobile station. In step 602, the network checks the value of the TR parameter from the received RLC block. If the parameter TR = 1, the uplink TBF is released, step 604. Next, the release of the downlink TBF depends on whether or not it is requested, steps 606 and 608.

If in step 602 the parameter TR = 0, the network then checks the value of the parameter CV ', step 610. If CV' = 0, this means that there is a passive transmission period in the data stream, and the channel packet data can be programmed for another mobile station (other mobile stations), step 612. However, if the CV 'parameter is different from 0, the channel permission is programmed for the same mobile station, step 620.

After the block has been received and processed in the previous steps, at 630, operation continues from step 600, upon receipt of a new data block.

Figure 7 shows a flow chart for the transmission of RLC blocks from the network to the mobile station, 700.

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In step 702, the network checks whether or not the RLC block to be transmitted is the last one in a TBF data block. If so, the mobile station sets the parameter Final Block Indicator FBI = 1. It also sets a valid Relative Reserve Block Periode (RRBP), step 710, and transmits the block. , step 720. The parameter FBI = 1 means that the current block is the last RLC block in the temporary block field and therefore the TBF can be released. The assignment of a TTBP field means that an uplink transmission block is assigned for the receiving mobile station, so that the mobile station can send a control message to the network.

If in step 702, the RLC block is not the last of the TBF, in step 704 the network sets the parameter FBI = 0. This means that the data flow may or may not start a passive period, but the RBF is not released. The network also sets a valid RRBP, if necessary, step 704.

After this, the network transmits the data block, step 720. After the block has been transmitted in any of the previous stages, the operation continues from step 700, when in the buffer there is a data block for transmit, 730.

Figure 8 shows a flow chart of the reception steps in a mobile station of an RLC block from the network 600. In step 602, the mobile station verifies the value of the FBI parameter of the received TCL block. If the parameter FBI = 1, the downlink TBF release procedure is started, step 810. If in step 802, the parameter FBI + 1, this means that the mobile station continues the procedure for receiving the TBF present, step 830.

Figure 9 shows successive TDMA frames, in which time slot 5 is used for a packet data channel. In TDMA frames 900 and 902, the packet data channel is allocated for an active delay-sensitive data transfer connection. As the active period changes to a passive (silent) period, the network assigns a transmission permission to a second connection in frame 904. During the passive period, frames 904 to 912, the network also periodically assigns broadcast permits to the mobile station of the first connection for a channel request, frame 908. When the active period starts again, frames 914, 916, are you can give the first connection permission for an uplink data transfer again. If the second connection is also transferring delay sensitive data, then one of the connections can be reassigned to another packet data channel at the beginning or end of the passive period.

When the same packet data channel is assigned for multiple passive connections, all other delay sensitive users can be reassigned to other packet data channels when one of them starts transmitting. Alternatively, they can wait for an uplink transmission permission on the same packet data channel. In practice, reassignment can be accomplished by issuing a signaling message, such as PACKET UPLINK ASSIGNMENT, which contains a new packet data channel assignment for each mobile station to be reassigned. Another alternative is to send an individual signaling message, such as a PACKET REALLOCATION, containing new packet data channel assignments to all / some mobile stations to be reassigned. By using just one signaling message, more radio capacity is free for other purposes.

When the network receives delay sensitive data for a mobile station, the network reserves as much downlink packet data channel capacity for the mobile station as necessary. This naturally requires that the network have the necessary resources available. This may mean that the data channel is temporarily dedicated to a single mobile station in the downlink direction. During passive periods of downlink delay sensitive data transfer, the network may assign downlink transmission permissions to other mobile stations, and therefore the network may transmit data to other mobile stations. To prevent a situation where the network receives delay sensitive data for more than one mobile station simultaneously on the same channel / packet channels and therefore would have to block all but one, the network can distribute the other mobile stations using delay sensitive data transfer to other packet data channels. Distribution can be done using the following mechanisms:

Downlink early allocation: When the network receives delay sensitive data for a mobile station, it reallocates the other delay sensitive data users residing on the same packet data channel. Users of non-delay sensitive data can be reassigned to other packet data channels or alternatively wait for a transmission permission on the same packet data channel. The network transmits a signaling message, such as a PACKET DOWNLINK ASSIGNMENT, which contains new packet data channel assignments for all / some mobile stations to be reassigned.

Downlink late allocation: When the network receives delay sensitive data for one mobile station, it does not immediately reassign the other mobile stations residing on the same packet data channel. Only when the network receives delay-sensitive data for a mobile station and the network is already transferring delay-sensitive data for some other mobile station on the same packet data channel, does the network assign the mobile station a new data channel per packages. The new packet data channel is allocated, for example, by sending a PACKET DOWNLiNk AsSiGNMENT signaling message to the mobile station.

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The network should control that delay sensitive data is not queued for too long to get permission for downlink transmission. The network should also control that the signaling messages related to the other temporary block flows from other mobile stations do not occupy excessively. the packet data channel. This can be done by giving the same or a higher priority to the transfer of delay sensitive data compared to signaling messages from other temporary block flows.

When the network does not have to temporarily transmit delay sensitive data, it reserves the temporary stream of blocks and does not set the FBI field to the value "1" after transmitting the last buffered RLC data block. The mobile station controls the termination of the downlink TBF or the network may contain a logical entity that is capable of determining when the TBF should be released.

Figure 10 shows a block diagram of a mobile station 100 according to the invention. The mobile station comprises an antenna 101 for receiving radio frequency signals from the base stations. The RF signal is conducted with the switch 102 to the RF receiver 111, where the RF signal is amplified and converted to digital. The signal is then detected and demodulated at block 112. The type of the demodulator depends on the radio interface of the system. It can include a QAM demodulator, or a RAKE combiner. Decryption and deinterpaging are performed in block 113. After this, the signal is processed according to the type of signal (voice / data). The received packet data can be acoustically converted with a speaker, or it can be connected to a different device, such as a video monitor. A control unit 103 controls the receiver blocks in accordance with a program that is stored in a memory 104.

During the transmission of a signal, the control unit controls the processing block 133 according to the type of signal. Block 121 further carries out encryption and interleaving of the signal. At block 122 bursts are formed from the encoded data. The bursts are further modulated and amplified at block 123. The RF signal is conducted to antenna 101 through switch 102 for transmission. The processing and transmission blocks are also controlled by the control unit. Especially, the control unit controls the transmission blocks in such a way that the parameters of the MAC header of the RLC block are encoded and transmitted according to the present invention. Furthermore, the channel selection is controlled by the control unit, such that the allocated packet data channel is used according to the invention.

In general, information processing in a telecommunications device takes place in an arrangement with processing capability in the form of microprocessor (s) and memory in the form of memory circuits. Such arrangements are known as such from the technology of mobile stations and fixed elements of the network. To convert a known telecommunications device into a telecommunications device according to the invention, it is necessary to store in the memory means a set of machine-readable instructions, which instruct the microprocessor (s) to perform the operations described above. . Composing and storing such instructions involves known technology, which when combined with the teachings of this present invention is within the capabilities of one of ordinary skill in the art. On the network side, the features according to the invention can be implemented, for example, in the packet control unit PCU, which assigns, for example, uplink and downlink broadcast permits for stations mobiles. The packet control unit may be located, for example, in the Base transceiver station BTS, in the base station controller BCS or in the serving GPRS support node SGSN.

An exemplary embodiment of the solution according to the invention has been described above. The principle according to the invention can, of course, be modified within the scope defined by the claims, for example by modifying details of the implementation and the limits of use.

Information about the next data transmission period can be transmitted on the packet data channel, or it can also be transmitted in a signaling message on the same control channel, such as SACCH (Slow Associated Control CHannel). slow) of the GSM system. Therefore, also the parameters in a MAC header field of an RLC block are given only as examples; there are many other signaling possibilities to convey the corresponding information. In particular, the use of the SACCH or a compatible control channel will allow the transmission of such information at any time, regardless of whether there is currently an active period or not.

The invention is by no means limited to the transmission of voice data, but can be applied to a packet radio service, where data streams are transferred with passive and active periods. An example is video data transmission, where a moving / variable video image would require an active data stream and yet periods of video images that would not require data transmission for image update.

Cited documents

[1] Digital cellular telecommunications system (Phase 2+); general packet radio service (GPRS); mobile station (MS) - base station system (BSS) interface; radio link control / medium access control protocol (RLC / MAC) (GSM 04.60 version 6.1.0); European Institute of Telecommunications Standards.