WO2007125428A2 - Individual and group identifiers for user equipment in wireless systems with a shared transport channel - Google Patents

Abstract

User equipment for communicating data in a communications system comprising a set of user equipment; comprising: a transceiver arranged to receive at least one data packet over a communications channel, wherein the data packet comprises an identifier; and a processor arranged to determine from the identifier if the said user equipment is one of the a subset of user equipment, wherein the processor is arranged to determine if the first identifier is one of the subset of user equipment when the identifier matches a first value if the communications channel is a common channel or a second value if the communications channel is a dedicated channel.

Description

User Equipment

Background to the invention:

Field of the Invention:

This invention relates to user equipment for communication systems and in particular, but not exclusively for high speed downlink packet access (HSDPA) for WCDMA communication systems.

Description of the Related Art:

As is known in the field a further development of the wideband code division multiple access (WCDMA)/ universal mobile telecommunications system (UMTS) communication system defined by the 3GPP organization, is the definition of the system known as high speed downlink packet access (HSDPA). HSDPA operates as a time shared communications channel which provides the potential for high peak data rates as well as the possibility for having a high spectral efficiency.

Current 3GPP HSDPA standards (e.g. 3GPP TS 25.858) define a HS-DSCH channel (high speed downlink shared channel), which is a downlink transport channel shared by several user equipment. The HS-DSCH is associated with one downlink DPCH (downlink dedicated physical channel) or F-DPCH (option in 3GPP Rel6) per active user, and one or several shared control channels (HS-SCCH). The HS-DSCH can be transmitted over the entire cell or over only part of the cell using for example beam-forming antennas.

HSDPA improves system capacity and increases user data rates in the downlink, in other words for transmission of data from a radio base station (RBS) which in a UMTS system is also known as a node B server (and in the GSM by the term base transceiver station BTS) to the user equipment. This improved performance is based on three aspects. The first aspect is the use of adaptive modulation and coding.

In HSDPA, the link adaptation entity in the radio base station (Node-B server) tries to adapt to the current channel conditions of a certain user equipment (or user terminal) by selecting the highest possible modulation and coding scheme keeping the frame error probability below a certain threshold. For that purpose, the user equipment periodically sends channel quality feedback reports to the respective serving RBS, which indicate the recommended transmission format for the next transmission time interval (TTI), including the recommended transport block size, the recommended number of codes and the supported modulation scheme as well as a possible power offset. The reported channel quality indicator (CQI) value is determined on the basis of measurements of a common pilot channel. In a typical implementation it is a pointer to an index in one of the tables specified in the document "3GPP TS 25.214 - Physical Layer Procedures (FDD)" that define the possible transmission format combinations (as mentioned above) for different categories of user equipment (UE).

The second aspect is the provision of fast retransmissions with soft combining and incremental redundancy, so that should link errors occur the user equipment rapidly requests retransmission of the data packets. Whereas the standard WCDMA network specifies that the requests are processed by the radio network controller (RNC), in HSDPA the request is processed by the RBS. Furthermore the use of incremental redundancy, allows the selection of correctly transmitted bits from the original transmission and retransmission in order to minimize the need for further repeat requests when multiple errors occur in transmitted signals.

The third aspect of HSDPA is fast scheduling in the RBS. This is where data to be transmitted to the user equipment is buffered within the RBS prior to transmission and the RBS using a selection criteria selects some of the packets to be transmitted based on information about the channel quality, user equipment capability, the quality of service class and power/code availability. A commonly used scheduler is the so-called proportional fair (P- FR) scheduler.

Although HSDPA is an efficient method for delivering relatively large amounts of data in relatively small time periods (the TTI for a HSDPA system is 2 ms). This performance however can only be used when the user equipment is operating within the dedicated channel state (CELL_DCH state), in other words after a physical layer connection between UE and the RBS has been established and the layer connection has dedicated channels allocated to it.

The transition of the UE to the dedicated channel state (CELL_DCH state) and establishing a HSDPA connection may take up to a second, Thus specifically where the amount of data required to be transmitted is relatively small the state transition to the CELLJDCH state can take longer that the actual data transmission.

Moreover, when the UE is in the process of changing state to the CELL_DCH state, the required state change has to be addressed to the UE by the forward access channel (FACH) which is significantly slower and less robust than the later HSDPA transmission channels.

Before and during the transition to the CELL_DCH state, the CELL_FACH state requires that both the downlink dedicated control channel (DCCH) and the downlink dedicated traffic channel (DTCH) are mapped onto the forward access channel (FACH). This requirement increases the radio resource control (RRC) signalling (caused by the extra DCCH information) and data (caused by the extra DTCH information) transmission delay. The minimum time duration of the FACH transmission (which is carried over the secondary common control physical channel (S-CCPCH)) is approximately 10 milliseconds.

During the radio resource control (RRC) connection establishment phase the common control channel (CCCH) transmission is mapped onto the forward access channel (FACH). Figure 1 shows the procedure for transition of the UE to the dedicated channel state (CELL_DCH) as described in 3GPP technical report TR 25.931. In step 107 of figure 1 (which is described in more detail later), the RRC connection setup message which is typically carried over the common control channel (CCCH) is carried on the forward access channel (FACH) which in turn is mapped on the secondary common control physical channel (S-CCPCH).

It is also known to deliver data to a UE not in the dedicated channel (CELLJDCH) state by using the forward access channel (FACH) to deliver small amounts of data or control information to the UE. However this approach suffers from the inherent problems associated with the FACH, a low data rate and slow retransmission.

The capacity on the forward access channel (FACH) carried on the S-CCPCH is relatively low, typically between 32 to 64 kbps, which limits the use of the forward access channel to small packets.

Typically it is therefore only possible to transmit one or two common control channel (CCCH) radio link control protocol data units (RLC PDU) in a single TTI (a typical CCCH RLC PDU packet is 152 bits). Signalling radio bearers (SRB) mapped onto the dedicated control channel (DCCH) and utilising unacknowledged mode radio link control (UM RLC) packets produce RLC PDUs which are either 136 or 120 bits long. SRBs using acknowledged mode radio link control (AM RLC) produce RLC PDUs which are 128 bits long. In both the unacknowledged and acknowledged modes using the common control channel (CCCH) one or two protocol data units can be transmitted per TTI.

A typical dedicated traffic channel (DTCH) RLC PDU size is 320 bits. As the typical TTI for FACH is 10ms a single DTCH RLC PDU (or packet) transmitted per TTI uses up all of a 32 kbps data rate capacity of the FACH alone.

The reliability of the forward access channel (FACH) is also limited since retransmissions take a considerable amount of time as retransmissions are carried out on the RLC based on the RLC status indicators transmitted on the random access channel in the uplink. In addition a message transmitted on CCCH does not have any retransmission on the RLC layer and in the case of signalling error the RRC layer needs to initiate retransmission of the RRC message if the appropriate response message is not received within a certain time. This time is typically very long (in the order of seconds), due to transmission delays in the FACH (DL) and RACH (UL) channels.

The typical 3G UE power consumption in the dedicated channel state (CELL_DCH) is approximately 250 mA, in the transitional forward access channel state (FACH) is approximately 120 mA, and in the paging channel state (CELL/URA_PCH) or in the idle state is typically < 5 mA. The use of the

FACH channel to transmit data can result in a higher power consumption as the forward access channel (FACH) reception requires more time to receive all of the (slow speed) data.

Therefore, in summary, the requirement to use the forward access channel (FACH) over the secondary common control physical channel (S-CCPCH) for transmission (either as an transitional state or as the operating state for passing data) are those of low data rates, slow retransmission rates, and also a relatively high UE power consumption.

A further issue with regards to the unique identifier H-RNTI which is used to identify the attended receiver of each transmitted packet already in the physical layer can lead to problems in identifying sub-groups within the common group responding to the common H-RNTI value. For example, when the user equipment does not have a valid RNTI identifying itself within the cell (C-RNTI).

Summary of the Invention:

It is an aim of the invention, and embodiments thereof, to provide an improvement to mobile access systems which at least partially addresses the problem disclosed above. Aspects of the invention can be seen from the appended claims.

Brief description of the figures:

The invention is described by way of example only with reference to the accompanying figures in which:

Figure 1 shows a flow diagram showing the steps performed as a UE establishes a RRC connection and moves to a dedicated channel (CEI_L_DCH) state;

Figure 2 shows a schematic view of a communications system within which embodiments of the present invention can be implemented; and

Figure 3 shows a flow diagram showing the steps performed in a first embodiment of the present invention; Figure 4 shows a flow diagram showing the steps performed for initialising the

UE in an embodiment of the invention;

Figure 5 shows a flow diagram showing the steps performed for initialising the

UE in a further embodiment of the invention;

Figure 6 shows a schematic view of the medium access control (MAC) architecture for common HS-DSCH in the user equipment as used within embodiments of the present invention;

Figure 7 shows a schematic view of the MAC architecture for common HS-

DSCH in the UTRAN; and

Figure 8 shows a flow diagram showing the steps performed in embodiments of the present invention.

Description of the preferred embodiments:

The invention is described herein by way of example with reference to a number of embodiments. The invention is described in the context of a cellular communications system and specifically to a HSDPA WCDMA/UMTS communications system. It is however understood that the invention may equally be capable of being implemented in any communications system which implements scheduling of data packets especially those which need to address the problem of latency and spectral efficiency in transmission of data packets.

Figure 2 shows a schematic view of a communications system within which the embodiments of the present invention can be implemented. The system comprises at least one user equipment (UE) 1. User equipment 1 can be for example a mobile telephone, but could also be for example a communication capable laptop, personal digital assistant, or any other suitable device.

User equipment 1 communicates wirelessly by radio with a series of radio base stations (RBS) 3. The radio base stations are also known in the UMTS standard as Node-B. In the following description the terms Node-B and radio base station (RBS) are to be used interchangeably.

Each user equipment 1 is arranged to be able to communicate to more than one RBS 3 and similarly each RBS 3 is arranged to be capable of communicating to more than one UE 1. The RBS 3 further communicates with a radio network controller (RNC) 5 (which is also known in the GSM standard as a Base station controller (BSC)). The RNC 5 can further communicate to a core network (CN) 7. The CN 7 can further communicate with other networks, for example further public land mobile networks (PLMNs) or to the network of computers known as the 'Internet'.

To clarify some of the terms used in the embodiments of the invention described below we describe with the assistance of figure 1 a flowchart for a radio resource controller (RRC) connection establishment as would be carried out by a UE 1 in the network as defined by 3GPP TR 25.931.

In step 101 , the UE 1 initiates set up of a radio resource controller connection by sending a radio resource controller (RRC) connection request message on the common control channel (CCCH) to the serving RNC 5 via the selected cell that is the cell of the RBS 3. The connection request contains the parameters of the initial user equipment (UE) 1 identity value, and the cause for establishment of the connection. In the step 102, the serving radio network controller (RNC) 5 establishes the Radio Resource Control (RRC) connection to the UE 1 and decides to use a dedicated channel for this particular RRC connection, and allocates a UTRAN (UMTS terrestrial radio access network) RNTI (radio network temporary identifier) and radio resources L1 , L2 for the radio resource controller connection. When a dedicated channel is to be set up, a node B application protocol (NBAP) message, a "radio link set up request" message, is sent to the RBS 3. The parameters contained within the radio link set up request include the cell identification value, the transport format set, the transport format combination set, the frequency, the uplink scrambling codes to be used (for frequency division duplex (FDD) communication only), the time slots to be used (for time division duplex (TDD) communication only), the user code (for TDD only) and power control information.

In step 103, the RBS 3 allocates the resources, starts reception of the uplink physical channels, and responds with a NBAP message, a "radio link setup response" message. The radio link set up response message contains parameters defining signalling link termination, transport layer addressing information (such as the ATM adaptation layout type 2 (AAL2) address, AAL2 binding identity) for the Iub data transport bearer.

In step 104, the serving radio network controller initiates the set up of Iub data transport bearer using the access link control application part protocol (ALCAP). This request contains the AAL2 binding identity to bind the Iub data transport bearer to the dedicated channel. The request for setup of Iub data transport bearer is acknowledged by the RBS 3.

In steps 105 and 106, the RBS 3 and the serving RNC 5 establish synchronism for the Iub and lur data transport bearers by means of exchange of the appropriate dedicated channel frame protocol frames, e.g. the "downlink synchronisation" and "uplink synchronisation" messages. Following synchronisation, the RBS 3 starts the downlink transmission to the UE 1. In step 107, a message is sent from the serving RNC 5 to the UE 1 , the message being a radio resource controller (RRC) connection set up message sent on the common control channel (CCCH). The RRC connection set up messages contains the parameters of the initial UE identity value, the U-RNTI, (valid inside UTRAN in CELL_FACH state and in CELL/URA_PCH), the C- RNTI (valid inside cell in CELL_FACH state), the capability update requirement, the transport format set, the transport format combination set, the frequency, the downlink frequency scrambling code (FDD only), the time slots (TDD only), the user code (TDD only), power control information and other data as defined in 3GPP standard TS25.331 section 10.2.40 in particular in order to configure the signalling connection on HSDPA.

In step 108, the RBS 3 achieves uplink synchronisation and notifies the serving RNC 5 with a NBAP message, a "radio link restore indication".

In step 109, a RRC connection set up complete message is sent on the dedicated control channel (DCH) from the UE 1 to the serving RNC 5 via the serving RBS 3. This RRC connection set up complete message contains the parameters of integrity information, ciphering information, and UE radio access capability.

As has been described above, these steps are required in order to carry out a high speed downlink packet access communication.

Thus in HSDPA operation in CELLJDCH state each UE is assigned a unique H-RNTI that is used to identify the intended receiver of each transmitted packet already in the physical layer.

In the embodiments of the invention as described in detail below the HSDPA usage in other than CELL_DCH state uses a common physical layer identifier (i.e. a group UE ID value) which is known to a UE 1 without the need to uniquely assign a ID to each UE. The intended UE receiver is then identified by the MAC header in case of DTCH or DCCH transmission or from UE ID included in RRC message in case of CCCH message (RRC connection setup, Cell update confirm) just as is done by the FACH in the prior art.

In embodiments of the present invention a UE in either the dedicated or non dedicated channel state can detect whether the transmission was for it or not, but in CELLJDCH the UE knows this from the physical layer without needing to receive and decode the data packet first.

In Figure 3 a flow chart showing the steps carried out in a first embodiment of the invention are described.

In step 201 a UE 1 receives a first common identification value (CCCH H- RNTI), which is used when the UE does not have a valid C-RNTI, (defining a group of UE ID values) from a system information broadcast (SIB) from the RNC that is typically used for HS-SCCH detection before the RRC connection has been established or when C-RNTI is not valid after cell reselection, i.e. to receive the RRC connection setup message or the cell update confirm (when only U-RNTI is valid).

In other embodiments of the invention the UE calculates the common parameter and corresponding HS-SCCH/HS-DSCH parameters from the SIB transmitter from the RNC.

In further embodiments the H-RNTI value is a known predetermined value set by the operator in advance.

The UE also receives a second common identification value (DCCH/DTCH H- RNTI). The UE uses the DCCH/DTCH H-RNTI when the UE has a valid C- RNTI. The manner by which the UE receives this second H-RNTI value and any corresponding HS-SCCH/HS-DSCH parameters is discussed later. However this information may be obtained from dedicated RRC signalling. For example, these values may be obtained from a physical channel reconfiguration request. In other embodiments, the UE obtains the DCCH/DTCH H-RNTI and corresponding HS-SCCH/HS-DSCH parameters from the SIB or paging transmitted from the RNC. In further embodiments, the DCCH/DTCH H-RNTI value and corresponding HS-SCCH/HS-DSCH parameters are predetermined and set by the operator.

The UE 1 also receives an individual identification value (an individual UE ID value) identifying a single UE 1. This ID value can be assigned, during a RRC connection (C-RNTI), at step 107, so that UE having RRC connection and valid C-RNTI can detect if the transmission is intended to it directly from HS- SCCH at physical layer. In some embodiments of the invention these ID values can be updated by dedicated RRC signalling. As discussed above in some embodiments the C-RNTI is not a valid value.

In step 203 the received identification values are stored in the UE 1.

In step 205 the UE receives a high speed downlink packet access (HSDPA) data frame sent using the high speed downlink shared channel (HS-DSCH) with a MAC header value indicating a unique UE ID value. The associated high speed shared control channel (HS-SCCH) data for the same frame comprises information identifying a common H-RNTI value. The HS-SCCH data also specifies the transport format and the rate of the associated high speed physical downlink shared channel - the physical channel the HS-DSCH data is transmitted over. As the values are used in the MAC header the UE can detect if the data transmission was intended for the UE or not, even when the common ID is used, for example in case of a CCCH transmission the UE 1 can identify if the transmission was for the UE in the RRC layer.

In step 207 the UE 1 checks to see if for the ID sent over the high speed shared control channel (HS-SCCH) matches the common ID of the UE (either the CCCH H-RNTI when the UE does not have a valid C-RNTI or the DCCH/DTCH H-RNTI when the UE has a valid C-RNTI), or if one was assigned, the dedicated ID of the UE. The common UE ID or dedicated ID value is transmitted in a known manner, i.e. the value within the HS-SCCH is transmitted in the same way as would be carried out for any UE in the dedicated channel state which has a specific UE ID assigned to it during the RRC setup.

The specific UE to which the data is addressed, rather than the group of UEs identified by the group UE ID value is determined by a unique identifier in the medium access control (MAC) protocol header associated with the HS-DSCH.

Thus in embodiments of the invention small amounts of high speed data can be received by a UE not in the dedicated channel without the requirement of passing through the forward access channel state.

In further embodiments of the invention any UE 1 establishing the RRC connection as described earlier can use the UE ID value transmitted to it in the system information broadcast (SIB). The SIB is information broadcast across the cell and can be received by any UE within the cell without the RBS 3 knowing which UE 1 have received the SIB. The SIB transmissions do not require an acknowledgement transmission and therefore can be advantageous carriers of the group UE ID value. In further embodiments the RNC 5 allocates the group UE ID values which are passed to the RBS 3 to be transmitted to the UE 1.

In some embodiments of the invention the unique ID is transmitted to the UE 1 by being masked directly to a CRC in the HS-SCCH. Masking a unique ID to a CRC on HS-SCCH means that the CRC, a checksum to enable the receiver to determine if a packet is correctly received, is modified by the ID value in such a way that only a receiver knowing the ID can determine the correct CRC value and therefore is able to detect whether the HS-SCCH was received correctly. The advantage with masking an ID to a CRC on the HS-SCCH is that no additional bits are inserted onto the HS-SCCH due to the inclusion of the UE unique ID, but the unique UE ID information is present in the HS- SCCH message. In other embodiments the ID value is inserted on the MAC header/RRC layer where there is a specific bit field for the UE ID value reserved. The embodiments using the MAC header are not required to carry out a masking or modification of the signal other than the insertion of the value in the bit field.

As the UE 1 must first detect the ID (i.e. determine if the UE-specific CRC indicates a correct reception) on the HS-SCCH before it tries to decode the

HS-DSCH to see if the unique ID in either the MAC header or the RRC message matches the UE unique ID value. Therefore the MAC/RRC level ID must be the unique UE ID if the HS-SCCH ID is the group UE ID and if the

HS-SCCH ID is the unique UE ID then the MAC/RRC UE ID can be considered to be equal in value.

In some embodiments of the invention UE 1 in the UTRAN registration area - paging channel state (CELL/URA_PCH) or in the idle state would not listen to the high speed downlink packet access information continuously, but is arranged to receive both HS-DSCH and HS-SCCH packets only at predetermined times.

In a further embodiment the UE 1 is arranged to listen for the HS-SCCH at predetermined times and then only if it receives a data packet with the predetermined group UE ID listen for the data on the HS-DSCH. This embodiment is similar to the conventional HSDPA reception mode whereby the UE detects a HS-SCCH packet addressed to it before arranging itself to receive an associated UE addressed HS-DSCH packet with the difference that the UE is only listening to the HS-SCCH at predetermined times and not therefore allowing the UE to switch off the radio receiver during the non- reception periods thus saving battery power.

In other embodiments of the invention, the UE listens when triggered by an event. For example the random access channel (RACH) can be used due to UE activity or in response to a paging message. In such embodiments the UE is able to conserve power, in other words toj'sleep" and save battery power if no activity is expected. In such an embodiment an UE 1 in idle mode would start high speed data packet access reception after sending the radio resource controller connection request on the random access channel (RACH). An UE 1 in CELL/URA_PCH state would start HSDPA reception after sending the cell update message. The sleep mode is simpler to organise with the use of the HS-DSCH since the TTI is short (2 milliseconds compared to the forward access channel with a 10 millisecond TTI).

The user equipment 1 in the transitional CELL_FACH state can be arranged in some embodiments to receive HSDPA data continuously if the network is able to transmit data or signalling to the user equipment on either the dedicated traffic channel (DTCH) or the dedicated control channel (DCCH).

UE 1 in the CELLJFACH state can also be arranged to receive the data occasionally where discontinuous reception periods (DRX) are indicated for the HSDPA data transmission.

In the above embodiments of the invention, compared against conventional HSDPA from UE in CELL_DCH states, does not have the provision to send from the UE 1 to the RBS 3 a specific channel quality indicator (CQI) report (this is typically transmitted on the high speed dedicated control channel - the uplink feedback channel of the HSDPA, for the user equipment in the dedicated channel mode in order to assist the selection of MCS (modulation and coding scheme) selection for the high speed physical downlink shared channel (HS-PDSCH) and the power setting of the high speed shared control channel (HS-SCCH). The selection of the MCS values is arranged so that for a good quality channel the MCS values can be chosen to use higher order modulation and less coding and thus increase the data throughput and in bad quality channels the MCS values can be chosen to use a simple modulation and more error correction coding to reduce errors at the cost of smaller data transmission capacity.

Furthermore the above embodiments have no acknowledgment feedback (ACK/NACK) for the high speed acknowledgement request (HARQ - the high speed downlink shared channel reception acknowledgement). Thus for the above embodiments there is no signal to indicate whether a retransmission is requested as the ACK/NACK signals are typically transmitted on the uplink on a high speed dedicated control channel (the uplink feedback channel of the HSDPA) for the user equipment in the dedicated channel state.

In a further embodiment of the invention, the RBS 3 selects the high speed - shared control channel power and the MCS values for the HS-DSCH accordingly in order that it is able to be received at the cell edge. In further embodiments of the invention mechanisms are provided for estimating the required HS-SCCH power requirements and suitable MCS values for the HS- DSCH are required and these values selected for the HS-SCCH and HS- DSCH data streams.

In other embodiments the same transmission values are transmitted more than once in order to produce the required time diversity in the system and also to produce a required HARQ gain.

In the above embodiments the transmission system is provided with a degree of system control - all of the UE 1 in the cell are able to receive the data.

In a further embodiment of the invention, the RBS 3, although not having a user equipment specific CQI report, receives from the UE 1 a predefined uplink scrambling code containing transmission feedback after receiving the high downlink shared channel transmission intended for it. The transmission feedback signal in these embodiments enables a HARQ method as known in the art to be used. This is shown in figure 3 in step 209.

In further embodiments of the invention, a CQI report is transmitted from the UE with transmission feedback in order to be able to calculate subsequent high speed shared control channel (HS-SCCH) power settings and high speed downlink shared channel (HS-DSCH) MCS selection.

Embodiments of this invention as described above can be implemented by requiring any UE with the group UE ID to acknowledge the receipt of the packet and to transmit CQI report as if the data was intended for it. An alternative embodiment requires that any UE identifying the UE's individual UE ID in the medium access controller protocol data unit and/or the radio resource controller message after first detecting the group UE ID in the HS- SCCH before transmitting any acknowledgment to the network.

In some embodiments of the invention the controlling radio network controller (RNC) could use single ATM adaptation layout type 2 (AAL2) connection over the lub interface for common control channel (CCCH) and for all downlink control channel (DCCH) and dedicated traffic channel (DTCH) allocated for the UE in the forward access channel transitional state. Thus MAC-c multiplexing can in some embodiments be used instead of forward access channel transmission state.

In further embodiments of the invention, where it is required to meet different priority and quality of service (QoS) requirements separate AAL2 connections are allocated for the CCCH, DCCH and DTCH. For example transmission of the common control channel (CCCH) and dedicated control channel (DCCH) could have in some embodiments a higher priority and reliability factor than the dedicated traffic channel (DTCH).

Although the embodiments described above refer to the use of the HSDPA channels to transmit moderate amounts of data to the UE this transmission of data also applies to the transmission of data in the RRC connection step 107 from the RNC 5 to the UE 1 via the RBS 3 as shown in figure 1. As described above by using a channel faster than the FACH the speed of receiving the CCCH data packets can be increased and therefore the time required to setup the UE in CELL_DCH mode decreased. A specific UE ID for the CELLJDCH state is assigned to the UE at this stage.

The embodiments as described above provide a more robust and faster way to deliver user data and RRC signalling messages to a UE than using a conventional delivery method (FACH) as used in the prior art. Also by using these embodiments, UE 1 not in the dedicated channel mode of operation have a faster state transition to the dedicated channel mode of operation from the idle or paging modes as they only require to receive a moderate amount of data which can be served with HSDPA techniques without requiring the user equipment to exchange data via the FACH state.

Although the above embodiments only have partial HSDPA support (for example in some embodiments there is no uplink feedback from the user equipment and therefore no knowledge of CQI or no possibility to receive ACK/NACK messages in the RBS 3), the gain in terms of decreased delays would be inevitable due to the much shorter TTI of the HSDPA over the FACH. Furthermore, as described in some embodiments there is a possibility of using blind retransmissions to achieve a gain from HARQ combining.

Although the system requires approximately 5 times more power to deliver the same data in 2 ms than in 10 ms and thus there is no power saving in this and, there is a benefit in that it is not necessary to allocate a specific power share for HSDPA transmission for users not in the dedicated channel state

(CELL_DCH) as all of the UE time-share the same power resource. In the prior art examples FACH power was needed to be statically allocated for FACH used whether the channel was actually utilised or not.

Furthermore, as the present invention uses the existing layer-1 of the HSDPA network specification the implementation of the invention is relatively simple.

As also described above the power consumption of the UE in the CELL_FACH state is an issue in always on applications for example in push mail which send periodic keep alive messages. In these situations, even if the amount of data is very low the user equipment is kept on the forward access channel until the inactivity timer expires. Typically the inactivity timer is about 2 seconds. Using discontinuous reception (DRX) as described above the power consumption could be considerably reduced. This would enable a major improvement in the UE stand by time for always on applications. As already described in figure 3, step 201 shows where the radio base station RBS 3 transmits the H-RNTI values to the user equipment 1. However, with respect to the figures 4 and 5, this process and the steps of determining the H-RNTI and other values with regards to the supply of the DCCH/DTCH H- RNTI are described in further detail.

With respect to figure 4 a first method of determining the DCCH/DTCH H- RNTI values and other data are shown as employed in embodiments of the invention. In this first method the H-RNTI values are transmitted to the UE using radio resource control messages. In these embodiments some of the information needs to be signalled over the lur interface.

In step 401 the serving radio network controller SRNC 5 determines that the user equipment (UE) 1 will use the common HS-DSCH in the cell under the control of a drift radio network controller/controlling radio network controller (D/CRNC).

In step 403 the SRNC 5 forwards to the D/CRNC at least one HS-SCCH/HS- DSCH parameter. For example in an embodiment of the invention the forwarded parameters include the number of priority queues used in the HS- DSCH and the scheduling priority indicator (SPI) for each of the priority queues.

In step 405 the SRNC 5 establishes an ATM adaptation layer 2 (AAL2) connection for the user equipment 1 over the lur interface for carrying the forward link access channel (SACH) data frame. The SACH data frame includes data mapped to the common HS-DSCH. In some embodiments of the invention, a single AAL2 connection could be set up and shared among all user equipment carrying out this process.

In step 407 the SRNC 5 locates the medium access control -d (MAC-d).

In step 409 the SRNC 5 transmits user equipment RRC signalling to the user equipment via the RBS 3. For example, the signalling may contain the C-RNTI value and/or the DCCH/DTCH H-RNTI values and furthermore the DRX cycle value for the HS-SCCH. At this stage it is not necessary for the SRNC 5 to know the CCCH H-RNTI for the cell under the D/CRNC.

In step 411 the serving radio network controller 5 then forwards data to the D/CRNC using the FACH data frame.

In step 413 the D/CRNC determines whether or not to transmit data to the UE as described in the embodiments of the description or to operate according to the known method of using the FACH or causing the UE to operate in Cell_DCH mode for the cell under the control of this D/CRNC.

In step 415 the D/CRNC locates the medium access control -c (MAC-c), in other words adding the C-RNTI value for the DCCH/DTCH packet data unit.

In step 417 the D/CRNC configures the common HS-DSCH/HS-SCCH information for each common H-RNTI. The same configuration is applied for all user equipment having the same H-RNTI value.

In step 419 the D/CRNC establishes an AAL2 connection for all user equipment 1 having a common HS-DSCH value. In other embodiments, the RNC establishes a separate AAL2 connection for each of the H-RNTI values.

In step 421 the D/CRNC allocates the C-RNTI values.

In step 423 the D/CRNC determines the user equipment capability for handling HS-DSCH parameters. For example, the D/CRNC receives an uplink CCCH message and determines the user equipment capacity from this message.

In step 425 the D/CRNC allocates the H-RNTI (DCCH/DTCH) based on the received common H-DSCH parameters from the serving RNC and forwards to the serving RNC the selected H-RNTI and the corresponding HS- DSCH/SCCH information for the H-RNTI. In step 427 the D/CRNC forwards the selected H-RNTI value and parameter data to the RBS over a frame protocol. A preferred frame protocol is the HS- DSCH frame protocol, the payload of which is a MAC-c packet data unit and includes power control information. In further embodiments, a different frame protocol is used to transfer this information.

In step 429 the RBS 3 locates the MAC-hs and the data flow is mapped to the common HS-DSCH.

In step 431 the RBS broadcasts the CCCH H-RNTI and the corresponding HS-SCCH/HS-DSCH information configured from the D/CRNC.

In step 433 the RBS 3 executes power control for the HS-SCCH. In other embodiments, the modulation and coding scheme (MCS) selection for the HS- DSCH is carried out based on the information included in the received HS- DSCH data frame or the new frame protocol data frame from the RNC.

In step 435 the user equipment obtains or calculates the H-RNTl for the CCCH and the corresponding HS-SCCH/HS-DSCH information from the SIB/paging message.

In step 437 the UE obtains or calculates the DCCH/DTCH H-RNTI for the DCCH/DTCH and the corresponding HS-SCCH/HS-DSCH information from the dedicated RRC message.

Thus the UE uses the allocated H-RNTI for CCCH and DCCCH/DTCH messages for the UE identification.

With respect to figure 5, the impact on the UE 1, RBS 3, Serving Radio Network Controller (SRNC) 5, and Drift Radio Network Controller Controlling Radio Network Controller D/CRNC 501 by broadcasting the H-RNTI values to the UE is shown. In step 501 the SRNC 5 does not determine if the FACH data is mapped to the common HS-DSCH or not (for example the FACH is mapped to S- CCPCH) for all RNCs operating under a specific D/CRNC. Furthermore the SRNC 5 does not know if the FACH data is mapped to the common HS- DSCH from signaling received via a Radio Network System Application Part from the D/CRNC.

In step 503 the SRNC 5 establishes an ATM Application Layer 2 (AAL2) connection for the UE over the lur interface which is arranged to carry the Forward Link Access Channel (FACH) Data Frame. In some embodiments of the invention the AAL2 connection is shared by more than one UE 1.

In step 505 the SRNC 5 then locates the Medium Access Control - d (MAC- d).

In step 507 the SRNC 5 forwards data to the D/CRNC using FACH frame protocol.

In step 509 the C/DRNC having received the data from the SRNC 5 then determines if it is to pass the data to the UE via the FACH channel or as detailed within the description by using the common value HS-DSCH method.

In step 511 the C/DRNC then locates the MAC - c (MAC-c). The C/DRNC adding the C-RNTI value for the DCCH/DTCH PDU.

In step 513 the C/DRNC configures the common HS-SCCH/HS-DSCH information info used in the H-RNTI and the further H-RNTI. The configuration values established are applied for all of the UEs sharing the same H-RNTI value.

In step 515 the C/DRNC establishes an AAL2 connection for all UEs using the common HS-DSCH method. In other embodiments of the invention the C/DRNC establishes a separate AAL2 connection for each group of UE's sharing the same H-RNTI common value. in step 517 the C/DRNC then allocates the C-RNTI values.

In step 519 the C/DRNC then determines for each UE using the common channel system the UE's capacity, i.e. whether the UE is able to receive and decode the common messages in line with the described manner. The determination can be carried out for example by receiving an Uplink (UL) Common control channel (CCCH) message.

In step 521 the C/DRNC then calculates and selects the DCCH/DTCH H-RNTI value for the UE's and also selects the CCCH H-RNTI if multiple CCCH H- RNTI are allocated in the cell.

In step 523 the C/DRNC then forwards the selected data to the RBS using a frame protocol. The preferred frame protocol is that of the HS-DSCH frame protocol (which has a MAC-c packet data unit payload and includes power control info). In other embodiments of the invention a frame protocol capable of transferring the selected data.

In step 525 the RBS 3, on receipt of the selected data, locates the medium access control - hs (MAC-hs) and maps the data flow to common HS-DSCH.

In step 527 the RBS 3 broadcasts the CCCH H-RNTI₁ DCCH/DTCH H-RNTI and the corresponding HS-DSCH/SCCH information for H-RNTIs, to the UEs 1.

In step 529 the RBS 3 furthermore executes power control on the HS-SCCH and/or selects the modulation and coding scheme (MCS) on the HS-DSCH based on the information included in the HS-DSCH data frame.

In step 531 the UE 1 , on receipt of the broadcast message, obtains and/or calculates the various H-RNTI value for the CCCH and H-RNTI value for the DCCH/DTCH groupings and the corresponding HS-SCCH/HS-DSCH Information from the SIB/Paging. As has been described above the UE, in order to determine if the message is for the UE₁ uses the allocated H-RNTI values for CCCH and DCCH/DTCH contained in the later messages.

The data flow i.e. the mapping of data from the core network 7 to the user equipment 1 differs dependent on whether the channel is a common or dedicated one.

For the common channels (common control channel (CCCH) and common traffic channel (CTCH)) within the core network, on passing to the C/DRNC are converted to a Medium access control - c flow, on further passing to the RBS are converted to medium access control - hs flow which are then transmitted as part of a high speed downlink shared channel (HS-DSCH).

The dedicated channels (dedicated control channel (DCCH) and dedicated traffic channel (DTCH)) within the core network, on passing to the serving radio network controller are converted to a medium access control - d flow; on passing to the controlling/drift RNC are converted to a medium access control -c flow, on passing to the RBS are converted to a medium access control - hs flow which is then transmitted as part of a high speed downlink shared channel (HS-DSCH).

Figures 6 and 7 show in schematic view the MAC layer interfaces in the UE and in the UTRAN.

Figure 6 shows an UE as used in embodiments of the present invention with MAC interfaces: MAC-es/MAC-e 601 ; MAC-m 603; MAC-hs 605; MAC-c/sh/m 607; MAC-d 609.

The MAC-es/MAC-e 601 is controlled by the MAC controller and is further connected to the MAC-d 609 interface. The MAC-es/MAC-e 601 receives associated downlink and uplink signaling and also receives the E-DCH data (enhanced data channel). The MAC-nn 603 is controlled by the MAC controller and is connected to the MSCH (Mobile shared channel) and MTCH (mobile traffic channel). The MAC- m 603 receives data via the FACH.

The MAC-hs interface 605 is controlled by the MAC controller and is connected to the MAC-d interface 609 and to the MAC-c interface 607. The MAC-hs 603 further receives data via the HS-DSCH. The MAC-hs interface carries data which does the following tasks: Re-ordering queue distribution, Re-ordering, Disassembly, HARQ (as described with regards to other embodiments no ACK/NACK generation and CQI reporting is carried out and soft combing is carried out).

The MAC-c/sh/m interface 607 is controlled by the MAC controller and is connected to the MAC-d interface 609 and the MAC-hs interface 605. It is connected within the UE to the channels: MTCH, MSCH, MCCH, PCCH,

BCCH, CCCH, CTCH, SHCCH (TDD only). The MAC-c/sh/m interface 607 receives data via the following external channels: PCH; FACH; RACH; USCH

(TDD only); DSCH (TDD only). The MAC-c/sh/m interface 607 carries data with does the following tasks: TCTF multiplexing, Reading the UE-ID value.

The MAC-d interface 609 is controlled by the MAC controller and is connected to the MAC-c/sh/m interface 607 and the MAC-hs interface 605. It is connected within the UE to the channels: DCCH, DTCH. The MAC-d interface 609 receives data via the DCH external channel. The MAC-d interface 609 carries data which carries out the task of switching channel type for example from common HS-DSCH to dedicated HS-DSCH and CT multiplexing.

Figure 7 shows an RAN as used in embodiments of the present invention with MAC interfaces: MAC-e 701 ; MAC-es 707; MAC-hs 703; MAC-c/sh/m 705; MAC-d 709.

The MAC-e interface 701 is controlled by the MAC controller and is further connected to the MAC-es interface 707. The MAC-e 701 interface receives associated downlink and uplink signaling and also receives the E-DCH data (enhanced data channel).

The MAC-es interface 707 is controlled by the MAC controller and is connected to the MAC-e interface 701 and the MAC-d interface 709.

The MAC-hs interface 703 is controlled by the MAC controller and is connected to the MAC-d interface 709 and to the MAC-c interface 705. The MAC-hs interface 703 further receives data via the HS-DSCH. The MAC-hs interface carries data which does the following tasks: Scheduling; Priority handling; Flow control; TFRC selection; HARQ (as described with regards to other embodiments no ACK/NACK generation and CQI reporting is carried out and instead the execution of a fixed number of transmission is carried out).

The MAC-c/sh/m interface 705 is controlled by the MAC controller and is connected to the MAC-d interface 709 and the MAC-hs interface 703. It is connected within the RAN to the channels: MTCH, MSCH, MCCH, PCCH, BCCH, CCCH, CTCH, SHCCH (TDD only). The MAC-c/sh/m interface 607 receives data via the following external channels: PCH; FACH; RACH; USCH (TDD only); DSCH (TDD only). The MAC-c/sh/m interface 607 carries data with does the following tasks: TCTF multiplexing, UEID multiplexing, Flow Control; Scheduling; Buffering; Priority Handling.

The MAC-d interface 709 is controlled by the MAC controller and is connected to the MAC-c/sh/m interface 705 and the MAC-hs interface 703. It is connected within the RAN/CN to the channels: DCCH, DTCH. The MAC-d interface 709 receives data via the DCH external channel. The MAC-d interface 709 carries data which carries out the task of switching channel type for example from common HS-DSCH to dedicated HS-DSCH, CT multiplexing; and Flow control.

Figure 8 shows the example of signaling flow from the RRC connection setup o state transition from the Cell FACH state to the Cell DCH state. In step 801 the serving/controlling radio network controller 5 in communication with the RBS 3 determines to use at least one of the embodiments as described above. The S/CRNC then establishes an AAL2 connection for common HS-DSCH and configures the HS-DSCH info for a common H-RNTI.

In step 803 the RBS 3 broadcasts the CCCH and DCCH/DTCH H-RNTI and the corresponding HS-DSCH information to the UE 1.

In step 805 the S/CRNC allocates the C-RNTI and calculates the UE's DCCH/DTCH H-RNTI.

In step 807 the UE 1 listens to the HS-SCCH using the value of the CCCH H- RNTI to identify if the message received is addressed to the UE.

In step 809 the RRC response message including the C-RNTI value is carried by the HS-DSCH frame protocol over the lub interface and the HS-PDSCH over the Uu interface.

In step 811 the UE listens to the HS-SCCH using the DCCH/STCH H-RNTI value(s) to identify if the message received is addressed to the UE.

In step 812 the S/CRNC decides to move the UE to the Cell_DCH state.

In step 813 the S/CRNC establishes RL and AAL2 connection and begins frame protocol synchronization.

In step 815 the S/CRNC transmits a RRC reconfiguration message which includes dedicated HS-DSCH information and a dedicated H-RNTI value (carried in the common HS-DSCH using DCCH/DTCH).

In step 817 the UE 1 performs synchronization based on the received information. In step 819 the Release 5 HS-DSCH transmission is initiated using the dedicated H-RNTI value.

The advantages as mentioned earlier are that is possible to increase the peak bit rate in the Cell_FACH state. Furthermore it increases the flexibility for cell capacity for transmitting signaling and data to the User Equipment in the

Cell_FACH state. The embodiments as described are backwards compatible with earlier specified HSDPA releases. Furthermore the second method for passing the H-RNTI value to the UE as described above is furthermore compatible with earlier specified Serving RNCs. Furthermore only limited changes to the architecture at network levels 2 and 3 are required with no changes required to network level 1.

The applicant hereby discloses in isolation each individual feature described herein and any combination of two or more such features, to the extent that such features or combinations are capable of being carried out based on the present specification as a whole in the light of the common general knowledge of a person skilled in the art, irrespective of whether such features or combinations of features solve any problems disclosed herein, and without limitation to the scope of the claims. The applicant indicates that aspects of the present invention may consist of any such individual feature or combination of features. In view of the foregoing description it will be evident to a person skilled in the art that various modifications may be made within the scope of the invention.

Claims

1. User equipment for communicating data in a communications system comprising a set of user equipment; comprising: a transceiver arranged to receive at least one data packet over a communications channel, wherein the data packet comprises an identifier; and a processor arranged to determine from the identifier if the said user equipment is one of the a subset of user equipment, wherein the processor is arranged to determine if the first identifier is one of the subset of user equipment when the identifier matches a first value if the communications channel is a common channel or a second value if the communications channel is a dedicated channel.

2. The user equipment as claimed in claim 1 , wherein the transceiver is further arranged to receive in a further data packet a further value arranged to identify the subset of user equipment as not being in a dedicated channel state.

3. The user equipment as claimed in claim 1 or 2, wherein the transceiver is further arranged to receive in the further data packet a second identifier value to identify each of the user equipment within the same subset.

4. The user equipment as claimed in claims 1 to 3, wherein the communications channel is a high-speed downlink shared channel (HS-

DSCH).

5. The user equipment as claimed in claim 4, wherein the communications channel comprises at least one of: a dedicated traffic channel (DTCH); a dedicated control channel (DCCH) and a common control channel (CCCH).

6. The user equipment as claimed in claims 1 to 5, wherein the first data packet comprises radio resource communication data.

7. The user equipment as claimed in claims 1 to 6, wherein the identifier is located in a medium access control (MAC) header of the data packet.

8. The user equipment as claimed in claims 1 to 7, wherein the identifier is in a RRC level message on top of the MAC layer.

9. The user equipment as claimed in claims 1 to 8, wherein at least one of the first and second values are received in or calculated from at least one of a paging message; a SIB; a dedicated paging message; a initial setup instruction.

10. A method for communicating a data packet over a communications data channel to at least one user equipment; comprising the steps of: transmitting a data packet over a communications channel, the data packet comprising a first identifier arranged to identify a subset of a set of user equipment; receiving the data packet at the at least one of the plurality of user equipment; determining from the data packet first identifier if the said user equipment is one of the said subset of user equipment, wherein step of determining determines if the first identifier is one of the subset of user equipment when the identifier matches a first value if the communications channel is a common channel or a second value if the communications channel is a dedicated channel.

11. A method as claimed in claim 10, wherein the communications channel comprises at least one of: a dedicated traffic channel (DTCH); a dedicated control channel (DCCH); and a common control channel (CCCH).

12. A computer program when loaded into a computer arranged to carry out the method of communicating a first data packet over a communications data channel to at least one user equipment; comprising the steps of: transmitting a data packet over a communications channel, the data packet comprising a first identifier arranged to identify a subset of a set of user equipment; receiving the data packet at the at least one of the plurality of user equipment; determining from the data packet first identifier if the said user equipment is one of the said subset of user equipment, wherein step of determining determines if the first identifier is one of the subset of user equipment when the identifier matches a first value if the communications channel is a common channel or a second value if the communications channel is a dedicated channel.