HK1098610B - Medium access control priority-based scheduling for data units in a data flow - Google Patents

Description

Media access control based on priority scheduling for data units in data streams

Technical Field

The present invention relates to wireless communication systems, and more particularly to packet transmission scheduling for High Speed Downlink Packet Access (HSDPA) operating in a Universal Mobile Telecommunications System (UMTS) terrestrial radio access network (UTRAN).

Background

The Universal Mobile Telecommunications System (UMTS) is a third generation mobile communication system developed by the global system for mobile communications (GSM) and is intended to provide an improved mobile communication service based on the GSM Core Network (CN) and Wideband Code Division Multiple Access (WCDMA) access technologies. Fig. 1 shows a UMTS Terrestrial Radio Access Network (UTRAN) defined in the third generation mobile communication standard 3 GPP.

As shown in fig. 1, the UTRAN 110 includes one or more Radio Network Subsystems (RNSs) 120 and 130. Each RNS120, 130 comprises a radio network controller, RNC121, 131 and one or more node bs 122, 123, 132, 133 (a node B is similar to a radio base station). For example, the node bs 122 are managed by the RNC121 and receive information transmitted from a physical layer of a User Equipment (UE)150 (sometimes referred to as a mobile terminal) via an uplink channel and transmit data to the UE 150 via a downlink channel. From the perspective of the UE, the node B acts as an access point for the UTRAN. The RNCs 121 and 131 allocate and manage radio resources of the UMTS and connect to an appropriate core network according to the type of service provided to the user. For example, the RNCs 121 and 131 are connected to a mobile switching center (NSC) for circuit-switched communications such as a voice call service, and a serving GPRS support node (SGNC)142 for packet-switched communications such as a wireless internet service. The RNC responsible for directly managing the node B is called a controlling RNC (crnc). The CRNC manages common radio resources. On the other hand, an RNC managing dedicated radio resources for a specific UE is called a serving RNC (srnc). The CRNC and the SRNC may be co-located in the same physical node. However, if the UE moves to an area of a new RNC different from the SRNC, the CRNC and the SRNC may be located at physically different places.

UMTS includes interfaces that operate as communication paths between different network elements. For example, the interface between a node B and an RNC is referred to as the Iub interface, and the interface between RNCs is referred to as the Iur interface. The interface between the RNC and the core network is called the Iu interface.

As wireless internet services become popular, different services require higher data rates and higher capacities. Although UMTS has been designed to support multimedia wireless services, the highest data rates are not sufficient to meet the required quality of service. Accordingly, 3GPP is conducting research directed to providing enhanced data rates and wireless capacity. One result of this study is High Speed Downlink Packet Access (HSDPA). The purpose of the HSDPA system is to provide a maximum data rate of 10Mbps and to improve the radio capacity in the downlink.

Various techniques in HSDPA include Link Adaptation (LA) and hybrid automatic repeat request (HARQ). In the LA method, the UTRAN can select an appropriate Modulation and Coding Scheme (MCS) according to channel conditions. For example, LA uses 16 Quadrature Amplitude Modulation (QAM) to increase throughput if channel conditions are good. However, if the channel conditions are not good, LA increases the probability of success using Quadrature Phase Shift Keying (QPSK).

The HARQ method retransmits a lost packet, but the exact operation is different from the retransmission method in the RLC layer. If one packet is corrupted during transmission, HARQ transmits another packet that contains additional information for recovery. The retransmitted packet is combined with the original packet in the receiver. The retransmission packet may contain the same information as the previously transmitted data or may contain any additional supplemental information for data recovery.

In order to reduce the impact of changes, most HSDPA features are supported in the node B, so other parts of the UMTS network will not be affected.

Fig. 2 shows a protocol structure of a radio interface protocol defined in 3 GPP. The radio interface protocol horizontally includes a physical layer, a data link layer, and a network layer, and is vertically divided into a control plane for control information (signaling) transmission and a user plane for data information transmission. The user plane is an area in which user traffic such as voice information or IP (internet protocol) packets is transmitted, and the control plane is an area in which control information required for network maintenance and management is transmitted.

The protocol layer structure 200 includes a Radio Link Control (RLC) layer 210, a Medium Access Control (MAC) layer 220, and a physical layer 230. The physical layer (PHY) handles the transmission of data using a radio physical channel between the UE and the UTRAN. Typical functions of the physical layer include data multiplexing, channel coding, spreading, and modulation. The physical layer exchanges information with a Medium Access Control (MAC) layer via a transport channel. The transport channel is classified as a dedicated transport channel or a common transport channel depending on whether its use is dedicated to one user or shared by several UEs.

The MAC layer is divided into a MAC-d sublayer 222 and a MAC-hs sublayer 224. The MAC-d sublayer performs a set of functions including (1) mapping logical channels to common and dedicated transport channels, (2) multiplexing one or more logical channels onto one transport channel (C/T MUX), (3) encryption/decryption, and so on. The MAC-d sublayer 222 provides data flows, each associated with a certain scheduling attribute, to a MAC-hs sublayer 224, described further below. The MAC layer transmits data by using an appropriate mapping between logical channels and transport channels. The MAC-d sublayer manages a dedicated transport channel, and the MAC-c/sh sublayer manages a common transport channel. The MAC-d sublayer is located in the SRNC and the MAC-c/sh sublayer is located in the CRNC.

The Radio Link Control (RLC) layer is responsible for the reliable transmission of RLC Protocol Data Units (PDUs). The RLC may segment or concatenate RLC Service Data Units (SDUs) delivered from a higher layer. If RLC PDUs are ready, they are passed to the MAC layer and in turn to other nodes (UE or UTRAN). Sometimes, RLC PDUs may be lost during transmission. In this case, the lost PDU may be retransmitted. The retransmission function of the RLC layer is called automatic repeat request (ARQ).

The RLC layer may include several RLC entities. Each RLC entity performs an independent radio link control function. The operation mode of each RLC entity is one of a Transparent Mode (TM), an Unacknowledged Mode (UM), and an Acknowledged Mode (AM), depending on the function used. In the RLC layer, data is processed to belong to a logical channel. There are various types of logical channels depending on what type of information the channel carries. A logical channel may be divided into two channels. One logical channel is a control channel for control plane information transmission and the other is a traffic channel for user plane information transmission.

A Packet Data Convergence Protocol (PDCP) layer is located above the RLC layer and efficiently transfers data of a network protocol such as IPv4 or IPv 6. For example, a header compression method that reduces packet header information may be used. The PDCP layer may include several independent PDCP entities such as an RLC layer. A broadcast/multicast control (BMC) layer is responsible for transmitting broadcast messages from a cell broadcast Center (CBS) located in a core network. The primary function of the BMC is to schedule and transmit cell broadcast messages destined for the UE. The BMC layer typically uses an RLC entity operating in unacknowledged mode in order to transmit broadcast messages. The Radio Resource Control (RRC) layer is a layer defined in the control plane. The RRC performs the functions of establishment, re-establishment, and release of radio resources. In addition, the RRC layer may exchange control information between the UE and the UTRAN using RRC messages.

In UE and UTRAN, MAC-HS sublayer transmits data to upper layer via MAC-c/sh and MAC-d sublayer.

Radio Link Control (RLC), when used with the HS-DSCH, typically operates in acknowledged mode to perform retransmissions between the Radio Network Controller (RNC) and the User Equipment (UE). MAC-hs level retransmissions for downlink data traffic are also performed between the node B and the UE. Since the node B serves a large number of users, data arriving at a particular UE for a particular priority data flow may need to be buffered in the node B until the data can be transmitted to the UE. If the UE uses several wireless data streams with different priorities, it is possible to buffer low priority data for a significant period of time if higher priority data transmission is feasible.

Since the scheduling decisions are made at the node B in HSDPA, the node B buffers the data prior to transmission. The amount of buffered data may be negotiated with the RNC using a credit scheme (credit scheme). Of course, there is some delay associated with this negotiation process. The node B must send a capacity allocation message, which needs to be processed by the RNC, and associated data to be transmitted. This negotiated delay is called the "credit round trip time" (cRTT).

At any time, the node B needs to store enough data for each UE data flow to satisfy all transmissions that may occur during such cRTT. Although it can buffer enough data for all data streams for all UEs in the cell, this may lead to sub-optimal scheduling decisions that are driven by data availability rather than channel conditions. Better over-the-air performance is achieved if there is sufficient memory and if the node B allocates enough credits for all data waiting on the RNC. Acknowledged Mode (AM) RLC relies on retransmissions to achieve an expected residual frame error rate. The retransmission is triggered by sending feedback information about the status of each frame. The amount of buffering required to avoid "stalling" (i.e., the transmission and retransmission buffers are full and cannot accept more data) is proportional to the air throughput and proportional to the retransmission round trip time (rRTT). rRTT is the time between when the receiver detects a "hole" in the packet sequence number and when the packet is retransmitted. It is desirable to reduce the rRTT to reduce the RLC buffer memory size or to improve the RLC performance for equal RLC buffer sizes.

The Frame Protocol (FP) used between the HS-DSCH in the node B and in the RNC does not identify the type of RLC packet sent, i.e. whether the packet is a first transmitted packet or a retransmitted packet. This means that in addition to the status report transmission delay, the rRTT will also include buffering delay on the node B. The larger the amount of data set in the node B buffer, the larger the rRTT becomes.

Buffering delay in the node B affects RLC retransmission round trip time (rRTT) and adversely affects RLC in terms of delay and throughput. By introducing different priorities for different types of RLC Packet Data Units (PDUs) in a single data flow, rRTT can be reduced. For example, a "status" PDU, i.e. ARQ feedback information transmitted to the UE in the downlink direction, has a high priority. For uplink traffic, performance is improved by transmitting RLC status PDUs as fast as is actually in the node B. As another example, a "retransmitted" PDU is given priority over a first transmitted PDU. For downlink traffic, the retransmitted PDUs are given priority over the PDUs transmitted for the first time, allowing faster delivery of the UE data to higher protocol layers. Since the AM RLC uses in-order delivery, data is delivered in the same order in which it was transmitted from the RNC RLC entity. If an RLC PDU is missing, all PDUs with higher sequence numbers are buffered until the missing PDU is received. Thus, the missing PDU causes a delay of all subsequent data. By indeed prioritizing the missing PDUs, i.e. retransmissions, the performance is improved.

Disclosure of Invention

For example, a 2-bit field indicating the priority of the PDU may be sent between the RNC and the node B. Even though the node B does not typically contain any RLC "awareness," if desired, the RLC awareness is implemented in the node B to allow the node B to verify some or all of the RLC PDU headers and/or PLC payloads.

The above-described identification techniques involve communicating data in a wireless communication system via a wireless interface between a wireless network and a user equipment node (UE). Communication is established when the UE has at least one data flow. A medium access control layer located in a radio network node receives data units from a higher radio link control layer located in another node. Some or all headers of radio link control data units associated with one data flow are analyzed at the medium access control layer, which, based on the analysis, determines a priority of the data units with respect to other data units associated with one data flow. The mac layer schedules transmission of higher priority data units associated with a data flow before lower priority data units associated with a data flow. The priority may be determined based on radio link control unit header information that does not explicitly indicate a priority of the data unit with respect to other data units associated with the data flow.

In one non-limiting example implementation, it is determined whether the data unit is a control-type data unit or a data-type data unit, and the priority determination is based on the determined data unit type. In another non-limiting example embodiment, retransmissions of previously transmitted data units associated with a data stream are prioritized above the original transmission of data units associated with a data stream. One non-limiting example way to determine the retransmitted data unit is to determine the highest sequence number among multiple data units associated with one data stream and then determine which of the other multiple data units to retransmit based on the determined highest sequence number.

Data units associated with a data flow are preferably stored in a memory of the medium access control layer to access higher priority data units for transmission before lower priority data units. In one non-limiting example implementation, duplicate data packets are fetched from memory to reduce latency and increase efficiency. The payload information of the radio link control data unit may be analyzed and used in determining the data unit priority, if desired. For example, if a query bit is set in a first data unit associated with a data stream, the query bit in a second data unit header associated with the data stream may be set to initiate an earlier query, where the second data unit has a higher priority than the first data unit.

In one non-limiting example implementation, the radio network node is a node B in a UMTS type system, which is connected to a radio network controller. The medium access control layer is a high speed downlink shared channel (HS-DSCH) medium access control layer implemented in the node B. An advantage of the above scheme is that it does not rely on priority specific signalling from the RNC to the node B to perform the determination of the data unit priority. In this way, the RNC does not need to be modified to insert priority type information in the data unit header or to send explicit priority based on control signaling to the node B. By making the node B "RLC aware," the node B can make a priority determination based on existing information in the RLC PDU.

Drawings

Figure 1 shows a UMTS type system in block format;

fig. 2 shows the 3 protocol layers used in the UMTS system shown in fig. 1;

FIG. 3 is a protocol layer diagram illustrating the application of a particular protocol to a particular node in the system shown in FIG. 1;

fig. 4 is a block diagram of an acknowledged mode RLC entity in an RNC;

fig. 5 shows different formats of PDUs and packets for radio link control and the medium access control protocol layers;

FIG. 6 shows an acknowledged mode radio link control packet data unit header;

figure 7 shows an acknowledged mode radio link control state packet data unit;

FIG. 8 shows an example procedure for "RLC aware" node B PDU scheduling;

FIG. 9 shows a non-limiting example implementation in node B scheduling for high speed downlink shared channels;

fig. 10 shows a complementary diagram of various medium access control layer entities receiving high speed downlink shared channel transmissions at a UE.

Detailed Description

The following description describes specific details such as particular implementations, procedures, techniques, etc., for purposes of explanation and not limitation. It will be apparent to one skilled in the art that other implementations may be practiced with some of these specific details. For example, although the following description is made using a non-limiting UMTS example, the present invention may be used in any mobile communication network that supports data services. In certain instances, detailed descriptions of well-known methods, interfaces, circuits, and signaling are omitted so as not to obscure the description with unnecessary detail. Further, individual blocks are shown in the drawings. Those skilled in the art will appreciate that the functions of these blocks may be implemented as follows: using respective hardware circuits, using software programs and data together with a suitably programmed digital microprocessor or general purpose computer, using application specific circuits (ASIC), and/or using one or more Digital Signal Processors (DSP).

Based on the UMTS system shown in fig. 1 and the establishment of RLC, MAC and physical layer protocols shown in fig. 2 and 3, fig. 4 shows a model of an Acknowledged Mode (AM) entity 250 contained in a Radio Network Controller (RNC), with emphasis on the transmitting side of the AM/RLC entity transmitting RLC Packet Data Units (PDUs). The word "transmit" in the context of fig. 4 includes a submission to a lower protocol layer. The AM RLC entity 250 is configured to transmit or receive PDUs using one logical channel (although more than one logical channel may be used). The RLC entity 250 receives RLC Service Data Units (SDUs) from a higher protocol layer via an AM Service Access Point (SAP). The RLC SDU is segmented and/or concatenated 252 into fixed length Acknowledged Mode Data (AMD) PDUs. Segmentation is performed if the received RLC SDU is larger than the length of the space available in the AMD PDU.

After segmentation/concatenation 252, an RLC header 254 is added, an RLC PDU 256 is placed in the retransmission buffer and provided to a multiplexer 258. The RLC PDU buffered in the retransmission buffer 256 is deleted, or the buffered RLC PDU is retransmitted according to a status report containing status PDU from the receiving side and eventually from the UE, or piggybacked status PDU sent by the peer RLC entity. The status report may contain positive and negative acknowledgements for each RLC PDU. The multiplexer 258 multiplexes the RLC PDUs from the buffer 256 that need to be retransmitted and regenerates the RLC PDUs delivered by the additional RLC header unit 254. The output of the multiplexer is provided to a transmission buffer 260, whereby the buffer PDU is passed to a function block that completes the PDU rlc PDU header, e.g. sets the poll bit, and possibly replaces the padding with piggybacked status information (see element 262). Unit 266 also multiplexes control PDUs received from RLC control unit 274 (e.g., reset and reset acknowledge PDUs) and from reception 268 (e.g., piggybacked status and status PDUs) with the data PDUs, if desired. Optional encryption may occur in element 262. The RLC PDUs are delivered to the lower MAC layer via a Dedicated Control Channel (DCCH) and a Dedicated Traffic Channel (DTCH).

On the receive side of the RLC entity 250, a demultiplexer/routing unit 264 receives data and control PDUs via configured logical channels from a lower protocol layer. If encryption is used, the data PDU is routed to decryption unit 266 and passed to conversation buffer 268. The PDUs are stored in a buffer 268 until a complete RLC SDU is received, the receiver acknowledges successful reception, or requests retransmission of the missing data PDU by sending one or more status PDUs to its transmitting side as shown in fig. 4, if a piggybacked status PDU is found in the PDU, it is passed to a retransmission buffer 256 on the transmitting side to clear the positively acknowledged PDU in the buffer 256 and indicate which PDU needs to be transmitted, upon reception of a complete RLC PDU, the RLC header is deleted and piggybacked information is extracted in unit 272, and the associated AMD PDU is assembled by the assembly unit 272 and passed to higher protocol layers via the AM service access point. The reset and reset acknowledge PDUs are passed to the RLC control unit 374 for processing. The reception status PDU is passed to the retransmission buffer 256 for positive acknowledgement AMD PDUs which clear the buffer and indicate which AMD PDU needs to be retransmitted. More details of the RLC layer can be found in the technical specification 3GPP TS25.322 "radio link control protocol specification" of the third generation partnership project.

Fig. 5 shows data encapsulation performed by the node B for transmission on the HS-DSCH. In W-CDMA, data to be transmitted on the downlink is provided by the RLC layer in RLC protocol data units (RLC PDUs), each RLC PDU including a Sequence Number (SN) and data. The MAC-d sublayer receives RLC PDUs for one or more logical channels and inserts a (C/T) field for each RLC PDU to form a corresponding MAC-d PDU. The C/T field identifies the logical channel associated with the RLC PDU.

The MAC-hs sublayer receives the MAC-d PDUs and forms MAC-hs PDUs. Each MAC-d flow may include data for one or more logical channels on the RLC layer and may be associated with a particular priority. Since data is transmitted according to priority and available resources, data flows with different priorities are stored in different data flow priority queues within the MAC-hs sublayer. Thereafter, data is retrieved from the appropriate priority queue when needed and further processed for transmission on the HS-DSCH.

To form a MAC-hs PDU, the MAC-hs sublayer first receives and concatenates one or more MAC-d PDUs in series from a particular data stream priority queue to form the payload of the MAC-hs PDU. Padding bits are added to fill the payload, if necessary. The MAC-hs sublayer then adds a header with a payload to form a MAC-hs PDU.

The MAC-hs header includes (1) a size index id (sid) field representing the length of each MAC-d PDU in the MAC-hs PDU, (2) an N field representing the number of MAC-d PDUs included in the MAC-hs PDU, (3) a transmission Sequence Number (SN) allocated and used to uniquely identify the MAC-hs PDU, (4) a queue id (qid) field representing a specific priority queue from which the MAC-d PDU included in the MAC-hs PDU is retrieved. The SN allows the UE to identify MAC-hs PDUs that have been recovered and is used to provide the RLC sublayer with MAC-d PDUs in sequence, in anticipation of delivering the data to the sublayer in the correct sequence. The MAC-hs PDUs may be generated over the air as needed. Each MAC-HS PDU is transmitted in a 2 ms Transmission Time Interval (TTI), the 2 ms TTI being the unit of transmission on the HS-DSCH.

Control information is transmitted on the shared HS-SCCH at the same time as each packet transmission. The control information includes (1) HARQ process id (hid), (2) new data indicator, (3) information identifying the control information and the specific UE to which the corresponding data transmission is scheduled, (4) other information. The HID indicates a specific HARQ process for the packet. Each packet may be transmitted and possibly retransmitted one or more times until (1) the UTRAN receives ACK feedback on the HS-DPCCH for the packet, or (2) the transmitter decides to abort the packet transmission. Each packet is associated with a specific HARQ process, which is one example of a stop-and-wait (SAW) protocol used to control transmission/retransmission control of the packet. Since three bits are defined for HID, transmission of up to 8 packets may be pending at any given instant. Thus, 8 HARQ processes may be viewed as 8 "HARQ channels" that may be used to transmit a packet, each HARQ channel being associated with and identified by a particular HID value.

Fig. 6 shows an AM RLC PDU format. The data/control (D/C) field indicates whether the rlc PDU is an Acknowledged Mode Data (AMD) PDU (data PDU) or a control PDU. For the control PDU format shown in fig. 7, the PDU type field indicates whether the PDU is a STATUS PDU, a RESET PDU, or a RESET ACK PDU.

The "RLC aware" node B scheduling procedure in fig. 8 will now be described. The node B receives RLC PDUs from the RNC. Typically, the node B does not examine the content of any data units received from higher protocol layers, such as the RLC layer. But the RLC aware node B checks all or part of the RLC PDU header (step S1). The node B may also examine the contents of part or all of the RLC PDU payload, depending on the application and type of priority decision that is expected to be made. Determining whether an RLC PDU is a data PDU or a control PDU at step S2 for the control PDU, determining the particular type of control PDU (step S3) and prioritizing the control PDU according to the determined type (step S4). for example, all status PDUs may be given priority over data PDUs to improve uplink data traffic performance data PDUs a data PDU with a poll bit setting one "1" may also be given priority over other data PDUs Before the data flow, one data flow transmission of the higher priority PDU is scheduled (step S7).

For a particular data flow, a PDU with a high priority is transmitted before a PDU with a lower priority, resulting in a lower average delay for the high priority PDUs. In particular, this priority scheduling for PDUs associated with a data flow reduces the various delays described in the background and applications and improves the performance of data transmission. Reducing the round trip time of selected RLC PDUs associated with a data flow may improve performance in terms of delay and throughput. Advantageously, this scheme does not rely on explicit signaling from the RNC to the node B and can be implemented with current 3GPP specifications.

If the node B analyzes the payload content of the RLC signal in addition to the RLC header, it may perform other performance enhancing functions. For example, if the same RLC PDU appears more than once in the buffer (e.g., due to RLC level retransmissions), the node B removes duplicate PDUs and transmits only the first instance of the PDU. Furthermore, if the poll bit is set in the first RLC PDU of the buffer, the node B may modify the header of the second RLC PDU previously located in the data flow buffer and instead set the poll bit in the second RLC PDU, (and if desired, eliminate the poll bit from the first PDU), thereby reducing the time before the poll is received in the UE.

Fig. 9 is a schematic diagram of a MAC-HS entity 224 that processes data transmitted on the HS-DSCH and manages physical resource allocation for HSDPA. The UTRAN MAC-hs entity includes: scheduling/priority handling entity 410, HARQ entity 420 and TFRC selection entity 430. The TFRC entity 430 selects the appropriate transport format and resources for the data to be transmitted on the HS-DSCH. The scheduling/priority handling entity 410 manages the data flows from the MAC-d entities according to priority, determines a data flow priority queue 414 for each MAC PDU being handled, and determines the transmission/retransmission of the PDUs. The node B scheduler 410 also includes an RLC analyzer and PDU scheduler 416 for processing PDUs for each flow from the flow priority queue 414. The RLC analyzer and PDU scheduler 416 includes a PDU buffer 418 in which higher priority PDUs are stored for transmission earlier than lower priority PDUs. The RLC analyzer and PDU scheduler 416 performs additional priority analysis in addition to the processing normally performed in the scheduler 410 for data flow priority. As an example, it may implement the process described in fig. 8 based on analysis of the RLC PDU header and, if desired, the RLC PDU payload. One HARQ 420 entity is arranged to handle the HARQ function per UE. The HARQ entity performs transmission and, if necessary, retransmission of packets in order to ensure reliable delivery of these packets to the UE. Packet retransmission is performed based on ACK/NAK feedback from the UE.

Fig. 10 is a diagram of the MAC-hs entity 224 on the UE side. The MAC-hs entity 224 handles HSDPA specific functions and includes: HARQ entity 440, reordering queue assignment entity 450, and a set of reordering buffers 462, reordering entity 464, and reassembly entity 466 for each queue ID configured on the UE. One reordering buffer 462 is thus provided and associated with each priority queue for the UE. The UE HARQ entity 440 processes all the jobs required for HARQ (e.g., generates the required ACK/NAK for each received packet transmission), the reordering queue assignment entity provides the recovered packets to the appropriate reordering buffer based on the queue ID sent for the packet, the reordering entity for each reordering buffer reorders the recovered packets in the buffer based on the SN assigned to each packet, each priority queue is associated with its own sequence of SNs, the reordering entity then provides the packets with consecutive SNs to the reassembly entity after recovering the packets, if a packet with a lower SN is being lost, the packet is not passed to the reassembly entity (i.e., "stalled"). the reassembly entity associated with each reordering buffer breaks down the packet by eliminating the header in each packet to obtain the MAC-hs payload, extracts the MAC-d PDU comprising the MAC-hs payload and discards the padding bits (if any). The reassembly entity then provides the MAC-d PDUs to the higher layers via the MAC-d sublayer.

While the invention has been described in connection with what is presently considered to be the most practical and preferred embodiment, it is to be understood that the invention is not to be limited to the disclosed embodiment, but on the contrary, is intended to cover various modifications and equivalent arrangements included within the scope of the appended claims.

Claims (28)

1. A method of communicating data in a wireless communication system via a radio interface between a radio network and a user equipment node, comprising the steps of establishing communication with the user equipment node with at least one data flow, and receiving data units at a medium access control layer located at the radio network node from a higher radio link control layer located at another node, the method being characterized by the further steps of:

analyzing, at a media access control layer, a portion or all of a radio link control data unit header associated with the one data flow;

determining, at a medium access control layer, a priority of data units related to other data units associated with the one data flow based on an analysis of header information of the radio link control data units, the header information not explicitly indicating the priority of data units related to other data units associated with the one data flow;

scheduling, at the media access control layer, transmission of higher priority data units associated with the one data flow before lower priority data units associated with the one data flow.

2. The method of claim 1, wherein the analyzing comprises determining the priority based on radio link control data unit header information that does not explicitly indicate a data unit priority.

3. The method of claim 1, wherein the determining further comprises:

determining whether the data unit is a control type data unit or a data type data unit; and is

A priority is determined based on the determined data unit type.

4. The method of claim 1, wherein the determining further comprises:

the retransmission of the previously transmitted data unit associated with said one data stream is prioritized above the original transmission of the data unit associated with said one data stream.

5. The method of claim 1, wherein the determining further comprises:

determining a sequence number of a data unit; and

determining a priority based on the determined sequence number.

6. The method of claim 5, wherein the determining further comprises:

determining a highest sequence number of a plurality of data units associated with the one data stream; and

determining which of the other data units associated with the one data stream to retransmit based on the determined highest sequence number.

7. The method of claim 6, wherein the determining further comprises:

the modular sequence number is considered in determining which data unit to retransmit.

8. The method of claim 2, wherein the determining further comprises:

determining a type of the control data unit; and

a priority is determined based on the determined control data unit type.

9. The method of claim 2, further comprising:

the data units associated with said one data flow are stored in a memory of the medium access control layer to access higher priority data units for transmission before lower priority data units.

10. The method of claim 9, further comprising:

duplicate data packets are eliminated from the memory.

11. The method of claim 9, wherein the analyzing further comprises:

information in a payload portion of a radio link control data unit is analyzed.

12. The method of claim 11, wherein the determining further comprises:

if the query bit is set in a first data unit associated with the one data stream, the query bit is set in a header of a second data unit associated with the one data stream, the second data unit having a higher priority than the first data unit.

13. The method of claim 1 wherein the wireless network includes a node B coupled for communication with a radio network controller, and wherein the higher radio link layer is a Radio Link Control (RLC) layer implemented in the radio network controller, and the medium access control layer is a high speed downlink shared channel (HS-DSCH) medium access control layer implemented in the node B.

14. The method of claim 13, wherein the method does not rely on priority-specific signaling from a radio network controller to a node B in performing the determination.

15. A node in a wireless network for facilitating communication with a user equipment node via a wireless interface, the communication comprising at least one data flow, wherein the node comprises a media access controller located at a radio network node for receiving data units from a higher level radio link controller located in another node comprised in the radio network controller, characterized in that the media access controller further comprises:

analyzing means for analyzing part or all of a radio link control data unit header associated with the one data flow;

determining means for determining a priority of one data unit relative to other data units associated with said one data stream based on an analysis of header information of said radio link control data unit, said header information not explicitly indicating a priority of data units relative to other data units associated with said one data stream; and

scheduling means for scheduling the transmission of higher priority data units associated with one data flow ahead of lower priority data units associated with said one data flow.

16. The node according to claim 15, wherein the analyzing means comprises means for determining the priority based on header information of radio link control data units not explicitly indicating the priority of the data unit.

17. The node of claim 15, wherein the determining means is configured to:

determining whether the data unit is a control type data unit or a data type data unit; and is

A priority is determined based on the determined data unit type.

18. The node of claim 15, wherein the determining means is configured to:

the retransmission of the previously transmitted data unit associated with said one data stream is prioritized above the original transmission of the data unit associated with said one data stream.

19. The node of claim 15, wherein the determining means is configured to:

determining a sequence number of a data unit; and

determining a priority based on the determined sequence number.

20. The node of claim 19, wherein the determining means is configured to:

determining a highest sequence number of a plurality of data units associated with the one data stream; and

determining which of the other data units associated with the one data stream to retransmit based on the determined highest sequence number.

21. The node of claim 20, wherein the determining means is configured to:

the modular sequence number is considered in determining which data unit to retransmit.

22. The node according to claim 16, wherein for a control-type data unit, the determining means is configured to:

determining a type of the control data unit; and

a priority is determined based on the determined control data unit type.

23. The node of claim 16, further comprising:

storage means for storing data units associated with said one data flow in the medium access control layer for accessing higher priority data units for transmission before lower priority data units.

24. The node of claim 23, wherein the analyzing means is configured to:

information in a payload portion of a radio link control data unit is analyzed.

25. The node of claim 24, wherein the determining means is configured to:

determining whether a query bit is set in a first data unit associated with the one data stream, and

if so, a query bit is set in a header of a second data unit associated with the one data stream, the second data unit having a higher priority than the first data unit.

26. The node according to claim 15, wherein the node is a node B and the medium access control layer is a high speed downlink shared channel (HS-DSCH) medium access control layer implemented in the node B.

27. The node according to claim 26, wherein the analyzing means and the determining means do not rely on priority-specific signaling from the radio network controller to the node B.

28. A mobile wireless communication system comprising the node of claim 15.