HK1138968B - Method and apparatus for versatile mac multiplexing in evolved hspa - Google Patents

Description

Method and apparatus for universal MAC multiplexing in evolved HSPA

Background

In order to provide global connectivity for wireless systems and to achieve performance goals, e.g., with respect to throughput, latency, and coverage, communication standards have been developed. One current standard in widespread use, known as High Speed Packet Access (HSPA), has evolved as part of third generation (3G) radio systems and is supported by the third generation partnership project (3 GPP).

High Speed Packet Access (HSPA) is a collection of mobile telephony protocols that extend and improve the performance of existing Universal Mobile Telecommunications System (UMTS) protocols. High Speed Downlink Packet Access (HSDPA) and High Speed Uplink Packet Access (HSUPA) provide enhanced performance by using improved modulation schemes and by refining the protocols by which handsets and base stations communicate.

HSPA provides improved theoretical Downlink (DL) performance up to 14.4Mbit/s and improved theoretical Uplink (UL) performance up to 5.76 Mbit/s. Existing configurations provide up to 7.2Mbit/s in DL and up to 384Kbit/s in UL. Evolved HSPA is defined in 3GPP release 7. It introduces a simpler mobile network architecture by bypassing most conventional equipment and enhancing radio data rates.

Above the physical layer in a 3GPP system, the Medium Access Control (MAC) layer may be divided into several entities. A new MAC entity, MAC enhanced high speed (MAC-ehs), has been introduced and optimized for HSPA in DL. The MAC-ehs entity may alternatively be used for MAC high speed (MAC-hs). A new MAC entity, modified MAC (MAC-i/is), has been introduced and optimized for HSPA in UL. The MAC-i/is entity can alternatively be used for MAC-e/es. The higher layer configures the MAC-ehs and/or MAC-i/is entity, the higher layer is configured to process data transmitted on a high speed downlink shared channel (HS-DSCH) and/or an enhanced uplink channel (E-DCH), and manages physical resources allocated to the HS-DSCH.

The MAC-ehs entity allows for support of flexible Radio Link Control (RLC) Protocol Data Unit (PDU) sizes and MAC segmentation and reassembly. Unlike MAC-hs for HSDPA, MAC-ehs allows multiplexing of data from several priority queues within one 2 millisecond Transmission Time Interval (TTI).

The scheduling/priority handling function is responsible for scheduling decisions. For each 2 ms TTI, it is decided whether to use single-stream transmission or dual-stream transmission. A new transmission or retransmission is sent based on acknowledgement/negative acknowledgement (ACK/NACK) UL feedback and can be started at any time. When in the CELL _ FACH, CELL _ PCH and URA _ PCH states, the MAC-ehs may additionally perform retransmissions on the HS-DSCH without relying on uplink signaling.

The reordering at the receiving side is based on a priority sequence. A Transmission Sequence Number (TSN) is assigned within each reordering queue to activate reordering. On the receiver side, the MAC-ehs SDU or its segments are assigned to the correct priority queue based on the logical channel identifier.

The MAC-ehs SDUs can be segmented at the transmitter side and reassembled at the receiver side. At the MAC layer, logical channel groups are mapped to transport channels. Two types of transport channels include a "common" transport channel (MAC-c), which can be shared by multiple WTRUs, and a "dedicated" transport channel (MAC-d), which is assigned to a single WTRU. The MAC-ehs SDU is a MAC-c PDU or a MAC-d PDU. The MAC-ehs SDUs contained in the MAC-ehs PDUs may have different sizes and different priorities and may belong to different MAC-d or MAC-c flows.

When the MAC-ehs multiplexes logical channels used by the release 7RLC Acknowledged Mode (AM) example with flexible RLC PDU sizes, the typical baseline for the MAC-ehs header results in a rather low overhead. This is because the size of the MAC SDU is significantly larger than the total size of the different fields of the header.

However, there are some typical baseline conditions that will result in undesirable levels of overhead. For example, logical channels are used by RLC AM examples configured with a fixed RLC PDU size, or for release 6RLC AM examples. The latter example may be due to the possibility of activating a handover from a release 6 base station to a 3GPP release 7 base station without resetting the RLC and keeping the RLC entity operating with fixed RLC PDUs. In another example, a MAC-ehs PDU that may have current channel conditions is small in size and contains few (e.g., 2) SDU segments. In this example, the header may form a significant overhead.

The typical signaling needs to be inefficient to support MAC-ehs functions. It would be desirable to reduce the amount of signaling required to support the MAC-ehs PDU function. One possibility to reduce the signaling would be to perform at the base station multiplexing/demultiplexing of different size SDUs from different logical channels and priority queues in a single MAC-ehs PDU. Another possibility would be to perform multiplexing/demultiplexing of SDUs of different sizes and belonging to different logical channels. Finally, concatenation/disassembly and segmentation/reassembly of the MAC-ehs SDUs will be expected.

Table 1 shows the encoding of the Segment Indication (SI) field when each priority queue defines a segment indication. The meaning of this field on the WTRU side may cause confusion when padding occurs at the end of the MAC-ehs header after the last segment of an SDU. In this case, the segmentation indication according to the indicated coding needs to be "11". However, the WTRU may interpret this as that the SDU is not complete and inserts it into the reassembly buffer. It is desirable to modify the encoding of this field to avoid such confusion.

SI field	Segment indication
		00	The first MAC-hs SDU of the addressed group of MAC-hs SDUs is a complete MAC-d PDU. The last MAC-hs SDU of the addressed group of MAC-hs SDUs is a complete MAC-d PDU.
01	The first MAC-hs SDU of the addressed group of MAC-hs SDUs is a MAC-d PDU segment. The last MAC-hs SDU of the addressed group of MAC-hs SDUs is a complete MAC-d PDU.
		10	The first MAC-hs SDU of the addressed group of MAC-hs SDUs is a complete MAC-d PDU. The last MAC-hs SDU of the addressed group of MAC-hs SDUs is a MAC-d PDU segment.
11	The first MAC-hs SDU of the addressed group of MAC-hs SDUs is a MAC-d PDU segment. The last MAC-hs SDU of the addressed group of MAC-hs SDUs is a MAC-d PDU segment.

TABLE 1

Disclosure of Invention

Methods and apparatus for multiplexing of universal (versatile) Medium Access Control (MAC) in evolved HSPA are disclosed. More particularly, a downlink optimization method for an enhanced high speed MAC (MAC-ehs) entity and an uplink optimization method for a MAS-i/is entity are disclosed. Apparatus for using optimized downlink and uplink MAC entities are also disclosed.

Drawings

The invention will be understood in more detail from the following description, given by way of example, and understood in conjunction with the accompanying drawings, in which:

figure 1 is a block diagram of a wireless communication system configured for universal MAC multiplexing in evolved HSPA;

fig. 2 is a payload header used in multiplexing SDUs from different logical channels and priority queues;

fig. 3a is a general structure of an SDU Description Super Field (SDSF) arranged to efficiently signal how SDUs are concatenated/segmented, their size and their corresponding logical channels;

FIG. 3b is a payload header format of a MAC-ehs PDU containing k reordering PDUs used in multiplexing reordering PDUs from different logical channels and priority queues;

FIG. 4 is a flowchart of the operations of processing a MAC-ehs PDU and reconstructing a MAC-ehs SDU;

FIG. 5 is a flow chart of the data processing functions within each decomposition/reassembly/demultiplexing unit;

FIG. 6 is a diagram depicting the header portion of an SDU belonging to a logical channel of interest, allowing different types of logical channels to be efficiently multiplexed in the same MAC-ehs PDU;

fig. 7 is an alternative configuration of a header describing an SDU belonging to a logical channel of interest, allowing different types of logical channels to be efficiently multiplexed in the same MAC-ehs PDU;

fig. 8 is an alternative configuration of a header describing an SDU belonging to a logical channel of interest, allowing different types of logical channels to be efficiently multiplexed in the same MAC-ehs PDU;

fig. 9 is an alternative configuration of a header describing an SDU belonging to a logical channel of interest, allowing different types of logical channels to be efficiently multiplexed in the same MAC-ehs PDU;

fig. 10 is a flow chart for explaining an improved method of SI field, wherein a reordering PDU contains only one reordering SDU;

FIG. 11 is how a 2-bit SI field can be used as one possible encoding for minimizing overhead;

FIG. 12 is an alternative method of indicating the encoding of a predetermined SI field;

FIG. 13 is a flow chart of how the reassembly unit processes the SI field associated with a rearranged PDU;

FIG. 14 is a flow chart of how the reassembly unit performs a combine function or a discard function;

fig. 15 is a flowchart of how to process a payload unit if there are multiple reordered SDUs in a reordered PDU;

FIG. 16 is a flow chart of the combined reassembly process illustrated in FIGS. 14 and 15;

fig. 17 is a flow chart of how the reassembly unit processes the SI field associated with a reassembled PDU.

Detailed Description

In the following, the term "wireless transmit/receive unit (WTRU)" includes, but is not limited to, a User Equipment (UE), a mobile station, a fixed or mobile subscriber unit, a pager, a cellular telephone, a Personal Digital Assistant (PDA), a computer, or any other type of user equipment capable of operating in a wireless environment. Hereinafter, the term "base station" includes, but is not limited to, a Node-B, a site controller, an Access Point (AP), or any other type of interfacing device capable of operating in a wireless environment.

Embodiments are disclosed that enable efficient MAC-ehs headers (or MAC-i/is in uplink) in the above cases. These embodiments improve the header structure to minimize the relative overhead while allowing multiplexing of different types of logical channels. These embodiments also address the problem that potential ambiguous interpretation of the header when a single SDU fragment is present in the payload can lead to. The following definitions are used throughout: a "MAC-ehs payload unit" ("MAC-is payload unit") or "payload unit" is synonymous with a MAC-ehs SDU or a MAC-ehs SDU ("MAC-is SDU") segment inserted in a MAC-ehs PDU ("MAC-is SDU"). It is also synonymous with the term "re-arranged SDU". Although these embodiments describe downlink optimization of the MAC-ehs entity, these concepts are also applicable to the Uplink (UL) by using MAC-i/is instead of MAC-ehs.

Fig. 1 is a block diagram of a wireless communication system configured for universal MAC multiplexing in evolved HSPA. The system includes a base station 105 and a Wireless Transmit Receive Unit (WTRU) 110. The base station 105 and the WTRU110 communicate via a wireless communication link.

As shown in fig. 1, the WTRU110 includes a transmitter 120, a receiver 130, and a processor 140. The processor 140 is coupled to the buffer 150 and the memory 160. The processor 140 is configured to process the payload unit using at least one of the techniques described below.

As also shown in fig. 1, the base station 105 includes a transmitter 165, a receiver 170, and a processor 180. Processor 180 is coupled to buffer 190 and memory 195. The processor 180 is configured to process the payload unit using at least one of the following techniques.

Fig. 2 is a diagram of a payload header 200 used in multiplexing data from different logical channels and priority queues. In a first embodiment, multiplexing SDUs from multiple priority queues into a single MAC-ehs PDU is disclosed. In addition, incorporating SDUs from multiple logical channels into a single priority queue is included.

The MAC-ehs PDU is constructed by concatenating and/or segmenting one or more SDUs from one or more priority queues. The header is attached to the payload in the structure described in fig. 2. Header 280 includes a plurality of k-queue sections 205, each k-queue section 205 including a Transmission Sequence Number (TSN)240, an SDU Description Super Field (SDSF)250, and an "end" flag (F) 260. Each k queue portion corresponds to a priority queue from which SDUs (or segments thereof) are extracted, where k is the number of priority queues in this MAC-ehs pdu in which SDUs are multiplexed. Header 280 may also include an optional version flag 210 and/or an optional queue ID field 230.

Alternate version flag 210 indicates which version of the protocol is used to ensure backward compatibility. This field should have two bits since the previous version of MAC-ehs exists. The version flag 210 may be used when the radio bearer is mapped to support different MAC-ehs header formats. Each radio bearer is configured for a specific format. Alternatively, the MAC-ehs format may be explicitly or implicitly identified by signaling on the high speed shared control channel (HS-SCCH). The radio bearers multiplexed into the MAC-ehs PDU may be limited by the MAC-ehs format configured for the radio bearers.

As shown in fig. 2, each header 280 may include an optional queue ID field 230 that identifies to which reordering queue the corresponding SDU in the payload belongs. The reordering queue may or may not be directly mapped to the priority queue. The header 280 also includes at least one Transmission Sequence Number (TSN) field 240 that identifies the sequence number of the data for this queue ID. Another feature included in the header 280 is at least one SDU Description Super Field (SDSF)250 that indicates how SDUs are decomposed and/or reassembled and to which logical channel they belong. Details and alternatives of this super field will be described below. The header 280 may also include at least one optional "end" flag 260 indicating whether this header portion is the last portion of the header or another sub-header follows.

The MAC-ehs header 280 is followed by a MAC-ehs payload 290, which MAC-ehs payload 290 comprises a series of MAC-ehs SDUs or MAC-ehs SDU fragments 295 and optional padding bits 270. Padding bits 270 may be added to the payload 290 as needed to maintain the octet alignment at the MAC-ehs PDU level. The permutation having the allowed Transport Block (TB) size is mapped to the HS-DSCH transport channel (TrCH).

As shown in fig. 3a, the SDU description super field 250 is arranged to efficiently signal how SDUs from one priority queue are concatenated/segmented, their size and their corresponding logical channels.

SDUs can be segmented in a continuous manner within the priority queue without loss of performance. This means that the transmission of SDUs or segments thereof is restricted unless the last SDU or segment of a previous SDU has been transmitted (or is being transmitted in the same MAC-ehs pdu). Due to this constraint, there are at most two segments of (different) SDUs for a particular reordering queue in a MAC-ehs pdu, along with an unconstrained number of complete (unsegmented SDUs) in between.

Fig. 3b is a payload header format of a MAC-ehs PDU, which contains k reordering PDUs used in multiplexing from different logical channels and priority queues. Assume that the starting position of the payload 290 within the MAC-ehs PDU 395 is identifiable for each reordering queue. For data corresponding to the first reordering queue listed in header 280, the start of payload 290 immediately follows the header. This is also possible for data corresponding to subsequent reordering queues, assuming that the SDSF field 250 shown in fig. 3a for each priority queue, except for the last priority queue, is configured to determine the total size of the corresponding payload. The structure in fig. 3a meets this requirement.

As shown in fig. 3a, the general structure of the SDSF field 250 includes the following elements. The "Full)/segment start" (FSS) flag 320 indicates whether the data for the start position of the payload corresponds to a segment of an SDU or an entire SDU for this reordering queue. An "end of whole/fragment" (FSE) flag 360 follows the FSS flag indicating whether the data for the end position of the payload corresponds to a fragment of an SDU or an entire SDU for this priority queue. The combination of FSS and FSE is equivalent to the Segment Indication (SI) field 397 shown in fig. 3 b. For each SDU or SDU fragment present in the payload 290, a Logical Channel Indicator (LCID) field 330 is included to indicate to which logical channel the SDU (or fragment thereof) belongs, and a Length Indicator (LI) field 340 indicates the length of the SDU (or fragment thereof); (this field is described in detail in the following embodiments); and an "end of SDU" flag 350 indicates whether at least another SDU (or segment thereof) follows this SDU or whether this is the last SDU (or segment thereof) of this reordering queue; this field may have one bit.

It should be noted that both FSS 320 and FSE 360 should be set to even if there is only one SDU (or fragment thereof). It should also be noted that FSS 320 and FSE 360 may be identified as a single field of two bits, referred to as SI, for example. In this case, a one-to-one mapping may be defined between each possible set of values for the flags FSS 320 and FSE and each possible combination with two bits of the SI field. For example:

-FSS ═ segmentation and FSE ═ segmentation, can be mapped to SI ═ 11

-FSS whole and FSE segment, which can be mapped to SI 10

Segment and whole FSS, which can be mapped to SI 01

-FSS-whole and FSE-whole, which may be mapped to SI-00

Instead, using the above mapping, the values of FSS and FSE may be reacquired from the SI field as follows:

-FSS ═ segment, corresponding to the first payload unit being a segment.

If there is only one payload unit and the segment is a middle segment, this case corresponds to SI 11 (i.e. FSE is also set to full).

If the fragment is the last fragment of a MAC-ehs SDU, this case corresponds to SI 01 when there is a single payload unit, or if the last payload unit is a complete MAC-ehs SDU (i.e. the FSE is set to whole), this case corresponds to SI 11 (i.e. the FSE is set to fragment) when the last payload unit is a fragment.

-FSS-full corresponds to SI-10 (i.e. FSE set to full) when there is a single payload unit or the last payload unit is the first segment of a MAC-ehs SDU, or FSS-full corresponds to 00 (i.e. FSE set to full) when only a full MAC-ehs SDU is present.

The FSE segment corresponds to SI 11 or SI 10, depending on the FSE as described above.

Overall, FSE corresponds to SI 01 or SI 00, depending on FSE as described above.

Also as shown in fig. 3a, the LCID 330 and LI 340 fields may be identified together as a single Data Description Indicator (DDI) field, similar to that used in uplink enhanced dedicated channel (E-DCH) coding. However, as described below, the encoding principles may be different.

Several options are possible for LCID field 330. In the case of dedicated control channel/dedicated traffic channel (DCCH/DTCH), one option is that the coding can follow the same identification scheme for the Target Channel Type Field (TCTF) and control the traffic coding (C/T mix). At the MAC-C layer, the TCTF field and the C/T mix field together identify a logical channel. The TCTF identifies the target channel type while the C/T mix identifies the index. In this option, the same type of encoding as MAC-c is possible. In this case, the mapping between the TCTF and the logical channel type, such as Common Control Channel (CCCH), Paging Control Channel (PCCH), Dedicated Control Channel (DCCH), etc., may be specified in the same manner as in the known embodiments. In this case, the number of bits occupied by the LCID field is variable. Alternatively, TCTF and C/T may be jointly encoded into a common parameter. The channel type may be configured as C/T or may specify a unique value for LCID.

Alternatively, assuming that the maximum possible number of logical channels (of all types) being used by the receiver at a given time is NLmax, and NLmax can be represented by the number of bits (NLMb bits) for these logical channels, the LCID field includes NLMb bits and contains the logical channel identifier. For example, the network may configure up to 16 logical channels (i.e., NLmax ═ 16). Therefore, in order to identify 16 logical channels, 4 bits (i.e., NLMb ═ 4) are required. The mapping between this logical channel identifier and its corresponding logical channel is known and/or specified (predetermined) in advance from the previous radio resource control/Node B application part (RRC/NBAP) signaling. Some values are reserved for logical channel types for which a single instance is possible. For example, there may be only one CCCH and a specific value predetermined for this channel.

Alternatively, there may be a maximum possible number of logical channels (NLQmax) multiplexed in the priority queue that may be given, which is less than the full maximum possible number of logical channels that the receiver may fully use. If NLQmax can be represented by the number of bits needed to identify NLQmax (NLMQb bits), the LCID field includes NLMQb bits. In that case, the mapping between each set of possible values of NLMQb bits and logical channel type and/or index is specific to each priority queue and is known from previous RRC/NBAP signaling (which specifies a potentially different mapping for each defined priority queue). This choice does not preclude the use of predetermined values for certain logical channels as described above.

There are several options to configure the MAC-ehs header, as described in detail below. As shown in fig. 3a, the SDSF field 250 may be defined to support the use of a "number" (N) field 380 to minimize signaling overhead when multiple SDUs belong to the same logical channel and/or have subsequently the same length as each other.

For each set of N consecutive SDUs having the same length and belonging to the same logical channel, an N field 380 may always be present and precede (or follow) the LCID 330 and LI 340 fields.

For each set of N consecutive SDUs belonging to the same logical channel, the N field 380 may always be present and precede (or follow) the LCID field 330; but each SDU has its own LI field 340.

If N is greater than 1, the N field 380 may only exist for a set of N consecutive SDUs (having the same length and logical channel). A "multiple SDU" (MS) flag 390 may indicate whether the N field 380 is present. This reduces the risk of additional signaling overhead due to the presence of the N field 380 when the SDUs of the payload are all of different lengths or belong to different logical channels.

If N is greater than 1, the N field 380 may only exist for a set of N consecutive SDUs (from the same logical channel). The MS flag 390 may indicate whether the N field 380 is present. In any case, each SDU has its own LI 340 field.

N field 380 may be configured for a particular LCID 330. LCID 330 may explicitly identify whether N field 380 is present.

For the first SDU, LCID 330 may be omitted if this SDU is a segment. The reason is that information should already be present in the previous MAC-ehs PDU when the first segment is transmitted. Alternatively, for the last SDU, LCID field 330 may be omitted only if this SDU is a segment.

Instead of inserting an "end of SDU" flag 350 for each SDU (or segment thereof) or group of SDUs, a single "NTot" field (not shown) for the entire SDSF field may be added, indicating the total number of SDUs or SDU segments in the payload for this priority queue. The size of this field depends on the maximum possible number of SDUs per priority queue within the MAC-ehs PDU.

There are several methods for indicating the length of each SDU or segment thereof. Several embodiments exist for utilizing LI 340 per SDU or group or segment thereof. This embodiment explains how the LI field 340 is constructed to efficiently signal the length of each SDU or group or segment thereof.

LI 340 specifies the exact number of bits (or octets if each SDU is forced to be octet aligned) that the SDU or segment thereof contains. This representation may be performed using one of the well-known binary formats, such as the Most Significant Bit (MSB) start or the Least Significant Bit (LSB) start. The length of the LI 340 field depends on the maximum possible length of the SDU. There are several possible options for the LI 340 field. In one option, the length of LI 340 is predetermined and fixed, regardless of the logical channel (LCID field 330), and is the number of bits required to represent the maximum SDU size in all logical channels (in bits or octets), regardless of any previous signaling to set the maximum SDU size for a given RLC instance. In an alternative option, the LI 340 length depends on the Logical Channel (LCID) field 330 and is the number of bits required (in bits or octets) to represent the maximum SDU size for that logical channel. The maximum SDU size may vary from one radio bearer instance to another, and may vary according to reconfiguration or even dynamically. To avoid possible ambiguity, the network signals to the receiver the size of the LI 340 field, while also signaling a change in the maximum SDU size.

Another variation includes a hybrid use of a Size Indicator (SID) (not shown) and LI 340. The transmitter uses a Size Indicator (SID) whenever the length of a MAC-ehs SDU is one of a predefined set of sizes. The size indicator is a field with a small number of bits (e.g., 3), where each possible value represents a predefined SDU size. Otherwise, if the SDU size is not one of the predefined set of sizes, LI 340 specifying the exact number of bits or octets (in binary format) is used for the case of non-octet aligned SDUs. To allow the receiver to distinguish between the SID and LI 340, a one-bit marker is inserted before the SID or LI 340 field. Alternatively, the application of the SID depends on the LCID configuration. In this case, the use of SID or LI 340 is known based on LCID value. It should be noted that the number of bits in the SID field need not be constant.

A minimization of the average number of bits required for the representation of the size of the SDU contained in the MAC-ehs PDU can be achieved if the predefined set of sizes represented by the SID corresponds to the most frequently used set of sizes. At least one of the transmitter and receiver should know the mapping between SID values and corresponding SDU sizes. Several methods may be defined to determine the appropriate mapping between SID values and SDU sizes and signal the mapping to the receiver and/or transmitter.

One SID mapping method utilizes explicit Radio Network Controller (RNC) based mapping. In this method, the RNC determines the SID mapping and signals the mapping to the base station and WTRU via Iub and RRC signaling, respectively. The use of this method may depend on which LCID is present in the MAC-ehs PDU. Using this approach, the base station can utilize LI if the size of the SDU that must be inserted is not one of a set of sizes mapped to SID values, depending on whether the RNC is required to define the SID for each possible SDU size. The RNC may select a SDU size that occurs (or is expected to occur) very frequently, such as, but not limited to, a maximum RLC PDU size, a status RLC PDU size, or an RLC PDU size that appears to occur frequently to the RNC

The second SID mapping method uses implicit mapping. In this method, the mapping between SID and SDU size is not explicitly signaled. Instead, SIDs are implicitly assigned certain SDU sizes by rules known to the transmitter and receiver. Examples of rules for SID mapping using this method include assigning a SID value # N1 to the maximum RLC PDU size, assigning a SID value # N2 to N, where N is a fixed value known to occur frequently, regardless of the circumstances (e.g., typical values for status RLC PDUs), or assigning a SID value # N3 to half (or a portion, such as one-third or one-fourth) of the maximum RLC PDU size, thereby supporting segmentation in 2, 3, or 4 equal sizes.

A third SID mapping method uses base station based mapping. In this method, the mapping between SID values and SDU sizes is determined based on observing which SDU sizes tend to occur most often. The mapping is conveyed by MAC signaling. One possible way to signal the mapping is by using a "map" flag that is defined to follow the LI. When the flag is set, following successful reception of a MAC-ehs PDU at the WTRU, in the subsequent MAC-ehs PDU the next bits indicate that the SID value, whose size is indicated by LI, is to be mapped. Thus, the receiver waits for the next time when it receives SDUs having sizes expected to be assigned to certain SID values. When the SDU is received and a MAC-ehs PDU is constructed, the LI is utilized to signal the length of the SDU as usual. The receiver sets the "map" flag and inserts the SID value to be set after the flag. Upon correct reception of the MAC-ehs PDU, the transmitter determines that the mapping flag is set and assigns a new size to the SID value following the mapping flag, discarding any previously mapped sizes for that SID value.

Some embodiments are disclosed that may be used to constrain MAC-ehs multiplexing. These constraints are considered to need to meet the quality of service (QoS) requirements of the logical channels (e.g., retransmission, latency, block error rate (BLER)).

The multiplexing restrictions are signaled over the Iub/Iur interface in the UMTS Terrestrial Radio Access Network (UTRAN) using control information that specifies which priority queues can be multiplexed. If a priority queue is formed from the multiplexing of logical channels, it can be determined which logical channel is multiplexed if the MAC-ehs multiplexing comes directly from the logical channel (i.e., no priority queue is formed from the logical channel or there is a one-to-one mapping between the priority queue and the logical channel).

One application of the above MAC-ehs multiplexing limitation is not to use non-signaling radio bearers to multiplex Signaling Radio Bearers (SRBs). If SRB is separately multiplexed from non-SRB, the TB size determination for SRB may be treated in the following manner. During configuration and reconfiguration of signaling from Radio Resource Control (RRC), RACH measurements can be used to determine the TB size of MAC-ehs PDUs carrying SDUs from SRBs and signal the RACH measurements to the MAC.

Fig. 4 is a flow diagram of operations 400 performed to process and reconstruct MAC-ehs PDUs. Upon receipt of the MAC-ehs PDU, the MAC-ehs PDU header is stripped from the payload and split into portions, using an "end" marker to find where the header ends, 405. For each header portion (priority queue), the corresponding payload (SDU and its fragments) is extracted as indicated by SDSF at 410, appended to the header portion itself at 420 to create a reordering "queue PDU" at 430, and inserted into the reordering queue corresponding to the reordering queue ID and TSN at 440. Alternatively, the PDU need not be created, but instead the information contained in the header portion (e.g., TSN, SDSF) is extracted and correlated with the corresponding payload within the reordering queue at 425, to enable reordering to be performed at 450, and then decomposition and/or reassembly to be performed. Following the rearrangement process at 450, recombination is performed at 460. After the reassembly at 460 is completed, the complete MAC PDU is delivered to the correct logical channel at 470.

Within each reordering queue, a reordering function 450 is performed such that the MAC-ehs PDUs are replaced by one or more reordering queue PDUs (or groups of TSNs, SDSFs and associated payloads) and the reordered PDUs are sent to a MAC SDU parsing/reassembly/demultiplexing unit (not shown), rather than just to a parsing unit (not shown). Also, a queue specific timer (T1) (not shown) may be signaled. Each reordering queue may optionally have a separate T1 timer.

Fig. 5 is a flow diagram of an example data processing function 500 within each decomposition/reassembly/demultiplexing unit. The SDSF field is read and the data is processed within each of the decomposition/reassembly/demultiplexing units. The following describes the data operation on TSN ═ n of this priority queue. As shown in fig. 5, each SDU or SDU segment is parsed at 505 using an LI field, an "SDU end" flag, and an N field if available. If the FSS flag is set to segmentation at 510 and data for this priority queue, TSN-1, has been previously delivered to this parsing/reassembly/demultiplexing unit at 520, the SDU segment (the first SDU of the payload for this priority queue) can be reassembled at 530 using the segment of the previous PDU stored in the reassembly unit. At 540, a determination is made whether the number of SDUs or SDU segments is greater than 1 or whether the FSE flag is set to "Whole". If the number of SDUs or SDU segments is greater than 1, or if the FSE flag is set to "full", the first SDU of the reordering PDU is the last segment of the MAC SDU and the fully reassembled SDU is delivered to the higher layer at the service access point corresponding to the logical channel indicated by the LCID field at 550. If the number of SDUs or SDU segments is less than 1, and if the FSE flag is set to "segment," then the SDU is the middle segment of the reordering PDU and the reassembled segment is stored at 545 and the procedure ends for that reordering queue PDU.

If the FSS flag is set to "segment" at 510 and no data for this priority queue TSN-1 was previously delivered at 520 (e.g., if the T1 timer has expired), then the SDU segment is a discarded and previous SDU segment of the previous PDU stored in the reassembly unit at 525. A decision is then made at 580 to determine whether SDU fragments greater than 1 have been extracted. If SDUs or SDU segments greater than 1 have been extracted, the receiver delivers the SDUs extracted between the first and last SDU or SDU segments to higher layers at the service access point corresponding to the logical channel indicated by the respective LCID field at 570. If the FSE flag is set to "segmentation", the segment is the first segment of a MAC-ehs SDU, and the receiver discards any segments from the previous PDU stored in the reassembly unit and inserts the last SDU segment into the reassembly unit at 590. If the FSE flag is set to "Whole," the last payload unit is a complete MAC-ehs SDU and the receiver delivers the last SDU to higher layers at the service access point corresponding to the logical channel indicated by the LCID field at 595.

If the FSS flag is set to "segment" at 510 and data for TSN-1 for this priority queue has been previously delivered at 520, the SDU segment is reassembled using the previously stored PDU segment. If at 540 it is determined that the SDU or SDU fragment is greater than 1, or the FSE flag is set to "whole," the fully reassembled SDU is delivered to higher layers at the service access point corresponding to the logical channel indicated by the LCID field at 550. A decision is then made at 580 to determine whether SDU segments greater than 1 have been extracted. If SDUs or SDU segments greater than 1 have been extracted, the receiver delivers the SDUs extracted between the first and last SDU or SDU segments to higher layers at the service access point corresponding to the logical channel indicated by the respective LCID field at 570. If the FSE flag is set to "segment", then the segment is the first segment of a MAC-ehs SDU and the receiver discards any segments from the previous PDU stored in the reassembly unit and inserts the segment into the reassembly unit at 590. If the FSE flag is set to "Whole," the receiver delivers the last SDU to higher layers at the serving access point corresponding to the logical channel indicated by the LCID field at 595. If at 540 it is determined that the SDU or SDU fragment is less than 1 or the FSE flag is set to "fragment," the packet is assembled and stored at 545 and the procedure ends.

When FSS is set to "whole" and FSE is not set to "segmented" at 510, the first payload unit is a complete SDU and the first SDU is delivered to higher layers at the service access point corresponding to the logical channel indicated by the LCID field at 560. A decision is then made at 580 to determine whether SDU segments greater than 1 have been extracted. If SDUs or SDU segments greater than 1 have been extracted, the receiver delivers the extracted SDUs up to the last SDU or SDU segment to higher layers at the service access point corresponding to the logical channel indicated by the respective LCID field at 570. If the FSE flag is set to "segmentation", the receiver discards any segments from the previous PDU stored in the reassembly unit and inserts the last SDU segment into the reassembly unit at 590. If the FSE flag is set to "Whole," the receiver delivers the last SDU to higher layers at the serving access point corresponding to the logical channel indicated by the LCID field at 595.

In another embodiment, modifications to the baseline header are introduced to more efficiently support a predefined set of RLC size applications to logical channels, i.e., logical channels with variable RLC pdu sizes available in 3GPP release 7 that are not used by RLC instances. For example, these channels may be used by AM RLC instances with fixed PDU sizes or Unacknowledged Mode (UM) RLC instances with fixed PDU sizes.

Fig. 6 is a section of a header 600 describing SDUs belonging to a logical channel of interest, allowing efficient multiplexing of different types of logical channels in the same MAC-ehs PDU. The modification described in this embodiment may affect only the part of the header 600 describing the SDUs belonging to the logical channel concerned. In other words, if other logical channels are multiplexed in the same MAC-ehs PDU, to which variable PDU sizes are applied, the header portions corresponding to these logical channels may still follow the baseline header or any improvement of the baseline header that may be applied to these channels. This allows for efficient multiplexing of different types of logical channels in the same MAC-ehs PDU. In this example, only the logical channels identified by the LCH-ID2610 are used by the RLC instance with fixed PDU size. The modifications described below apply only to their associated fields 620 (indicated by the bold boxes in fig. 6). This portion of the header 600 is referred to below as the "header portion".

There are several options for this embodiment. The choice of 1 does not allow segmentation of the logical channel of interest, but is simpler. Selection of 2a and 2b allows segmentation.

Fig. 7 is a portion of a header 700 depicting SDUs belonging to a logical channel of interest, allowing different types of logical channels to be efficiently multiplexed in the same MAC-ehs PDU. Option 1 does not allow for the application of a fixed PDU size logical channel segment. The header portion following logical channel ID 710 includes the following fields, not necessarily in order. Optionally, a Transmission Sequence Number (TSN)720 follows the logical channel ID 710. This field may not be needed when the previous logical channel in the header is utilizing the same reordering queue. Optionally, a field flag (Fh)730 may follow to indicate whether this is the last set of MAC-ehs payload units of the header. This field may not be needed when the end of the header is determined by comparing the sum of the size of the MAC-ehs PDU and the size of the payload unit that has been decoded so far. Alternatively, this field may be used to indicate the end of the priority queue.

The header 700 generally includes a field (N)740 for indicating the number of consecutive SDUs having the same size from the logical channel. In one option, a field (SID)750 for indicating the size of the SDU, the number of which has been indicated in the previous field, may be included. An optional "end" (Fc) flag 760 may be included that indicates whether the header portion corresponding to the logical channel is complete. If the flag is present and indicates that the header is incomplete, an additional set of (N, SID, Fc) fields for this logical channel follows to indicate another set of N SDUs with the size indicated by the SID field. In another option, padding bits 770 may be included for maintaining byte alignment of the header, as desired. In case SDUs from multiple logical channels are multiplexed in a MAC-ehs PDU, these padding bits may instead be present at the very end of the header.

For logical channels applying a single fixed RLC PDU size, as used by the AM RLC instance, the Fc field (end field) 760 may be omitted because it is known in advance that there is no other set of SDUs of different sizes. Also, the SID field 750 may be omitted if the size itself is known.

Examples of alternative configurations are shown in fig. 8 and 9. The components shown in fig. 8 and 9 correspond to the components in fig. 7. Fig. 8 is an example of a header 800 where the LCH-ID includes a single fixed RLC PDU size. Fig. 9 is an example of a header 900 in which MAC-ehs SDUs from two logical channels are multiplexed together. RLC instances with flexible RLC PDU sizes use one logical channel while RLC instances with a single fixed RLC PDU size use the other logical channel. In this example, the two logical channels 910 and 915 are not in the same priority queue, so the TSN field 920 is present for both.

Option 2a allows segmentation of logical channels applying a fixed PDU size. Because of this option, the header portion following the logical channel ID includes a 1-bit flag field (Ff) (not shown) to indicate whether the following fields are "N" and "SID" as described in option 1. If this flag indicates the presence of "N" and "SID", the remainder of the header portion may be as explained in option 1.

If the Ff flag does not indicate the presence of "N" and "SID," a fragmentation indication (SI) field 980 may be included for indicating the fragmentation status of the payload. For example, this field may indicate whether the first payload unit is a fragment and whether the last payload unit is a fragment. This field indicates whether the payload unit is a complete SDU or a starting, middle, or last segment of an SDU when a single payload unit is allowed. The SI field 980 may not exist if it has been indicated in the previous header portion for a logical channel multiplexed on the same priority queue as this logical channel. In one option, a TSN 920 may be included. This field may not be needed in the case where the previous logical channel in the header is utilizing the same reordering queue.

Optionally, a field flag (Fh) may be included to indicate whether this is the last set of MAC-ehs payload units of the header. This field may not be needed when determining the end of the header by comparing the MAC-ehs PDU size with the sum of the currently decoded payload unit sizes. Alternatively, this field may be used to indicate the end of the priority queue.

In another option, a Length Indicator (LI)990 for indicating the length of the payload unit of this logical channel may be included. As will be described in another embodiment, this field may not be needed if this payload unit is fragmented and at the end of the MAC-ehc PDU. LI 990 may also be used to indicate a group of payload units (e.g., a complete SDU, possibly followed by an SDU fragment) when a single fixed PDU size is applied to a logical channel (e.g., if used by an AMRLC entity with a fixed RLC PDU size) and assuming the transmitter knows this size. This may be achieved by having the LI 990 indicate the total number of bytes from the group of payload units. The single payload unit is determined by performing an integer division of the LI 990 value by the known fixed RLC PDU size. The result is the number of complete SDUs, and the remainder of the division is the size of the SDU segment at the end. In another configuration, padding bits 970 may be included as needed to maintain the byte arrangement of the header. These padding bits 970 may instead appear at the very end of the header in the case where SDUs from multiple logical channels are multiplexed in a MAC-ehs PDU.

Option 2b allows segmentation of logical channels applying a fixed PDU size. This option may be used when the SI field 980 indicates once per priority queue. Because of this option, the header portion immediately following logical channel ID910 may include a 1-bit flag field (Ff) (not shown) to indicate whether the payload unit is the end of the priority queue on which the logical channel is multiplexed. Otherwise the flag may not be needed if the payload unit is known to be the end of the priority queue (e.g., using other fields in the previous header portion).

If this is not the last payload unit of the priority queue, or if the SI field 980 applicable to this priority queue indicates that the last payload unit of this priority queue is not a segment, then the remainder of the header portion may be as explained in option 1.

If this is the last payload unit of the priority queue, or if the SI field 980 applicable to this priority queue indicates that the last payload unit of this priority queue is a segment, then an LI 990 for indicating the length of the payload unit of this logical channel may be included. As will be described in another embodiment, this field may not be needed if this payload unit is fragmented and at the end of the MAC-ehc PDU. LI 990 may also be used to indicate a complete set of SDUs, possibly followed by SDU fragments, in case a single fixed PDU size is applied to the logical channel, as described in option 2 a. In another configuration, padding bits 970 may be included as needed to maintain the byte arrangement of the header. These padding bits 970 may instead appear at the very end of the header in the case where SDUs from multiple logical channels are multiplexed in a MAC-ehs PDU.

A new definition for SI has been proposed due to the introduction of an optimized MAC-ehs header. However, the proposed scheme is not suitable for handling the differentiation between multiple and single payload units within a reordering PDU. It is not clear which SI indication should be used when a single payload unit is present in the reordering PDU. In the proposed SI structure, "10" corresponds to the first payload unit being a complete unit and the last payload unit being a segment if more than one payload unit appears in the reordering PDU. According to this definition, if only one payload is present, it will be a complete MAC-ehs PDU, but it should be a segment corresponding to the first segment of the MAC-ehs PDU. Also, when the SI is equal to "11", the definition corresponds to only a plurality of payload units. When setting the SI field, the transmitter must know exactly how to indicate the presence of a single payload unit in the reordering PDU. Since a single payload unit may correspond to the first, middle, last or complete MAC-ehs sdu, the transmitter should specify the correct SI indication so that the segments can be correctly reassembled. More specifically, the following SI field variations and/or interpretation may be considered to explicitly cover the case where the reordering PDU contains only one payload unit.

Fig. 10 and table 2 show an improved method 1000 for interpreting the SI field, wherein a reordering PDU contains only one payload unit. When the SI is equal to "00" (not shown), all SDUs of the reordering PDU are complete MAC PDUs. As shown in fig. 10, when the SI equals "01" at 1002, the first payload unit of the reordering PDU is a segment and corresponds to the last segment of a MAC-ehs SDU (MAC-ehs SDU and MAC-d PDU are used interchangeably) at 1007. This is applicable to a single payload unit 1005 or multiple payload units 1010 in a PDU. If there is more than one payload unit, then the last payload unit is a complete MAC-ehs SDU at 1009.

When the SI equals "10" at 1012, if there is more than one payload unit in the reordering PDU, the first payload unit is a complete MAC-ehs SDU at 1019. At 1019, the last payload unit of the reordering PDU is a segment of the MAC-ehs SDU and corresponds to the first field of the MAC-ehs SDU. This may correspond to the case where there is a single payload unit or multiple payload units in the reordered PDUs at 1017 and 1019.

When the SI equals "11" at 1022, the first payload unit is a fragment of the MAC-ehsSDU at 1027. Note that this segment may be the last segment of a MAC-ehs SDU (when there are multiple payload units) or it may be an intermediate segment if there is only one payload unit in the reordering PDU. For example, if there are multiple payload units at 1027, the segment is the last segment of the MAC-ehs SDU. If there is a single payload unit at 1027, the segment is the middle segment of the MAC-ehs SDU. If there are multiple payload units, then the last payload unit is a segment at 1029. At 1029, the segment will be the first segment of a MAC-ehs SDU.

Table 2 shows the encoding of the SI field as described above, where the term MAC PDU corresponds to a MAC-c/d PDU or a MAC-ehs SDU. An SDU is a reordered SDU or a MAC-ehs SDU or the equivalent of a segmentation of both.

SI field	Segment indication
		00	The first SDU of the reordering PDU is a complete MAC PDU. The last SDU of the reordering PDU is the complete MAC PDU.
01	The first SDU of the reordering PDU is the last segment of the MAC PDU. If there is more than one SDU in the reordering PDU, the last SDU of the reordering PDU is a complete mac PDU.
		10	If there is more than one SDU in the reordering PDU, the first SDU of the reordering PDU is a complete MAC PDU. Last of the reordering PDUsOne SDU is the first segment of a MAC PDU.
11	If there is more than one SDU in the reordering PDU, the first SDU is the last segment of the MAC PDU and the last SDU of the reordering PDU is the first segment of the MAC PDU. If there is a single SDU in the reordering PDU, the segment is the middle segment of the MAC PDU.

TABLE 2

The following embodiments provide for improved signaling of fragmentation. This embodiment describes a method of encoding the SI field 980 bits when the SI field 980 appears once per priority queue. There are two options, one for the 2-bit SI field and the other for the 1-bit SI field.

As shown in fig. 11 and table 3 below, a 2-bit SI field may be one possible encoding to minimize signaling overhead. It should be understood that the exact choice of bit combination for each value is arbitrary and may vary if two values are assigned to the same bit combination. Table 3 shows an example of segment indication field improvement signaling.

SI field	Segment indication
		Value #1 (e.g., 00) (1110)	The first payload unit of the addressed payload group is a complete MAC-ehs (or MAC-is) SDU. The last payload unit of the addressed payload group isA complete MAC-ehs (or MAC-is) SDU. (1120)

Value #2 (e.g. 10) (1130)	The first payload unit of the addressed payload group is the complete MAC-ehs (or MAC-is) SDU or MAC-ehs ((ii))Or MAC-is) first partition of SDU Segment of. The last payload unit of the addressed group is a segment of a MAC-ehs (or MAC-is) SDU. (1140)
		Value #3 (e.g. 01) (1150)	The first payload unit of the addressed payload group is a segment of a MAC-ehs (or MAC-is) SDU. The last payload unit of the addressed payload group is a complete MAC-ehs (or MAC-is) SDUOr MAC-ehs (or MAC-is) last segment of SDU.(1160)
Value #4 (e.g. 11) (1170)	The first payload unit of the addressed payload group is of a MAC-ehs (or MAC-is) SDUIntermediate or last segment. The last payload unit of the addressed payload group is of a MAC-ehs (or MAC-is) SDUFirst of all Individual segments or intermediate segments.(1180)

TABLE 3

An advantage of the coding described in table 3 is that in case the addressed payload group is a single SDU segment, the determination is based on the SI field and whether this SDU segment is a complete SDU. Otherwise, the determination is made based on the presence of padding bits, and there is even ambiguity if the last segment does fit in the remaining available 5 payloads.

In addition, the coding described in Table 3 is more robust to lost MAC-ehs PDUs. For example, if a MAC-ehs PDU of TSN # n for a given priority queue is lost and the first payload unit of a MAC-ehs PDU of TSN # n +1 is a segment, the original encoding does not allow a determination of whether the first payload unit is the first or an intermediate segment. In the latter case, the payload unit must be discarded because the first part of the SDU is missing. New codes correct this problem by distinguishing between the two cases.

Fig. 12 is a flow chart illustrating an alternative method 1200 of encoding in which the SI field is defined as shown in table 4. Table 4 shows an alternative representation of the improved signaling of the segmentation indication field. This representation is fully equivalent to that shown in table 3, but is more readily understood. This may be achieved by separating the cases depending on whether there is a single payload unit or multiple payload units in the addressing group.

TABLE 4

With the proposed encoding type, the reassembly function is modified as follows, such that the selection of the SI field value corresponds to the example shown in Table 4. The "reordering PDUs" mentioned in the following procedure refer to MAC-ehs payload groups belonging to the same priority queue. It is also noted that the term "output entity" may refer to a demultiplexing entity, or a layer/sublayer on the MAC-ehs, or any other entity to which the reassembly unit delivers SDUs.

The SI field may be used to determine whether a segment is a starting or intermediate segment. The situation that can be distinguished depends on the number of bits of the SI field and the presence of one time for each priority queue or the presence of each SDU or packet therein.

The first example is a 2-bit SI, one SI per priority queue, where the encoding is per embodiment described in tables 3 or 4. In this example, the bit combination indicates that the last SDU or SDU segment of the priority queue addressing group is the start or middle segment of an SDU.

A second example is a 2-bit SI, one SI corresponding to each SDU or SDU segment encoded as shown in table 3 or 4. In this example, the bit combination indicates that the SDU or SDU segment is the start or middle segment of the SDU.

Fig. 13 is a flow diagram of a reassembly unit process 1300 for an SI field associated with a reassembled PDU. If the SI field is set to "00" at 1310 to indicate that the first and last MAC-ehs payload units of the group are complete MAC-ehs SDUs, all MAC-ehs SDUs in the group corresponding to the MAC-ehs payload units are delivered to the output entity at 1315.

If the SI field is set to "01" at 1320 to indicate that the first MAC-ehs payload unit is a segment of a MAC-ehs SDU but the last MAC-ehs payload unit is a complete MAC-ehs SDU or is the last segment of a MAC-ehs SDU, a determination may be made at 1325 as to whether the received and stored MAC-ehs payload units are contiguous. If the received and stored MAC-ehs payload units are contiguous, the first received MAC-ehs payload unit is combined with the stored MAC-ehs SDU at 1330 and the MAC-ehs SDU corresponding to the combined MAC-ehs payload unit is delivered to the output entity. If the received and stored MAC-ehs payload units are not contiguous, the received and stored MAC-ehs payload units are discarded 1335 and all MAC-ehs SDUs in the group corresponding to subsequent MAC-ehs payload units are delivered to the output entity.

If the SI field is set to "10" at 1340 to indicate that the last MAC-ehs payload unit is a segment of a MAC-ehs SDU, but the first is a complete MAC-ehs SDU or the first segment of a MAC-ehs SDU, all MAC-ehs SDUs in the group corresponding to all but the last MAC-ehs payload units are delivered to the output entity and any previously stored MAC-ehs payload units are discarded at 1345, while the last MAC-ehs payload unit of the received reordering PDU is stored.

If the SI field is set to "11" at 1350 to indicate that the first MAC-ehs payload unit is the middle or last segment of a MAC-ehs SDU and the last MAC-ehs payload unit is the first segment or middle segment of a MAC-ehs SDU, a determination may be made at 1355 as to whether the received and stored MAC-ehs payload units are contiguous. If the received and stored MAC-ehs payload units are contiguous, the first received MAC-ehs payload unit is combined with the stored MAC-ehs payload unit at 1360. If there are several MAC-ehs payload units in the group, then at 1365 the MAC-ehs SDUs corresponding to the combined MAC-ehs payload unit are delivered to the egress entity, and all MAC-ehs SDUs in the group corresponding to all but the last MAC-ehs payload unit are delivered to the egress entity, and any previously stored MAC-ehs payload units are discarded, while the last MAC-ehs payload unit that received the reordered PDUs is stored. If the received and stored MAC-ehs payload units are not contiguous, the received and stored MAC-ehs payload units are discarded 1370.

To illustrate reflecting these definitions, one possible alternative to updating the table using the SI field structure is shown in table 4. Table 4 is a representation of the SI field equal to table 3. Tables 2, 3 and 4 appear as alternatives, but redefine the equivalent representation of the solution for the 2-bit case SI field.

The reorganization function may perform reorganization based on one of the descriptions disclosed herein. If the reassembly function is described such that these definitions are considered, the transmitter optionally need not know what the SI field indicates. The receiver is responsible for assigning the correct SI indication to each reordered PDU so that the transmitter can correctly perform reassembly based on the SI field value.

The definitions described above may be used regardless of the definitions in the 3GPP specifications. For example, the SI structure may remain unchanged, but the solution of the above-mentioned patent allows for the correct SI setting so that the reorganization function works correctly.

When the SI equals "11", the above reassembly procedure proceeds to discard SDUs that should not be discarded. More specifically, when received and stored MAC-ehs SDUs are not contiguous, these SDUs are discarded. This means that all remaining payload units in the received reassembled PDU are discarded and/or incorrectly processed.

Fig. 14 is a flow chart of how the reassembly unit performs the combining function when SI equals "11" to avoid this problem. A determination is made at 1410 as to whether the received and stored MAC-ehs payload units are contiguous. If the received and stored MAC-ehs payload units are contiguous at 1420, the first received and stored payload units are combined. Because the first payload unit corresponds to the last segment of the MAC-ehs SDU, if the reordering PDU contains several payload units at 1425, the combined packet is only delivered to the outgoing higher layer at 1430. Otherwise, if there is only one payload unit in the reassembled PDU, the segment is a middle segment, and thus the combined packet is stored at 1440.

When the SI is equal to "11", the reassembly unit may perform a discard function, as shown in fig. 14. If the payload unit is discontinuous at 1410, the stored payload unit and the first received payload unit (the first segment in the reordering PDU or just the payload unit) are discarded at 1450. If there are multiple payload units in the reordering PDU at 1460, all other payload units should be processed.

Fig. 15 is a flowchart of how to process the remaining payload units in 1460 of fig. 14 if there are multiple payload units in the reordering PDU. If there are multiple payload units in the reordering PDU at 1510, all but the last full MAC-ehs sdu must be forwarded to the higher layer (or output entity) at 1520. Note that the first payload unit is assumed to have been combined or discarded. At 1530, the last payload unit corresponding to the first segment of the SDU should be stored in the reassembly unit. If the PDU does not contain multiple payload units, the stored payload units and the combined payload units are combined and stored. This is shown at 1440 of fig. 14. Fig. 16 is a flow chart of the combined reassembly process illustrated in fig. 14 and 15.

To reflect the above SI definition and reorganization function description, it is possible to update the reorganization unit function in the following manner. Note that the change includes the fact that the SI field interpretation need not be known, but is optionally added to the description. The terms MAC-d and MAC-c PDU are used interchangeably with MAC PDU and MAC-ehs SDU, which are used interchangeably with payload unit.

Fig. 17 is a flow chart of how the reassembly unit processes 1700 the SI field associated with a reassembled PDU. If the SI field is set to "00" at 1710, all MAC-d PDUs in the group corresponding to the MAC-ehs SDUs are delivered to higher layers at 1720.

If the SI field is set to "01" at 1730, a determination is made at 1735 as to whether the received and stored MAC-ehs SDUs are contiguous. If the received and stored MAC-ehs SDUs are contiguous, the first received MAC-ehs SDU is combined with the stored MAC-ehs SDU and the MAC-d PDU corresponding to the combined MAC-ehs SDU is delivered to the higher layer (or output entity) at 1740. If the received and stored MAC-ehs SDU is not contiguous, the received and stored MAC-ehs SDU is discarded 1745 while all MAC-d PDUs corresponding to the subsequent MAC-ehs SDU are delivered to the higher layer (or output entity).

If the SI field is set to "10" at 1750, all MAC-d PDUs in the group corresponding to all but the last MAC-ehs SDU are delivered to the higher layer (or an output entity) and any previously stored MAC-ehs SDUs are discarded at 1760, while the last MAC-ehs SDU of the received reordering PDU is stored.

If the SI field is set to "11" at 1770, a determination is made at 1775 as to whether the received and stored MAC-ehs SDUs are contiguous. If the received and stored MAC-ehs SDUs are contiguous, the first received MAC-ehs SDU is combined with the stored MAC-ehs SDU at 1780. If the received and stored MAC-ehs SDUs are not contiguous, the first received MAC-ehs SDU and stored MAC-ehs SDU are discarded at 1785. If there are several MAC-ehs SDUs in the group, the MAC-d PDU corresponding to the combined MAC-ehs SDU is delivered to the higher layer (or an output entity), all MAC-d PDUs in the group corresponding to all but the last MAC-ehs SDU are delivered to the higher layer (or an output entity) and the last MAC-ehs SDU of the received reordering PDU is stored at 1790. This procedure is essentially the same as the procedure described in page 10, paragraph 1.

When using a 1-bit SI field on a per MAC-ehs payload unit basis, the coding that would exhibit the same advantages as the previous one is shown in table 5. As shown in table 5, the following example is a 1-bit SI, one SI for each SDU or SDU segment coding. In this example, the bit indicates that the payload unit is the beginning or middle segment of an SDU.

SI field	Segment indication
		0	The MAC-ehs payload unit is a complete MAC-ehs SDU orMaximum of MAC-ehs SDU The latter section
1	The MAC-ehs payload unit being a MAC-ehs SDUFirst or intermediate section

TABLE 5

It is to be noted that in this case the term reordering PDU may also be used instead of MAC-ehs payload unit, since each reordering PDU may have a single MAC-ehs payload unit.

Another embodiment shows how the inclusion of the SI field is omitted. While the size of this field may be significant (e.g., 11 bits for byte-aligned payload), its relative overhead is valid in the case where the MAC-ehs PDU is not very large (e.g., less than 1000 bits).

The principle of this embodiment is to omit the LI for the last payload unit, if it is an SDU segment that is not the last segment (i.e. the starting segment or the middle segment), which is included in the MAC-ehs PDU. The presence of a start or middle segment at the end of the payload means that there is no padding. Therefore, when processing the MAC-ehs PDU, it is not necessary to accurately indicate the segment length corresponding to the MAC-ehs PDU since the end of the segment.

Different methods may be used to indicate in the header whether this applies and thus whether LI is present. Method 1 describes an implicit indication of the presence of the LI field. In this method, no specific field is added to the header to indicate the presence or absence of the LI field. The dependent Segmentation Indication (SI) field may be applied to the last priority queue or last SDU and any other methods or fields to determine the end of the header.

The method of indicating the end of the header may include adding a flag field (FQ or otherwise) indicating whether the header portion is the last of the header. If this option is included in the method, the tag field must appear before the LI. Another alternative method has to calculate the difference between the MAC-ehs PDU size and the sum of the payload unit lengths decoded from the header to determine if the header is too small to accommodate the additional payload unit.

Method 2 describes an explicit indication of the presence of the LI field. In this method, a flag (Fli) following the logical channel identity is present to indicate whether LI is present for the payload unit from this logical channel.

The presence of this field may be defined based on logical channels and signaled by higher layers. Alternatively, a predetermined rule with respect to the nature of the logical channel may determine the presence of this field. For example, it may be meaningful to limit this field to a logical channel applying a single fixed RLC PDU size (as used by an AM RLC instance with a fixed RLC PDU size) or applying a fixed set of RLC PDU sizes (as used by an UM RLC instance with a fixed set of RLC PDU sizes).

The reason that the above rule is available is that the LI relative overhead in case of flexible RLC PDU size application is typically very small, and hence omitting the length field is unnecessary.

Although the features and elements of the present invention are described in the preferred embodiments in particular combinations, each feature or element can be used alone without the other features and elements of the preferred embodiments or in various combinations with or without other features and elements of the present invention. The methods or flow charts provided in the present invention may be implemented in a computer program, software, or firmware tangibly embodied in a computer-readable storage medium, examples of which include Read Only Memory (ROM), Random Access Memory (RAM), registers, buffer memory, semiconductor memory devices, magnetic media such as internal hard disks and removable disks, magneto-optical media, and optical media such as CD-ROM disks and Digital Versatile Disks (DVDs), for execution by a general purpose computer or a processor.

For example, suitable processors include: a general-purpose processor, a special-purpose processor, a conventional processor, a Digital Signal Processor (DSP), a plurality of microprocessors, one or more microprocessors in association with a DSP core, a controller, a microcontroller, an Application Specific Integrated Circuit (ASIC), a Field Programmable Gate Array (FPGA) circuit, any Integrated Circuit (IC), and/or a state machine.

A processor in association with software may be used to implement a radio frequency transceiver for use in a Wireless Transmit Receive Unit (WTRU), user equipment, terminal, base station, radio network controller, or any host computer. The WTRU may be used in conjunction with modules, implemented in hardware and/or software, such as a camera, a video camera module, a video circuit, a speakerphone, a vibration device, a speaker, a microphone, a television transceiver, a hands free headset, a keyboard, bluetoothA module, a Frequency Modulation (FM) radio unit, a Liquid Crystal Display (LCD) display unit, an Organic Light Emitting Diode (OLED) display unit, a digital music player, a media player, a video game player module, an internet browser, and/or any Wireless Local Area Network (WLAN) module.

Examples

1. A method for multiplexing Service Data Units (SDUs) from different logical channels and priority queues, the method comprising:

concatenating a plurality of reordering Protocol Data Units (PDUs), each reordering PDU comprising at least one reordered SDU, wherein a reordered SDU is at least a segment of an SDU;

creating a MAC-ehs header comprising:

providing each segment of at least a Medium Access Control (MAC) SDU with a Logical Channel Indicator (LCID) for indicating to which logical channel the reordered SDU belongs;

providing each of said at least segments of the MAC SDU with a Length Indicator (LI) field for indicating the length of the reordered SDU;

providing each of said reordered PDUs with a Transmission Sequence Number (TSN) field for indicating a data sequence number for reordering purposes;

providing each of said reordering PDUs with a Segmentation Indication (SI) field for indicating whether the first and last SDU of the reordering PDU have been segmented or not; and

-providing a flag (F) for each of said at least segments of MAC SDUs indicating whether it is the last re-ordered SDU.

2. A method for encoding and interpreting a Segment Indication (SI) field, comprising:

determining whether the SI field value is '00' and, if so, reordering a first Service Data Unit (SDU) of a Protocol Data Unit (PDU) into a complete Media Access Control (MAC) PDU and a last SDU of the reordered PDU into a complete MAC PDU;

determining whether the SI field value is '01', and if so, reordering the first SDU of the PDU to be the last segment of the MAC PDU, and if there are multiple SDUs in the reordering PDU, reordering the last SDU of the PDU to be a complete MAC PDU;

determining whether the SI field value is '10' and, if so, reordering the last SDU of the PDU to be the first segment of the MAC PDU and, if there are multiple SDUs in the reordering PDU, the first SDU of the reordering PDU to be a complete MAC PDU; and

it is determined whether the SI field value is '11', and if so, when a plurality of SDUs exist in the reordering PDU, a first SDU of the reordering PDU is a last segment of the MAC PDU and a last SDU of the reordering PDU is a first segment of the MAC PDU, and when a single SDU exists in the reordering PDU, the segment is a middle segment of the MAC PDU.

3. A method for encoding a Segment Indication (SI) field when a reordering PDU comprises a single reordering SDU, the method comprising:

when the re-arranged SDU is a complete MAC-ehs SDU, a first value is appointed;

assigning a second value when the reordered SDU is a first segment of the MAC-ehs SDU;

assigning a third value when the reordered SDU is the last segment of the MAC-ehs SDU; and

when the reordered SDU is a middle segment of a MAC-ehs SDU, a fourth value is specified.

4. A method for encoding a Segment Indication (SI) field when a reordered SDU comprises a plurality of reordered SDUs, wherein the plurality of reordered SDUs comprises at least one reordered PDU, the method comprising:

assigning a first value when the first re-arranged SDU is a complete MAC-ehs SDU and the last re-arranged SDU is a complete MAC-ehs SDU;

assigning a second value when the first re-arranged SDU is a complete MAC-ehs SDU and the last re-arranged SDU is a first segment of the MAC-ehs SDU;

assigning a third value when the first re-arranged SDU is the last segment of the MAC-ehs SDU and the last re-arranged SDU is the complete MAC-ehs SDU; and

a fourth value is assigned when the first reordered SDU is the last segment of a MAC-ehs SDU and the last reordered SDU is the first segment of a MAC-ehs SDU.

5. A method for interpreting a Segment Indication (SI) field when a reordering PDU contains a reordering SDU, the method comprising:

determining whether the SI field value is '01', and if so, the first re-arranged SDU is a segment and corresponds to a MAC-ehs SDU or the last segment of a PDU;

determining whether the SI field value is '10' and, if so, the last re-arranged SDU is a segment of a MAC-ehs SDU and corresponds to the first segment of the MAC-ehs SDU; and

it is determined whether the SI field value is '11' and, if so, the first re-ordered SDU of the re-ordered PDU is a segment of a MAC-ehs SDU.

6. A method for interpreting a Segment Indication (SI) field, wherein a reordering PDU comprises a plurality of reordering SDUs, the method comprising:

determining whether the SI field value is "01" and, if so, the first reordered SDU is a segment and corresponds to the last segment of the MAC-ehs SDU, and the last reordered SDU is a complete MAC-ehs SDU;

determining whether the SI field value is "10" and, if so, the first reordered SDU is a complete MAC-ehs SDU and the last reordered SDU is a segment of a MAC-ehs SDU and corresponds to the first segment of the MAC-ehs SDU; and

it is determined whether the SI field value is '11' and, if so, the first re-ordered SDU is a fragment of the MAC-ehs SDU and the last re-ordered SDU is a fragment.

7. A method for processing a Segment Indication (SI) field associated with a reordering PDU using a reassembly unit, the method comprising:

passing all MAC PDUs corresponding to the MAC-ehs SDU to a higher layer when the SI field is '00';

when the SI field is "01", determining whether the received and stored MAC-ehs SDUs are contiguous;

when the received and stored MAC-ehs SDUs are contiguous, combining the first received MAC-ehs SDU with the stored MAC-ehs SDU and delivering a MAC PDU corresponding to the combined MAC-ehs SDU to a higher layer;

discarding the received and stored MAC-ehs SDU and passing all MAC PDUs corresponding to the subsequent MAC-ehs SDU to a higher layer when the received and stored MAC-ehs SDU is non-continuous;

passing all MAC PDUs corresponding to all MAC-ehs SDUs except the last MAC-ehs SDU to the higher layer when the SI field is "10", discarding any previously stored MAC-ehs SDUs and storing the last MAC-ehs SDU of the received reordering PDU;

when the SI field is "11", determining whether the received and stored MAC-ehs SDU is continuous, discontinuous, or whether several MAC-ehs SDUs exist;

combining a first received MAC-ehs SDU with a stored MAC-ehs SDU when said received and stored MAC-ehs SDUs are contiguous;

discarding the first received MAC-ehs SDU and the stored MAC-ehs SDU when the received and stored MAC-ehs SDU is discontinuous; and

when there are several MAC-ehs SDUs, a MAC PDU corresponding to the combined MAC-ehs SDU is delivered to a higher layer or an output entity, all MAC PDUs corresponding to all MAC-ehs SDUs except the last MAC-ehs SDU are delivered to a higher layer or an output entity, and the last MAC-ehs SDU of the received reordering PDU is stored.

8. The method of embodiment 1 wherein the LI field specifies the exact number of octets contained in the re-ordered SDU.

9. A payload header for multiplexing Service Data Units (SDUs) from different logical channels and priority queues, the payload header comprising:

a plurality of queue portions, each queue portion comprising:

a Transmission Sequence Number (TSN) indicating a data sequence number of the queue ID; and

the SDU describes a super field (SDSF) that indicates how to decompose and/or reassemble at least the segments of the SDU and to which logical channels the SDU belongs.

10. The payload header of embodiment 9, wherein the SDSF further comprises:

a whole/segment start (FSS) flag for each priority queue indicating whether data located at a start position of the payload for the reordering queue corresponds to a segment of an SDU;

a whole/fragment end (FSS) flag for each priority queue indicating whether data located at an end position of the payload for the reordering queue corresponds to a fragment of an SDU;

a Logical Channel Indicator (LCID) for each segment of at least a Medium Access Control (MAC) SDU indicating to which logical channel the segment of the at least a MAC SDU belongs;

a Length Indicator (LI) field for each segment of the at least MAC SDU indicating a length of the segment of the at least MAC SDU; and

an SDU end marker for each segment of said at least MAC SDU indicating whether this is the last segment of said at least MAC SDU.

11. A payload header according to embodiment 10, wherein the LI field specifies the exact number of bytes comprised by the at least a segment of the MAC SDU.

12. A payload header as in any of the embodiments 10-11, wherein the LI field specifies the exact number of octets that the at least a segment of the MAC SDU contains.

13. A payload header as in any of embodiments 10-12 wherein a length of the LI field is dependent on a maximum length of the MAC SDU.

14. The payload header of embodiment 13, wherein the maximum length of the MAC SDU changes upon reconfiguration.

15. The payload header of embodiment 13, wherein the maximum length of the MAC SDU is dynamically changed.

16. A payload header as in any of embodiments 10-15 wherein the length of the LI field is predetermined.

17. The payload header of embodiment 16, wherein the predetermined length of the LI field is a number of bits representing a maximum MAC SDU size.

18. A payload header as in any of embodiments 10-17 wherein the maximum length of a mac sdu changes upon reconfiguration.

19. A payload header as in any of embodiments 10-18 wherein the maximum length of a mac sdu is dynamically changed.

20. A payload header as in any of embodiments 10-19, wherein a length of the LI field is dependent on the LCID.

21. The payload header of embodiment 20, wherein the length of the LI field is a number of bits representing a maximum MAC SDU size.

22. A payload header as in any of embodiments 20-21 wherein a maximum length of a mac sdu changes upon reconfiguration.

23. A payload header as in any of embodiments 20-22 wherein the maximum length of a mac sdu is dynamically changed.

24. A method for processing an enhanced high speed medium access control (MAC-ehs) header, the method comprising:

stripping the MAC-ehs PDU header;

segmenting the MAC-ehs PDU header into portions;

extracting a corresponding payload;

appending a corresponding payload to the header;

constructing a rearrangement queue PDU;

inserting a reordering queue PDU into a reordering queue corresponding to a reordering queue Identification (ID) and a Transmission Sequence Number (TSN);

performing a reordering function;

performing a disaggregation and/or reassembly function; and

demultiplexing by delivering the complete MAC SDU to the correct logical channel.

25. The method of embodiment 24 wherein the partitioning of the MAC-ehs PDU comprises utilizing an end marker.

26. A method for processing a modified high speed medium access control (MAC-i/is) header, the method comprising:

stripping the MAC-i/is PDU header;

segmenting the MAC-i/is PDU header into portions;

extracting a corresponding payload;

appending a corresponding payload to the header;

constructing a rearrangement queue PDU;

inserting a reordering queue PDU into a reordering queue corresponding to a reordering queue Identification (ID) and a Transmission Sequence Number (TSN);

performing a reordering function;

performing a disaggregation and/or reassembly function; and

demultiplexing by delivering the complete MAC SDU to the correct logical channel.

27. The method as in embodiment 26 wherein the segmenting the MAC-i/is PDU comprises utilizing an end marker.

28. A method at a Wireless Transmit Receive Unit (WTRU) for processing data for each decomposition/reassembly/demultiplexing unit, the method comprising:

receiving at least one Protocol Data Unit (PDU), the at least one PDU comprising a plurality of segments of at least a Service Data Unit (SDU);

parsing segments of each of the at least SDUs;

passing the first SDU to a higher layer corresponding to the logical channel when a whole/segment start (FSS) flag is set to 'whole' and a FSE flag is set to 'whole'; when the FSS flag is set to "whole", if the segmentation of said at least SDU larger than 1 has been extracted, passing the extracted SDU up to the last segmentation of said at least SDU to a higher layer corresponding to the logical channel indicated by the LCID field; discarding any segments from the previous PDU stored in the reassembly unit and inserting the last SDU segment into said reassembly unit if the FSE flag is set to "segmentation"; and if the FSE flag is set to "whole", delivering the last SDU to the higher layer corresponding to the logical channel indicated by the LCID field;

when the FSS flag is set to "segment" and data of TSN-1 has been previously delivered, reassembling the SDU segment with the previously stored PDU segment; delivering the fully reassembled SDU to a higher layer corresponding to a logical channel indicated by a Logical Channel Indicator (LCID) field if the SDU or segmentation of the SDU is greater than 1 or a full/segment end (FSE) flag is set to "full"; passing the extracted SDU between the first and last segment of said at least SDU to a higher layer corresponding to the logical channel indicated by the LCID field if segments of said at least SDU larger than 1 have been extracted; if the FSE flag is set to "segmentation", discarding any segments from previous PDUs stored in the reassembly unit and inserting the last SDU segment into said reassembly unit; and if the FSE flag is set to "whole", passing the last SDU to a higher layer corresponding to the logical channel indicated by the LCID field;

discarding any segment from the previous PDU stored in the reassembly unit and inserting the last SDU segment into said reassembly unit if data of TSN-1 has not been previously delivered; passing the extracted SDU between the first and last segment of said at least SDU to a higher layer corresponding to the logical channel indicated by the LCID field if segments of said at least SDU larger than 1 have been extracted; if the FSE flag is set to "segmentation", discarding any segments from previous PDUs stored in the reassembly unit and inserting the last SDU segment into said reassembly unit; and if the FSE flag is set to "whole", passing the last SDU to a higher layer corresponding to the logical channel indicated by the LCID field; and

when the FSS flag is set to "segment" and data of TSN-1 has been previously delivered, the SDU segment is reassembled with the previously stored PDU segment, and the combined packet is stored if the at least segment of the SDU is less than 1 or the FSE flag is set to "segment".

29. A Wireless Transmit Receive Unit (WTRU), comprising:

a receiver configured to receive a payload unit;

a processor configured to multiplex and demultiplex the payload units;

a buffer configured to store incomplete Service Data Units (SDUs) for reassembly; and

a transmitter configured to transmit the reassembled SDU.

30. The WTRU of embodiment 29 wherein the processor includes a reordering unit.

31. The WTRU of embodiment 29 wherein the processor includes a decomposition/reassembly unit.

32. A Wireless Transmit Receive Unit (WTRU) configured to process an enhanced high speed medium access control (MAC-ehs) header, the WTRU comprising:

circuitry configured to strip off a MAC-ehs PDU header;

circuitry configured to segment a MAC-ehs PDU header into portions;

circuitry configured to extract a corresponding payload;

circuitry configured to append a corresponding payload to a header;

circuitry configured to construct a reordering queue PDU;

circuitry configured to insert a reordering queue PDU into a reordering queue corresponding to a reordering queue Identification (ID) and a Transmission Sequence Number (TSN);

circuitry configured to perform a reordering function;

circuitry configured to perform decomposition and/or recombination functions; and

circuitry configured to deliver a complete MAC SDU to the correct logical channel.

33. A base station, comprising:

a receiver configured to receive a payload unit;

a processor configured to multiplex and demultiplex payload units;

a buffer configured to store incomplete Service Data Units (SDUs) for reassembly; and

a transmitter configured to transmit a MAC-ehs Protocol Data Unit (PDU).

34. A base station configured to process a modified high speed medium access control (MAC-i/is) header, the base station comprising:

circuitry configured to strip off MAC-i/is PDU headers;

circuitry configured to segment a MAC-i/is PDU header into portions;

circuitry configured to extract a corresponding payload;

circuitry configured to append a corresponding payload to a header;

circuitry configured to construct a reordering queue PDU;

circuitry configured to insert a reordering queue PDU into a reordering queue corresponding to a reordering queue Identification (ID) and a Transmission Sequence Number (TSN);

circuitry configured to perform a reordering function;

circuitry configured to perform decomposition and/or recombination functions; and

circuitry configured to deliver a complete MAC SDU to the correct logical channel.

Claims (2)

1. A method of creating a Media Access Control (MAC) header, the method comprising:

creating a MAC enhanced high speed MAC-ehs header for a media Access control, MAC, protocol data Unit, PDU, the header comprising:

a segment indication SI field having:

a value of "00" to indicate that a first SDU of a reordering PDU is a complete MAC enhanced high speed (MAC-ehs) SDU and a last SDU of the reordering PDU is a complete MAC-ehs SDU;

a value of "01" to indicate that the first reordered SDU of the reordered PDU is the last segment of a MAC-ehs SDU and that the last reordered SDU of the reordered PDU is a complete MAC-ehs SDU when more than one reordered SDU is present in the reordered PDU;

a value of "10" to indicate that the first reordered SDU of the reordered PDU is a complete MAC-ehs SDU and the last reordered SDU of the reordered PDU is the first segment of a MAC-ehs SDU when more than one reordered SDU is present in the reordered PDU; or

A value of "11" to indicate that the first reordered SDU of the reordered PDU is the last segment of a MAC-ehs SDU and the last reordered SDU of the reordered PDU is the first segment of a MAC-ehs SDU when more than one reordered SDU is present in the reordered PDU, and that a single reordered SDU is a middle segment of a MAC-ehs SDU when a single reordered SDU is present in the reordered PDU; and transmitting the MAC PDU.

2. A method of processing a medium access control, MAC, protocol data unit, PDU, the method comprising:

determining a value of a Segment Indication (SI) field in a header of a Media Access Control (MAC) Protocol Data Unit (PDU),

wherein the SI field with a value of "00" is used to indicate that the first reordering service data unit SDU of a reordering PDU is a complete MAC enhanced high speed MAC-ehs SDU and the last reordering SDU of the reordering PDU is a complete MAC-ehs SDU;

wherein the SI field having a value of "01" is used to indicate that the first reordered SDU of the reordered PDU is the last segment of a MAC-ehs SDU and that the last reordered SDU of the reordered PDU is a complete MAC-ehs SDU when more than one reordered SDU is present in the reordered PDU;

wherein the SI field having a value of "10" is used to indicate that the first reordered SDU of the reordered PDU is a complete MAC-ehs SDU and the last reordered SDU of the reordered PDU is the first segment of a MAC-ehs SDU when more than one reordered SDU is present in the reordered PDU; and

wherein the SI field having a value of "11" is used to indicate that the first reordered SDU of the reordered PDU is the last segment of a MAC-ehs SDU and the last reordered SDU of the reordered PDU is the first segment of a MAC-ehs SDU when more than one reordered SDU is present in the reordered PDU, and that a single reordered SDU is the middle segment of a MAC-ehs SDU when a single reordered SDU is present in the reordered PDU.