HK1131291A - Radio resource control-service date unit reception - Google Patents

Description

Radio resource control service data unit reception

The application is a divisional application of the chinese patent application No. 200610156218.1, which is a divisional application of the chinese patent application No. 02818138.7 entitled "radio resource control service data unit reception" filed on 9, 13/2002.

Technical Field

The present invention relates to a method for processing a received communication.

Background

The Universal Mobile Telecommunications System (UMTS) network architecture of fig. 1 includes a Core Network (CN)2, a UMTS Terrestrial Radio Access Network (UTRAN)3, and at least one User Equipment (UE)18 (only one UE 18 is shown for simplicity). There are two common interfaces, the Iu interface between the UTRAN and the core network, and the radio interface Uu between the UTRAN and the UE.

The UTRAN consists of several Radio Network Subsystems (RNS)10, 11. The two can be connected with each other by Iur interface. Each RNS 10, 11 may be divided into Radio Network Controllers (RNCs) 12, 13 and several base stations (node bs) 14-17. Node bs 14-17 would be connected to RNCs 12, 13 over an Iub interface. One node B14-17 can serve one or several cells.

The UTRAN3 may support FDD mode and TDD mode in the radio interface. For both modes, the same network architecture and the same protocol are used.

Communication between the node bs 14-17 and the UE 18 over the radio interface Uu is performed using a radio interface protocol. Fig. 2 shows a radio interface protocol stack architecture. Those skilled in the art will appreciate that the design of the radio interface protocol stack 20 can be divided into three layers: a physical layer (L1)21, a data link layer (L2)22, and a network layer (L3) 23. L2 can be split into four sublayers: medium Access Control (MAC)24, Radio Link Control (RLC)25, broadcast/multicast control (BMC)27, and Packet Data Convergence Protocol (PDCP) 26.

L323 includes Radio Resource Control (RRC) 28. RRC is responsible for L3 control plane signaling between UTRAN3 and UE 18. It is also responsible for the configuration and control of all other protocol layers in the UTRAN3 and can be used to control the available radio resources. Which includes allocation, reconfiguration and release of radio resources, and continuous control of the required quality of service.

The Radio Link Control (RLC) layer 25 may provide transparent, unacknowledged or acknowledged mode data transmission to upper layers. The approved mode of transmission uses a sliding window protocol with selective rejection of automatic repeat request.

The MAC layer 24 maps the logical channels of the RLC 25 into transport channels provided by the physical layer. The RRC 28 informs the MAC layer 24 about resource allocation, which is mainly composed of a multitasking function. The MAC layer 24 is also responsible for handling priorities between different data streams, which are mapped to the same physical layer. The function and operation of the BMC 27 and the PDCP 26 are well known to those skilled in the art and will not be explained in detail herein.

The physical layer 21 is responsible for the transmission of the transfer blocks in the air interface. Which includes forward error correction, multitasking of the same physical resources in different delivery channels, rate matching (i.e., matching the amount of user data to the available physical resources), modulation, spreading, and radio frequency RF processing. The physical layer 21 also performs error detection and informs the higher layers 22, 23.

Shown in fig. 3 is the data flow through L222. Protocol Data Units (PDUs) of higher layers are transferred to the RLC layer 25. Service Data Units (SDUs) may be segmented and concatenated in the RLC layer 25. Together with the RLC header, an RLC PDU is established. No error detection code is added in the RLC layer 25. For RLC in transparent mode, the RLC layer 25 is not segmented and no RLC header or MAC header is added to the higher layer PDU.

Only one header is added in the MAC layer 24. The header contains the transport information describing the mapping of logical channels and transport channels. UE identification information can also be included in the shared channel.

CRC is added to L121 (physical layer) for error detection purposes. The CRC check result in the receiver is transferred to the RLC layer 25 for retransmission control.

In current UMTS TDD or FDD systems, radio resource control service data units (RRC-SDUs) may be transferred between UTRAN-RRC and UE-RRC in an RLC transparent, unacknowledged, or acknowledged mode. Approved modes will not be discussed later. However, when the RRC-SDU is delivered in a transparent or unacknowledged mode, the RLC and MAC layers at the receiving end cannot know the RRC-SDU. Therefore, any errors in the received RRC-SDU caused during transmission or other resources must be performed in the RRC layer, not in the lower layers.

The RRC-SDU may be transmitted in several individual segments called Transport Blocks (TBs). One example of an RRC-SDU is a broadcast control channel system information block (BCCH-SIB).

In the case of BCCH-SIB, the TBs associated with this SIB are repeatedly retransmitted in the broadcast control function physical (UE-BCFE) from UTRAN-RRC to UE. The SDU version indication message can be regarded as a 'value tag'. When the value tag is not changed, UE 18 can assume that UTRAN is repeatedly transmitting the same BCCH-SIBs. If there is a change in the BCCH-SIB transmitted by UTRAN3, UTRAN3 informs UE 18 that the change has occurred using the value tag. Before the UTRAN3 transmits, the UE 18 must first know the scheduling information (when the TBs of the BCCH-SIB should arrive at the UE 18) and the version of the BCCH-SIB.

Shown in fig. 4 is UE 18 receiving L1 SDUs. The TBs included in the SDU carry BCCH-SIBs and CRCs for L1 of UE 18 to perform transmission error detection. As shown, the TB may also include a System Frame Number (SFN), which for the TB of the BCCH-SIB indicates the time when the TB should arrive at the UE 18. Alternatively, for TBs that do not explicitly contain SFNs, the arriving SFN can be derived from the physical layer timing as L1. The L1 of UE 18 passes the TB, SFN, and CRC results to higher layers. However, since both the RLC and MAC layers 25, 24 operate in a transparent mode for Broadcast Channel (BCH) data, the TB is also passed to the RRC layer.

Since the TB is often transmitted between the UE 18 and the UTRAN3 in an environment where the signal is unstable, the transmission of the TB is related to the set successful transmission/reception probability, for example, ninety-nine percent (99%). If the BCCH-SIB is composed of a very large number of TBs, the probability that all TBs of the BCCH-SIB can be correctly received is approximately 0.99 to the power of the number of TBs. For example, a broadcast control channel (BCCH-SIB) may require more than ten TBs to be transmitted, and the probability of the UE 18 successfully receiving the BCCH-SIB is 10 power of 0.99, less than ninety percent (90%). Therefore, the probability of successfully receiving the BCCH-SIB decreases as the number of TBs increases.

In UMTS TDD or FDD systems, the time to successfully receive the SIB determines the performance of many system functions. In addition, to maintain proper performance of these system functions, it may be necessary to increase the repetition rate of the SIB to compensate for the failed transmissions, but this reduces resource efficiency and usability.

Fig. 5 and 6 are a schematic diagram and a flowchart, respectively, illustrating a current method for successfully receiving an RRC SDU transmitted by the UTRAN3 to the UE 18. As shown, the UE-BCFE receives an RRC-SDU (step 60), which for purposes of this example comprises 9 TBs, numbered SFN-2 to SFN-18, with a repetition rate of 64 frames. The UE-BCFE reads the RRC-SDU and determines whether the TB in the RRC-SDU is faulty or missing (step 61). For the purposes of this example, assume that SFN 10 is in error. Because an error occurs in the received RRC-SDU, the UE-BCFE discards the entire RRC-SDU and waits for a period of repetition rate (i.e., 64 frames) before receiving another RRC-SDU carrying the same informationRRC-SDU (step 62). The UE-BCFE will re-receiveIt contains 9 TBs, numbered from SFN-66 to SFN-82 (step 63), and determines whether an error exists (step 61). In this example, SFN 70(SFN 6+64 (repetition rate)) is in error or missing. If no error is found in the received RRC-SDU, the UE-BCFE can successfully receive the RRC-SDU and decode it (step 64). Otherwise, as in the case of this example, the UE-BCFE discards the entire already received RRC-SDU (step 62), which contains 9 TBs, and waits for a repetition rate time before receiving the next RRC-SDU (step 63). This process continues until the UE-BCFE receives nine (9) correct consecutive TBs.

There are two problems associated with this type of method for receiving RRC-SDUs from UTRAN. The first problem is the proper/correct reception latency, which can cause the performance of the system functions requiring system information to slip and/or increase the number of receptions, thereby reducing the efficiency of radio resources. The second problem is that if the UE L1 has to repeatedly receive, decode and process all TBs in an RRC-SDU each time an error occurs, it increases processing cost and battery overhead.

Therefore, there is a need for an improved UMTS TDD or FDD system.

Disclosure of Invention

A method for processing a received communication including a periodic transmission of a set of information segments includes receiving a first transmission of the set of information segments and processing to confirm that each segment is legitimate or illegitimate. Then, the legal segments in the first set are stored. If not all segments of the set are valid and stored, subsequent transmissions of the set of information segments are transmitted, and only segments previously stored that were not validated are received and processed to determine whether each of the transmitted segments is valid or invalid. The valid segments are then stored. The method continues to receive subsequent transmissions until all segments of the set have been validated and stored.

Drawings

Fig. 1 shows a block diagram of a Universal Mobile Telecommunications System (UMTS).

Fig. 2 is a schematic diagram of a radio interface protocol stack architecture.

Figure 3 shows a schematic of the data flow through layer 2.

Fig. 4 is a diagram illustrating a UE receiving a layer 1 SDU.

Fig. 5 is a diagram illustrating a method for receiving RRC-SDU at present.

Fig. 6 is a flow chart illustrating a method for receiving RRC-SDU at present.

Fig. 7 is a diagram illustrating a method for receiving RRC-SDU according to the preferred embodiment of the present invention.

Fig. 8 is a flowchart illustrating a method for receiving RRC-SDU according to the preferred embodiment of the present invention.

Detailed Description

Preferred embodiments of the present invention will now be described with reference to the drawings, wherein like reference numerals represent like elements throughout.

Referring again to fig. 4, the UE-L1 passes the received TB group, SFN, and CRC error detection result of each TB to higher layers (L2 and L3). Since both the MAC and RLC layers 24, 25 operate in the transparent mode of the BCCH, the BCCH TB is forwarded to L3 without processing. It is also possible that either L2 or L3 would discard TBs with CRC errors before forwarding to L3.

Fig. 7 and 8 show a schematic diagram and a flowchart, respectively, of a method used in a preferred embodiment of the present invention. In the example shown in fig. 7, the RRC-SDU is composed of nine (9) TBs and has a repetition period of 64 frames. The UE-BCFE is informed in advance that the RRC-SDU will be expected to have SFN 2 to SFN 18. The UE-BCFE receives a TB group corresponding to the RRC-SDU from one of the node bs 14-17 (step 80) and determines whether one or more TBs are missing or an error has occurred (step 81).

According to the preferred embodiment of the present invention, there are at least two ways for the UE-BCFE to make the determination. In the first way, the UE L1 uses CRC error detection to detect whether there is transmission error, and then notifies the UE-BCFE of the SFN of the erroneous TB. In the second way, the UE-BCFE determines the not-successfully received TB by using the scheduling information and the SFN of the TB that has been correctly received. Although only two methods are disclosed herein to determine if a TB is erroneous or missing, other methods may be employed that are within the scope of the present invention.

After the UE-BCFE determines that the TB is correct, the UE-BCFE stores the correct TB (step 82) and discards the missing or erroneous TB (step 83). It should be noted that step 83 may be accomplished by either L1 or L2 in the same manner before the UE-BCFE processing is performed. The RRC 28 then calculates the next SFN for the TB with error or missing for the next RRC-SDU transmission (step 84). Using the example shown in fig. 7, the UE-BCFE may add the wrong TB (SFN 10) to the repetition rate of 64 to determine the next occurrence time of the SFN (74 in this example). There may also be several TBs in error, in which case the SFN of each invalid TB in the following RRC-SDU transmission must be calculated. After the UE-BCFE has determined the corresponding SFN for each inactive TB for subsequent transmissions, RRC 28 informs L1 to receive and decode only the determined SFN. In this example, only the TBs corresponding to SFN 74 have to be re-received are acknowledged. After L1 receives the TBs for the next group of SFNs calculated, L1 simply forwards the TBs, SFN, and CRC to RRC 28 for the particular SFN requested by RRC 28 (step 85). If no errors are detected in the retransmission and the received TB set and no further TBs are missing from the RRC-SDU, the UE-BCFE stores the correct TBs in its place along with other correct TBs (step 82) and decodes the RRC-SDU (step 86). If there are TBs with CRC errors remaining in the received RRC-SDU, the RRC 28 determines SFNs and repeats the above process (step 84). This process continues until the UE-BCFE has stored the entire TB associated with the RRC-SDU and has undergone processing by the RRC 28 (step 86).

The invention can be applied to all segmented RRC-SDUs transmitted periodically. The process is initiated when an updated value tag is detected. If the UE-BCFE is receiving and updating the value tag, the UE-BCFE deletes all TBs of the previous group.

One of the advantages of the present invention is that the successful RRC-SDU reception time (or latency) can be significantly reduced to a latency associated with a target error rate for transmitting individual TBs between the UE 18 and the UTRAN3, independent of the size of the RRC-SDU. Reducing the reception latency improves the performance of UE functions related to acquiring system information, such as faster cell search, lower handover transmission interruption period, faster establishment of RAN connections, and transitions between UE states.

Furthermore, because the present invention allows more UEs 18 to efficiently receive system information, the scheduling rate (i.e., the period of retransmissions) can be reduced. This improves efficiency and increases the usability of the limited BCCH physical resources.

Another advantage of the present invention is that UE processing time and battery overhead are reduced. With the ability to detect reception errors for individual TBs and ack for TB scheduling information, the UE 18 is able to receive only the particular invalid TB without having to receive the entire RRC-SDU. In addition, since only a small number of transmissions are required to achieve successful RRC-SDU reception, UE battery consumption and processing time can be further reduced.

The application of the invention can enable the UE-BCFE to receive RRC-SDU (for example BCCH-SIB in BCH) more quickly and reduce the processing time/battery consumption of the UE.

While the invention has been described in terms of preferred embodiments, other variations which are within the scope of the invention as described in the claims will be apparent to those skilled in the art.

Claims (14)

1. A method for receiving a segment communication, comprising the steps of:

periodically receiving an entire sector communication;

examining each segment of the segment communication to determine if the segment is legitimate;

if the section is legal, storing the legal section;

if the segment is illegal, then

Identifying the illegal segment;

receiving the entire retransmission segment communication;

checking only segments of the retransmission segment communication that have been identified as illegal; and

the entire segment communication is repeatedly received until all segments are legitimately received.

2. The method of claim 1, wherein the checking comprises:

detecting an error in a sector using an error code contained in each sector; and

a sector number of each sector in which an error is detected is determined.

3. The method of claim 1, wherein the entire sector communication is received after a preset repetition rate.

4. The method of claim 1, wherein each segment includes a value tag.

5. The method of claim 4, wherein each receipt of the entire sector communication has a same value tag.

6. The method of claim 4 wherein if a received retransmission of the entire block communication has a different value tag, discarding the stored valid block.

7. The method of claim 1, wherein the sector communication comprises a broadcast control channel system information block.

8. A user equipment to receive a periodically transmitted segment communication, comprising:

a receiver for receiving the segment communication;

a checking device for checking each segment of the segment communication to determine whether the segment is legal;

a memory for storing the valid segments; and

an identification device for identifying an illegal segment in the segment communication, so that the checking device only checks the segment identified as illegal during the subsequent reception of the entire segment communication.

9. The user equipment of claim 8, wherein the checking means is arranged to

Detecting a sector number in a sector by using an error code contained in each sector; and

a sector number of each sector in which an error is detected is determined.

10. The user equipment of claim 8, wherein each subsequent reception of the entire sector communication occurs after a preset repetition rate.

11. The user equipment of claim 8 wherein the section comprises a numerical tag.

12. The user equipment of claim 11 wherein each receipt of the segment communication has a same value tag.

13. The user equipment of claim 11 wherein the valid segment stored in the memory is discarded if a subsequently received retransmission of the entire segment communication has a different value tag.

14. The user equipment of claim 8, wherein the segment communication comprises a broadcast control channel system information block.