AU2007231897B2 - Generation of user equipment identification specific scrambling code for the high speed shared control channel - Google Patents

Description

Pool Section 29 Regulation 3.2(2) AUSTRALIA Patents Act 1990 COMPLETE SPECIFICATION STANDARD PATENT Application Number: Lodged: Invention Title: Generation of user equipment identification specific scrambling code for the high speed shared control channel The following statement is a full description of this invention, including the best method of performing it known to me / us: 1 GENERATION OF USER EQUIPMENT IDENTIFICATION SPECIFIC SCRAMBLING CODE FOR THE HIGH SPEED SHARED CONTROL CHANNEL BACKGROUND The present invention relates to wireless communication systems. More 5 particularly, the present invention relates to user equipment identification specific scrambling sequences for high speed shared control channels (HS-SCCH). A high speed downlink packet access (HSDPA) is proposed for wideband code division multiple access communication systems. HSDPA allows for high downlink data rates to support multimedia services. 10 To support HSDPA, high speed shared control channels (HS-SCCHs) are used. The HS-SCCHs are used to signal vital control information to the user equipments (UEs). Each HS-SCCH has two parts, referred to as Part-1 and Part 2. Part-1 carries time critical information needed by the UE. This information includes the channelization code set and the modulation type used by the high 15 speed physical downlink shared control channel (HS-PDSCH) which carries the HSDPA payload. This information is vital to support HSDPA, since HSDPA uses adaptive modulation and coding (AMC). To obtain its Part-1 information, each HSDPA UE monitors up to four HS SCCHs for its information. The information for a particular UE is distinguished 20 from other UEs by its UE identification (UE ID) specific scrambling sequence. The UE processes each monitored HS-SCCH with its UE ID specific scrambling sequence to detect the HS-SCCH intended for the UE. After processing, the UE determines on which HS-SCCH, if any, information was carried using its scrambling sequence. The UE descrambles the data carried on Part-1 of its HS 25 SCCH using its scrambling sequence. Until recently, a 10 bit UE ID was used as the basis for the UE ID specific scrambling sequence. In this case, this UE ID was converted into a 40 bit scrambling sequence. To turn the 10 bit UE ID into the 40 bit UE ID specific scrambling sequence, the 10 bit UE ID is processed by a Reed-Muller block to 30 produce a 32 bit code. The first 8 bits of the produced code are repeated and appended onto the back of the 32 bit code to produce a 40 bit code. Although it is proposed to extend the UE ID length to 16 chips, the current proposal for the HS-SCCHs uses a 10 bit UE ID. This UE ID is converted into a 2 40 bit scrambling sequence. To turn the 10 bit UE ID into the 40 bit scrambling sequence, the 10 bit UE ID is processed by a Reed-Muller block to produce a 32 bit code. The first 8 bits of the produced code are repeated and appended onto the back of the 32 bit code to produce a 40 bit code. 5 To reduce the occurrence of false detections, it is desirable to have good separation between the produced scrambling codes for each UF ID. Accordingly, it is desirable to have alternate approaches to producing scrambling codes. SUMMARY OF THE INVENTION A code is produced for use in scrambling or descrambling data associated 10 with a high speed shared control channel (HS-SSCH) for a particular user equipment. A user identification of the particular user equipment includes L bits. A rate convolutional encoder processes at least the bits of the user identification by a rate convolutional code to produce the code. According to a first aspect, the present invention provides a wideband 15 code division multiple access, W-CDMA, base station comprising: means for transmitting a high-speed-shared control channel, HS-SCCH, including a user equipment, UE, identification, ID, specific scrambling sequence for a W-CDMA UE, control information carried using the UE ID specific scrambling sequence, the control information including channelization code set and modulation type 20 information used for high speed downlink packet access, HSDPA, the W-CDMA base station being characterized by encoding means adapted to produce the UE ID specific scrambling sequence from a result of 1/2 rate convolutional encoding at least an L-bit UE ID; the 1/2 rate convolutional encoding being utilized for forward error correction in addition to its use for the UE ID specific scrambling 25 sequence. This embodiment may also be incorporated into a wideband code division multiple access W-CDMA, communication system, wherein the W-CDMA UE is adapted to distinguish the control information of the HSSCCH from the other UEs by the UE ID specific scrambling sequence. 30 3 BRIEF DESCRIPTION OF THE DRAWINGS Figure 1A is a preferred diagram of a circuit for producing a code associated with a particular user for a HS-SCCH. Figure 1B is a diagram of a rate matching block used in conjunction with 5 Figure 1A. Figure 2A is a preferred diagram of a circuit for producing a code associated with a user identification of 16 bits. Figure 20 is a diagram of a rate matching block used in conjunction with Figure 2A. 10 Figure 3 is a simplified user equipment using the UE ID specific scrambling code. Figure 4 is a simplified base station using the UF ID specific scrambling code DESCRIPTION OF PREFERRED EMBODIMENT 15 Although the preferred embodiments are described in conjunction with the preferred application of the invention for use with the HSDPA of the third generation partnership project (3GPP) wideband code division multiple access (W-CDMA) communication system, the invention can be applied to other code division multiple access communication systems. Figures 1A and 1B are 20 diagrams of a preferred UE ID specific scrambling sequence circuit. A UE ID, XUE, of length L is input into the circuit. L can be any length, such as 8 bits, 10 bits, 16 bits, etc. The UE ID, XUE = {XUE1, ---, XUEL}, is input into a 1/2 rate convolutional encoder 10 as shown in Figure 1A. Along with the UE ID, extra bits, such as zeros, may be added to the end of the input string to extend the 25 length of the input string and, accordingly, the output string. The use of a 1/2 rate 4 convolutional encoder 10 provides for a high level of code separation between the output strings produced by different UE IDs. Additionally, current proposed 3GPP W-CDMA communication systems utilize a 2 rate convolutional encoder 10 for a forward error correction (FEC) technique. Accordingly, no additional hardware is 5 required to generate the convolutionally encoded UE ID specific scrambling sequence. After encoding, based on the length of the output string, a rate matching stage 12 may be added to puncture bits to obtain a desired string length. Figures 2A and 2B are diagrams of preferred UE ID specific scrambling 10 sequence circuit for a preferred UE ID codes of length 16, L=16. The 16 bit UE ID, XUE = {XUE1, ... , XUE16}, is input into a 1/2 rate convolutional encoder 14 along with eight zero bits appended onto the end of the input string. As a result, the input string is XUE1, ... ; XUE16; 0, 0, 0, 0, 0, 0, 0, 0. After being processed by the 2 rate convolutional encoder 14, the output code is 48 bits in length, CUE 15 {CUE1, -.. , CUE48}. To reduce the length of the code to a preferred length of 40 bits, eight bits are preferably punctured. Figure 2B illustrates the rate matching stage 16 to perform the puncturing. After the rate matching stage 16, the effective length of the scrambling code is 40 bits. 20 Figure 4 is a simplified diagram of a user equipment descrambling a HS-SCCH using the UE ID specific scrambling code. The UE ID scrambling code is mixed, such as by exclusive-or gate 18, with the received HS-SCCH for use in recovering the encoded HS-SCCH data. Figure 3 is a simplified diagram of a base station scrambling encoded data 25 with the UE ID specific scrambling code for transfer over the HS-SCCH. The encoded data is mixed with the UE ID scrambling code, such as by an exclusive or gate 20, for a particular user. The scrambled data is used to produce the HS SCCH for transfer to the particular user.

Claims (19)

1. A wideband code division multiple access, W-CDMA, base station including: means for transmitting a high-speed-shared control channel, HS-SCCH, 5 including a user equipment, UE, identification, ID, specific scrambling sequence for a W-CDMA UE, control information carried using the UE ID specific scrambling sequence, the control information including channelization code set and modulation type information used for high speed downlink packet access, HSDPA, the W-CDMA base station being characterized by encoding means 10 adapted to produce the UE ID specific scrambling sequence from a result of 112 rate convolutional encoding at least an L-bit UE ID; the 1/2 rate convolutional encoding being utilized for forward error correction in addition to its use for the UE ID specific scrambling sequence.

2. The W-CDMA base station of claim 1 wherein the L-bit UL ID is a sixteen 15 bit UE ID.

3. The W-CDMA base station of claim 1 or claim 2 wherein the 1/2 rate convolutional encoding encodes that L-bit UE ID followed by eight zero bits.

4. The W-CDMA base station of any one of claims 1 to 3 wherein the UE ID specific scrambling sequence is the result of 112 rate convolutional encoding at 20 least the L-bit UE ID followed by rate matching to puncture bits of an output of the 1/2 rate convolutional encoding of the at least L-bit UE ID.

5. The W-CDMA base station of claim 4 including a rate matching means for puncturing the bits of the 1/2 rate convolutional encoding output.

6. The W-CDMA base station of claim 4 or 5 wherein the rate matching 25 punctures eight bits. 6

7. The W-CDMA base station of any one of claims 1 to 6 wherein the control information carried by the UE ID specific scrambling sequence is in Part-I of the HS-SCCH and the HS-SCCH has the Part-I and a Part-2.

8. A wideband code division multiple access, W-CDMA, communication 5 system including a W-CDMA base station according to claim 1, wherein the W CDMA UE is adapted to distinguish the control information of the HSSCCH from other UEs by the UE ID specific scrambling sequence.

9. The W-CDMA system of claim 8 wherein the L-bit UE ID is a sixteen bit UE ID.

10 10. The W-CDMA system of claim 8 or claim 9 wherein the 1/2 rate convolutional encoding encodes that L-bit UE ID followed by eight zero bits.

11. The W-CDMA system of any one of claims 8 to 10 wherein the UE ID specific scrambling sequence is the result of 112 rate convolutional encoding at least the L-bit UE iD followed by rate matching to puncture bits of an output of the 15 1/2 rate convolutional encoding of the at least L-bit UE ID.

12. The W-CDMA system of claim 11 including a rate matching means for puncturing the bits of the 1/2 rate convolutional encoding output.

13. The W-CDMA system of claim 11 or claim 12 wherein the rate matching punctures eight bits. 20

14. The W-CDMA system of any one of claims 8 to 13 wherein the control information carried by the UE ID specific scrambling sequence is in Part-I of the HS-SCCH and the HS-SCCH has the Part-I and a Part-2.

15. The W-CDMA system of any one of claims 8 to 14 wherein the WCDMA UE being adapted to distinguish the control information of the HS-SCCH by 25 processing the HS-SCCH using the UE ID specific scrambling sequence 7

16. The W-CDMA system of claim 15 wherein processing the HS-SCCH includes descrambling.

17. The W-CDMA system of claim 15 or claim 16 wherein the W-CDMA UE being adapted to monitor a plurality of HS-SCCHs. 5

18. The W-CDMA system of any one of claims 15 to 17 wherein the WCDMA UE is adapted to produce the UE ID specific scrambling sequence from a result of 1/2 rate convolutional encoding at least the L-bit UE ID.

19. The W-CDMA base station of claim 1 and substantially as hereinbefore described with reference to the accompanying figures. 10 INTERDIGITAL TECHNOLOGY CORPORATION WATERMARK PATENT & TRADE MARK ATTORNEYS P24811AUO2