Generation of user equipment identification specific scrambling code for the high speed shared control channel

The present invention relates to a wireless communication system. More specifically, the present invention relates to an identifier of a user device that identifies a scrambled sequence for a high speed common control channel (HS-SCCH).

High Speed Downlink Packet Access (HSPDA) is provided for wideband code division multiple access communication systems. HSPDA guarantees high downlink data rates and supports multimedia services.

A high speed common control channel (HS-SCCH) is used to support HSPDA. Use HS-SCCH to send important common control information signals to the user equipment (UE). Each HS-SCCH has two parts, called Part 1 and Part 2. Part 1 carries the information needed by the UE due to time constraints. This information includes the channelization code and modulation type used by the High Speed Physical Downlink Common Control Channel (HS-PDSCH) carrying the HSPDA payload. This information is important to support HSPDA as it uses adaptive modulation and coding (AMC).

Part 1 To obtain information, each HSPDA UE monitors four HS-SCCH for that information. Information on a particular UE is distinguished from other UEs by a UE identifier (UEID) that identifies the scrambled sequence. The UE processes each HS-SCCH monitored using the UE ID that identifies the scramble sequence to detect the HS-SCCH used by the UE. After processing, the UE determines which HS-SCCH, if any, information carried using that scrambled sequence. The UE uses the scramble sequence to descramble the data carried in Part 1 of HS-SCCH.

Traditionally, 10-bit UE IDs have been used as the basis for UE IDs to identify scrambled sequences. In this case, this UE ID is converted to a 40-bit scrambled sequence. In order to change the 10-bit UE ID into a 40-bit UE ID that identifies the scrambled sequence, the 10-bit UE ID is processed by the Reed-Muller section to generate a 32-bit code. The first 8 bits of the generated code are repeated and added after the 32-bit code to generate a 40-bit code.

<p> Despite extending the UE ID length to 16 chips, the current HS-SCCH proposal uses a 10-bit UE ID. In order to convert a 10-bit UE ID into a 40-bit scrambled sequence, the 10-bit UE ID is processed by the Reed-Muller section to generate a 32-bit code. The first 8 bits of the generated code are repeated and added after the 32-bit code to generate a 40-bit code.</p><p> Good separation between the scrambled codes generated for each UE ID is desirable to reduce the occurrence of detection errors. Therefore, there is a need for an alternative method of generating scrambled code.</p>

<p> Generate code to scramble and descramble the data associated with the high-speed common control channel (HS-SCCH) for a particular user device. The user identifier of a specific user device includes an L bit. The 1/2 rate convolutional encoder processes at least the bits of the user identifier with the 1/2 rate convolutional code to generate the code.</p>

A preferred embodiment is disclosed as a preferred application of the present invention for use as a 3GPP (The third generation partnership project) wideband code division multiple access (W-CDMA) communication system. It can be applied to communication systems. Figures 1A and 1B are diagrams of suitable circuits for UE IDs that identify scrambled sequences. X, the UE ID of length L_UEIs input to the circuit. L can be any length, such as 8-bit, 10-bit, 16-bit, and so on. UE ID, X_UE= {X_UE1, ..., X_UEL} Is input to the 1/2 rate convolution encoder 10 shown in FIG. 1A. An additional bit such as 0 can be added to the end of the input bit string along with the UE ID to extend the length of the input bit string and the length of the output bit string accordingly. A 1/2 rate convolution encoder 10 is used to provide a high level of code separation between output bit strings produced by different UE IDs. In addition, current 3GPP W-CDMA communication systems utilize a 1/2 rate convolution encoder 10 for forward error correction (FEC) technology. Therefore, no hardware is required to generate a convolutionally encoded, scrambled sequence-identifying UE ID. After encoding, based on the output bit string, rate matching stage 12 can be applied to the vacant bits to obtain the desired bit string.

2A and 2B are suitable diagrams of a suitable UE ID circuit for identifying a scrambled sequence for a suitable UE ID code with L = 16 and length 16. 16-bit UE ID, X_UE= {X_UE1, ..., X_UE16} Is input to the 1/2 rate convolution encoder 14 together with the eight zero bits added to the end of the input bit string. As a result, the input bit string is X_UE1, ..., X_UE16, 0,0,0,0,0,0,0,0. After processing by the 1/2 rate convolution encoder 14, the output code is 48 bits long, C_UE{C_UE1, ..., C_UE48}.

To reduce the code length to a suitable length of 40 bits, preferably reduce 8 bits. FIG. 2B shows a speed arbitration stage 16 that performs bit deletion. After speed arbitration stage 16, the valid bits of the scrambled code are 40 bits.

FIG. 4 is a simplified diagram of descrambling the HS-SCCH of a user device that uses a UE ID that identifies the scramble code. The UE ID scramble code is mixed with the received HS-SCCH by the exclusive OR gate 20, etc., and used for decoding the encoded HS-SCCH data.

FIG. 3 is a simplified diagram of a base station that scrambles encoded data containing a UE ID that identifies the scramble code and transfers it via HS-SCCH. The encoded data is mixed with the UE ID scramble code for a specific user, such as by exclusive OR gate 18. Using scrambled data, HS-SCCH is generated and transferred to a specific user.

<figref num="1A">FIG. 5 is a preferred diagram of a circuit that generates code associated with a particular user for HS-SCCH.</figref><figref num="1B">It is a figure of the speed arbitration part used in connection with FIG. 1A.</figref><figref num="2A">FIG. 5 is a preferred diagram of a circuit that generates a code associated with a 16-bit user identifier.</figref><figref num="2B">It is the figure of the speed arbitration part used in connection with FIG. 2A.</figref><figref num="3">It is a figure which shows the simplified base station which uses the UE ID which identifies a scramble code.</figref><figref num="4">It is a figure which shows the simplified user equipment which uses the UE ID which identifies a scramble code.</figref>