Allocation of Block Spreading Sequences

• US 20080298488A1
• Filed: 05/29/2008
• Published: 12/04/2008
• Est. Priority Date: 06/04/2007
• Status: Active Grant

• Current Assignee: Texas Instruments, Inc.
• Original Assignee: Texas Instruments, Inc.
• Inventors: Shen, Zukang, Bertrand, Pierre, Muharemovic, Tarik
• Granted Patent: US 8,059,735 B2
• Time in Patent Office: Days
• US Class Current: 375/260
• CPC Class Codes: H04W 72/20 Control channels or signalling for resource management

Abstract

A transmission of information from a secondary to a primary node occurs in a plurality of N logical time durations. The transmission from the secondary to primary node in a wireless network is obtained using a first and a second sequence. Embodiments of the present invention mitigate interference by restricting the choice of the first sequence. Thus, in an embodiment of the invention, the first sequence is selected from a set of M sequences wherein M is strictly less than N. In order to accommodate high—velocity users, the restricted set contains a pair of sequences whose element—wise product is mirror symmetric. A transmission component for K-th logical time duration is obtained from the entire second sequence and K-th element of the first sequence.

Claims

1. A method for operating a wireless communication system, comprising:

sending an indication of a first sequence from a primary node to at least one secondary node, wherein the first sequence is of length N, and wherein the first sequence is selected from a restricted set comprising of M sequences of length N each, wherein M<

N;

sending an indication of a second sequence from the primary node to the secondary node, wherein the secondary sequence comprises at least two samples; and

receiving a transmission signal produced by the secondary node, wherein transmission signal comprises a plurality of logical time durations, wherein a K-th logical time duration of the transmission signal is generated by operating on the entire second sequence with the K-th element of the first sequence.

2. The method of claim 1 wherein an element-wise product of at least one pair of sequences from the restricted set results in a mirror-symmetric sequence.

3. The method of claim 1, wherein each logical time duration constitutes an OFDM symbol.

4. The method of claim 1, wherein sending an indication of a first sequence comprises:

transmitting from the first node to a secondary node using a channel element with index L; and

deriving the first sequence at the secondary node using L.

5. The method of claim 4, wherein the channel element with index I carries control information.

6. The method of claim 1 wherein N logical time durations are not all consecutive.

7. The method of claim 1 wherein the restricted set is fixed.

8. The method of claim 2, wherein the restricted set comprises M orthogonal sequences.

9. The method of claim 8 wherein the restricted set consists of three sequences:

[1 1 1 1], [1 −

1 1 −

1], and [1 −

1 −

1 1].

10. The method of claim 8 wherein the restricted set consists of two sequences:

[1 1 1 1], and [1 −

1 −

1 1].

11. The method of claim 1, wherein the transmission signal of the secondary node comprises a 0.5 ms slot, wherein a first half of logical time durations are present at the beginning of the slot, wherein a second half of logical time durations are present at the end of the slot, and wherein reference signals are present in the middle of the slot.

12. The method of claim 11, wherein the restricted set consists of three sequences:

[1 1 1 1], [1 −

1 1 −

1], and [1 −

1 −

1 1].

13. The method of claim 11, wherein the restricted set consists of two sequences [1 1 1 1], and [1 −

1 −

1 1].

14. The method of claim 12, wherein the element of uplink control information (UCI) is used to produce the transmission signal at the secondary node.

15. The method of claim 14, wherein the element of UCI is selected from the set consisting of:

ACKNAK information, scheduling request indicator (SRI), and rank indicator (RI).

16. The method of claim 13, wherein the element of uplink control information (UCI) is used to produce the transmission signal at the secondary node.

17. The method of claim 16, wherein the element of UCI is selected from the set consisting of:

ACKNAK information, scheduling request indicator (SRI), and rank indicator (RI).

18. The method of claim 1, further comprising evaluating inter-sequence interference in the restricted set;

evaluating velocity for each secondary node;

ranking the sequences in the restricted set according to the evaluated interference;

ranking the secondary nodes according to evaluated velocities; and

assigning the first sequence with lowest interference to the secondary node with highest velocity.

19. The method of claim 18, further comprising:

evaluating interference I_j of a first sequence C_j=[c_j,1, c_j,2, . . . , c_j,N] in the restricted set according to

$I_j=\underset{1\le <br><br>i\le <br><br>M,i\ne <br><br>j}{\max }<br><br><br><br>\underset{n=1}{\overset{N}{\sum <br><br>}}<br><br>c_{i,n}^{*}<br><br>c_{j,n}<br><br>w_n<br><br>,$

wherein w_n is a weighting vector of length N.

20. A base—

station for use in a cellular network, comprising;

means for sending an indication of a first sequence to at least one user equipment (UE), wherein the first sequence is of length N, and where the first sequence is selected from a restricted set comprising of M sequences of length N each, wherein M<

N; and

means for sending an indication of a second sequence to the UE, wherein the secondary sequence comprises at least two samples.

21. A method for transmission in a wireless communication system, comprising:

receiving an indication of a first sequence from a primary node at a user equipment (UE), wherein the first sequence is of length N, and wherein the first sequence is selected from a restricted set comprising M sequences of length N each, wherein M<

N;

producing a second sequence at the UE; and

forming a transmission signal by the UE, wherein the transmission signal comprises a plurality of logical time durations, wherein a K-th logical time duration of the transmission signal is generated by operating on the entire second sequence with the K-th element of the first sequence.

22. A UE apparatus for use in a cellular network, comprising:

means for producing a first sequence;

wherein the first sequence is selected from a restricted set comprising of M sequences of length N each, wherein M<

N;

means for producing a second sequence; and

means for using the entire second sequence and the K-th element of the first sequence to generate a transmission signal for the K-th logical time duration.

23. The apparatus of claim 22, wherein means for producing the first sequence comprises an apparatus for receiving a transmission on a channel element with index L, and wherein L indicates the first sequence.

24. The apparatus of claim 23 for use in an OFDMA network, further comprising an apparatus for multi-carrier modulation.

25. The apparatus of claim 22 further comprising:

an apparatus for generating an element of UCI; and

means for generating a transmission signal for K-th logical time duration using the element of UCI.