Different Orthogonal Code Sets with Members in Common

• US 20080285534A1
• Filed: 07/06/2005
• Published: 11/20/2008
• Est. Priority Date: 07/06/2004
• Status: Active Grant

• Current Assignee: Telefonaktiebolaget LM Ericsson
• Original Assignee: Telefonaktiebolaget LM Ericsson
• Inventors: Dent, Paul W.
• Granted Patent: US 8,004,959 B2
• Time in Patent Office: Days
• US Class Current: 370/342
• CPC Class Codes: H04J 13/0044 OVSF [orthogonal variable spreading factor]
• CPC Class Codes: H04J 13/0048 Walsh
• CPC Class Codes: H04J 13/105 by extending
• CPC Class Codes: H04J 13/12 Generation of orthogonal codes
• CPC Class Codes: H04J 13/18 Allocation of orthogonal codes

Abstract

A first orthogonal codeset, obtainable in various manners, is used in a first cell to provide orthogonal spreading codes for traffic signals originating within the first cell. A second orthogonal code set for use in a second cell is obtained that has at least a first code in common with the first orthogonal code set by selecting any code in the first codeset to be the first common code. The plural orthogonal codesets can be utilized in various ways and in various environments. For example, the plural orthogonal codesets can be used for operation of a user equipment unit in a code division multiple access (CDMA) network.

Claims

1. A user equipment unit for use in a code division multiple access (CDMA) network, comprising:

a transceiver for performing radio communications with a radio access network;

a memory for storing plural orthogonal codesets;

a code selector for selecting a code from one of the plural codesets for use in performing the radio communications with the radio access network;

wherein the plural orthogonal codesets have at least a first code in common with one another.

14. The apparatus of claim 1, wherein each codeset of the plural orthogonal codesets is configured to have at least the first code in common with one another by being generated by a process comprising:

(1) forming a set of simplex codesets, each simplex codeset of the set being configured using a different maximum length sequence;

(2) extending each simplex codeset of the set to obtain an extended orthogonal codeset;

(3) using at least some extended orthogonal codesets for inclusion as one of the plural orthogonal codesets; and

,

(4) including a Walsh Hadamard codeset as one of the plural orthogonal codesets.

15. The apparatus of claim 1, wherein each codeset of the plural orthogonal codesets is configured to have at least the first code in common with one another by being generated by a process comprising:

forming initial codesets by determining maximum length sequences of length L−

1, and using the sequences to form extended simplex codesets;

augmenting the initial codesets by including a Walsh-Hadamard codeset in the initial codesets;

determining a column permutation of L−

1 non-zero columns that, when applied repeatedly, form a closed cycle of distinct codesets for the initial codesets;

optionally including another initial codeset that does not use any of the codes in the closed cycles generated so far, and which is also closed-cycled by the same column permutation;

aligning cycles of the codesets if necessary to obtain a desirable correlation;

reordering codes for obtaining minimum correlation between adjacent codes.

2. The apparatus 1, wherein the code selector selects the code for use in performing the radio communications in accordance with a code selection indicator included in a channel assignment message received from the radio access network.

16. The apparatus of claim 2, wherein extending each simplex codeset of the set includes:

adding an all-zero codeword to each simplex codeset;

adding a zero column to each simplex codeset.

17. The apparatus of claim 2, further comprising using cross correlation values as a criteria for determining which of the extended orthogonal codesets to include as one of the plural orthogonal codesets.

3. The apparatus 1, wherein the code selector selects the code for use in performing the radio communications based on an identity of a cell in which the user equipment unit operates.

4. A radio access network comprising:

a user equipment unit for performing code division multiple access (CDMA) radio communications between the user equipment unit and the radio access network;

a radio access network node comprising;

a memory for storing plural orthogonal codesets, the plural orthogonal codesets having at least a first code in common with one another;

a code selector for selecting a specified code from the plural codesets for use by the user equipment unit in performing the radio communications between the user equipment unit and the radio access network;

means for transmitting the specified code or an indication of the specified code to the user equipment unit.

5. A code division multiple access (CDMA) communications network comprising:

a service area comprising cells that re-use same spectral resources;

at least one network node for selecting, from plural orthogonal codesets, a codeset for use in each cell, a codeset in one cell being different than a codeset in an adjacent cell apart from having at least one code in common.

6. The apparatus of claim 5, wherein the network is a terrestrial cellular network and wherein the at least one network node comprises a memory for storing the plural orthogonal codesets;

and wherein the network comprises at least one radio base station node for transmitting into a corresponding cell.

7. The apparatus of claim 5, wherein the network is a satellite communications network comprising a network node, and wherein the network comprises:

a memory for storing plural orthogonal codesets, the plural orthogonal codesets having at least a first code in common with one another;

a satellite antenna system for transmitting plural radio beams into respective plural cells in accordance with the codeset reuse pattern, the codesets employed in the reuse pattern belonging to the plural orthogonal codesets.

8. The apparatus of claim 7, wherein the first code in common is used as for a common pilot code for the plural radio beams.

9. The apparatus of claim 7, wherein radiation in the plural beams is phased so that constructive addition occurs at beam edges to produce a substantially uniform pilot signal illumination for the plural cells.

10. A radio access network node for a code division multiple access (CDMA) radio access network, the radio access network node comprising:

a memory for storing plural orthogonal codesets, the plural orthogonal codesets having at least a first code in common with one another;

an antenna system for transmitting into differing cell sectors using codes selected from the plural orthogonal codesets.

11. The apparatus of claim 10, wherein codes utilized within a sector are orthogonal and wherein two codes used in adjacent sectors are selected based on a correlation value.

12. The apparatus of claim 10, wherein the first code in common is used in plural sectors as a pilot code.

13. The apparatus of claim 10, wherein at least one code in common is used in plural sectors for a calling channel.

18. A method of generating plural orthogonal codesets, the method comprising:

(1) forming a set of simplex codesets, each simplex codeset of the set being configured using a different maximum length sequence;

(2) extending each simplex codeset of the set to obtain an extended orthogonal codeset;

(3) using at least some extended orthogonal codesets for inclusion as one of the plural orthogonal codesets; and

,

(4) including a Walsh Hadamard codeset as one of the plural orthogonal codesets.

19. The method of claim 18, wherein extending each simplex codeset of the set comprises:

adding an all-zero codeword to each simplex codeset;

adding a zero column to each simplex codeset.

20. The method of claim 18, further comprising using cross correlation values as a criteria for determining which of the extended orthogonal codesets to include as one of the plural orthogonal codesets.

21. A method of generating codesets, the method comprising:

forming initial codesets by determining maximum length sequences of length L−

1, and using the sequences to form extended simplex codesets;

augmenting the initial codesets by including a Walsh-Hadamard codeset in the initial codesets;

determining a column permutation of L−

1 non-zero columns that, when applied repeatedly, form a closed cycle of distinct codesets for the initial codesets;

optionally including another initial codeset that does not use any of the codes in the closed cycles generated so far, and which is also closed-cycled by the same column permutation;

aligning cycles of the codesets if necessary to obtain a desirable correlation;

reordering codes for obtaining minimum correlation between adjacent codes.

22. A method of operating a radio access network comprising:

selecting, at a node of the radio access network, a specified code from plural codesets for use in performing the radio communications between the radio access network and a user equipment unit, the plural orthogonal codesets having at least a first code in common with one another;

transmitting to the user equipment unit the specified code or an indication of the specified code.

30. The method of claim 22, wherein each codeset of the plural orthogonal codesets is configured to have at least the first code in common with one another by being generated by a process comprising:

(1) forming a set of simplex codesets, each simplex codeset of the set being configured using a different maximum length sequence;

(2) extending each simplex codeset of the set to obtain an extended orthogonal codeset;

(3) using at least some extended orthogonal codesets for inclusion as one of the plural orthogonal codesets; and

,

(4) including a Walsh Hadamard codeset as one of the plural orthogonal codesets.

31. The method of claim 22, wherein each codeset of the plural orthogonal codesets is configured to have at least the first code in common with one another by being generated by a process comprising:

forming initial codesets by determining maximum length sequences of length L−

1, and using the sequences to form extended simplex codesets;

augmenting the initial codesets by including a Walsh-Hadamard codeset in the initial codesets;

determining a column permutation of L−

1 non-zero columns that, when applied repeatedly, form a closed cycle of distinct codesets for the initial codesets;

optionally including another initial codeset that does not use any of the codes in the closed cycles generated so far, and which is also closed-cycled by the same column permutation;

aligning cycles of the codesets if necessary to obtain a desirable correlation;

reordering codes for obtaining minimum correlation between adjacent codes.

32. The method of claim 30, wherein extending each simplex codeset of the set includes:

adding an all-zero codeword to each simplex codeset;

adding a zero column to each simplex codeset.

33. The method of claim 30, further comprising using cross correlation values as a criteria for determining which of the extended orthogonal codesets to include as one of the plural orthogonal codesets.

23. A method of operating a code division multiple access (CDMA) communications network comprising:

dividing a service area into cells that re-use same spectral resources;

selecting, from plural orthogonal codesets, a codeset for use in each cell, a codeset in one cell being different than a codeset in an adjacent cell apart from having at least one code in common.

24. The method of claim 23, wherein the network is a satellite communications network, and wherein the method further comprises:

transmitting plural radio beams into respective plural cells in accordance with a codeset reuse pattern, the codesets employed in the reuse pattern belonging to the plural orthogonal codesets

using the first code in common as for a common pilot code for the plural radio beams.

25. The method of claim 24, further comprising phasing radiation in the plural beams so that constructive addition occurs at beam edges to produce a substantially uniform pilot signal illumination for the plural cells.

26. A method of operating a radio access network node for a code division multiple access (CDMA) radio access network, the method comprising:

storing plural orthogonal codesets in a memory of a network node, the plural orthogonal codesets having at least a first code in common with one another;

transmitting into differing cell sectors using codes selected from the plural orthogonal codesets.

27. The method of claim 26, further comprising using orthogonal codes within a sector and wherein two codes used in adjacent sectors are selected based on a correlation value.

28. The method of claim 26, further comprising using the first code in common in plural sectors as a pilot code.

29. The method of claim 26, further comprising using the least one code in common in plural sectors for a calling channel.