SYSTEM AND METHOD FOR RANDOM ACCESS IN A WIRELESS COMMUNICATION SYSTEM

• US 20080049708A1
• Filed: 08/08/2007
• Published: 02/28/2008
• Est. Priority Date: 08/25/2006
• Status: Active Grant

• Current Assignee: Samsung Electronics Co. Ltd.
• Original Assignee: Samsung Electronics Co. Ltd.
• Inventors: Khan, Farooq, Lee, Juho
• Granted Patent: US 8,184,609 B2
• Time in Patent Office: Days
• US Class Current: 370/343
• CPC Class Codes: H04B 1/713 using frequency hopping
• CPC Class Codes: H04W 16/12 Fixed resource partitioning
• CPC Class Codes: H04W 74/0866 using a dedicated channel for access

Abstract

The present disclosure relates generally to systems and methods for random access in a wireless communication system. In one example, the method includes allocating first and second random access orthogonal frequency subbands to first and second subdivisions, respectively, in a wireless communication network. The first subband is assigned to a first position in a first subframe for use in the first subdivision during a first transmission slot, and the second subband is assigned to a second position in the first subframe for use in the second subdivision during the first transmission slot. The first subband is then assigned to a third position in a second subframe for use in the first subdivision during a second transmission slot following the first transmission slot, and the second subband is assigned to a fourth position in the second subframe for use in the second subdivision during the second transmission slot.

Claims

1. A method comprising:

allocating first and second random access frequency subbands from a plurality of random access orthogonal subbands to first and second subdivisions, respectively, in a wireless communication network;

assigning the first random access frequency subband to a first position in a first subframe for use in the first subdivision during a first transmission slot;

assigning the second random access frequency subband to a second position in the first subframe for use in the second subdivision during the first transmission slot;

assigning the first random access frequency subband to a third position in a second subframe for use in the first subdivision during a second transmission slot following the first transmission slot; and

assigning the second random access frequency subband to a fourth position in the second subframe for use in the second subdivision during the second transmission slot.

2. The method of claim 1 wherein the first and second subdivisions are cells, and wherein the method further comprises selecting the first and second subdivisions from a plurality of cells in the wireless communication network.

3. The method of claim 1 wherein the first and second subdivisions are sectors within a cell, and wherein the method further comprises selecting the first and second subdivisions from a plurality of sectors within the cell.

4. The method of claim 1 further comprising:

identifying a total number of available random access sequences;

identifying an amount of information to be transferred from a mobile station to a base station in the wireless network via the random access sequences;

defining a plurality of sequence groups based on the total number of available random access sequences and the amount of information to be transferred; and

assigning at least one of the plurality of sequence groups to the first and second subdivisions.

5. The method of claim 4 wherein the first and second subdivisions are sectors within a single cell, and wherein the cell is assigned a single one of the plurality of sequence groups, and wherein adjacent cells are assigned other sequence groups selected from the plurality of sequence groups.

6. The method of claim 4 wherein the first and second subdivisions are cells, and wherein each of the first and second subdivisions is divided into at least first and second sectors, and wherein the first and second sectors within each of the first and second cells are assigned a different sequence group selected from the plurality of sequence groups.

7. The method of claim 4 further comprising associating each of the plurality of random access orthogonal frequency subbands with each of the plurality of orthogonal sequence groups to form unique pairs of random access orthogonal frequency subbands and sequence groups, wherein assigning the first and second random access frequency subbands to the first and second subdivisions also assigns the sequence groups associated with the first and second random access subbands to the first and second subdivisions.

8. The method of claim 1 further comprising identifying a predefined sequence of positions within the first and second subframes for each of the first and second random access frequency subbands.

9. The method of claim 1 wherein at least two of the first, second, third, and fourth positions are the same position.

10. The method of claim 1 wherein at least one of the first, second, third and fourth positions is sent from a base station to a mobile device.

11. A method comprising:

identifying a total number of available random access sequences for use in a portion of a wireless network;

identifying an amount of information to be transferred from a mobile station to a base station in the portion of the wireless network via the random access sequences;

defining a plurality of random access sequence groups based on the total number of available random access sequences and the amount of information to be transferred; and

assigning first and second random access sequence groups of the plurality of random access sequence groups to first and second subdivisions of the wireless network for random access requests in the first and second subdivisions.

12. The method of claim 11 wherein the first and second subdivisions are cells and wherein the method further comprises assigning a random access frequency subband to each of a plurality of sectors within each of the first and second subdivisions.

13. The method of claim 11 wherein the first and second subdivisions are sectors within a cell, and wherein the method further comprises assigning a single random access frequency subband to the cell.

14. The method of claim 11 further comprising creating random access pairs by associating each of the plurality of random access sequence groups with each of a plurality of random access frequency subbands, wherein assigning the first and second random access sequence groups to the first and second subdivisions also assigns the random access frequency subband associated with each of the first and second random access sequence groups to the first and second subdivisions, respectively.

15. A method comprising:

waiting for a random access request on a designated random access subband during a first transmission period, wherein the designated random access subband is located at a first position in a designated subframe used during the first transmission period;

waiting for a random access request on the designated random access subband during a second transmission period, wherein the designated random access subband is located at a second position in the designated subframe used during the second transmission period; and

responding to a random access request during the first and second transmission periods only if the random access request is transmitted on the designated random access subband.

16. The method of claim 15 further comprising:

determining whether the random access request corresponds to a designated sequence group; and

responding to a random access request during the first and second transmission periods only if the random access request corresponds to the designated sequence group.

17. A method comprising:

waiting for a random access request associated with a designated random access sequence group during a first transmission period, wherein the designated random access sequence group is located at a first position in a designated subframe of the first transmission period;

waiting for a random access request on the designated random access subband during a second transmission period, wherein the designated random access subband is located at a second position in the designated subframe of the second transmission period; and

responding to a random access request during the first and second transmission periods only if the random access request is transmitted on the designated random access subband.

18. The method of claim 17 further comprising:

determining whether the random access request corresponds to a designated random access subband; and

responding to a random access request during the first and second transmission periods only if the random access request corresponds to the designated random access subband.

19. A method comprising:

identifying a random access frequency subband for use in submitting a random access request in a subdivision of a wireless network;

transmitting a random access request using the random access frequency subband in a first designated position of a designated subframe during a first transmission period; and

waiting for a response to the random access request.

20. The method of claim 19 further comprising retransmitting the random access request using the random access frequency subband in a second designated position of the designated subframe during a second transmission period if no response is received to the random access request transmitted during the first transmission period.

21. The method of claim 19 further comprising receiving a message designating at least one of the first and second positions for use for random access requests during the corresponding first and second transmission periods.