System and method for random access in a wireless communication system

• US 8,184,609 B2
• Filed: 08/08/2007
• Issued: 05/22/2012
• 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
• Primary Examiner(s): Pham, Chi
• Assistant Examiner(s): Mohebbi, Kouroush
• Application Number:
  US11/835,569
• Publication Number:
  US 20080049708A1
• Time in Patent Office: 1,749 Days
• Field of Search: None
• 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:

defining a plurality of unique subband-sequence pairs by associating each of a plurality of random access orthogonal subbands with each of a plurality of random access sequence groups, each random access orthogonal subband comprising a plurality of subcarriers;

allocating first and second subband-sequence pairs from the plurality of unique subband-sequence pairs to first and second subdivisions, respectively, in a wireless communication network;

assigning the first subband-sequence pair to a first position in a first subframe for use in the first subdivision during a first transmission slot;

assigning the second subband-sequence pair to a second position in the first subframe for use in the second subdivision during the first transmission slot; and

frequency hopping the first and second unique subband-sequence pairs in a second subframe during a 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 the plurality of sequence groups based on the total number of available random access sequences and the amount of information to be transferred.

5. The method of claim 4 wherein the first and second subdivisions are sectors within a single cell, and wherein the cell is assigned unique subband-sequence pairs that have a common sequence group, and wherein adjacent cells are each assigned other unique subband-sequence pairs that have a different sequence group.

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, wherein each random access orthogonal frequency subband further comprises a plurality of resource block, each resource block comprising at least one subcarrier.

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 subband-sequence pairs.

9. The method of claim 1 wherein frequency hopping the first and second subband-sequence pairs in the second subframe during the second transmission slot comprises:

assigning the first subband-sequence pair 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 subband-sequence pair to a fourth position in the second subframe for use in the second subdivision during the second transmission slot.

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:

determining, by a transmitter in a wireless communications network, a plurality of random access orthogonal subbands;

determining, by the transmitter, a plurality of random access sequence groups;

defining, by the transmitter, a plurality of unique subband-sequence pairs by associating each of the plurality of random access orthogonal subbands with each of the plurality of random access sequence groups; and

assigning, by the transmitter, first and second subband-sequence pairs from the plurality of unique subband-sequence pairs to first and second subdivisions of a wireless network, respectively, for random access requests in the first and second subdivisions.

12. The method of claim 11 wherein the first and second subdivisions are cells.

13. The method of claim 11 wherein the first and second subdivisions are sectors within a cell, the first subband-sequence pair comprises a first subband from the plurality of random access orthogonal subbands, and the second subband-sequence pair comprises a second subband from the plurality of random access orthogonal subbands.

14. The method of claim 11, wherein the first subdivision is a sector within a first cell, the second subdivision is a sector within a second cell, the first subband-sequence pair comprises a first subband from the plurality of random access orthogonal subbands, and the second subband-sequence pair comprises a second subband from the plurality of random access orthogonal subbands.

15. A method comprising:

defining a plurality of unique subband-sequence pairs by associating each of a plurality of random access orthogonal subbands with each of a plurality of random access sequence groups, each random access orthogonal subband comprising a plurality of subcarriers;

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

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

responding to the random access requests during the first and second transmission periods only if the random access request is transmitted with random access sequences from a designated random access sequence group that is associated with the designated random access orthogonal subband.

16. The method of claim 15, wherein the designated random access subband is designated for a subdivision from a plurality of random access orthogonal subbands, and the subdivision is one of a cell and a sector within a cell.

17. A method comprising:

defining a plurality of unique subband-sequence pairs by associating each of a plurality of random access orthogonal subbands with each of a plurality of random access sequence groups, each random access orthogonal subband comprising a plurality of subcarriers;

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 associated with the designated random access sequence group during a second transmission period, wherein the designated random access sequence group 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 a designated random access subband that is associated with the designated random access sequence group.

18. The method of claim 17, wherein the designated random access subband is designated for a subdivision from a plurality of random access orthogonal subbands, and the subdivision is one of a cell and a sector within a cell.

19. A method comprising:

defining a plurality of unique subband-sequence pairs by associating each of a plurality of random access orthogonal subbands with each of a plurality of random access sequence groups, each random access orthogonal subband comprising a plurality of subcarriers;

identifying a subband-sequence pair from the plurality of unique subband-sequence pairs for use in submitting random access requests in a subdivision of a wireless network;

transmitting a random access request using the identified subband-sequence pair 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 identified subband-sequence pair 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.