OFFSETTING BEACON POSITIONS IN A TIME DIVISION DUPLEX COMMUNICATION SYSTEM

• US 20110116358A9
• Filed: 09/19/2007
• Published: 05/19/2011
• Est. Priority Date: 08/26/2002
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Das, Arnab, Li, Junyi, Laroia, Rajiv
• Granted Patent: US 8,693,304 B2
• Time in Patent Office: Days
• US Class Current: 370/203
• CPC Class Codes: H04L 27/2656 Frame synchronisation, e.g. packet synchronisation, time division duplex [TDD] switching point detection or subframe synchronisation
• CPC Class Codes: H04L 5/0007 the frequencies being orthogonal, e.g. OFDM(A), DMT
• CPC Class Codes: H04L 5/0048 Allocation of pilot signals, i.e. of signals known to the receiver
• CPC Class Codes: H04L 5/1469 using time-sharing
• CPC Class Codes: H04W 72/04 Wireless resource allocation

Abstract

Systems and methodologies are described that facilitate generating and/or analyzing downlink transmission units in OFDM TDD environments. Beacon signals may be selectively inserted within downlink transmission units; for example, the position of Beacon signals may vary from cell to cell. Further, the position may be a function of a characteristic of a cell (e.g., cell identifier) and/or an expected drift. Moreover, a Beacon signal may be interjected at a location in a downlink transmission unit so as to mitigate alignment with disparate Beacon signals in downlink transmission units associated with differing cells. Additionally, an identity of a cell providing downlink transmission units may be determined by analyzing a position of the Beacon signal within the downlink transmission units.

Claims

1. A method that facilitates generating downlink transmission units in an Orthogonal Frequency Division Multiplexing (OFDM) time division duplex (TDD) environment, comprising:

selectively positioning a Beacon signal within a downlink transmission unit based upon a characteristic of a cell; and

transmitting the downlink transmission unit.

2. The method of claim 1, wherein the characteristic is a cell identifier.

3. The method of claim 1, wherein the characteristic is a physical layer identifier that is uniquely assigned in a geographic region.

4. The method of claim 1, selectively positioning the Beacon signal further comprises mitigating alignment between the Beacon signal and a disparate Beacon signal in a differing downlink transmission unit generated for transfer by a different cell.

5. The method of claim 1, further comprising selectively interposing the Beacon signal based upon expected drift.

6. The method of claim 1, selectively positioning the Beacon signal further comprises locating the Beacon signal in a subset of strip OFDM symbols included in the downlink transmission unit and disparate downlink transmission units associated with the cell,

7. The method of claim 6, further comprising selectively incorporating the Beacon signal in one of eight strip OFDM symbols.

8. The method of claim 6, further comprising selectively locating the strip OFDM symbols in the downlink transmission unit and the disparate downlink transmission units as a function of the characteristic of the cell.

9. The method of claim 1, further comprising identifying a subband position for the Beacon signal.

10. The method of claim 1, wherein a time position at which the Beacon signal is selectively positioned varies from a differing time position of a disparate Beacon signal of a disparate cell.

11. The method of claim 1, further comprising employing a tone set in connection with the Beacon signal that differs from a disparate tone set utilized by a disparate sector associated with the cell.

12. A wireless communications apparatus, comprising:

a memory that retains instructions for determining a time location for a Beacon signal within a downlink transmission unit, determining a subband position for the Beacon signal, and sending the Beacon signal with the time location and the subband position via a downlink; and

a processor, coupled to the memory, configured to execute the instructions retained in the memory.

13. The wireless communications apparatus of claim 12, wherein the memory further retains instructions for determining the time location and the subband position to mitigate alignment with a disparate Beacon signal associated with a disparate cell.

14. The wireless communications apparatus of claim 12, wherein the memory further retains instructions for determining the time location and the subband position based upon a cell identifier.

15. The wireless communications apparatus of claim 12, wherein the memory further retains instructions for including the Beacon signal in a subset of selectively positioned strip OFDM symbols.

16. The wireless communications apparatus of claim 12, wherein the memory further retains instructions for determining the time location for the Beacon based upon expected drift.

17. A wireless communications apparatus that generates downlink transmission units in an OFDM TDD environment, comprising:

means for selectively interposing a Beacon signal in a downlink transmission unit to mitigate alignment with a disparate Beacon signal between cells; and

means for transferring the downlink transmission unit via a downlink.

18. The wireless communications apparatus of claim 17, further comprising means for identifying a subband position for the Beacon signal.

19. The wireless communications apparatus of claim 17, further comprising means for selectively incorporating the Beacon signal in a subset of selectively positioned strip OFDM symbols.

20. The wireless communications apparatus of claim 17, further comprising selectively interposing the Beacon signal as a function of expected drift and/or a cell identifier.

21. In a wireless communication system, an apparatus comprising:

a processor configured to;

selectively position a Beacon signal within downlink transmission units so as to mitigate alignment with a disparate Beacon signal associated with a disparate cell; and

transfer the downlink transmission units over a downlink.

22. A method that facilitates analyzing downlink transmission units in an OFDM TDD environment, comprising:

receiving downlink transmission units from a base station associated with a cell;

analyzing a time position of a Beacon signal included in the downlink transmission units; and

determining an identity of the cell based upon the time position.

23. The method of claim 22, further comprising:

evaluating a subband position of the Beacon signal; and

determining the identity of the cell based upon the time position and the subband position.

24. The method of claim 22, further comprising:

identifying a beginning and an end of a downlink transmission interval; and

evaluating a location of the Beacon signal within the downlink transmission interval.

25. The method of claim 22, wherein the time position corresponds to a cell identifier.