Methods and apparatus for use in a wireless communications system that uses a multi-mode base station

• US 7,756,548 B2
• Filed: 09/19/2005
• Issued: 07/13/2010
• Est. Priority Date: 09/19/2005
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Das, Arnab, Laroia, Rajiv, Rangan, Sundeep, Anigstein, Pablo
• Primary Examiner(s): Sobutka; Philip J
• Application Number:
  US11/229,846
• Publication Number:
  US 20070066329A1
• Time in Patent Office: 1,758 Days
• Field of Search: 455/522, 455/524, 455/561, 455/562.1, 455/422.1, 455/423, 455/424, 455/502, 455/127.1, 455/127.5
• US Class Current: 455/561
• CPC Class Codes: H04B 7/2678 Time 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 5/0053 Allocation of signaling, i.e. of overhead other than pilot signals
• CPC Class Codes: H04W 52/0206 in access points, e.g. base stations access point devices per se H04W88/08
• CPC Class Codes: H04W 56/00 Synchronisation arrangements
• CPC Class Codes: H04W 72/20 Control channels or signalling for resource management
• CPC Class Codes: Y02D 30/70 in wireless communication networks

Abstract

A multi-mode base station includes a transmit standby mode and an active mode. Transmit standby mode of base station operation is a low power/low interference level of operation as compared to active mode. In transmit standby mode at least some of the synchronization signaling such as pilot tone signaling is reduced in power level and/or rate with respect to the active mode. In transmit standby mode, the base station has no active state registered wireless terminals being serviced but may have some sleep state registered wireless terminals being serviced. Mode transitions from active to transmit standby may be in response to: a detected period of inactivity, scheduling information, base station mode change signals, and/or detected wireless terminal state transition. Mode transitions from transmit standby to active may be in response to: scheduling information, access signals, wake-up signals, hand-off signals, wireless terminal state change signals, and/or base station mode change signals.

Claims

1. A method operating a base station, comprising:

operating in an active mode of operation during a first period of time, said active mode of operation including transmitting synchronization signals at a first rate; and

operating in a transmit standby mode of operation during a second period of time during which at least some of said synchronization signals are transmitted at at least one of;

i) a lower rate than in said active mode, and ii) at a lower power level than said synchronization signals transmitted in said active mode.

5. The method of claim 1, wherein said synchronization signals are pilot signals.

12. The method of claim 1, further comprising:

operating the base station to receive a signal; and

to transition from said transmit standby mode of operation to said active mode of operation in response to said received signal.

13. The method of claim 12, wherein said received signal is one of an access signal, a base station wake-up signal, a handoff signal, and a state change signal.

14. The method of claim 13, wherein said signal is from the wireless terminal.

15. The method of claim 13, wherein said step of receiving a signal includes receiving said signal over a wireless communications link.

16. The method of claim 13, wherein said step of receiving a signal includes receiving said signal from a network node coupled to said base station.

17. The method of claim 1, further comprising:

operating the base station to transition from said transmit standby mode of operation to said active mode of operation on a scheduled basis.

18. The method of claim 1, further comprising:

operating the base station to transition from said transmit standby mode of operation to said active mode in response to a signal received from another node.

19. The method of claim 1, further comprising:

operating the base station to transition from said active mode of operation to said transmit standby mode of operation in response to detecting a period of transmission channel inactivity.

20. The method of claim 1, further comprising:

transitioning from said active mode of operation to said transmit standby mode of operation in response to detecting a transition of at least one wireless terminal from an active to a sleep state of operation.

21. The method of claim 20, wherein the detected transition of at least one wireless terminal from an active to a sleep state of operation signifies that no wireless terminals currently being serviced by the base station are in an active state of operation.

22. The method of claim 1, further comprising:

transitioning from said active mode of operation to said transmit standby mode of operation according to a schedule.

2. The method of claim l, wherein the average transmission power level of said synchronization signals during said first period of time is higher than the average transmission power level of said at least some periodic signals during the second period of time.

3. The method of claim 2, wherein during said first period of time a first average amount of power is used for transmission of said synchronization signals, said synchronization signals being a set of non-traffic channel signals, said set of non-traffic channel signals including one of control and synchronization signals;

and

wherein during said second period of time the base station transmitter transmits said synchronization signals using an average transmission power level that is lower than said first average transmission power level.

4. The method of claim 3, wherein transmitting during said second period of time includes:

transmitting at least one of said synchronization signals at a reduced power level relative to a power level at which said synchronization signals are transmitted during said first period of time.

6. The method of claim 3, wherein transmitting during said second period of time includes transmitting at least some of said synchronization signals at a reduced rate.

7. The method of claim 6, wherein said at least some synchronization signals includes at least one of beacon signals and pilot signals.

8. The method of claim 6, wherein said first period of time is a single OFDM symbol transmission time period in which at least some synchronization signals which are pilot signals are transmitted in parallel and wherein transmitting at least some of said synchronization signals at a reduced rate includes transmitting fewer pilot signals in a symbol transmission time period than said first number of synchronization signals.

9. The method of claim 8, wherein said first and second time periods correspond to the same symbol transmission time period in a recurring downlink timing structure.

10. The method of claim 2, wherein the first period of time is a period of time in which user data is communicated over a traffic channel between said base station and said wireless terminal;

and

wherein said second period of time is a period of time during which no user data is communicated between said base station and said wireless terminal.

11. The method of claim 8, wherein during said second period of time the base station does not service any wireless terminals over a wireless communications link or all wireless terminals being serviced by said base station over a wireless communications channel are in a sleep state.

23. A base station, comprising:

a transmitter for transmitting signals;

a first control module for controlling the transmission of synchronization signals during a first active mode of operation, said first control module controlling the transmission of at least some synchronization signals at a first rate and a first power level during said first active mode of operation; and

a second control module for controlling the transmission of synchronization signals during a second synchronization signal mode of operation, said second control module controlling the transmission of said at least some synchronization signals at a second rate and a second power level wherein at least one of said second rate and second power level are reduced relative to the first rate and first power level respectively.

24. The base station of claim 23, further comprising:

a base station mode transition control module for controlling transitions between said first and second synchronization signal modes of operation.

25. The base station of claim 24, further comprising:

a memory for storing schedule information used by said base station mode transition control module in determining when to transition between synchronization signaling modes of operation.

26. The base station of claim 25, wherein said schedule information includes date, time and corresponding mode information for a plurality of different times.

27. The base station of claim 24, further comprising:

a receiver for receiving signals from wireless terminals; and

wherein said base station mode transition control module is responsive to at least one of a wake signal, access request signal and mobile node state transition request signal received via said receiver.

28. The base station of claim 27, further comprising:

an interface coupling said base station to a network node; and

wherein said base station mode transition control module is responsive to at least one of a handoff signal, a wake signal, a state change command signal and a state change request signal communicated through said interface.

29. The base station of claim 28 wherein said base station mode transition control module transitions from said first active mode of operation to said second synchronization signal mode of operation in response to detecting no users with an active uplink over which user data is communicated for a period of time.

30. The base station of claim 29, wherein said base station transmitter is an OFDM signal transmitter.