Efficient paging in a wireless communication system

• US 7,711,377 B2
• Filed: 06/10/2004
• Issued: 05/04/2010
• Est. Priority Date: 06/10/2004
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Laroia, Rajiv, Li, Junyi, Rangan, Sundeep, Hande, Prashanth
• Primary Examiner(s): Appiah; Charles N
• Assistant Examiner(s): Vu; Michael T
• Application Number:
  US10/865,616
• Publication Number:
  US 20050277429A1
• Time in Patent Office: 2,154 Days
• Field of Search: 455/458, 455/426.1, 455/434, 455/343, 455/575, 455/67.1, 370/312, 370/332, 370/335, 370/210
• US Class Current: 455/458
• CPC Class Codes: H04W 68/025 Indirect paging
• CPC Class Codes: Y02D 30/70 in wireless communication networks

Abstract

Methods and apparatus for efficient two-stage paging wireless communications systems are described. Wireless terminals are assigned to paging groups. A few first paging message information bits are modulated (using non-coherent modulation) into a first paging signal and communicated from a base station to wireless terminals. WTs wake-up, receive the first paging signal and quickly ascertain whether its paging group should expect a second paging signal, if so, the WT is operated to receive the second paging signal; otherwise, the WT goes back to sleep conserving power. The base station modulates (using coherent modulation) a number of second message information bits into a second paging signal and transmits the signal to WTs. From the information in first and second paging signals, a WT can determine that it is the paged WT and process the paging instructions. The intended paged WT can transmit an acknowledgement signal on a dedicated uplink resource.

Claims

1. A method of operating a wireless terminal, the method comprising:

awaking from a sleep mode of operation to receive a first paging signal indicating if there is a paging message for at least one wireless terminal in a first group of wireless terminals, said first group being one of a plurality of wireless terminal groups, said first group including multiple wireless terminals, said wireless terminal being a member of said first group;

performing a first demodulation operation on said first paging signal to produce demodulated information;

determining if said demodulated information indicates that a paging message was transmitted to at least one member of the first group; and

if it is determined that said demodulated information indicates that a paging message was transmitted to at least one member of the first group;

i) performing a second demodulation operation on a second paging signal; and

ii) determining from information included in said second paging signal if the second paging signal includes at least a portion of a paging message directed to said wireless terminal.

2. The method of claim 1, further comprising:

if it is determined that said demodulated information indicates that a paging message was not transmitted, returning to a sleep mode of operation.

3. The method of claim 1, wherein said demodulated information produced by demodulating the first paging signal includes multiple individual bits of information, some of said individual bits corresponding to different groups of wireless terminals, an individual bit corresponding to a group of wireless terminals indicating if there is a paging message for at least one wireless terminal in the group of wireless terminals to which the individual bit corresponds;

and

wherein determining if said demodulated information indicates that a paging message was transmitted to at least one member of the first group includes examining the bit in said multiple individual bits corresponding to the first group of wireless terminals to make said determination.

4. The method of claim 3, wherein multiple second type paging signals correspond to said first paging signal, said second type paging signals having different time offsets from said first paging signal, the method further comprising:

receiving said second paging signal at a time offset from the point in time at which said first paging signal was received, said time offset being a predetermined time offset corresponding to the first group of wireless terminal.

5. The method of claim 4, further comprising:

returning to said sleep mode of operation prior to receiving said second paging signaling;

awakening from said sleep mode of operation for another time prior to receiving said second paging signal;

initiating a channel estimation operation prior to receiving said second paging signal; and

wherein said wireless terminal consumes less power while in said sleep mode than when operating in an active mode of operation which occurs upon being woken up from said sleep mode of operation.

6. The method of claim 1, wherein said first demodulation operation is a non-coherent demodulation operation which does not use channel information;

and

wherein said second demodulation operation is a coherent demodulation operation which uses a communications channel estimate to perform said demodulation operation.

7. The method of claim 1, wherein said first paging signal includes a first number of bits and said second paging signal includes a second number of bits which is greater than said first number of bits.

8. A wireless terminal comprising:

means for performing a first demodulation operation on a first paging signal, said first paging signal indicating if there is a paging message for at least one wireless terminal in a first group of wireless terminals, said first group being one of a plurality of wireless terminal groups, said first group including multiple wireless terminals, said wireless terminal being a member of said first group, said first demodulation being performed to recover modulated information indicating whether a paging message directed to at least one member of the first group will be transmitted;

control means for controlling the wireless terminal to receive a second paging signal of a second type at a pre-selected time when information recovered from said first paging signal indicates a paging message corresponding to the first paging signal will be transmitted and for controlling the wireless terminal to enter a sleep mode of operation and remain in said sleep mode of operation until after said pre-selected time when said information recovered from said first paging signal indicates a paging message corresponding to the first paging signal will not be transmitted; and

means for performing a second demodulation operation on the received second paging signal to recover modulated information including at least a portion of a paging message directed to said wireless terminal and sufficient information to identify an individual wireless terminal in the first group.

9. The wireless terminal of claim 8, further comprising:

means for performing a channel estimation operation following receipt of a first paging signal including information indicating a paging message will be transmitted and prior to receipt of said second paging signal.

10. The wireless terminal of claim 9, further comprising:

timing control means for controlling said wireless terminal to enter a sleep mode of operation following receipt of a first paging signal including information indicating a paging message will be transmitted and for awakening said wireless terminal to a more active state prior to said pre-selected time.

11. The wireless terminal of claim 8, wherein means for performing a first demodulation operation on a first paging signal to recover modulated information indicating whether a paging message includes at least one of an on/off modulation demodulator, an orthogonal modulation demodulator, and a differential modulation demodulator.

12. The wireless terminal of claim 8, wherein means for performing a second demodulation operation on a second paging signal includes at least one of a quadrature phase shift keying modulation demodulator and a quadrature amplitude modulation demodulator.

13. A wireless terminal comprising:

a first demodulation module for performing a first demodulation operation on a first paging signal, said first paging signal indicating if there is a paging message for at least one wireless terminal in a first group of wireless terminals, said first group being one of a plurality of wireless terminal groups, said first group including multiple wireless terminals, said wireless terminal being a member of said first group, said first demodulation being performed to recover modulated information indicating whether a paging message directed to at least one member of the first group will be transmitted;

a control module for controlling the wireless terminal to receive a second paging signal of a second type at a pre-selected time when information recovered from said first paging signal indicates a paging message corresponding to the first paging signal will be transmitted and for controlling the wireless terminal to enter a sleep mode of operation and remain in said sleep mode of operation until after said pre-selected time when said information recovered from said first paging signal indicates a paging message corresponding to the first paging signal will not be transmitted; and

a second demodulation module for performing a second demodulation operation on the received second paging signal to recover modulated information including at least a portion of a paging message directed to said wireless terminal and sufficient information to identify an individual wireless terminal in the first group.

14. The wireless terminal of claim 13, further comprising:

a channel estimation module for performing a channel estimation operation following receipt of a first paging signal including information indicating a paging message will be transmitted and prior to receipt of said second paging signal.

15. The wireless terminal of claim 14, further comprising:

a timing control module for controlling said wireless terminal to enter a sleep mode of operation following receipt of a first paging signal including information indicating a paging message will be transmitted and for awakening said wireless terminal to a more active state prior to said pre-selected time.

16. A computer readable medium including machine executable instructions for use in a wireless terminal, said computer readable medium comprising:

instructions for causing the wireless terminal to awake from a sleep mode of operation to receive a first paging signal indicating if there is a paging message for at least one wireless terminal in a first group of wireless terminals, said first group being one of a plurality of wireless terminal groups, said first group including multiple wireless terminals, said wireless terminal being a member of said first group;

instructions for causing the wireless terminal to perform a first demodulation operation on said first paging signal to produce demodulated information;

instructions for causing the wireless terminal to determine if said demodulated information indicates that a paging message was transmitted to at least one member of the first group; and

instructions for causing the wireless terminal to;

i) perform a second demodulation operation on a second paging signal if it is determined that said demodulated information indicates that a paging message was transmitted to at least one member of the first group; and

ii) determine from information included in said second paging signal if the second paging signal includes at least a portion of a paging message directed to said wireless terminal.

17. The computer readable medium of claim 16, further comprising:

instructions for causing the wireless terminal to return to a sleep mode of operation if it is determined that said demodulated information indicates that a paging message was not transmitted.