Power saving protocol for TDMA multi-line wireless telephone handsets

• US 6,788,924 B1
• Filed: 11/16/2000
• Issued: 09/07/2004
• Est. Priority Date: 12/12/1997
• Status: Expired due to Term

• Current Assignee: Magnolia Licensing LLC (IP Edge LLC)
• Original Assignee: Thomson Licensing SA (Vantiva SA)
• Inventors: Ramaswamy, Kumar, Knutson, Paul Gothard
• Primary Examiner(s): Nguyen, Lee
• Assistant Examiner(s): Tran, Tuan A
• Application Number:
  US09/581,148
• Time in Patent Office: 1,391 Days
• Field of Search: 455/255, 455/257-259, 455/343--34, 455/208, 455/265, 455/574, 370/311, 370/350, 370/503, 370/508, 370/516, 370/518, 340/7.32, 340/7.38, 375/354
• US Class Current: 455/265
• CPC Class Codes: H04B 7/2681 Synchronisation of a mobile station with one base station
• CPC Class Codes: H04W 56/009 Closed loop measurements
• CPC Class Codes: Y02D 30/70 in wireless communication networks

Abstract

A wireless telephone system comprises a base unit having a base transceiver, and one or more wireless handsets, each handset comprising a handset transceiver. Each handset establishing a time-division multiple access (TDMA) link over a shared RF channel with the base unit via the base transceiver in accordance with a TDMA epoch, which allocates exclusive data and audio packet time slots to each handset. Each handset powers on its transceiver during its respective data and audio packet time slots as necessary to synchronize with the base unit using synchronization data transmitted with a data packet, to detect incoming call data transmitted with a data packet, or to transmit and receive audio information over the TDMA link. The handset powers off its transceiver otherwise during the epoch to minimize handset power use.

Claims

1. A wireless telephone system, comprising:

a base unit having a base transceiver; and

one or more wireless handsets, each handset comprising;

a handset transceiver that establishes a time-division multiple access (TDMA) link over a shared RF channel with the base unit via the base transceiver in accordance with a TDMA epoch divided into data and audio packet time slots which are allocated to each handset, wherein each handset may be in one of an operational mode and a sleep mode,

a clock;

counters; and

a timer;

the clock, counters and timer remaining operational when the handset transceiver is powered off, the clock and counters maintain synchronization between the handset and the base unit,

wherein when the handset is in the sleep mode, the handset powers on its transceiver in response to the timer, only during its respective receive data time slot of every Nth epoch, to receive a data packet and to re-synchronize the clock with the base unit using synchronization data contained in the received data packet;

while in the sleep mode, after receiving the data packet and after re-synchronizing the clock the handset transmits a data packet to the base unit during the next transmit data time slot for the handset to notify the base unit that the handset is still synchronized with the base unit, the handset being operable to maintain synchronization with the base unit, the clock and counters over a time period lasting at least N epochs without receiving synchronization data from the base unit.

2. The system of claim 1, wherein if the base unit does not receive the data packet from a handset to notify the base unit that the handset is still synchronized with the base unit, after the base unit has transmitted a data packet to the handset containing synchronization information during an Nth epoch, then the base unit attempts to restore synchronization with the handset by transmitting subsequent data packets to the handset with synchronization information during the transmit data time slot.

3. The system of claim 1, wherein after receiving the data packet during the receive data time slot of an Nth epoch when the handset is in sleep mode and after re-synchronizing the clock using synchronization data contained in the received data packet, the handset transmits a data packet to the base unit during the next transmit data time slot for the handset, only during every N*kth epoch, where k is an integer greater than 1, to notify the base unit that the handset is still synchronized with the base unit.

4. The system of claim 1, wherein N is selected so that the handset is able to maintain synchronization with the base unit with the clock and cascade of counters over a time period lasting at N epochs without receiving synchronization data from the base unit and also so that the handset is able to perform real-time call monitoring by detecting incoming call data transmitted with a data packet.

5. The system of claim 1, wherein N is a user programmable parameter.

6. The system of claim 1, wherein N>

1.

7. The system of claim 1, wherein, the handset is in the operational mode when the handset is off hook and is in the sleep mode when the handset is on hook.

8. The system of claim 1, wherein:

the epoch has a plurality of transmit and receive data row pairs, one such row pair for each handset; and

each handset, when in operational mode, receives and transmits data packets via receive and transmit data packet slots only once during each epoch, during the transmit and receive data row pair for each said operational handset, and receives and transmits audio packets during allocated audio time slots of the epoch for the handset.

9. The system of claim 1, wherein:

each handset is always in a state within one of the following layers;

an inactive layer;

an initialization layer, a standby link layer, and an active link layer;

the inactive layer occurs when the handset is out of contact with the base unit;

the initialization layer occurs as a TDMA link is being established between the handset and the base unit;

the standby link layer occurs when the base unit and handset have obtained synchronization lock, and comprises the sleep mode; and

the active link layer occurs when there is active audio communication between the handset and the base unit and comprises the operational mode.

13. The system of claim 1, wherein N is selected so that the handset is able to maintain synchronization with the base unit with the clock and cascade of counters over a time period lasting at N epochs without receiving synchronization data from the base unit and also so that the handset is able to perform real-time call monitoring by detecting incoming call data transmitted with a data packet.

10. A wireless telephone system, comprising:

a base unit having a base transceiver; and

one or more wireless handsets, each handset including a handset transceiver for establishes a time-division multiple access (TDMA) link over a shared RF channel with the base transceiver according to a TDMA epoch divided into data and audio packet time slots allocated to each handset, each handset being in one of an operational mode and a sleep mode and including a clock, counters, and a timer;

the clock, counters and timer remaining operational when the handset transceiver is powered off, and the clock and counters maintaining synchronization between the handset and the base unit,

wherein during the sleep mode the handset transceiver is powered and responsive to the timer during its respective receive data time slot of every Nth epoch to receive a data packet and to re-synchronize the clock with the base unit using synchronization data contained in the received data packet and after receiving the data packet and after re-synchronizing the clock the handset transmits a data packet to the base unit during the next transmit data time slot for the handset to notify the base unit that the handset is still synchronized with the base unit.

11. The system of claim 10, wherein the handset is operable to maintain synchronization between the base unit, clock and counters over a time period lasting at least N epochs without receiving synchronization data from the base unit.

12. The system of claim 11, wherein if the base unit does not receive the data packet from a handset to notify the base unit that the handset is still synchronized with the base unit, after the base unit has transmitted a data packet to the handset containing synchronization information during an Nth epoch, then the base unit attempts to restore synchronization with the handset by transmitting subsequent data packets to the handset with synchronization information during the transmit data time slot.

14. The system of claim 11, wherein N is a user programmable parameter.

15. The system of claim 11, wherein N>

1.

16. The system of claim 11, wherein, the handset is in the operational mode when the handset is off hook and is in the sleep mode when the handset is on hook.