Wireless communication system with symmetric communication protocol

• US 6,366,572 B1
• Filed: 02/04/1999
• Issued: 04/02/2002
• Est. Priority Date: 02/04/1999
• Status: Expired due to Fees

• Current Assignee: Senora Trading Company
• Original Assignee: Senora Trading Company
• Inventors: Esterberg, Aanand, Akrouf, Ali, Chen, Jyun-Cheng
• Primary Examiner(s): Chin, Wellington
• Assistant Examiner(s): PHAN, MAN U
• Application Number:
  US09/244,572
• Time in Patent Office: 1,153 Days
• Field of Search: 370/343, 370/335, 370/344, 370/445, 370/473, 370/329, 370/331, 370/278, 370/310, 370/318, 370/321, 455/446, 455/507, 455/524, 455/455, 455/500, 455/501, 455/504, 455/505
• US Class Current: 370/343
• CPC Class Codes: H04M 1/724 User interfaces specially adapted for cordless or mobile telephones
• CPC Class Codes: H04M 1/72505 Radio link set-up procedures
• CPC Class Codes: H04M 1/72513 On hold, intercom or transfer communication modes
• CPC Class Codes: H04W 24/00 Supervisory, monitoring or testing arrangements
• CPC Class Codes: H04W 52/383 power control in peer-to-peer links
• CPC Class Codes: H04W 76/10 Connection setup

Abstract

A symmetrical communication protocol allows handsets to operate as a master unit or a slave unit and operate independently of any base station. Remote units may contact each other directly with the calling unit being temporarily designated as a master unit and the called unit being designated temporarily as a slave unit. A wireless communication link is established between the two units and the units frequency-hop in synchronization in accordance with FCC requirements. The units independently monitor the signal strength of the incoming signal and can transmit power change commands to the other unit to increase or decrease transmission power as required. A calling unit initially transmits a call request on a limited number of the available frequency channels in order to decrease the acquisition time period. An idle unit has a sleep cycle and an awake cycle. When entering the awake cycle, the idle unit is programmed for operation at one of the acquisition channels and monitors for an incoming data frame intended for that unit. If a data frame is not detected, the unit returns to the sleep cycle. If a data frame is detected, the handsets synchronize and communicate over the entire range of operational frequency channels utilizing a predetermined pseudo-random sequence.

Claims

1. A wireless communication system, comprising:

a first transmitter in a first wireless communication unit to transmit data to a second wireless unit, the first transmitter operating at a selected frequency to transmit a request to communicate with the second wireless unit;

a first receiver in the first wireless communication unit to receive data from the second wireless unit;

a second receiver in the second wireless unit monitoring the selected frequency to thereby detect the request to communicate transmitted from the first wireless unit;

a second transmitter to transmit a response signal to the first wireless unit to indicate reception of the request to communicate, the first and second wireless units thereby establishing a communication link with the first wireless unit functioning as a master unit and the second wireless unit functioning as a slave unit;

a first signal monitor in the first wireless unit coupled to the first receiver and determining a first received signal strength indicative of a strength of the signal received from the second wireless unit, the first transmitter transmitting a power change request signal to the second wireless unit if the first received signal strength is above or below a first set of predetermined limits; and

a second signal monitor in the second wireless unit coupled to the second receiver and determining a second received signal strength indicative of a strength of the signal received from the first wireless unit, the second transmitter transmitting a power change request signal to the first wireless unit if the second received signal strength is above or below a second set of predetermined limits.

2. The system of claim 1, further including a base station coupled to a switched telephone network and having a base station transmitter and a base station receiver wherein the first and second wireless units communicate via the switched telephone network by transmitting data to and receiving data from the base station.

3. The system of claim 2 wherein the base station is coupled to a public switched telephone network.

4. The system of claim 1 wherein the first transmitter and the second receiver are programmable for operation at a plurality of different frequencies, the first transmitter transmitting the request to communicate at a selected one of the plurality of frequencies, the second receiver being programmed for operation at the plurality of frequencies, including the selected frequency, to detect the request to communicate transmitted by the first wireless unit.

5. The system of claim 4 wherein the first transmitter periodically transmits the request to communicate, each of the plurality of periodic transmissions occurring at a different one of the plurality of different frequencies.

6. The system of claim 4 wherein the first transmitter is initially programmed for operation at a subset of the plurality of different frequencies and periodically transmits the request to communicate, each of the plurality of periodic transmissions occurring at a different one of the subset of different frequencies.

7. The system of claim 6 wherein the first transmitter is programmed for operation at a subset of the plurality of different frequencies for an initial time period and is subsequently programmed for operation at the plurality of different frequencies, the transmitter periodically transmitting the request to communicate at a different one of the subset of different frequencies for the initial period of time and, subsequent to the initial period of time, periodically transmitting the request to communicate at a different one of the plurality of different frequencies.

8. The system of claim 1 wherein the first and second transmitters and the first and second receivers are programmable for operation at a plurality of different frequencies, the communication link between the first and second wireless units being established by periodically programming the first and second transmitters and the first and second receivers for operation at a different one of the plurality of frequencies, whereby the first and second transmitters and the first and second receivers are all operating at the same frequency and periodically all change to a different frequency.

9. The system of claim 8 wherein the different ones of the plurality of frequencies for the first and second transmitters and the first and second receivers are selected based on a pseudo-random sequence, where by the first and second transmitters and the first and second receivers are all operating at the same frequency and periodically all change to a different frequency in accordance with a pseudo-random pattern.

10. The system of claim 1 wherein the first and second sets of predetermined limits are identical.

11. The system of claim 1 wherein the request to communicate is contained within a data frame transmitted from the first wireless unit to the second wireless unit.

12. The system of claim 11 wherein the first data frame further comprises an identification data field to indicate the second wireless unit as a called party.

13. The system of claim 1 wherein the first transmitter transmits the power change request signal within a data frame transmitted from the first wireless unit to the second wireless unit.

14. The system of claim 1 wherein the first and second transmitters transmit a plurality of data frames to the second and first receivers, respectively, while the communication link is established.

15. The system of claim 14 wherein the first transmitter transmits the power change request signal within a data frame transmitted from the first wireless unit to the second wireless unit after the communication link has been established, said power change request signal being transmitted in at least one of the plurality of data frames transmitted while the communication link is established.

16. A wireless communication system to control communication between first and second wireless units, comprising:

a first transmitter in the first wireless communication unit to transmit data to the second wireless unit, the first transmitter operating at a selected frequency to transmit a request to communicate with the second wireless unit;

a first receiver in the first wireless communication unit to receive data from the second wireless unit;

a second receiver in the second wireless unit monitoring the selected frequency to thereby detect the request to communicate transmitted from the first wireless unit;

a second transmitter to transmit a response signal to the first wireless unit to indicate reception of the request to communicate, the first and second wireless units thereby establishing a communication link with each other;

a first signal monitor in the first wireless unit coupled to the first receiver and determining a first received signal strength indicative of a strength of the signal received from the second wireless unit, the first transmitter transmitting a power change request signal to the second wireless unit if the first received signal strength is above or below a first set of predetermined limits; and

a second signal monitor in the second wireless unit coupled to the second receiver and determining a second received signal strength indicative of a strength of the signal received from the first wireless unit, the second transmitter transmitting a power change request signal to the first wireless unit if the second received signal strength is above or below a second set of predetermined limits.

17. The system of claim 16 wherein the first and second sets of predetermined limits are identical.

18. The system of claim 16 wherein the first transmitter transmits the power change request signal within a data frame transmitted from the first wireless unit to the second wireless unit.

19. The system of claim 16 wherein the first and second transmitters transmit a plurality of data frames to the second and first receivers, respectively, while the communication link is established.

20. The system of claim 19 wherein the first transmitter transmits the power change request signal within a data frame transmitted from the first wireless unit to the second wireless unit after the communication link has been established, said power change request signal being transmitted in at least one of the plurality of data frames transmitted while the communication link is established.

21. The system of claim 16 wherein the request to communicate Is contained within a data frame transmitted from the first wireless unit to the second wireless unit.

22. The system of claim 21 wherein the first data frame further comprises an identification data field to indicate the second wireless unit as a called party.

23. A method to control communication between first and second wireless units in a wireless communication system, the method comprising:

transmitting, at a selected frequency, a request to communicate with the second wireless unit from the first wireless communication unit;

monitoring the selected frequency to thereby detect the request to communicate transmitted from the first wireless unit;

transmitting, at the selected frequency, a response signal from the second wireless unit to the first wireless communication unit to thereby establish a communication link between the first wireless unit and the second wireless unit with the first wireless unit functioning as a master unit and the second wireless unit functioning as a slave unit;

determining a first received signal strength indicative of a strength of the signal received from the second wireless unit;

transmitting a power change request signal from the first wireless unit to the second wireless unit if the first received signal strength is above or below a first set of predetermined limits;

determining a second received signal strength indicative of a strength of the signal received from the first wireless unit; and

transmitting a power change request signal from the second wireless unit to the first wireless unit if the second received signal strength is above or below a second set of predetermined limits.

24. The method of claim 23 wherein a selected one of the first and second wireless units is coupled to an external telephone network, the method further including communicating via the external telephone network by relaying data between the external telephone network and the selected one of the first and second wireless units coupled to the external telephone network.

25. The method of claim 24 wherein the external telephone network is a public switched telephone network.

26. The method of claim 23 wherein the first and second wireless units are programmable for operation at a plurality of different frequencies, the first wireless unit transmitting the request to communicate at a selected one of the plurality of frequencies, the second wireless unit being programmed for operation at the plurality of frequencies, including the selected frequency, to detect the request to communicate transmitted by the first wireless unit.

27. The method of claim 26 wherein the first wireless unit is initially programmed for operation at a subset of the plurality of different frequencies and periodically transmits the request to communicate, each of the plurality of periodic transmissions occurring at a different one of the subset of different frequencies.

28. The method of claim 27 wherein the first wireless unit is programmed for operation at a subset of the plurality of different frequencies for an initial time period and is subsequently programmed for operation at the plurality of different frequencies, the first wireless unit periodically transmitting the request to communicate at a different one of the subset of different frequencies for the initial period of time and, subsequent to the initial period of time, periodically transmitting the request to communicate at a different one of the plurality of different frequencies.

29. The method of claim 23 wherein the first and second wireless units are programmable for operation at a plurality of different frequencies, the communication link between the first and second wireless units being established by periodically programming the first and second wireless units at a different one of the plurality of frequencies, whereby the first and second first wireless units are both operating at the same frequency and periodically both change to a different frequency.

30. The method of claim 23 wherein the first and second sets of predetermined limits are identical and the steps of transmitting the power change request signal from the first wireless unit to the second wireless unit and transmitting the power change request signal from the second wireless unit to the first wireless unit uses the identical predetermined limits.

31. The method of claim 23 wherein the first wireless unit transmits the power change request signal to the second wireless unit within a data frame transmitted from the first wireless unit to the second wireless unit.

32. The method of claim 23 wherein the first and second wireless units transmit a plurality of data frames to each other while the communication link is established.

33. The method of claim 32 wherein the first wireless unit transmits the power change request signal within a data frame transmitted from the first wireless unit to the second wireless unit after the communication link has been established, said power change request signal being transmitted in at least one of the plurality of data frames transmitted while the communication link is established.