Method and system for protocols for providing voice, data, and multimedia services in a wireless local loop system

• US 6,115,370 A
• Filed: 05/26/1998
• Issued: 09/05/2000
• Est. Priority Date: 05/26/1998
• Status: Expired due to Term

• Current Assignee: Quarterhill Inc. (f/k/a Wi-LAN Inc.)
• Original Assignee: Nera Wireless Broadband Access AS
• Inventors: Struhsaker, Paul F., Easson, Michael J., Hudson, Thomas C., Quinn, Patrick Wilton
• Primary Examiner(s): Jung, Min
• Application Number:
  US09/085,264
• Time in Patent Office: 833 Days
• Field of Search: 370/350, 370/342, 370/503, 370/516, 375/354, 375/356, 375/365, 375/368
• US Class Current: 370/342
• CPC Class Codes: H04J 13/0077 Multicode, e.g. multiple codes assigned to one user
• CPC Class Codes: H04Q 11/0457 Connection protocols

Abstract

A method and system for implementing various protocols for a Time Division Duplex (TDD) Code Division Multiple Access (CDMA) wireless local loop system that utilizes unique embedded concentrated access and embedded data access in a Wireless Local Loop (WLL) is described. The method and system further provides for dynamic pool sizing of the access channels. The protocols support POTS (Plain Old Telephone), ISDN, and direct data service in a point to multi-point configuration. The protocols are inherently flexible so as to provide Enhanced Bandwidth and quality of service (QOS) via CDMA. Channel concatenation (multi-code modulation) provides a multiplicity of channels. The system utilizes frequency division duplex (FDD) operation so as to double capacity. The system further utilizes scaleable architecture for bandwidth expansion and higher data rate services.

Claims

1. In a spread spectrum wireless system, a method for synchronizing a pseudo-noise sequence comprising the steps of:

determining a range of frequency offsets for a received carrier signal;

centering the range of frequency offsets about a nominal frequency;

determining a frequency step;

correlating a received signal with a psuedo-noise code at each possible phase shift throughout the centered range of frequency offsets at steps equal to the frequency step; and

storing the result of the correlations in a memory along with the corresponding frequencies.

2. A method as in claim 1, wherein iterations are completed by starting at a particular frequency and incrementing by the frequency step.

3. A method as in claim 1, wherein iterations are completed by starting at a particular frequency and decrementing by the frequency step.

4. The method as in claim 1, wherein at least two correlations are performed at each iteration and the result is stored in a media along with the corresponding frequencies.

5. The method as in claim 4, wherein a comparison is made of all stored correlations to choose the maximum correlation and the corresponding frequency.

6. The method as in claim 5, wherein the receiver frequency is set to the chosen corresponding frequency.

7. The method as in claim 6, wherein stored phase settings are retrieved to be used in specifying a second range of phase settings.

8. The method as in claim 7, wherein the phase is iterated through a range and correlations are performed and stored in a memory along with the corresponding phase.

9. The method as in claim 8, wherein a comparison is made of all stored correlations to choose the maximum correlation and the corresponding phase.

10. The method as in claim 8, wherein the receiver is tuned to the corresponding phase.

11. A method as in claim 1, wherein the receiver is iteratively set to all predetermined phase settings.

12. A method as in claim 11, wherein iterations are completed by starting at a particular phase and incrementing by a specified phase amount.

13. A method as in claim 11, wherein iterations are completed by starting at a particular phase and decrementing by a specified phase amount.

14. A method as in claim 11, wherein correlations are performed at each iteration and the result is stored in a memory.

15. In a spread spectrum wireless system, a method for aligning a frame comprising the steps of:

receiving a signal at a receiver; and

performing a correlation on the received signal with a composite code over a symbol period and determining if the result of the correlation is above a predetermined threshold to determine whether the portion of the signal is in a receive or transmit mode;

wherein a correlation above the predetermined threshold level means that the frame is currently in a receive mode, otherwise, the frame is in transmit mode.

16. The method as in claim 15, further comprising the step:

after a mode of a frame is determined, either transmit or receive, confirming frame alignment by calculating high correlations for a first number of occurrences and then calculating low correlations for a second number of occurrences.

17. The method as in claim 16, further comprising the step:

after the second number of low correlations is performed, advancing or retarding pseudo noise code timing.

18. A method for synchronizing a subscriber station receiver to a transmitter of a base station in a wireless local loop comprising the steps of:

tuning the receiver to a specified frequency channel;

switching the receiver to a basestation pilot code division multiple access channel;

synchronizing the receiver to the basestation transmittal;

switching the receiver to a basestation control code division multiple access channel; and

waiting for synchronization message.

19. A method as in claim 18, wherein the synchronization step further comprises the step of recovering pseudo-noise.

20. A method as in claim 18, wherein the synchronization step further comprises the step of adjusting frequency error to zero.

21. A method as in claim 18, wherein the synchronization step further comprises the step of resetting oscillators.

22. A method as in claim 18, wherein the synchronization step further comprises the step of aligning the burst frame.

23. A method as in claim 18, wherein the synchronization step further comprises the step of confirming synchronization.

24. A method as in claim 18, wherein the waiting step further comprises the step of confirming frame alignment.

25. A method as in claim 18, wherein the waiting step further comprises the step of waiting for transmitter synchronization.

26. A method for synchronizing a subscriber station transmitter to a receiver of a base station in a wireless local loop comprising the steps of:

receiving a basestation transmitter synchronization message from a basestation on a first code division multiple access channel;

switching the subscriber station transmitter to a second code division multiple access channel;

establishing a link by setting the subscriber transmitter to a coarse time delay received from the basestation in a coarse offset message and sending a message to the basestation on the second code division multiple access channel;

receiving a signal from the basestation to the subscriber that a link has been established; and

signaling by the subscriber to the basestation confirming that the link is established.

27. A method as in claim 26, further comprising the step of timing synchronization.

28. A method as in claim 26, further comprising the step of stopping the attempt to achieve synchronization if time exceeds a predetermined duration.

29. A method as in claim 26, further comprising the step of returning the subscriber to a basestation control channel if synchronization is achieved within a predetermined duration.

30. A method as in claim 26, further comprising the step of adjusting differential phase and power adjustments.

31. A method as in claim 26, further comprising the step of saving the value of the differential phase and power adjustments upon achieving synchronization.

32. A method as in claim 26, after the transmitter is switched to the pilot channel, including the step of aligning to a radio overhead frame.

33. A method as in claim 26, wherein the link establishment step further comprises transmitting a subscriber radio overhead message.

34. A method as in claim 26, wherein the first code division multiple access channel is a basestation control channel and the second code division multiple access channel is a basestation pilot channel.

35. A method for synchronizing a subscriber station transmitter to a receiver of a base station in a wireless local loop comprising the steps of:

transmitting a basestation transmitter synchronization message to the subscriber station on a first code division multiple access channel;

offsetting receive correlators for a second code division multiple access channel by a median time delay;

transmitting a coarse offset message including a coarse time delay to the subscriber station on the second code division multiple access channel;

receiving a message from the subscriber station;

transmitting a signal to the subscriber indicating that a link has been established; and

receiving a signal from the subscriber confirming the link is established.

36. A method as in claim 35, wherein the first code division multiple access channel is a basestation control channel and the second code division multiple access channel is a basestation pilot channel.