Method for power control in a TDMA spread spectrum communication system

• US 5,648,955 A
• Filed: 06/07/1995
• Issued: 07/15/1997
• Est. Priority Date: 11/01/1993
• Status: Expired due to Term

• Current Assignee: Intel Corporation
• Original Assignee: Omnipoint Corp. (Deutsche Telekom AG)
• Inventors: Scott, Logan, Jensen, Ryan N., Williams, Claude M.
• Primary Examiner(s): Chin, Wellington
• Assistant Examiner(s): VU, HUY DUY
• Application Number:
  US08/480,898
• Time in Patent Office: 769 Days
• Field of Search: 370/13, 370/17, 370/18, 370/95.1, 370/95.3, 370/110.1, 455/38.3, 455/63, 455/68, 455/69, 455/133, 455/134, 455/135, 455/136, 455/67.1, 455/67.3, 455/70, 455/115, 455/127, 379/58, 379/59, 379/60, 379/63, 375/200, 375/267
• US Class Current: 370/252
• CPC Class Codes: G10L 19/012 Comfort noise or silence coding
• CPC Class Codes: H04B 7/0805 with single receiver and antenna switching H04B7/0822 takes precedence
• CPC Class Codes: H04B 7/10 Polarisation diversity; Directional diversity
• CPC Class Codes: H04B 7/2618 using hybrid code-time division multiple access [CDMA-TDMA]
• CPC Class Codes: H04B 7/2643 using time-division multiple access [TDMA] H04B7/2615, H04B7/2618 take precedence
• CPC Class Codes: H04B 7/2668 Arrangements for Wireless Code-Division Multiple Access [CDMA] System Synchronisation, for code acquisition H04B1/7075, for code tracking H04B1/7085
• CPC Class Codes: H04L 1/0002 by adapting the transmission rate
• CPC Class Codes: H04L 1/0025 Transmission of mode-switching indication
• CPC Class Codes: H04L 1/20 using signal quality detector
• CPC Class Codes: H04L 47/50 Queue scheduling
• CPC Class Codes: H04L 47/522 Dynamic queue service slot or variable bandwidth allocation
• CPC Class Codes: H04L 47/6215 Individual queue per QOS, rate or priority
• CPC Class Codes: H04L 49/90 Buffering arrangements
• CPC Class Codes: H04L 49/901 using storage descriptor, e.g. read or write pointers
• CPC Class Codes: H04W 24/10 Scheduling measurement reports ; Arrangements for measurement reports
• CPC Class Codes: H04W 36/0058 Transmission of hand-off measurement information, e.g. measurement reports
• CPC Class Codes: H04W 36/18 for allowing seamless reselection, e.g. soft reselection
• CPC Class Codes: H04W 36/30 by measured or perceived connection quality data
• CPC Class Codes: H04W 36/36 by user or terminal equipment
• CPC Class Codes: H04W 52/04 TPC
• CPC Class Codes: H04W 52/08 : Closed loop power control
• CPC Class Codes: H04W 52/24 : using SIR [Signal to Interference Ratio] or other wireless path parameters
• CPC Class Codes: H04W 52/36 : with a discrete range or set of values, e.g. step size, ramping or offsets
• CPC Class Codes: H04W 52/362 : Aspects of the step size
• CPC Class Codes: H04W 52/367 : Power values between minimum and maximum limits, e.g. dynamic range
• CPC Class Codes: H04W 52/38 : TPC being performed in particular situations
• CPC Class Codes: H04W 52/40 : during macro-diversity or soft handoff
• CPC Class Codes: H04W 56/00 : Synchronisation arrangements
• CPC Class Codes: H04W 72/044 : based on the type of the allocated resource
• CPC Class Codes: H04W 72/0446 : Resources in time domain, e.g. slots or frames
• CPC Class Codes: H04W 72/20 : Control channels or signalling for resource management
• CPC Class Codes: H04W 74/06 : using polling
• CPC Class Codes: H04W 76/10 : Connection setup
• CPC Class Codes: H04W 8/04 : Registration at HLR or HSS [Home Subscriber Server]
• CPC Class Codes: H04W 92/12 : between access points and access point controllers

Abstract

A simple and flexible over-air protocol for use with a mobile telephone system, having hand-held telephones in a microcell or other type of cellular communication system. A method in which user stations communicate with one or more base stations to place and receive telephone calls, in which the user stations are provided a secure voice or data link and have the ability to handoff calls between base stations while such calls are in progress. Each base station has a set of "air channels" to which it transmits in sequence. The air channels supported by each base station are called that base station'"'"'s "polling loop". A user station receives general polling information on an unoccupied air channel, transmits responsive information to the base station, and awaits acknowledgment from the base station. Each base station may therefore simultaneously maintain communication with as many user stations as there are air channels in its polling loop. The ability of a user station to communicate on any unoccupied air channel makes the protocol air-channel agile, while the stability of user station and base station clocks may define air channels, gaps, and minor frames.

Claims

1. In a time division multiple access communication system having a base station and a plurality of user stations, a method for closed loop power control comprising the steps of

transmitting with a power level, in a designated minor time frame of a major time frame, a pulse signal from a user station to a base station,

receiving said pulse signal at said base station,

measuring an indication of link quality based on said pulse signal,

transmitting, in said designated minor time frame of said major time frame and following said pulse signal, a first spread spectrum signal from said base station to said user station, said first spread spectrum signal comprising a power adjustment command,

receiving said first spread spectrum signal at said user station,

adjusting said power level at said user station in response to said power adjustment command,

transmitting, in said designated minor time frame of said major time frame and following said first spread spectrum signal, a second spread spectrum signal from said user station to said base station, and

receiving said second spread spectrum signal at said base station.

2. The method of claim 1 wherein said step of measuring an indication of link quality comprises the step of measuring at least one of a received power of said pulse signal, an envelope of said pulse signal, and a phase of said pulse signal.

3. The method of claim 1 wherein said indication of link quality comprises a signal-to-noise ratio.

4. The method of claim 1 wherein said indication of link quality comprises a degree of measured error.

5. The method of claim 1 wherein said power adjustment command comprises a plurality of command bits.

6. The method of claim 1 wherein said power adjustment command comprises one of a discrete set of predefined command values.

7. The method of claim 1 wherein said step of adjusting said power level comprises the step of increasing or decreasing said power level by a relative amount indicated by said power adjustment command.

23. The method of claim 1 wherein said pulse signal, said first spread spectrum signal, and said second spread spectrum signal are each transmitted over the same frequency band.

8. A method for closed loop power control in a time division multiple access communication system, comprising the steps of

transmitting at periodic intervals a control pulse from a user station to a base station, said base station capable of communicating with a plurality of user stations using time division multiplexing,

receiving said control pulse at said base station,

calculating a received signal strength indication in response to each control pulse,

transmitting, after each control pulse and within a predetermined time interval, a spread-spectrum forward link communication message from said base station to said user station, said spread-spectrum forward link communication message comprising a power adjustment command,

receiving said spread-spectrum forward link communication message including said power adjustment command at said user station,

transmitting, after receiving said spread-spectrum forward link communication message from said base station, a spread-spectrum reverse link communication message from said user station to said base station, using a power level selected in response to said power adjustment command, and

receiving said spread-spectrum reverse link communication message at said base station.

9. The method of claim 8 wherein said power level is offset by a relative amount according to said power adjustment command from a previous power level.

10. The method of claim 8 wherein said power adjustment command comprises one of a discrete set of predefined command values.

24. The method of claim 8 wherein said control pulse, said spread-spectrum forward link communication message, and said spread-spectrum reverse link communication message are all transmitted over the same frequency band.

25. The method of claim 8 wherein said predetermined time interval is of a duration short enough to counteract small scale multipath fading effects and propagation shadow effects.

26. The method of claim 8 wherein said predetermined time interval is less than 500 microseconds.

11. A method for closed loop power control in a spread spectrum, time division multiple access communication system, comprising the steps of

monitoring at a base station a received strength of a user station signal periodically transmitted from a user station, said base station capable of communicating over a designated frequency band with a plurality of user stations using time division multiplexing,

transmitting from said base station a base-to-user spread spectrum message immediately following said user station signal, said base-to-user spread spectrum message comprising a power adjustment command, and

receiving at said base station, within a predetermined time interval, a user-to-base spread spectrum message immediately following said base-to-user spread spectrum message, said user-to-base spread spectrum message being transmitted with a power level set at said user station in response to said power adjustment command.

12. The method of claim 11 wherein said user station signal, said base-to-user spread spectrum message, and said user-to-base spread spectrum message are each transmitted over the same frequency band.

13. The method of claim 11 wherein said user station comprises a spread spectrum code.

14. The method of claim 11 wherein said power adjustment command comprises one of a discrete set of predefined command values.

27. The method of claim 11 wherein said user station signal, said base-to-user spread spectrum message, and said user-to-base spread spectrum message are all transmitted over said designated frequency band.

28. The method of claim 11 wherein said predetermined time interval is of a duration short enough to counteract small scale multipath fading effects and propagation shadow effects.

29. The method of claim 11 wherein said predetermined time interval is less than 500 microseconds.

15. A method for closed loop power control in a time division multiple access communication system, comprising the steps of

transmitting, during each minor time frame of a major time frame in which any of a plurality of user stations is in established communication with a base station, a control pulse from a corresponding one of said user stations to said base station,

receiving said control pulse from each of said user stations at said base station,

transmitting, in response to each of said control pulses and within the same minor time frame of the same major time frame, a power adjustment command from said base station to the user station which sent the control pulse, said power adjustment command based on a received signal quality of said control pulse,

receiving said power adjustment command at the user station which sent the control pulse,

adjusting a power level at the user station which sent the control pulse,

transmitting, in the same minor time frame and same major time frame as said power adjustment command, a spread spectrum signal from the user station which sent the control pulse to said base station, and

receiving said spread spectrum signal at said base station.

16. The method of claim 15 wherein said control pulse comprises a plurality of chips.

30. The method of claim 15 wherein said control pulse, said power adjustment command, and said spread spectrum signal are all transmitted over the same frequency band.

17. A method for power control in a time division multiple access communication system, comprising the steps of:

transmitting, over a designated frequency band and in a minor time frame of each one of a series of major time frames, a spread-spectrum user station signal from a user station to a base station,

receiving said spread-spectrum user station signal at said base station,

transmitting, within a predetermined interval following said spread-spectrum user station signal and over said designated frequency band, a spread-spectrum base station signal from said base station to said user station, said spread-spectrum base station signal comprising a power adjustment command,

receiving said spread-spectrum base station signal at said user station, and

adjusting a transmission power at said user station in response to said power adjustment command.

18. The method of claim 17 wherein said predetermined interval is less than 500 microseconds.

19. The method of claim 17 wherein said predetermined interval is less than a remainder of said minor time frame.

20. The method of claim 17 further comprising the step of selecting at least one base station antenna from among a plurality of base station antennas in response to receiving said spread-spectrum user station signal at said base station.

21. The method of claim 20 wherein said selected at least one base station antenna is used for both transmitting to and receiving from said user station.

22. The method of claim 17 further comprising the step of transmitting, in said minor time frame and over said designated frequency band, a second spread-spectrum user station signal from said user station to said base station.