Adaptive method for channel assignment in a cellular communication system

• US 6,047,189 A
• Filed: 10/11/1996
• Issued: 04/04/2000
• Est. Priority Date: 10/11/1996
• Status: Expired due to Term

• Current Assignee: Intel Corporation
• Original Assignee: ArrayComm LLC (Ygomi LLC)
• Inventors: Yun, Louis C., Barratt, Craig H., Uhlik, Christopher
• Primary Examiner(s): Bost, Dwayne D.
• Assistant Examiner(s): WYCHE, MYRON
• Application Number:
  US08/729,387
• Time in Patent Office: 1,271 Days
• Field of Search: 455/450, 455/451, 455/452, 455/453, 455/464, 455/509, 455/510, 455/512, 455/513, 455/516, 455/517, 455/423, 455/424, 455/425, 455/522
• US Class Current: 455/452.2
• CPC Class Codes: H04W 52/50 at the moment of starting communication in a multiple access environment
• CPC Class Codes: H04W 72/00 Local resource management
• CPC Class Codes: H04W 72/04 Wireless resource allocation
• CPC Class Codes: H04W 76/10 Connection setup

Abstract

An adaptive method for channel assignment in a cellular multiple access wireless communication system that has a cell station (CS) and a number of subscriber stations augments existing channel assignment protocol and thus is downward compatible with existing time division multiple access (TDMA), frequency division multiple access (FDMA), code division multiple access (CDMA), and spatial division multiple access (SDMA) system protocols. The method adaptively determines the power required for establishing an acceptable quality connection between a subscriber station and the cell station and provides an early warning trial signal for advising existing connections that a new connection is about to be established. The early warning, followed by a pause, provides a basis and a time interval for taking corrective interference action if the trial signal indicates that an unacceptable level of interference will result if the trial connection is established. The early warning signal and associated pause are useful for intracellular and intercellular interference management.

Claims

1. An adaptive method for use in a wireless cellular communication system having a cell station and a plurality of subscriber stations, the method for minimizing interference with any existing connections between the cell station and the subscriber stations by determining an acceptable low power level required for establishing a new connection between a subscriber station and the cell station in the presence of any existing connections, the method comprising:

(a) the subscriber station requiring a new connection transmitting a first signal on the uplink traffic channel designated by the cell station at a prescribed power level;

(b) the subscriber station listening for a second signal transmitted by the cell station on the downlink traffic channel indicating that the cell station received the first signal from the subscriber station requiring a new connection with acceptable quality, and if not received, incrementing the subscriber station transmitting power level by a prescribed amount until the second signal is received thus indicating that the last used transmitting power level is sufficient;

(c) the cell station listening for the first signal transmitted by the subscriber station requiring a new connection and noting the elapsed time between the assignment of the traffic channel to the subscriber station requiring a new connection and the time an acceptable quality first signal was received at the cell station;

(d) the cell station determining an acceptably low cell station transmitting power level for use in communicating with the subscriber station requiring a new connection based on the elapsed time between the assignment of the traffic channel to the subscriber station requiring a new connection and the time an acceptable quality first signal was received at the cell station.

2. The adaptive method of claim 1 wherein the acceptably low power level is determined by computing a function of the subscriber station transmit power level and the subscriber station receiver sensitivity relative to the cell station receiver sensitivity.

3. The method of claim 1 wherein the first and second signals are synchronization signals.

4. The method of claim 1 wherein, in step (b), incrementing the subscriber station transmitting power level by a prescribed amount is performed at prescribed time intervals.

5. The method of claim 1 wherein, in step (c), noting the elapsed time between the assignment of the traffic channel to the subscriber station requiring a new connection and the time an acceptable quality first signal was received is performed by counting the number of prescribed time intervals that have elapsed.

6. An adaptive method for managing interference in a wireless cellular communication system having a plurality of cell stations and a plurality of subscriber stations, when establishing a new connection between a particular cell subscriber and a subscriber station requiring a connection, the method comprising:

(a) establishing a tentative connection on a traffic channel between the particular cell station and the subscriber station requiring a connection;

(b) the particular cell station and the subscriber station transmitting a prescribed test signal, both the particular cell station and the subscriber station using a predetermined acceptably low power level for determining if the tentative connection; and

(c) if so, each station experiencing unacceptable interference levels in other than the tentative connection and recognizing the prescribed test signal, invoking a prescribed protocol for new connection interference management the adaptive method not requiring cell station to cell station communications.

7. The method of claim 6 wherein prescribed test signal is an idle traffic signal.

8. The method of claim 6 wherein the prescribed test signal is a sequence of on-off idle traffic signals.

9. The method of claim 6 wherein the prescribed test signal conveys auxiliary non-user-data information.

10. The method of claim 9 wherein the prescribed test signal conveys message priority information.

11. The method of claim 6 wherein, after the cell station and the subscriber station transmitting a prescribed test signal step, the method further comprises a step for introducing a pause of prescribed duration for allowing any cell station or subscriber station affected by unacceptable interference due to the tentative connection to take corrective action.

12. The method of claim 6 further including steps for adaptively determining a minimum effective power level required for establishing the new connection, the further included steps comprising:

(a) the subscriber station requiring a connection transmitting a first signal on an uplink traffic channel designated by the cell station at a prescribed power;

(b) the subscriber station listening for a second signal transmitted by the cell station on the downlink traffic channel indicating that the cell station received the first signal from the subscriber station requiring a new connection with acceptable quality, and if not received, incrementing the subscriber station transmitting power level by a prescribed amount until the second signal is received with acceptable quality, thus indicating that the last used transmitting power level is sufficient;

(c) the cell station listening for the first signal transmitted by the subscriber station requiring a new connection and noting the time elapsed between the assignment of the traffic channel to the subscriber station requiring a new connection and the time an acceptable quality first signal was received at the cell station;

(d) the cell station computing a cell station acceptably low transmitting power level for use in communicating with the subscriber station requiring a new connection based on the elapsed time between the assignment of the traffic channel to the subscriber station requiring a new connection and the time an acceptable quality first signal was received at the cell station.

13. The method of claim 12 for managing intracellular interference in a wireless cellular communication system further being used for also managing intercellular interference with any existing connections within a neighboring cellular system, the neighboring cellular system recognizing the prescribed test signal and invoking a prescribed interference protocol if an unacceptable level of interference results from the prescribed test signal.

14. The method of claim 12, step (a), wherein the prescribed power level approximately corresponds to a lowest power level at which acceptable quality reception by the CS might be expected.

15. The method of claim 12 where, in step (b), incrementing the subscriber station transmitting power level by a prescribed amount until the cell station first signal is received with acceptable quality, is performed at prescribed time intervals.

16. The method of claim 12 where, in step (c), noting the time elapsed between the assignment of the traffic channel to the subscriber station requiring a new connection and the time an acceptable quality first signal was received, is performed by counting the number of prescribed time intervals that have elapsed.

17. An adaptive method for channel assignment in a cellular wireless communication system having a cell station and at least one subscriber station, the method comprising:

(a) the cell station transmitting a tentative link channel assignment to a subscriber station;

(b) the subscriber station transmitting a first signal at a prescribed power level and on the assigned link channel;

(c) the subscriber station incrementing transmitting power and transmitting the first signal until a first signal of acceptable quality is received in response from the cell station;

(d) the cell station listening for the first signal transmitted by the subscriber station requiring a new connection and noting the elapsed time between the assignment of the traffic channel to the subscriber station requiring a new connection and the time an acceptable quality first signal is received at the cell station; and

(e) the cell station determining a cell station adequate transmitting power level for use in communicating with the subscriber station requiring a new connection based on the elapsed time between the assignment of the traffic channel to the subscriber station requiring a new connection and the time an acceptable quality first signal was received at the cell station;

(f) the cell station transmitting a second signal to the subscriber station using the adequate power level determined in step (e) for indicating to the subscriber station that the transmitting power last used is the power level for the tentative link channel assignment;

(g) both the cell station and the subscriber station transmitting, at the power levels determined in step (e), a second signal on the tentatively assigned link channel for indicating to all stations that might experience interference that a tentative channel assignment has been made for a new connection so that, if an unacceptable level of interference is experienced, each station experiencing unacceptable levels of interference may take action in accordance with a prescribed interference management protocol, otherwise the new connection is established using the determined acceptably low power levels.

18. The method of claim 17 wherein step (a) is in response to a link channel assignment request from a subscriber station.

19. The method of claim 17, step (b), wherein the prescribed power level approximately corresponds to a lowest power level at which acceptable quality reception by the CS might be expected.

20. The method of claim 17 wherein the link channel assignment request is in response to a page from the cell station.

21. The method of claim 17 wherein the first and second signals are synchronizing signals.

22. The method of claim 17 wherein the prescribed test signal is an idle traffic signal.

23. The method of claim 17 wherein the prescribed test signal is a sequence of on-off idle traffic signals.

24. The method of claim 17 further comprising in step (g), after both the cell station and the subscriber station transmitting, pausing for a prescribed duration to allow any station affected by unacceptable interference due to the tentatively assigned connection to take corrective action.

25. The method of claim 17 where, in step (c), the subscriber station incrementing transmitting power increments at prescribed time intervals.

26. The method of claim 17 where, in step (d), noting the elapsed time between the assignment of the traffic channel to the subscriber station requiring a new connection and the time an acceptable quality first signal is received is performed by counting the number of prescribed time intervals that have elapsed.

27. An adaptive method for channel assignment in cellular wireless communication system having a cell station (CS) and a plurality of spatially dispersed personal stations (PSs), the CS for communicating with and coordinating simultaneous separate communications with each of the personal stations, the method comprising:

(a) at a PS that is requesting a connection,

(i) transmitting a link channel establishment request to the CS on a prescribed signaling control channel (SCCH) and at a prescribed power level,

(ii) listening on the SCCH for a CS transmitted link channel assignment assigning a full-duplex traffic channel (TCH), hereinafter called a link channel (LCH),on which a tentative connection is to be made,

(iii) transmitting a synchronization (SYNC) burst on the LCH at a prescribed initial power level and listening for a prescribed time interval on the LCH for a SYNC burst transmitted by the CS in response that indicates that the last SYNC-burst transmitted by the requesting PS has been received with acceptable quality, otherwise repeating, in accordance with a prescribed schedule, the transmitting of the SYNC burst with an incremented power level and listening,

(iv) sending a predetermined new connection message on the tentatively assigned LCH at the transmitter power level last used for transmitting the SYNC burst, for advising any stations that might be affected that a new connection is being initiated, and for allowing any stations affected by the tentative new connection to assess if any interference requires corrective action,

(v) listening on the tentatively assigned LCH for a CS transmitted new connection message for determining if the new connection message transmitted by the CS on the tentatively assigned LCH was received with acceptable interference level quality, and, if the interference level quality is acceptable and no corrective action message is received from the CS, using the tentatively assigned LCH for the connection, otherwise

(vi) transmitting a message to the CS, advising that the interference level is not acceptable and implementing any corrective action instructions from the CS; and

(b) at the CS,

(i) monitoring the SCCH for any PS connection request,

(ii) upon receipt of a PS connection request, selecting a traffic channel as a tentatively assigned LCH,

(iii) transmitting, on the SCCH, the tentatively assigned LCH to the requesting PS,

(iv) listening on the tentatively assigned LCH for the requesting PS transmitting a SYNC burst,

(v) upon receiving a SYNC burst from the requesting PS, transmitting a SYNC burst on the tentatively assigned LCH for advising the requesting PS that the transmitted SYNC burst has been received,

(vi) monitoring the tentatively assigned LCH and all active connections for determining if transmitting a new connection message by the requesting PS causes unacceptable interference and, if unacceptable interference results, taking corrective action in accordance with a prescribed protocol for all active connections, otherwise

(vii) transmitting a new connection message on the tentatively assigned LCH, for advising all stations that a new connection is being initiated and waiting for a prescribed time interval to determine if unacceptable interference from the transmission of the new connection message, and, if no unacceptable interference has occurred, making the tentatively assigned LCH connection the assigned connection, and otherwise

(viii) taking corrective action in accordance with a prescribed protocol for all active connections.

28. The method of claim 27 wherein the link channel assignment is in response to a page from the cell station.

29. The method of claim 27 further comprising, after step (a)(iv) and after step (b)(vii), pausing for a prescribed duration to allow any station affected by unacceptable interference due to the tentatively assigned connection to take corrective action.

30. The method of claim 27 wherein the communication system is a personal handy phone system substantially as described in the Association of Radio Industries and Businesses (ARIB) Preliminary Standard, Version 2, RCR STD-28.

31. The method of claim 27 wherein the predetermined new connection message is an idle traffic signal.

32. The method of claim 27 wherein the prescribed test signal is a sequence of on-off idle traffic signals.