Power control of plural packet data control channels

• US 20040043784A1
• Filed: 06/05/2003
• Published: 03/04/2004
• Est. Priority Date: 06/06/2002
• Status: Active Grant

• Current Assignee: Apple Inc.
• Original Assignee: Via Telecom Co., Ltd.
• Inventors: Czaja, Stanislaw, Yang, Hong Kui
• Granted Patent: US 7,353,039 B2
• Time in Patent Office: Days
• US Class Current: 455/522
• CPC Class Codes: H04W 52/26 using transmission rate or quality of service QoS [Quality of Service]
• CPC Class Codes: H04W 52/32 TPC of broadcast or control channels
• CPC Class Codes: H04W 52/325 Power control of control or pilot channels
• CPC Class Codes: H04W 52/343 taking into account loading or congestion level
• CPC Class Codes: H04W 52/54 Signalisation aspects of the TPC commands, e.g. frame structure

Abstract

A method and apparatus for enabling more efficient use of plural packet data control channels (PDCCHs) that are associated with a common block of one or more packet data channels in a cellular communication system capable of high-speed data communications. Mobile stations (MSs) within a coverage area of a base station (BS) are categorized in accordance with an expected ability to receive signal transmissions, by determining position, transmission path length, reported channel quality, required reverse transmit power, or otherwise. The plural PDCCHs are preferentially associated with different categories of MSs, and are transmitted at different levels of robustness. The most robust PDCCH reaches all served MSs, and another PDCCH is transmitted at a lower robustness for more efficient utilization. Power may be reduced, and/or data density increased, on a less robust PDCCH.

Claims

1. A method of controlling power in a cellular telecommunications system that provides high-speed packet data to a multiplicity of mobile stations (MSs) from a serving base station (BS), the method comprising:

a) evaluating an expected reception quality for a multiplicity of MSs served by a serving BS;

b) categorizing the MSs served by the serving BS into a plurality of reception categories that reflect results of the expected reception quality evaluation;

c) assigning a first one of a plurality of packet data control channels (PDCCHs) preferentially to MSs in a first reception category;

d) transmitting information on the first PDCCH with a first robustness to MSs in the first reception category; and

e) transmitting information on a different second PDCCH at a second robustness lower than the first robustness to MSs of a second reception category, such that more transmit power is attributable to the first PDCCH than to the second PDCCH.

2. The method of claim 1, wherein the plurality of PDCCHs are associated with a single sharable packet data channel.

3. The method of claim 1, wherein the lower robustness of the second PDCCH transmission is at least partly due to transmitting the second PDCCH at a lower power than the first PDCCH.

4. The method of claim 1, further including reducing robustness of the second PDCCH transmission by changing a modulating and/or coding scheme (MCS) for the second PDCCH so as to convey data more densely on the second PDCCH than on the first PDCCH.

5. The method of claim 4, further including modulating and coding symbols for the second PDCCH at a selected one of a plurality of MCS levels that are known to a target MS.

6. The method of claim 5, further comprising blind decoding a message on the second PDCCH at the target MS according to a first MCS, and blind decoding the message according to a second MCS upon failure of decoding according to the first MCS.

7. The method of claim 1, wherein the lower robustness of the second PDCCH transmission is at least partly due to time multiplexing a plurality of messages on the second PDCCH during a period concurrent with a single message transmission on the first PDCCH.

8. The method of claim 1, wherein the lower robustness of the second PDCCH transmission is at least partly due to transmitting the second PDCCH within a smaller Walsh space than the first PDCCH.

9. The method of claim 1, wherein step (a) of evaluating expected reception quality for a particular MS includes evaluating a path length between the serving BS and the particular MS.

10. The method of claim 9, further comprising estimating location parameters for the particular MS.

11. The method of claim 9, further comprising estimating propagation delay for signals between the serving BS and the particular MS.

12. The method of claim 1, wherein step (a) of evaluating expected reception quality for a particular MS includes evaluating a plurality of channel quality indications (CQIs) transmitted to the serving BS by the particular MS.

13. The method of claim 12, further comprising filtering CQIs transmitted to the serving BS by the particular MS to substantially reflect only changes in CQI that persist for about 100 ms.

14. Cellular communication system base station (BS) apparatus for transmitting high-speed data to a multiplicity of users, the apparatus comprising:

a) packet data channel transmission facilities configured to share a packet data channel between a plurality of user transceivers by transmitting different packet data to each of a plurality of distinct user tranceivers on the packet data channel during a common packet transmission period;

b) a plurality of distinct packet control channel (PCC) signal processing paths, including a first PCC and a second PCC;

c) a user transceiver receive evaluation block configured to estimate ability to receive signals for each of a multiplicity of user transceivers assigned to share the packet data channel, and to categorize the user transceivers in a plurality of receive ability categories according to such estimated ability to receive;

d) processing facilities configured to prepare first and second information messages regarding the packet data channel for concurrent transmission on the first and second PCCs, respectively, to a corresponding plurality of user transceivers selected based in part according to receive ability categories of the user transceivers; and

e) robustness control facilities for controlling a second PCC message transmission robustness distinctly from a robustness of a concurrent first PCC message transmission.

15. The BS apparatus of claim 14, wherein the robustness control facilities include a channel power control block for controlling a transmission power of the second PCC distinctly from transmission power applied to the first PCC.

16. The BS apparatus of claim 15, wherein the user transceiver receive evaluation block is configured to estimate ability to receive signals for a particular MS based upon a signal propagation delay estimate for the MS.

17. The BS apparatus of claim 15, wherein the user transceiver receive evaluation block is configured to estimate ability to receive signals for a particular MS based upon signal quality reports transmitted by the particular MS.

18. The BS apparatus of claim 15, wherein the user transceiver receive evaluation block is configured to estimate ability to receive signals for a particular MS based upon a speed estimate for the particular MS.

19. The BS apparatus of claim 14, wherein the robustness control facilities include a data density control block for controlling data density of a message transmitted on the second PCC distinctly from data density of a message transmitted concurrently on the first PCC.

20. The BS apparatus of claim 19, wherein the robustness control facilities further include a channel power control block for controlling a transmission power of the second PCC distinctly from transmission power applied to the first PCC.

21. Cellular communication system mobile station (MS) apparatus for receiving high-speed data from a base station, the apparatus comprising:

a) packet data channel receive facilities configured to receive data received in a selectable portion of a packet data channel;

b) receive processing facilities for processing signals on a plurality of distinct packet control channels (PCCs), including a first PCC and a second PCC, to obtain messages for controlling processing of the packet data channel; and

c) a modulation and/or coding scheme (MCS) selection block for selectably controlling the modulation and/or coding used for the second PCC distinctly from modulation and/or coding used for the first PCC.

22. The MS apparatus of claim 21, wherein the MCS selection block is configured to select a first MCS for blind decoding a particular message received on the second PCC, and to select different second MCS for blind decoding the message if decoding according to the first MCS fails to produce a valid message.

23. The MS apparatus of claim 21, further comprising a block configured to parse previously decoded PCC messages for information regarding an appropriate MCS for a PCC message that has not yet been decoded.

24. A method of controlling power in a cellular telecommunications system that provides high-speed packet data to a multiplicity of mobile stations (MSs) from a serving base station (BS), the method comprising:

a) a step for evaluating an expected reception quality for a multiplicity of MSs served by a serving BS;

b) a step for categorizing the MSs in accordance with results of the reception quality evaluation step;

c) a step for assigning a plurality of packet data control channels (PDCCHs) to MSs in accordance with a reception category; and

d) a step for transmitting information on the plurality of PDCCHs with different robustness depending upon a target MS reception category.