Communication of control information in wireless communication systems

• US 20040013103A1
• Filed: 06/26/2002
• Published: 01/22/2004
• Est. Priority Date: 06/27/2001
• Status: Active Grant

• Current Assignee: Ericsson AB (Telefonaktiebolaget LM Ericsson)
• Original Assignee: Nortel Networks Limited (Nortel Networks Corporation)
• Inventors: Zhang, Hang, Fong, Mo-Han
• Granted Patent: US 7,492,788 B2
• Time in Patent Office: Days
• US Class Current: 370/345
• CPC Class Codes: H04L 1/0026 Transmission of channel quality indication
• CPC Class Codes: H04L 1/16 in which the return channel carries supervisory signals, e.g. repetition request signals
• CPC Class Codes: H04L 2001/0093 Point-to-multipoint
• CPC Class Codes: H04W 36/16 Performing reselection for specific purposes
• CPC Class Codes: H04W 52/146 Uplink power control
• CPC Class Codes: H04W 52/267 taking into account the information rate
• CPC Class Codes: H04W 52/285 taking into account the mobility of the user
• CPC Class Codes: H04W 52/60 using different transmission rates for TPC commands
• CPC Class Codes: H04W 72/23 in the downlink direction of a wireless link, i.e. towards a terminal

Abstract

A wireless system has a high rate data channel for time multiplexed communications to multiple mobile stations (MSs). Control channels include a forward link common power control channel and reverse link feedback channels for pilot, forward channel quality, and data acknowledgements from each MS. An MS can have an active state for data communications, for which these control channels are used at the full (time slot) rate, or a control hold state, in which acknowledgements are not needed and the others of these control channels can be shared among a plurality of MSs in the control hold state and each using a reduced rate such as ½, ¼, or ⅛ of the full rate. The arrangement can support an increased number of active MSs, facilitating an increased total throughput on the high rate data channel, without increasing system resources for the control channels.

Claims

1. A method of communicating control information in a wireless communications system, comprising the steps of:

in a first state of a terminal for traffic communication with the terminal, communicating control information with the terminal at a first rate;

in a second state of the terminal, communicating at least some of said control information at a second rate which is less than the first rate; and

sharing a communication channel for the control information at the second rate for communicating control information among a plurality of terminals in the second state.

2. A method as claimed in claim 1 wherein the control information communicated at the second rate in the second state of the terminal comprises power control information for the terminal.

3. A method as claimed in claim 1 wherein the control information communicated at the second rate in the second state of the terminal comprises a pilot from the terminal.

4. A method as claimed in claim 1 wherein the control information communicated at the second rate in the second state of the terminal comprises a channel quality indication from the terminal.

5. A method as claimed in claim 1 wherein the control information communicated at the second rate in the second state of the terminal comprises a pilot and a channel quality indication from the terminal.

6. A method as claimed in claim 1 wherein the second rate is a sub-multiple of the first rate.

7. A method as claimed in claim 1 wherein the control information is communicated in time slots of at least one communication channel of the system, wherein control information at the first rate is communicated with a terminal in the first state in each time slot on the communication channel, and wherein control information at the second rate is communicated with a terminal in the second state in only one of every N time slots on the communication channel, where N is an integer greater than one.

8. A method as claimed in claim 1 and including the step of switching between the first and second states of the terminal in dependence upon whether or not a data buffer for traffic communication with the terminal is empty.

9. A method of communicating control information in a wireless communications system having forward and reverse channels for communicating traffic and control information with a plurality of terminals, the forward channels including a time division multiplexed (tdm) channel for communicating traffic in respective time slots to respective terminals, and the reverse channels including channels for communicating pilot and feedback information from the terminals, the method comprising the steps of:

in a first state of a terminal for receiving traffic for the terminal in respective time slots of the tdm channel, communicating said pilot and feedback information at a first rate;

in a second state of the terminal, communicating said pilot and feedback information at a second rate which is less than the first rate; and

sharing the channels for communicating said pilot and feedback information at the second rate among a plurality of terminals in the second state.

10. A method as claimed in claim 9 wherein the first rate is equal to a rate of said time slots and the second rate is ½

, ¼

, or ⅛

of the first rate.

11. A method as claimed in claim 10 wherein the forward channels include a power control channel for controlling, at the first rate, power on the reverse channels of a respective terminal in the first state, the method further comprising the step of using the power control channel for controlling, at the second rate, power on the reverse channels of a plurality of terminals in the second state.

12. A method as claimed in claim 9 wherein the forward channels include a control channel for identifying, for each time slot of the tdm channel, a terminal to which traffic in the time slot is being communicated, and the terminals monitor said control channel at said first rate in both the first and second states.

13. A method as claimed in claim 12 and including the step of switching a terminal from the second state to the first state in response to identification of said terminal on said control channel.

14. A method as claimed in claim 9 and including the step of switching between the first and second states of the terminal in dependence upon whether or not a data buffer, for traffic communication with the terminal via the tdm channel, is empty.

15. A terminal for use in a wireless communications system, the terminal being operable in a first state to receive traffic for the terminal in respective time slots of a tdm channel of the system and to communicate pilot and feedback information at a first rate, and being operable in a second state to communicate said pilot and feedback information at a second rate which is less than the first rate, the terminal further being operable in the first and second states to monitor a control channel of the system to identify, for each time slot of the tdm channel, traffic in the time slot communicated to the terminal, and in response to such identification in the second state to switch to the first state.

16. A terminal as claimed in claim 15, the terminal being further operable in said first state to receive and respond to power control information at the first rate and in said second state to receive and respond to power control information at the second rate.

17. Apparatus for use in a wireless communications system having forward and reverse channels for communicating traffic and control information with a plurality of terminals, the forward channels including a time division multiplexed (tdm) channel for communicating traffic in respective time slots to respective terminals, and the reverse channels including channels for communicating pilot and feedback information from the terminals, wherein the apparatus is operable to receive said pilot and feedback information from each of a plurality of terminals in a first state at a first rate, and to receive said pilot and feedback information from each of a plurality of terminals in a second state, at a second rate which is less than the first rate, via a channel shared by said plurality of terminals in the second state.

18. Apparatus as claimed in claim 17 and being further operable to supply power control information, via a shared power control channel, at the first rate to terminals in said first state and at the second rate to terminals in said second state.

19. A method for transmitting control information from a network apparatus to a plurality of mobile stations via a common control channel, the method comprising:

transmitting control information to a first set of mobile stations at a first rate of transmission via the common control channel; and

transmitting control information to a second set of mobile stations at a second rate of transmission via the common control channel, the second rate of transmission being less than the first rate of transmission.

20. A method according to claim 19, wherein the common control channel is a common power control channel.

21. A wireless communications system comprising:

first and second sets of mobile stations; and

an apparatus that operates to transmit control information to, and/or to receive control information from, the first and second sets of mobile stations at respective first and second rates of transmission via a shared control channel, the second rate of transmission being less than the first rate of transmission.

22. A wireless communications system as claimed in claim 21 wherein the shared control channel comprises a power control channel for controlling power of the mobile stations.