Communication system

Abstract

A communication method which uses a plurality of sub-carriers, the method includes receiving uplink data from one or more user devices and generating corresponding ACK/NACK messages for the received data, forming control data defining an allocation of the sub-carriers for each of a plurality of user devices, transmitting the control data to the user devices, determining the sub-carriers to be used to transmit the ACK/NACK messages to a user device in dependence upon sub-carriers allocated to that user device, and transmitting the ACK/NACK messages to the corresponding user devices using the determined sub-carriers, wherein the control data for each user device is transmitted over a control channel using a first subset of the plurality of sub-carriers and the ACK/NACK messages for each user device are transmitted over an ACK/NACK channel that is separate from the control channel using a second different subset of the plurality of sub-carriers.

1 . A communication method which uses a plurality of sub-carriers, the method comprising:
 receiving uplink data from one or more user devices and generating corresponding ACK/NACK messages for the received data;   forming control data defining an allocation of said sub-carriers for each of a plurality of user devices;   transmitting said control data to said user devices;   determining the sub-carriers to be used to transmit the ACK/NACK messages to a user device in dependence upon sub-carriers allocated to that user device; and   transmitting said ACK/NACK messages to the corresponding user devices using the determined sub-carriers;   wherein the control data for each user device is transmitted over a control channel using a first subset of said plurality of sub-carriers and the ACK/NACK messages for each user device are transmitted over an ACK/NACK channel that is separate from said control channel using a second different subset of said plurality of sub-carriers.   
     
     
         2 . A method according to  claim 1 , further comprising grouping the sub-carriers into a sequence of chunks and wherein said control data is operable to allocate one or more chunks of sub-carriers to each of said plurality of user devices. 
     
     
         3 . A method according to  claim 2 , wherein said forming forms control data that allocates said one or more chunks of sub-carriers to each of said user devices for use in transmitting uplink data. 
     
     
         4 . A method according to  claim 3 , wherein said generating generates an ACK/NACK message for the data received on each chunk of sub-carriers. 
     
     
         5 . A method according to  claim 4 , wherein said transmitting transmits each ACK/NACK message in a respective ACK/NACK channel, each formed using a respective one or more sub-carriers from said second subset. 
     
     
         6 . A method according to  claim 1 , wherein said forming forms two types of control data, one for user devices that are scheduled to receive downlink data and one for user devices that are scheduled to transmit uplink data. 
     
     
         7 . A method according to  claim 1 , further comprising forming respective control data for each user device scheduled to transmit and/or receive data in a current sub-frame and transmitting the respective control data to the corresponding user device over a channel that is dedicated to the user device. 
     
     
         8 . A method according to  claim 1 , wherein said communication system uses a plurality of sub-bands, each of which comprises sub-carriers arranged in a sequence of chunks, and wherein the method generates respective control data for sub-carrier allocation in each sub-band. 
     
     
         9 . A method according to  claim 1 , wherein a separate control channel is provided for each user device scheduled in a current sub-frame and wherein a maximum number of user devices can be scheduled within the current sub-frame. 
     
     
         10 . A communication method which uses a plurality of sub-carriers, the method comprising:
 receiving control data defining an allocation of said sub-carriers;   transmitting uplink data;   determining the sub-carriers on which ACK/NACK messages are to be received in dependence upon the allocated sub-carriers; and   receiving ACK/NACK messages for the transmitted uplink data using the determined sub-carriers:   wherein said control data is received over a control channel using a first subset of said plurality of sub-carriers and said ACK/NACK messages are received on an ACK/NACK channel that is separate from said control channel using a second different subset of said plurality of sub-carriers.   
     
     
         11 . A method according to  claim 10 , wherein said received control data identifies one or more chunks of sub-carriers to be used for transmitting said uplink data and wherein said receiving receives an ACK/NACK message for the uplink data transmitted on each chunk of sub-carriers. 
     
     
         12 . A method according  claim 10 , wherein said receiving receives said control data over a channel that is dedicated to the user device. 
     
     
         13 . Computer implementable instructions for causing a programmable computer device to perform the method of  claim 1 . 
     
     
         14 . A communications node which is operable to communicate with a plurality of user devices using a plurality of sub-carriers, the communications node comprising:
 a receiver operable to receive uplink data from one or more user devices and operable to generate corresponding ACK/NACK messages for the received data;   a controller operable to form control data defining an allocation of said sub-carriers for each of a plurality of user devices and to determine the sub-carriers to be used to transmit the ACK/NACK messages to a user device in dependence upon the sub-carriers allocated to that user device; and   a transmitter operable to transmit said control data to said user devices and to transmit said ACK/NACK messages to the corresponding user devices using the determined sub-carriers;   wherein said transmitter is operable to transmit said control data to each user device over a control channel using a first subset of said plurality of sub-carriers and to transmit said ACK/NACK messages on an ACK/NACK channel that is separate from said control channel using a second different subset of said plurality of sub-carriers.   
     
     
         15 . A user device which is operable to communicate with a communication node which is operable to communicate with a plurality of user devices using a plurality of sub-carriers, the user device comprising:
 a receiver operable to receive control data defining an allocation of said sub-carriers;   a transmitter operable to transmit uplink data; and   a controller operable to determine the sub-carriers on which ACK/NACK messages are to be received in dependence upon the allocated sub-carriers;   wherein said receiver is also operable to receive ACK/NACK messages for the transmitted uplink data using the determined sub-carriers;   wherein said receiver is operable to receive said control data over a control channel using a first subset of said plurality of sub-carriers and to receive said ACK/NACK messages on an ACK/NACK channel that is separate from said control channel using a second different subset of said plurality of sub-carriers.