| 摘要 |
A technique for reducing the probability of false alarms leading to responses of terminals (1) to control channel messages in a wireless communication system, false alarms being when a terminal detects and responds to a control channel message when no such message was sent. This is a particular problem in carrier aggregation in LTE when large numbers of carriers may be configured for a terminal. The terminal is expected to blindly search for a number of possible control channel messages from the base station (21, 22, ... 2n) for each carrier, and determine whether such a message has been correctly received by means of a Cyclic Redundancy Check. With a large number of candidates the probability of falsely detecting a message and responding (e.g. with an erroneous uplink transmission causing interference) can be significant. It is assumed that when there is active data transmission, more than one message (or data packet) is likely to be sent to the terminal (1) at any given moment. Thus by making the validity of a control channel message depend on additional conditions being satisfied, the probability of false alarm can be greatly reduced, without otherwise impacting system operation, for example if the terminal (1) only responds if two (or more) messages with particular characteristics are received in the same subframe. |
