A receiver for a telecommunications system in which a data signal is transmitted using a closed loop transmit diversity system and a pilot signal is transmitted using a space time transmit diversity system, the receiver comprising an equalizer for equalising a signal received by the receiver, wherein the equalizer is configured to produce an equalized signal in which effects caused by a propagation channel through which the data signal was transmitted are alleviated, the receiver further comprising a processor for processing the equalized received signal to recover the pilot signal.
1. A receiver for a telecommunications system in which a data signal is transmitted using a closed loop transmit diversity system and a pilot signal is transmitted using a space time transmit diversity system through two different channels H 1 and H 2 , the receiver comprising:
a single equalizer for equalizing a signal received by the receiver, which signal contains the pilot signal and the data signal,
wherein the equalizer is configured to produce an equalized signal in which effects caused by a propagation channel, H, through which the data signal was transmitted are alleviated, wherein the propagation channel H is a combination of channels H 1 and H 2 ,
a despreading and descrambling unit for generating, from the equalized signal, an improperly equalized version of the pilot signal which includes combined pilot signals received from at least two transmit antennas of the space time transmit diversity system through channels H 1 and H 2 , and equalized according to the propagation channel H, and
a processor for processing the equalized signal to recover the pilot signal,
wherein the processor is configured to recover the pilot signal by modifying the improperly equalized version of the pilot signal by reference to a known pilot signal.
2. A receiver according to claim 1 wherein the improperly equalised version of the pilot signal is a symbol-level signal.
3. A receiver according to claim 1 wherein the processor is configured to recover the pilot signal by processing a received chip-level signal.
4. A receiver for a telecommunications system in which a data signal is transmitted using a closed loop transmit diversity system and a pilot signal is transmitted using a space time transmit diversity system through two different channels H 1 and H 2 , the receiver comprising:
a single equalizer for equalizing a signal received by the receiver, which signal contains the pilot signal and the data signal, wherein the equalizer is configured to produce an equalized signal in which effects caused by a propagation channel, H, through which the data signal was transmitted are alleviated, wherein the propagation channel H is a combination of channels H 1 and H 2 ,
a despreading and descrambling unit for generating, from the equalized signal, an improperly equalized version of the pilot signal which includes combined pilot signals received from at least two transmit antennas of the space time transmit diversity system through channels H 1 and H 2 , and equalized according to the propagation channel H, and
a processor for processing the equalized signal to recover the pilot signal,
wherein the processor is configured to separate contributions of the at least two transmit antennas to the improperly equalized version of the pilot signal.
5. A method of recovering a pilot signal which has been transmitted using a space time diversity system through two different channels H 1 and H 2 with a data signal which has been transmitted using a closed loop transmit diversity system, the method comprising:
receiving a signal containing the pilot signal and the data signal,
equalizing the received signal using an equalizer which is configured to produce an equalized signal in which effects caused by a propagation channel, H, through which the data signal was transmitted are alleviated, wherein the propagation channel H is a combination of channels H 1 and H 2 ,
despreading and descrambling the equalized signal to generate an improperly equalized version of the pilot signal which includes combined pilot signals received from at least two transmit antennas of the space time transmit diversity system through channels H 1 and H 2 , and equalized according to the propagation channel H, and
modifying the improperly equalized version of the pilot signal by reference to a known pilot signal to recover the pilot signal.
6. A method according to claim 5 wherein the improperly equalised version of the pilot signal is a symbol-level signal.
7. A method according to claim 5 further comprising processing a received chip-level signal.
8. A method of recovering a pilot signal which has been transmitted using a space time diversity system through two different channels H 1 and H 2 with a data signal which has been transmitted using a closed loop transmit diversity system, the method comprising:
receiving a signal containing the pilot signal and the data signal,
equalizing the received signal using an equalizer which is configured to produce an equalized signal in which effects caused by a propagation channel, H, through which the data signal was transmitted are alleviated, wherein the propagation channel H is a combination of channels H 1 and H 2 ,
despreading and descrambling the equalized signal to generate an improperly equalized version of the pilot signal which includes combined pilot signals received from at least two transmit antennas of the space time transmit diversity system through channels H 1 and H 2 , and equalized according to the propagation channel H, and
separating contributions of the at least two transmit antennas to the improperly equalized version of the pilot signal to recover the pilot signal.