Process and receiver for interference cancellation of interfering base stations in a synchronized OFDM system
View Patent ↗A process and receiver for canceling interference generated by a set interference base stations in a synchronized OFDM communication system and receiver in a User Equipment comprising a set of Nrx antennas. The process and receiver that cancels interference generated by a set of base stations performs OFDM demodulation on a receiver signal for each antenna of a user equipment (UE). The process and receiver also monitors each UE antenna for pilot signals generated by nearby base stations. Then the process or receiver extracts the pilot signals and establishes a list of existing base station antennas. The channel power of any interfering antennas is measured and then the Nrx-N most powerful antenna is selected. The process or receiver then performs a joint detection of the N useful Data Symbols (UDS), together with the (Nrx-N) Interfering Data Symbols (IDS) that are demodulated by demodulation blocks. Thus, after being detected, the Nrx-N most powerful IDSs can be encoded and re-injected into a cancellation loop.
1. A process for canceling interference generated by a set interference base stations in a synchronized OFDM communication system that is received in a User Equipment comprising a set of Nrx antennas, the process comprising:
performing an OFDM demodulation of the received signal from each Nrx antenna of said UE;
monitoring, on each Nrx antenna of said UE, pilot signals generated by one or more present base stations;
extracting said pilot signals and establishing a list of existing base station antennas;
measuring a channel power of one or more interfering antennas of the set of Nrx antennas;
selecting the Nrx-N antennas receiving the most powerful interfering channels;
performing a joint detection of N Useful Data Symbol (UDS) streams and (Nrx-N) Interfering Data Symbol (IDS) streams that were demodulated by OFDM demodulation blocks in the User Equipment.
2. The process according to claim 1 , further comprising:
decoding the IDS streams by a joint decoder into decoded IDS symbols;
reinjecting the decoded IDS symbols in a cancellation loop prior to the joint decoder so as to cancel interference of the Nrx-N most powerful interfering channels.
3. The process according to claim 1 , wherein the joint decoder is a sphere decoder.
4. The process according to claim 1 , wherein the joint decoder is a linear equalizer.
5. The process according to claim 1 , wherein the joint decoder is a maximum likelihood decoder.
6. A receiver for a synchronous OFDM cellular system comprising:
a set of Nrx OFDM demodulators associated to a set of Nrx antennas, the OFDM demodulators adapted to perform time and frequency synchronization, cyclic prefix discard and IFFT conversion of Nrx data streams;
channel estimation and controller blocks configured to estimate the channels associated to each of the Nrx data streams received through the set of Nrx antennas and originating from base stations belonging to said OFDM cellular system, the controller block further configured to select N useful data streams and Nrx-N most powerful interfering data streams from the Nrx data streams, the controller block further comprising a control line;
a joint decoder, being controlled via the control line from the controller block, configured to
perform joint detection of both the selected N useful data streams and Nrx-N most powerful interference data streams.
7. The receiver according to claim 6 , further configured to re-encode symbols in the detected interference data streams so as to in-inject them in an interference cancellation loop.
8. The receiver according to claim 6 , wherein the joint decoder is a sphere decoder.
9. The receiver according to claim 6 , wherein the joint decoder is a linear equalizer.
10. The receiver according to claim 6 , wherein the joint decoder is a maximum likelihood decoder.
11. User equipment for an OFDM cellular system comprising the receiver of claim 6 .
12. The user equipment according to claim 11 , wherein the user equipment complies with a LTE standard.