Interference cancellation with a time-sliced architecture
View Patent ↗Example embodiments include methods of interference cancellation at NodeB receivers of baseband antenna signals including physical channels. The methods include canceling interference from a received baseband antenna signal by removing a reconstructed baseband signal from the processed received baseband antenna signal. The processed reconstructed baseband signal includes users whose physical data channel signals were successfully decoded. Methods also include removing interference from a received baseband signal to form an interference cancelled baseband signal that will be processed by the receiver. The interference cancelled baseband signal is the received baseband antenna signal minus users' signal interference contributions whose demodulated physical data channel signals have a determined user symbol energy value that exceeds a threshold. Methods further include removing interference from a user's signal to be error corrected. The interference is symbol interference from an earlier successfully decoded user's symbols. The user symbol interference is determined by cross correlations.
1. A method of decoding physical channels, comprising:
receiving a multi-user baseband antenna signal at a receiver, the multi-user baseband antenna signal including received physical channel transmissions;
demodulating received physical data channel transmissions symbol by symbol;
demodulating previous interference cancelled physical data channel transmissions of a delayed multi-user interference cancelled baseband antenna signal, symbol by symbol; and
combining the demodulated received physical data channel transmissions with the demodulated previous interference cancelled physical data channel transmissions.
2. The method of claim 1 , further comprising:
error correcting the combined demodulated transmissions; and
decoding the error corrected transmissions.
3. The method of claim 1 , wherein each symbol time period for the received physical data channel transmissions is divided into equal time slices and each user is assigned a single time slice per symbol.
4. The method of claim 1 , wherein each symbol time period for the previous interference cancelled physical data channel transmissions is divided into equal time slices based on the number of users, and each user is assigned a single time slice per symbol.
5. The method of claim 1 , wherein the method increases the decoding success for previously unsuccessfully decoded users.
6. The method of claim 1 , wherein the receiving, demodulation, and combining steps are repeated for newly received multi-user baseband antenna signals.
7. The method of claim 1 , wherein the step of demodulating the received physical data channel transmissions, further includes:
at least partially despreading and maximal ratio combining the multi-path components of the received multi-user baseband antenna signal.
8. The method of claim 1 , wherein the step of demodulating the previous interference cancelled physical data channel transmissions, further includes:
at least partially despreading and maximal ratio combining the multi-paths components of the delayed multi-user interference cancelled baseband antenna signal.
9. The method of claim 1 , wherein the physical data channels are enhanced dedicated physical data channels (E-DPDCHs).
10. The method of claim 1 , further comprising:
demodulating received physical control channel transmission;
demodulating previous interference cancelled physical control channel transmissions of the delayed multi-user interference cancelled baseband antenna signal; and
combining the demodulated received physical control channel transmissions with the demodulated previous interference cancelled physical control channel transmissions.
11. The method of claim 10 , wherein the step of demodulating the received physical control channel transmissions, further includes:
at least despreading and maximal ratio combining the multi-path components of the received multi-user baseband antenna signal.
12. The method of claim 10 , wherein the step of demodulating the previous interference cancelled physical control channel transmissions, further includes:
at least despreading and maximal ratio combining the multi-paths components of the delayed multi-user interference cancelled baseband antenna signal.
13. The method of claim 10 , wherein the physical control channels are an enhanced dedicated physical control channels (E-DPCCHs).
14. The method of claim 1 , wherein the error correcting step further includes,
Hybrid Automatic Repeat Request (HARQ) combining multiple physical data channel transmissions of a same transport block; and
the decoding steps further includes, decoding the output of the HARQ combiner.
15. The method of claim 1 , wherein the receiving step further includes receiving channel estimates and multi-path delay profiles to assist in the reconstruction of the signal.
16. The method of claim 1 , further comprising:
receiving a multi-user baseband antenna signal at a receiver, the multi-user baseband antenna signal including physical channel transmissions;
demodulating physical data channel transmissions;
determining a user symbol energy value for each of the multiple users;
removing a reconstructed chip data rate signal for each user with a determined symbol energy value exceeding a threshold from the multi-user baseband antenna signal to form an interference cancelled baseband antenna signal;
substituting the received multi-user baseband antenna signal with the interference cancelled baseband antenna signal.
17. The method of claim 16 , further comprising;
error correcting the combined demodulated physical data channel transmission for a first user;
decoding the error corrected first user transmission;
re-encoding the successfully decoded first user transmission;
determining an interference of the first user on other users; and
removing the determined interference from the demodulated physical data channel transmission for a second user, forming an interference cancelled combined demodulated physical data channel transmission for the second user.