Method to control the effects of out-of-cell interference in a wireless cellular system using backhaul transmission of decoded data and formats
Successfully decoded data received from a mobile terminal as well as the transmission format of that data is relayed over the backhaul from a base station receiver that successfully decoded the mobile terminal's transmission to the base stations in the mobile terminal's active set that presumably were unable to decode the mobile terminal's transmission due to inadequate signal-to-noise ratio. A base station that receives this transmission from the relaying base station that did'successfully decode and demodulate the mobile terminal's transmission is then able to reconstruct the data and subtract it from the total interference, thereby increasing the signal-to-noise ratio at this base station for its in-cell processing.
1. A method at a base station, the base station being within an active set of base stations with which a mobile terminal in handoff is sending data in a signal, the active set comprising a serving base station and one or more non-serving base stations, the method comprising:
receiving a received signal at the serving base station from the mobile terminal and carrying out a decoding operation for the received signal;
sending successfully decoded data decoded at the serving base station, and a transmission format of the received signal, to one or more of the non-serving base stations in the active set, the decoded data and the transmission format being sent via a backhaul network interconnecting the base stations of the active set;
wherein the transmission format includes a number of retransmissions that were required for the serving base station to successfully decode the data, and the decoded data and the transmission format sent from the serving base station are usable by at least one of the one or more non-serving base stations in the active set to remove, from other signals received at the non-serving base station, interference attributable to transmission of the received signal.
2. The method of claim 1 wherein the transmission format comprises a modulation and coding format of the received signal.
3. A method at a first base station, the base station being a non-serving base station within an active set of base stations with which a mobile terminal in handoff is communicating, the method comprising:
receiving at the non-serving base station, from a serving base station in the active set, data that was successfully decoded by the serving base station from a received signal received by the serving base station from the mobile terminal, along with a transmission format of the received signal, the decoded data and the transmission format being received via a backhaul network interconnecting the base stations of the active set;
wherein the transmission format includes a number of retransmissions that were required for the serving base station to successfully decode the data, and the decoded data and the transmission format received from the serving base station are usable by the non-serving base station to remove, from signals received at the non-serving base station, interference attributable to transmission of the received signal.
4. The method of claim 3 wherein the transmission format comprises a modulation and coding format of the signal.
5. The method of claim 3 further comprising:
reconstructing the signal from the mobile terminal using the data received from the serving base station and the received transmission format; and
subtracting the reconstructed signal from a composite signal received at the non-serving base station from other mobile terminals.
6. A serving base station within an active set of base stations, the active set of base stations including the serving base station and one or more non-serving base stations, the serving base station comprising:
a receiver configured to:
receive a received signal from a mobile terminal;
decode the received signal to produce decoded data; and
send the decoded data and a transmission format of the received signal to one or more of the non-serving base stations in the active set, the decoded data and the transmission format being sent via a backhaul network interconnecting the base stations of the active set, the transmission format including a number of retransmissions that were required for the serving base station to successfully decode the data;
wherein the decoded data and the transmission format are usable by at least one of the one or more non-serving base stations in the active set to remove, from other signals received at the non-serving base station, interference attributable to the received signal.
7. The serving base station of claim 6 wherein the receiver is further configured to determine whether the mobile terminal is in handoff, and if so, sends the decoded data and the transmission format to the one or more non-serving base stations.
8. The serving base station of claim 6 wherein the transmission format further includes a modulation and coding format of the received signal.
9. A non-serving base station within an active set of base stations, the non-serving base station comprising:
a receiver configured to:
receive, from a serving base station in the active set, data that was successfully decoded by the serving base station from a received signal received by the serving base station from a mobile terminal, along with a transmission format of the received signal, the decoded data and transmission format being received via a backhaul network interconnecting the base stations of the active set, the transmission format including a number of retransmissions that were required for the serving base station to successfully decode the data; and
remove, from other signals received at the non-serving base station, interference attributable to transmission of the received signal using the decoded data and the transmission format.
10. The non-serving base station of claim 9 wherein the transmission format comprises a modulation and coding format of the received signal.
11. The non-serving base station of claim 9 wherein the receiver is further configured to:
reconstruct the received signal from the mobile terminal using the decoded data and the transmission format; and
subtract the reconstructed signal from a composite signal including the received signal and the other signals.