Decentralized slow-fading precoding for multi-cell wireless systems
View Patent ↗Methods and apparatuses for slow-fading precoding for multi-cell wireless systems are provided. At a base station of a cellular network in which a plurality of terminals are served, the base station serving pluralities of same-cell terminals and neighboring-cell terminals, and the cellular network including neighboring-cell base stations that serve respective pluralities of same-cell terminals and neighboring-cell terminals, a same-cell and one or more neighboring cells within the cellular network are selected, the same-cell and one or more neighboring cells comprising a truncated network. A plurality of slow-fading coefficients is obtained, each of the plurality of slow-fading coefficients being associated with channel state information for communication within the truncated network between a neighboring-cell base station and one of the respective same-cell terminals or neighboring-cell terminals, and a set of slow-fading precoding coefficients is generated for transmitting signals within the truncated network to same-cell terminals and neighboring-cell terminals based on the plurality of slow-fading coefficients.
1. A method for transmitting signals in a cellular network comprising a plurality of base stations, each of the plurality of base stations serving respective pluralities of same-cell terminals and neighboring-cell terminals, the method comprising:
for each respective base station of the plurality of base stations:
selecting a same-cell and one or more neighboring cells within the cellular network, the selected same-cell and one or more neighboring cells comprising a truncated network;
obtaining a plurality of slow-fading coefficients, each of the plurality of slow-fading coefficients being associated with channel state information for communication within the truncated network between a neighboring-cell base station and one of the respective pluralities of same-cell terminals and neighboring-cell terminals; and
generating a set of slow-fading precoding coefficients for transmitting the signals within the truncated network to the respective pluralities of same-cell terminals and neighboring-cell terminals based on the plurality of slow-fading coefficients,
wherein the respective generated set of slow-fading precoding coefficients is used for transmitting the signals by the respective base station of the plurality of base stations without using sets of slow-fading precoding coefficients generated by other base stations of the plurality of base stations.
2. The method of claim 1 , wherein one or more of the same-cell and the one or more neighboring cells are selected for each respective base station of the plurality of base stations to comprise a plurality of neighboring truncated network that intersect with each other.
3. The method of claim 1 , wherein generating the set of slow-fading precoding coefficients comprises determining optimized slow-fading precoding coefficients.
4. The method of claim 3 , wherein each optimized slow-fading precoding coefficient is determined based on at least one of:
maximizing a minimum signal to interference and noise ratio,
maximizing a sum of data transmission rates, and
maximizing a sum of logarithms of data transmission rates for transmitting a signal to same-cell terminals and other-cell terminals.
5. The method of claim 3 , wherein generating the set of slow-fading precoding coefficients includes performing an iterative function, wherein the iterative function is terminated based on a precision control threshold.
6. The method of claim 5 , wherein the iterative function includes a quasi-convex optimization algorithm.
7. The method of claim 1 , further comprising receiving data signals, by the respective base station, intended for one or more of the same-cell terminals and neighboring-cell terminals located within the truncated network.
8. The method of claim 1 wherein the respective base station comprises a central hub of the truncated network.
9. The method of claim 1 further comprising, for each respective base station:
obtaining pilot signals from the pluralities of same-cell terminals and neighboring-cell terminals; and
beam-forming signals to one or more of the same-cell terminals and neighboring-cell terminals based on the set of slow-fading precoding coefficients.
10. The method of claim 9 wherein the beam-forming is based on a set of fast-fading coefficients.
11. The method of claim 9 wherein the beam-forming is performed using OFDM modulation.
12. A cellular network, comprising:
a plurality of base stations each serving respective pluralities of same-cell terminals and other-cell terminals in the cellular network;
each respective base station of the plurality of base stations comprising:
a processor configured to select a same-cell and one or more neighboring cells within the cellular network, the selected same-cell and one or more neighboring cells comprising a truncated network;
a receiver module configured to obtain a plurality of slow-fading coefficients, each of the plurality of slow-fading coefficients being associated with channel state information for communication within the truncated network between a neighboring-cell base station and one of the respective pluralities of same-cell terminals and neighboring-cell terminals; and
a precoding module configured to generate a set of slow-fading precoding coefficients for transmitting the signals within the truncated network to the respective pluralities of same-cell terminals and neighboring-cell terminals based on the plurality of slow-fading coefficients,
wherein the respective generated set of slow-fading precoding coefficients is used for transmitting the signals by the respective base station of the plurality of base stations without using sets of slow-fading precoding coefficients generated by other base stations of the plurality of base stations.
13. The cellular network of claim 12 , wherein generating the set of slow-fading precoding coefficients comprises determining optimized slow-fading precoding coefficients.
14. The cellular network of claim 13 , wherein each optimized slow-fading precoding coefficient is determined based on at least one of:
maximizing a minimum signal to interference and noise ratio,
maximizing a sum of data transmission rates, and
maximizing a sum of logarithms of data transmission rates for transmitting a signal to same-cell terminals and other-cell terminals.
15. The cellular network of claim 13 , wherein generating the set of slow-fading precoding coefficients includes performing an iterative function, wherein the iterative function is terminated based on a precision control threshold.
16. The cellular network of claim 15 , wherein the iterative function includes a quasi-convex optimization algorithm.
17. The cellular network of claim 12 , wherein the receiver module of each respective base station is further configured to receive data signals intended for one or more of the same-cell terminals and neighboring-cell terminals located within the truncated network.
18. The cellular network of claim 12 wherein the respective base station comprises a central hub of the truncated network.
19. The cellular network of claim 12 , wherein:
the receiver module of each respective base station is further configured to obtain pilot signals from the pluralities of same-cell terminals and neighboring-cell terminals; and
a beam-forming module of each respective base station is configured to beam-form signals to one or more of the same-cell terminals and neighboring-cell terminals based on the set of slow-fading precoding coefficients.
20. The cellular network of claim 19 wherein the beam-forming is based on a set of fast-fading coefficients.
21. The cellular network of claim 19 , wherein the beam-forming is performed using OFDM modulation.