Coordinating transmission scheduling among multiple base stations
View Patent ↗A method and an apparatus for scheduling transmissions of a plurality of cells in a wireless communications system including one or more base stations is provided. The method comprises providing a set of virtual channels to enable an intra-cell transmission orthogonal to another transmission within each cell of the plurality of cells and inter-cell transmissions orthogonal to other transmissions across a cluster of cells associated with the one or more base stations. The method further comprises exchanging signaling messages between two or more base stations to coordinate scheduling of the intra-cell transmission with the inter-cell transmissions for the cluster of cells. For optimizing a parameter associated with scheduling of a plurality of users from a cluster of cells in a wireless communication system, an optimal power level for the parameter of each active user may be searched to maximize an indication of system capacity of the wireless communication system. This enables a coordinated jointly scheduling of the users active in the cluster of cells based on the optimal power levels such that the total interference within the cluster may be minimized to maximize the system throughput/capacity.
1. A method for scheduling transmissions by a plurality of base stations that serves a plurality of users in a wireless communication system, the method comprising:
calculating, in a scheduling device, throughput gains for a plurality of subchannels between each user and each base station that result from incrementing power allocated to each sub channel by a selected amount;
calculating, in the scheduling, device, interference penalties for the plurality of subchannels between each user and each base station that result from incrementing the power allocated to each sub channel by the selected amount;
calculating, in the scheduling device, a transmission credit for each sub channel by setting each transmission credit equal to a measure of a difference between a throughput gain for each sub channel and an interference penalty for each sub channel and a power penalty for each base station; and
allocating, in the scheduling device, an incremented power to each sub channel based on the transmission credit for each sub channel.
2. The method of claim 1 , wherein calculating the throughput gains comprises calculating the throughput gains based on link gains for each of the plurality of subchannels and powers allocated to each of the plurality of subchannels prior to incrementing the power allocated to each sub channel by the selected amount.
3. The method of claim 1 , wherein calculating the interference penalties comprises calculating at least one of a co-channel interference penalty or an inter-channel interference penalty.
4. The method of claim 3 , wherein calculating the interference penalties comprises calculating the interference penalties based on link gains for each of the plurality of subchannels and powers allocated to each of the plurality of subchannels prior to incrementing the power allocated to each sub channel by the selected amount.
5. The method of claim 1 , wherein allocating the incremented power comprises:
incrementing the power allocated to the subchannels when a maximum value of the transmission credits of the subchannels exceeds a threshold;
recalculating the throughput gains, the interference penalties, and the transmission credits using a further incremented value of the power allocated to the subchannels; and
iteratively repeating the incrementing and recalculating steps until the maximum values of the transmission credits for all the subchannels is below the threshold, thereby determining a final incremented value of the allocated power.
6. The method of claim 5 , wherein allocating the incremented power comprises recalculating the power penalty for each of the base stations based on the final incremented value of the allocated power.
7. The method of claim 6 , comprising:
determining whether the recalculated value of the power penalty for each of the base stations differs from the previous value of the power penalty for each of the base stations by less than a threshold value; and
iteratively repeating calculation of the throughput gains, interference penalties, and transmission credits using the recalculated value of the power penalty for each of the base stations until the difference is less than the threshold value.