Coordinating transmission scheduling among multiple base stations

Abstract

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 of a plurality of cells in a wireless communications system including one or more base stations, the method comprising:
 providing a set of channels to enable an intra-cell transmission orthogonal within each cell of said plurality of cells and inter-cell transmissions orthogonal across a cluster of cells associated with said one or more base stations; and   coordinating scheduling of said intra-cell transmission with said inter-cell transmissions for said cluster of cells between at least two base stations of said base stations.   
   
   
       2 . A method, as set forth in  claim 1 , wherein coordinating scheduling of said intra-cell transmission with said inter-cell transmissions further comprises:
 exchanging signaling messages between said at least two base stations.   
   
   
       3 . A method, as set forth in  claim 1 , wherein coordinating scheduling of said intra-cell transmission with said inter-cell transmissions further comprises:
 managing one or more radio resources of said one or more base stations in real time to jointly schedule said intra-cell transmission with said inter-cell transmissions of said cluster of cells, wherein said set of channels being virtual channels having an orthogonality property effective to reduce interference among said intra-cell and inter-cell transmissions; and   controlling interference between said cluster of cells jointly to optimize an overall performance parameter of said wireless communications system.   
   
   
       4 . A method, as set forth in  claim 3 , wherein controlling interference between said cluster of cells jointly further comprises:
 minimizing a parameter associated with a source responsible for generating said interference between said cluster of cells.   
   
   
       5 . A method, as set forth in  claim 2 , wherein managing one or more radio resources of said one or more base stations in real time further comprises:
 transforming an indication of the transmitted power into a diversity gain.   
   
   
       6 . A method, as set forth in  claim 1 , further comprising:
 using a set of virtual channels to provide said set of channels; and   partitioning said set of virtual channels by at least one of time, frequency, space, antenna, and codes for said cluster of cells.   
   
   
       7 . A method, as set forth in  claim 6 , wherein partitioning said set of virtual channels further comprises:
 dynamically partitioning a resource of said set of virtual channels in real time to adapt a channel variation of each user and an indication of user mobility within said cluster of cells.   
   
   
       8 . A method, as set forth in  claim 6 , further comprising:
 supporting at least one of a diversity combining or soft-handover for users of said cluster of cells in a High-Speed Packet Access interface to cause one or more sources of an inter-cell interference for each user to provide a signal enhancement in a handover region.   
   
   
       9 . A method, as set forth in  claim 8 , further comprising:
 providing a macro diversity gain in each received signal on a physical channel of a High-Speed Packet Access interface for said set of virtual channels from each cell of said cluster of cells that is associated with said at least one of diversity combining or soft-handover.   
   
   
       10 . A method, as set forth in  claim 6 , further comprising:
 supporting macro-diversity coherent combining in an Orthogonal Frequency Division Multiple Access interface to mitigate one or more sources of co-channel interference to a diversity transmission from a neighboring cell of said cluster of cells.   
   
   
       11 . A method, as set forth in  claim 8 , wherein supporting macro-diversity coherent combining in an Orthogonal Frequency Division Multiple Access interface further comprises:
 scheduling substantially the same set of data transmission of each sub-channel from each cell of said cluster of cells for a user.   
   
   
       12 . A method, as set forth in  claim 11 , further comprising:
 coordinating a joint assignment of said each sub-channel for each cell of said cluster of cells.   
   
   
       13 . A method, as set forth in  claim 1 , further comprising:
 fetching user information of a radio resource characteristic for each user and an indication of cross correlation between said cluster of cells to manage overall interference for said cluster of cells; and   coordinating control and virtual channel assignment between said cluster of cells by delivering control information and an indication of interference to each base station of said one or more base stations with a time stamp based on said user information and said indication of cross correlation.   
   
   
       14 . A method, as set forth in  claim 13 , further comprising:
 distributing a joint scheduler in said one or more base stations for scheduling a virtual channel of said set of virtual channels for each user and to interconnect said one or more base stations with a virtual interconnect;   using high-speed communication links between said one or more base stations to enable said joint scheduler to collect feedback information and user information from each base station of said one or more base stations; and   assigning said virtual channel of said set of virtual channels to each user in said cluster of cells based on said feedback information and said user information.   
   
   
       15 . A method, as set forth in  claim 14 , wherein coordinating control and virtual channel assignment between said cluster of cells further comprises:
 using a common reference time among said cluster of cells for the reference of control information and to manage overall interference for said cluster of cells.   
   
   
       16 . A method, as set forth in  claim 15 , wherein using a common reference time among said cluster of cells further comprises:
 synchronizing said high-speed communication link and said virtual interconnect between said one or more base stations based on at least one of a system and frame counter.   
   
   
       17 . A method, as set forth in  claim 1 , further comprising:
 using a client-server architecture based joint scheduling control for jointly assigning a corresponding virtual channel of said set of virtual channels to each user in said cluster of cells.   
   
   
       18 . A method, as set forth in  claim 17 , wherein using a client-server architecture based joint scheduling control further comprises:
 enabling a virtual scheduler for said one or more base stations each being a client to a dedicated scheduling server for jointly controlling scheduling of radio resources in said wireless communication system and managing overall interference of said wireless communication system for said cluster of cells;   
   
   
       19 . A method, as set forth in  claim 18 , further comprising:
 collecting feedback and user information from said cluster of cells as an input to said virtual scheduler.   
   
   
       20 . A method for, as set forth in  claim 19 , further comprising:
 assigning said corresponding virtual channel of said set of virtual channels to each user in said cluster of cells based on said feedback and user information to minimize said overall interference and maximize throughput of said wireless communication system.   
   
   
       21 . A method for optimizing a transmission parameter associated with scheduling of a plurality of users from a cluster of cells in a wireless communication system, the method comprising:
 searching an optimal power assignment for said transmission parameter of each user of said plurality of users to maximize an indication of system capacity of said wireless communication system; and   jointly scheduling said plurality of users active in said cluster of cells based on said optimal power assignments.   
   
   
       22 . A method, as set forth in  claim 21 , wherein jointly scheduling said plurality of users active in said cluster of cells further comprises:
 scheduling each user in said cluster of cells based on an optimization of power level as an objective function being the sum of the Shannon capacity of said plurality of users in said cluster of cells.   
   
   
       23 . A method, as set forth in  claim 21 , wherein searching an optimal power level for said parameter of each user of said plurality of users further comprises:
 using a parameter optimization algorithm to search for a sub-optimal solution of a resource for each user in said cluster of cells.