With increasing demands on wireless network data traffics, it has become a focus of concern in next generation of wireless network how to improve system throughput and spectral efficiency to the utmost. Coordination between base stations is an important technology for fully achieving the potential capacity of a system. An inter-cell interaction enables fully utilization of local information of each cell, coordinative scheduling of network resources, and achievement of better global performance. However, the first step of coordination is to determine the coordination area, as well as base stations and cells to be coordinated.
Generally, there are three approaches to determine the cells to be coordinated: determining by network, determining by user, and tradeoff therebetween. The approach of determining by network means all coordination cells are partitioned by the network in advance, such that once a user locates in a certain cell, it has to coordinate with other cells that have already been defined in advance, and it cannot make selection according to the strength of the signal received by the user. This approach has an advantage of relative simplicity, but its drawbacks are rather apparent: the coordination performance is greatly limited. The approach of determining by user means all coordination cells are determined by the user in real-time, such that once the user locates in a certain cell, he/she may freely select a coordination cell according to the strength of the signal received by himself/herself. This approach has an advantage of improved coordination performance, but the coordination transmission between cells will further increase the complexity of scheduling network resources and the workload of network information interaction. The coordination transmission requires that different cells simultaneously perform transmission to the user; thus, it is require to negotiate between cells how to allocate wireless resources such as antennas, sub-carriers, and power of respective cells. However, as a node of the entire network, the decision of each cell is not only restrained by its neighboring cells, but also affects the decision of the neighboring cells; in light of the adjacency of cells, such impact will inevitably spread throughout the entire network, thereby causing an extremely complex problem in scheduling resources throughout the whole network. In view of the above drawbacks, an approach of tradeoff therebetween evolves. According to this tradeoff approach, first the network is partitioned into coordination areas such that the complexity of scheduling wireless resources is restricted within acceptable scope, and then within respective areas, the user determines the actual coordination cells.
However, this tradeoff approach further causes a problem that a coordination area-edge user cannot coordinate with a neighboring cell that belongs to another coordination area, which therefore dampens the performance of the coordination area-edge user. In order to solve the above problem, another approach is proposed, the basic idea of which is to make the cell at the coordination area-edge as an overlapping cell of two coordination areas, and then through the negotiation between the two areas, the coordination transmission to the user in the overlapping area is handled. Although this approach relieves the edge effect of the coordination areas to a certain extent, it essentially still needs the interaction between different coordination areas, coupling still exists between the coordination areas, and the complexity of scheduling still exists.
Therefore, a simple and easy method of partitioning a coordination area is desired.
USPTO Backgrounds
USPTO Backgrounds