Exploiting cell dormancy and load balancing in LTE HetNets

摘要

At a coarse time-scale, at the start of each frame the choice of TPs to be made active and users to associate with the active TPs are determined by solving an optimization problem. The inputs to the optimization problem are averaged slowly varying metrics that are relevant for a period longer than the backhaul latency. At a the fine time-scale, in each slot each active TP independently does scheduling over the set of users associated with it, without any coordination with any of the other active TPs, based on fast changing information, such as instantaneous rate or SINR estimates.

主权项

1. A computer implemented method for LTE heterogenous networks (HetNets), the method comprising:
considering some transmission points (TPs) from a set of TPs of interest that are made inactive over a frame, and load balancing (known as user association), associating users to active TPs in the set of TPs such that each user is associated to any one active TP over the frame; reformulating the user association for any given set of active TPs in an LTE heterogenous network as coarse time-scale (frame-level granularity) and fine-time scale (fine sub-frame/slot level) approaches; performing periodically the coarse frame-level granularity based on averaged slowly varying metrics that are relevant for a period longer than a backhaul latency; and doing the fine sub-frame/slot level granularity with no coordination among TPs and independently by each active TP based on fast changing information; and determining joint on-off and user association asmax⊆⁢{maxxu,b∈{0,1}⁢∀u,b⁢{∑u∈⁢∑b∈⁢xu,b⁢ln⁡(Ru(b)⁡()∑k∈⁢xk,b)}}s.t.∑b∈⁢xu,b=1,⁢∀u∈,∑u∈⁢xu,b≤Nb,⁢∀b∈, where inputs include an average single user rate of user u when connected to TP b in any active set of TPs ⊂B:Ru(b)(), with a user limit TP b of Nb· and variables are a candidate set of active (on) TPs ⊂B, and an indicator variable for connection of user u to TP b in active set xu,b; and reformulating the user association by selecting and adding to a (user,TP) pair such that the user has not been selected before and the pair offers a highest incremental gain among all pairs containing such users with responsive to an input of average single-user rates, per-TP user limits, and active set of TPs.