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Among the goals of 3GPP LTE networks are higher user bit rates, lower delays, increased spectrum efficiency, support for diverse QoS requirements, reduced cost, and operational simplicity. Resource scheduling and interference mitigation are two functions which are key to achieving these goals. This paper provides a survey of related techniques which have been proposed and shown to be promising. A brief discussion of the challenges for LTE-Advanced, the next step in the evolution, is also provided.

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A two-phase approach for the train unit scheduling problem is proposed. The first phase assigns and sequences train trips to train units temporarily ignoring some infrastructure details at train stations. The solutions of the first phase would be near-operable. The second phase focuses on satisfying the remaining constraints with respect to detailed station layouts. Real-world scenarios such as compatibility among traction types and time allowances for coupling/decoupling activities are considered, so that the solutions would be fully operable.The first phase is modeled as a large scale integer multi-commodity network flow (MCNF) problem. A branch-and-price integer linear programming approach is proposed. Preliminary experiments have shown that the approach would not yield solutions in reasonable time for problem instances exceeding about 1000 train trips. The train company collaborating in this research operates over 2400 train trips on a typical weekday. Hence, a heuristic has been designed for compacting the problem instance to a much smaller size before the ILP solver is applied. The process is iterative with evolving compaction based on the results from the previous iteration thereby converging to near optimal results.The second phase is modeled as a multidimensional matching problem with a mixed integer linear programming (MILP) formulation.