Armin Dekorsy

On MAC Layer Throughput Enhancements in LTE-A by Downlink Macro Diversity

Coordinated transmission between base stations is one of the techniques under investigation to further improve the system performance of E-UTRA. In general, such a coordination, sometimes also called network MIMO, requires a large amount of signaling between cells. A relatively simple scheme for cell coordination is macro diversity. In this paper we consider macro diversity for the downlink direction of LTE-Advanced as a means to improve cell edge user throughput. We investigate the frequency-selectivity gains offered by over the air combining for different radio channels at link level. The impact on cell throughput as well as on user throughput for mobiles operated in macro diversity mode and for legacy mobile stations is investigated by means of system level simulations. Additionally, open issues related to network coordination are identified for future work.

Incentive based Allocation of Terminals in Heterogeneous Access Networks

The contribution of this paper is a solution to the problem of allocating terminals to the appropriate access network in locations where an operator owns multiple access networks with overlapping coverage. This problem is destined to narise since the 3GPP Evolved Packet Core (EPC) allows operators to efficiently manage multiple access networks under one core network. The underlying assumption nof this work is that user preferences, terminals, services and access networks are heterogeneous. While in state-of-the-art methods the network decides which terminal goes to which access network, we propose that this decision is taken at the terminal. nThe essence of our mechanism is that the network gives the terminals an incentive to hand over from an access network if the operator wants them to do so. The network offers the terminal a reward in form of loyalty program points, free minutes, money, or something alike for a handover. The terminal then decides whether to hand over based on the potential reward and other parameters. We further develop na highly configurable framework which allows a vast amount of terminal allocation methods, including incentive based ones. This is achieved by adopting a terminal-centric network paradigm, i.e., all actions are initiated by the terminals but need to be authorized by the network.

An active constraint method for distributed routing, and power control in wireless networks

Efficiently transmitting data in wireless networks requires joint optimization of routing, scheduling, and power control. As opposed to the universal dual decomposition we present a method that solves this optimization problem by fully exploiting our knowledge of active constraints. The method still maintains main requirements such as optimality, distributed implementation, multiple path routing and per-hop error performance. To reduce the complexity of the whole problem, we separate scheduling from routing and power control, including it instead in the constraint set of the joint optimization problem. Apart from the mathematical framework we introduce a routing and power control decomposition algorithm that uses the active constraint method, and we give further details on its distributed application. For verification, we apply the distributed RPCD algorithm to examples of wireless mesh backhaul networks with fixed nodes. Impressive convergence results indicate that the distributed RPCD algorithm calculates the optimum solution in one decomposition step only.

Joint Routing and Power Allocation for IDMA Applied in Multi-Hop Wireless Networks

Efficiently transmitting data in wireless mesh networks requires an integrated routing, scheduling, and power control strategy. Extending previous work on fast distributed routing and power allocation in multi-hop wireless networks we present an algorithmic solution taking the transceiver structure based on interleave-division multiple access and the resulting combinatorial structure of the overall problem explicitly into account. The algorithm offers fast convergence to an optimum solution while providing robust capacity-achieving transmission in each link of a given network.