Leistungsallokation in Interferenzkanälen
Zusammenfassung der Projektergebnisse
In this work, the power allocation optimization problem aiming at maximizing the sum rate with a total power constraint is tackled. In interference channels, this optimization problem is non-convex. As a result, a suboptimum solution is proposed which is called iterative waterfilling. Furthermore, the optimum solution of the non-convex problem is found by reformulating the optimization problem to a difference of two concave functions programming problem (D.C. programming problem). A branch and bound algorithm is applied to the D.C. programming problem which asymptotically converges to the global optimum power allocation. For the interference-free channels, waterfilling achieves the maximum sum rate but it is not fair among the users. Therefore, a total fairness constraint is added. The resulting problem is decomposed so that every user allocates the minimum total transmit power to achieve equal rates. The optimum sum rate is upper bounded by the water filling's achieved sum rate and is found using the bisection method. Most future cellular and mobile systems will use OFDMA as a physical layer multiple access scheme. Subsequently, both the inter-symbol interference (ISI) and the intra-cell interference can be omitted. But the inter-cell interference, i.e., the interference which occurs upon using the same resource in two or more cells, is still a challenging issue in these systems which limits the performance significantly. In the present project, the optimum power allocation in interference channels is found using D.C. programming. Due to the complexity of finding the optimum power allocation over a large number of users and subcarriers, a combined approach of both resource allocation and power allocation will relax the optimization problem and reduce the complexity significantly. This proposal aims at finding a consistent low complexity algorithm which finds successively the best resource and power allocations in interference channels with a minimum loss in the sum rate as compared to the optimum solution. Under the assumption that the system users are sharing multiple non-interfering subcarriers, the complexity of the proposed solutions of the resource and power allocations will be decreased significantly as well as the overall system performance will increase.
Projektbezogene Publikationen (Auswahl)
- Power Allocation in Service Area Interference Channels, Proc. International ITG/IEEE Workshop on Smart Antennas (WSA'08), Darmstadt, February 2008
S. Deng, T. Weber, A. Ahrens
- Capacity Optimizing Power Allocation in Interference Channels, AEU - International Journal of Electronics and Communications, vol. 63, no. 2, 2009, pp. 139-147
S. Deng, T. Weber, A. Ahrens
- Transmitter Power Allocation for Optimizing Sum Capacity in Interference Channels, Proc. 14th International OFDM-Workshop (InO-Wo'09), Hamburg, September 2009
H. Al-Shatri, N. Palleit, T. Weber
- Fair Power Allocation for Sum Rate Maximization in Multiuser OFDMA, Proc. International ITG/IEEE Workshop on Smart Antennas (WSA'IO), Bremen, February 2010
H. Al-Shatri, T. Weber
- Optimizing Power Allocation in Interference Channels Using D.C. Programming, Proc. 6th Workshop on Resource Allocation in Wireless Networks, (RAWNET'10), Avignon, June 2010
H. Al-Shatri, T. Weber
