Anke Feiten Rudolf Mathar Michael Reyer Rate and Power Allocation for Multiuser OFDM: An Effective Heuristic Verified by Branch-and-Bound. 60-64 2008 7 IEEE Transactions on Wireless Communications 1 http://dx.doi.org/10.1109/TWC.2008.060559 db/journals/twc/twc7.html#FeitenMR08