Elements of information theory
Elements of information theory
Convex Optimization
A performance study of dual-hop transmissions with fixed gain relays
IEEE Transactions on Wireless Communications
Bidirectional regenerative half-duplex relaying using relay selection
IEEE Transactions on Wireless Communications - Part 2
Performance Bounds for Bidirectional Coded Cooperation Protocols
IEEE Transactions on Information Theory
Spectral efficient protocols for half-duplex fading relay channels
IEEE Journal on Selected Areas in Communications
Performance analysis of user selection for multiuser two-way amplify-and-forward relay
IEEE Communications Letters
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A two-way relay channel (TWRC) in which two terminals T1 and T2 exchange orthogonal frequency division multiplexing (OFDM) signals with the help of an amplify-and-forward (AF) relay T3 is considered here, and an efficient technique for allocating powers to N parallel tones of OFDM is developed. A sum rate maximization problem is formulated by replacing the individual power constraints of the conventional sum rate maximization problem, which limit the power of each terminal, with the total power constraint limiting the sum of powers of all terminals. The maximization problem with the total power constraint yields a more efficient power allocation policy than the conventional problem with individual power constraints. It is shown that the closed-form solution of the maximization problem under the total power constraint can be obtained for a single-tone system (N = 1). Based on this result, a two-step suboptimal approach is proposed in which the power is optimally assigned to each tone first, and then at each tone the assigned power is distributed to the three terminals. The proposed method is shown to assign 50% of the total power to relay T3 irrespective of the channels. It is demonstrated that the proposed method is considerably simpler to implement than the conventional dual-decomposition method (DDM), yet the performance of the former is almost identical to that of the latter.