Abstract
This article proposes both centralized and decentralized design schemes for an analog network coding multiple-input multiple-output system with a relay node between two end nodes. The proposed centralized scheme is called the generalized iterative approach (GIA). It jointly designs the precoders and decoders at the two end nodes, and the processor at the relay to maximize the sum mutual information. Numerical results for the per-node power constraint show the convergence behavior of the GIA and give a performance benchmark for the analog network coding scheme. The proposed decentralized scheme is a practical joint transceiver and signaling design scheme. The keys to its low signaling load are time-division duplex and a symmetric relay processing matrix. The proposed signaling protocol enables the needed information, including channel state information (CSI), to be available at each node. With the needed CSI, a novel symmetric processor design at the relay is developed to maximize an approximate sum mutual information formula (to reduce the signaling loading, the precoders at both end nodes and the noise propagated from the relay are not considered). Employing singular value decomposition transceivers at the two end nodes, it is remarkable that the proposed decentralized approach performs almost as well as the centralized GIA design. It is concluded that the proposed decentralized scheme is a feasible way to implement analog network coding systems.
Highlights
Analog network coding (e.g., [1-16]), known as twoway amplify-and-forward relaying, is a bi-directional relaying technique
To the best of the authors’ knowledge, our generalized iterative approach (GIA) is the first work on joint precoders, decoders, and relay processors design to maximize the sum mutual information of multiple-input multipleoutput (MIMO) analog network coding systems
We demonstrate the sum mutual information performance of the proposed protocol with three relay designs
Summary
Analog network coding (e.g., [1-16]), known as twoway amplify-and-forward relaying, is a bi-directional relaying technique. To evaluate the performance of the proposed decentralized scheme, a generalized iterative approach (GIA) is developed for jointly designing the precoders, decoders, and relay processor to maximize the true sum mutual information. To the best of the authors’ knowledge, our GIA is the first work on joint precoders, decoders, and relay processors design to maximize the sum mutual information of MIMO analog network coding systems. Each node works in half-duplex mode, receiving and transmitting data in different time slots These nodes perform analog network coding, completing a bidirectional communication between the two end nodes in just two time slots (see Figure 1)—note that this does not include the time slots for signaling. Ei has the options of regular point to point transmissions (e.g., applying a dj × Mi decoder Gi)
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