Achieving full diversity in multi-antenna two-way relay networks via symbol-based physical-layer network coding

This paper considers physical-layer network coding (PNC) with M-ary phase-shift keying (MPSK) modulation in two-way relay channel (TWRC). A low complexity detection technique, termed symbol-based PNC (SPNC), is proposed for the relay. In particular, attributing to the outer product operation imposed on the superposed MPSK signals at the relay, SPNC obtains the network-coded symbol (NCS) straightforwardly without having to detect individual symbols separately. Unlike the optimal multi-user detector (MUD) which searches over the combinations of all users’ modulation constellations, SPNC searches over only one modulation constellation, thus simplifies the NCS detection. Despite the reduced complexity, SPNC achieves full diversity in multi-antenna relay as the optimal MUD does. Specifically, antenna selection based SPNC (AS-SPNC) scheme and signal combining based SPNC (SC-SPNC) scheme are proposed. Our analysis of these two schemes not only confirms their full diversity performance, but also implies when SPNC is applied in multi-antenna relay, TWRC can be viewed as an effective single-input multiple-output (SIMO) system, in which AS-PNC and SC-PNC are equivalent to the general AS scheme and the maximal-ratio combining (MRC) scheme. Moreover, an asymptotic analysis of symbol error rate (SER) is provided for SC-PNC considering the case that the number of relay antennas is sufficiently large

Transmit Antenna Selection for Physical-Layer Network Coding Based on Euclidean Distance

Physical-layer network coding (PNC) is now well-known as a potential candidate for delay-sensitive and spectrally efficient communication applications, especially in two-way relay channels (TWRCs). In this paper, we present the error performance analysis of a multiple-input single-output (MISO) fixed network coding (FNC) system with two different transmit antenna selection (TAS) schemes. For the first scheme, where the antenna selection is performed based on the strongest channel, we derive a tight closed-form upper bound on the average symbol error rate (SER) with $M$-ary modulation and show that the system achieves a diversity order of 1 for $M > 2$. Next, we propose a Euclidean distance (ED) based antenna selection scheme which outperforms the first scheme in terms of error performance and is shown to achieve a diversity order lower bounded by the minimum of the number of antennas at the two users.Comment: 15 pages, 4 figures, Globecom 2017 (Wireless Communications Symposium

Bit Error Rate Analysis of Physical Layer Network Coding Spatially Modulated Full-Duplex Nodes Based Bidirectional Wireless Relay Network

In this paper, Physical Layer Network coding (PLNC)-Spatially Modulated Full-Duplex (SMFD) nodes based two-way/bidirectional cooperative wireless relay network is proposed. The PLNC-SMFD-based system is a viable technology in the field of next-generation wireless networks to enhance spectral efficiency. In the proposed system model, both the source nodes and relay nodes are employed with 2 × 2 antenna configurations where 2 bits of information are exchanged between the source nodes through a relay node. Transmit antenna selection at the source nodes is based on the incoming bitstreams. For instance, the transmit antenna is selected at PLNC-SMFD nodes based on the data symbols of the Most Significant Bit (MSB). Whereas the selected transmit antenna sends the Least Significant Bit (LSB) bit of data symbol at any time instance. Further, the self-interference at the transmitting and receiving nodes is modeled as Gaussian with the thermal noise power as a variance. The Bit Error Rate (BER) analytical expressions for both the upper and lower bound are derived in a Rayleigh Fading channel background. It has been graphically shown that the BER performance of the proposed system analyzes the effect of self-interference