Degrees of Freedom for separated and non-separated Half-Duplex Cellular MIMO Two-way Relay Channels (original) (raw)

We study a cellular setting in which an introduced multiple-antenna relay station (RS) can possibly assist the bidi-rectional communication between a multiple-antenna base station (BS) and a set of single-antenna mobile stations (MSs). Through a proposed six-phase communication protocol with arbitrary number of antennas and MSs, we characterize the maximum number of degrees of freedom (DoF) that can be attained when the BS-MSs direct link is active or down. When the direct link is available, we show that the introduction of a multiple-antenna RS cannot increase the maximum DoF regardless of the number of antennas it is equipped with. In the absence of a BS-MSs direct link, the maximum DoF can be limited by the number of RS antennas since all ongoing communication takes place through the RS. It is also shown that the characterized maximum DoF is achieved via recently proposed network-coding based two-way relaying techniques. Finally, we conclude that a widely used two-phase multiple ...

Achievable Degrees of Freedom for the Two-Cell Two-Hop MIMO Interference Channel with Half-Duplex Relays

—We consider the two-cell two-hop multiple-input-multiple-output (MIMO) interference channel with half-duplex relays, where each source group having M single antenna users, communicates with the corresponding destination with M antennas via two relays, each of which has M antennas. For such a channel, by exploiting three time slots, the previously known achievable degrees of freedom (DoF) is 2M/3 regardless of whether the half-duplex relays have global channel state information (CSI) for the first hop. In this paper, we show that using n ≥ 3 time slots, the achievable DoF is (n − 1)M/n, which is higher than the previous result of 2M/3 DoF for the case of n ≥ 4. The achievability is shown by a new relaying protocol which combines the alternate transmission strategy with an interference cancellation technique. A major implication of the derived result is that a normalized DoF of one can be achieved asymptotically without requiring global CSI at the source and relay nodes. Index Terms—Interference alignment (IA), degrees of freedom (DoF), multi-hop, multiple-input-multiple-output (MIMO).

Full-Duplex Massive MIMO with Physical Layer Network Coding for the Two-Way Relay Channel

IEEE Sensor Array and Multichannel Signal Processing Workshop (SAM), 2016

The role of interference in wireless networks has recently been profoundly rethought with the emergence of new techniques for combating it and exploit it to maximize the use efficiency of the physical resources. This paper presents a two-way relay channel using a lattice-based physical layer network coding scheme, a massive MIMO array, and in-band full-duplex, taking into account the residual self-interference that results after applying recently developed cancellation techniques for the loopback interference. The proposed scheme is able to ultimately exchange information across the TWRC in only one time slot, whereas four time slots would be needed in a conventional TWRC. The system's performance is shown to be mostly dependent on the number of antennas at the relay, and also dependent on the channel state information of all the channel matrices, including the one describing the loopback interference at the relay. For base-stations and relays with a few hundred antennas, the proposed scheme is feasible for wireless systems. Index Terms—In-band full-duplex, massive multiple-input multiple-output (MIMO), Physical Layer Network Coding (PLNC), Two-way Relay Channel.

Loading...

Loading Preview

Sorry, preview is currently unavailable. You can download the paper by clicking the button above.