Simultaneous Transmission and Reception: Algorithm, Design and System Level Performance

Abstract

Abstract-Full Duplex or Simultaneous transmission and reception (STR) in the same frequency at the same time can potentially double the physical layer capacity. However, high power transmit signal will appear at receive chain as echoes with powers much higher than the desired received signal. Therefore, in order to achieve the potential gain, it is imperative to cancel these echoes. As these high power echoes can saturate low noise amplifier (LNA) and also digital domain echo cancellation requires unrealistically high resolution analog-to-digital converter (ADC), the echoes should be cancelled or suppressed sufficiently before LNA. In this paper we present a closed-loop echo cancellation technique which can be implemented purely in analogue domain. The advantages of our method are multiplefold: it is robust to phase noise, does not require additional set of antennas, can be applied to wideband signals and the performance is irrelevant to radio frequency (RF) impairments in transmit chain. Next, we study a few protocols for STR systems in carrier sense multiple access (CSMA) network and investigate MAC level throughput with realistic assumptions in both single cell and multiple cells. We show that STR can reduce hidden node problem in CSMA network and produce gains of up to 279% in maximum throughput in such networks. Moreover, at high traffic load, the gain of STR system can be tremendously large since the throughput of non-STR system is close to zero at heavy traffic due to severe collisions. Finally, we investigate the application of STR in cellular systems and study two new unique interferences introduced to the system due to STR, namely BS-BS interference and UE-UE interference. We show that these two new interferences will hugely degrade system performance if not treated appropriately. We propose novel methods to reduce both interferences and investigate the performances in system level. We show that BS-BS interference can be suppressed sufficiently enough to be less than thermal noise power, and with favorable UE-UE channel model, capacities close to double are observed both in downlink (DL) and uplink (UL). When UE-UE interference is larger than DL co-channel interferences, we propose a simple and "non-cooperative" technique in order to reduce UE-UE interference.

Joint power allocation for MIMO-OFDM full-duplex relaying communications

“…3 shows that HD two-way relaying does not double the throughput of HD one-way relaying. This is because in the two-way relaying, (i) our precoding design may have amplified noise, (ii) the available power is further constrained by (15) and (16), and (iii) the denominator of the SINR expression is a i x (1) i + x (2) i which is greater than or equal to a…”

“…To the best of our knowledge, the FD two-way relaying problems (14) (14) is a very complex nonconcave function with many fractional and cross terms in the source power variables x x (1) , x (2) and the relay variable y. Moreover, this objective function is not individually concave in either x or y.…”

“…The κ-iteration of the generic Algorithm 1 is thus to solve the following problem in x (x (1) , x (2) ) and y:…”

“…Moreover, R ( ) D,k is no longer diagonal even when R ( ) D is diagonal. 2 As the noises in (7) are correlated, the subchannel-wise decoding is not optimal. Therefore, the objective function in (14) provides a lower bound instantaneous capacity of the network.…”

“…Only after fully receiving a data packet, the HD relay nodes forward it to the destination. Full-duplexing *Correspondence: duy.ngo@newcastle.edu.au 2 School of Electrical Engineering and Computing, The University of Newcastle, University Drive, Callaghan, NSW 2308, Australia Full list of author information is available at the end of the article (FD) has recently been proposed as one of the key 5G transceiver techniques with the hope of doubling the spectral efficiency [2,3]. With simultaneous signal transmission and reception in the same time slot and on the same frequency band, an FD relay node transmits a packet while receiving another packet, thereby significantly reducing the end-to-end delay.…”