A performance comparison of in-band full duplex and dynamic TDD for 5G indoor wireless networks

EURASIP Journal on Wireless Communications and Networking, Mar 2017

In-band full duplex has emerged as a solution for high data rate and low access delay for 5G wireless networks after its feasibility has been demonstrated. However, the impact of the in-band full duplex on the system-level performance of multi-cell wireless networks has not been investigated thoroughly. In this paper, we conduct an extensive simulation study to investigate the performance of in-band full duplex for indoor 5G small cell wireless networks. Particularly, we compare the in-band full duplex with static and dynamic time division duplexing schemes which require much less hardware complexity. We examine the effects of beamforming and interference cancellation under various traffic demands and asymmetry situations in the performance comparison. Our objective is to identify under which condition and with which technology support the in-band full duplex becomes advantageous over the simpler duplexing schemes. Numerical results indicate that for highly utilized wireless networks, in-band full duplex should be combined with interference cancellation and beamforming in order to achieve a performance gain over traditional duplexing schemes. Only then in-band full duplex is considered to be advantageous at any number of active mobile stations in the network and any downlink to uplink traffic proportion. Our results also suggest that in order to achieve a performance gain with the in-band full duplex in both links, the transmit power of the access points and the mobile stations should be comparable.

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A performance comparison of in-band full duplex and dynamic TDD for 5G indoor wireless networks

Al-Saadeh and Sung EURASIP Journal on Wireless Communications and Networking A performance comparison of in-band full duplex and dynamic TDD for 5G indoor wireless networks Osama Al-Saadeh 0 Ki Won Sung 0 0 Communication Systems Department, KTH Royal Institute of Technology , Stockholm , Sweden In-band full duplex has emerged as a solution for high data rate and low access delay for 5G wireless networks after its feasibility has been demonstrated. However, the impact of the in-band full duplex on the system-level performance of multi-cell wireless networks has not been investigated thoroughly. In this paper, we conduct an extensive simulation study to investigate the performance of in-band full duplex for indoor 5G small cell wireless networks. Particularly, we compare the in-band full duplex with static and dynamic time division duplexing schemes which require much less hardware complexity. We examine the effects of beamforming and interference cancellation under various traffic demands and asymmetry situations in the performance comparison. Our objective is to identify under which condition and with which technology support the in-band full duplex becomes advantageous over the simpler duplexing schemes. Numerical results indicate that for highly utilized wireless networks, in-band full duplex should be combined with interference cancellation and beamforming in order to achieve a performance gain over traditional duplexing schemes. Only then in-band full duplex is considered to be advantageous at any number of active mobile stations in the network and any downlink to uplink traffic proportion. Our results also suggest that in order to achieve a performance gain with the in-band full duplex in both links, the transmit power of the access points and the mobile stations should be comparable. Wireless networks; In-band full duplex; Static time division duplexing; Dynamic time division duplexing; Interference mitigation techniques; Small cell; 5G; mmWave bands; Beamforming; Interference cancellation - time division duplex (TDD). Both FDD and TDD have the disadvantage of wasting time and frequency resources [5]. However, recent advances in signal processing have made it possible to reduce the effect of SI, allowing IBFD wireless communications [6, 7]. The authors of [6] demonstrated that it is possible to reduce the SI using analog and digital interference cancellation techniques by more than 78 dB with antenna separations of 20 and 40 cm. In [7], a 110 dB of SI cancellation was achieved in a dense indoor office environment with 80 MHz bandwidth. The analog cancellation circuit in [7] has the dimensions of (10cm × 10cm). Both [6] and [7] suggest that it would be difficult to implement the IBFD in user equipments due to the limited device sizes, whereas it is not a limiting factor for access points (APs). The IBFD can bring benefits to the wireless systems in various angles. For example, the IBFD can provide a better way to detect collisions in contention-based access © The Author(s). 2017 Open Access This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. protocols [8]. Also, in [9], it is reported that IBFD can improve the secrecy of relay networks significantly. In this study, we focus on the improvement of user data rate in a capacity-demanding indoor environment. In an ideal situation, a wireless system that operates in IBFD only requires half the frequency and time resources required to operate in FDD and TDD or double the data rate with the same amount of resources. In practice, however, IBFD might not lead to the performance improvement because it induces higher interference compared to its half duplex alternatives. It can be particularly the case for a network of high utilization. Thus, system-level performance of full duplex is of profound interest for the design of 5G wireless networks. Several investigations have been conducted on the performance of IBFD-enabled systems. In [10], the performance of IBFD in a dense small cell network was evaluated and compared against the conventional half duplex transmission. It is argued in [10] that IBFD provides 30–40% mean throughput gain over the half duplex for indoor scenarios. The 100% throughput gain is only noticed when the cells are isolated by extremely high wall loss figures. In [11], it was demonstrated that IBFD cannot double the throughput of half duplex transmission with ALOHA medium access control (MAC) protocol. Even with the perfect SI cancellation, the actual throughput gain ranges from 0–33% for the path loss exponent range [2, 4]. The authors of [11] arrived to the conclusion that there is a strong need fo (...truncated)


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Osama Al-Saadeh, Ki Won Sung. A performance comparison of in-band full duplex and dynamic TDD for 5G indoor wireless networks, EURASIP Journal on Wireless Communications and Networking, 2017, pp. 50, Volume 2017, Issue 1, DOI: 10.1186/s13638-017-0833-3