The development of self-interference (SI) cancelation technology makes full-duplex (FD) communication possible. Considering the quality of service (QoS) of flows in small cells densely deployed scenario with limited time slot resources, this paper introduces the FD communication into the concurrent scheduling problem of millimeter-wave wireless backhaul network. We propose a QoS-aware FD concurrent scheduling algorithm to maximize the number of flows with their QoS requirements satisfied. Based on the contention graph, the algorithm makes full use of the FD condition. Both residual SI and multi-user interference are considered. Besides, it also fully considers the QoS requirements of flows and ensures the flows can be transmitted at high rates. Extensive simulations at 60 GHz demonstrate that with high SI cancelation level and appropriate contention threshold, the proposed FD algorithm can achieve superior performance in terms of the number of flows with their QoS requirements satisfied and the system throughput compared with other state-of-the-art schemes.
Recently, the development of SI cancelation technology has made FD communication possible. Jain @cite_5 proposed the signal inversion and adaptive cancelation. Combining signal inversion cancelation with digital cancelation can reduce SI by up to 73dB. Everett @cite_8 showed the BS could exploit directional diversity by using directional antennas to achieve additional passive suppression of the SI. Besides, Miura @cite_3 proposed a novel node architecture introducing directional antennas into FD wireless technology. Rajagopal @cite_11 proved enabling backhaul transmission on one panel while simultaneously receiving backhaul on an adjacent panel is attainable for next generation backhaul designs. In @cite_12 , Xiao showed the configuration with separate Tx Rx antenna arrays appeared more flexible in SI suppression, and proposed the beamforming cancelation in FD mmWave communication.
@cite_8 @cite_3 @cite_5 @cite_12 @cite_11
2545232960 2008689146 2128938148 2963903846 2058707124
The potential of doubling the spectrum efficiency of FD transmission motivates us to investigate FD-mmWave communication. To realize FD transmission in the mmWave band, we first introduce possible antenna configurations for FD-mmWave transmission. It is shown that, different from the cases in microwave band FD communications, the configuration with separate Tx Rx antenna arrays appears more flexible in SI suppression while it may increase some cost and area versus that with the same array. We then model the mmWave SI channel with separate Tx Rx arrays, where a near-field propagation model is adopted for the LOS path, and it is found that the established LOS-SI channel with separate Tx Rx arrays also shows spatial sparsity. Based on the SI channel, we further explore approaches to mitigate SI by signal processing, and we focus on a new cancellation approach in FD-mmWave communication, that is, beamforming cancellation. Centered on the CA constraint of the beamforming vectors, we propose several candidate solutions. Lastly, we consider an FD-mmWave multi-user scenario, and show that even if there are no FD users in an FD-mmWave cellular system, the FD benefit can still be exploited in the FD base station. Candidate solutions are also discussed to mitigate both SI and MUI simultaneously. Recent works have considered the feasibility of full duplex (FD) wireless communications in practice. While the first FD system by Choi et.al. relied on a specific antenna cancellation technique to achieve a significant portion of self-interference cancellation, the various limitations of this technique prompted latter works to move away from antenna cancellation and rely on analog cancellation achieved through channel estimation. However, the latter systems in turn require the use of variable attenuator and delay elements that need to be automatically tuned to compensate for the self-interference channel. This not only adds complexity to the overall system but also makes the performance sensitive to wide-band channels. More importantly, none of the existing FD schemes can be readily scaled to MIMO systems. In this context, we revisit the role of antenna cancellation in FD communications and show that it has more potential in its applicability to FD than previously thought. We advocate a design that overcomes the limitations that have been pointed out in the literature. We then extend this to a two-stage design that allows both transmit and receive versions of antenna cancellation to be jointly leveraged. Finally, we illustrate an extension of our design to MIMO systems, where a combination of both MIMO and FD can be realized in tandem. Full-duplex (FD) technology has been regarded as a promising solution to improve the spectral efficiency of the 5th generation (5G) wireless communication system. In this paper, we focus on a small-area radio system, where a FD base-station serves two half-duplex users simultaneously with one in the uplink and the other one in downlink direction. However, the self-interference (SI) and the inter-user interference (IUI) may largely degrade the system performance. Therefore we propose a simple but effective inter-user interference cancellation (IIC) strategy to cope with the IUI. This method is based on the fact that the downlink user observes a multiple access channel (MAC) of two user, the BS and the uplink user, respectively. Hence, the downlink user has an opportunity to remove the IUI according to the transmission rates and its received powers. Therefore, we call this method as multi-access channel IIC (MIIC). Then, we analyze the achievable rate region of the FD system with and without MIIC when taking the SI into consideration. To obtain the rate region, analytic power allocation strategies are derived. Simulation results show that, by applying the proposed power allocation strategies, the performance of FD system with MIIC is as good as the system without IUI under the 3GPP assumptions. Given that full duplex (FD) and MIMO both employ multiple antenna resources, an important question that arises is how to make the choice between MIMO and FD? We show that optimal performance requires a combination of both to be used. Hence, we present the design and implementation of MIDU, the first MIMO full duplex system for wireless networks. MIDU employs antenna cancellation with symmetric placement of transmit and receive antennas as its primary RF cancellation technique. We show that MIDU's design provides large amounts of self-interference cancellation with several key advantages: (i) It allows for two stages of additive antenna cancellation in tandem, to yield as high as 45 dB self-interference suppression; (ii) It can potentially eliminate the need for other forms of analog cancellation, thereby avoiding the need for variable attenuator and delays; (iii) It easily scales to MIMO systems, therefore enabling the coexistence of MIMO and full duplex. We implemented MIDU on the WARP FPGA platform, and evaluated its performance against half duplex (HD)-MIMO. Our results reveal that, with the same number of RF chains, MIDU can potentially double the throughput achieved by half duplex MIMO in a single link; and provide median gains of at least 20 even in single cell scenarios, where full duplex encounters inter-client interference. Based on key insights from our results, we also highlight how to efficiently enable scheduling for a MIDU node. The use of directional antennas in wireless networks has been widely studied with two main motivations: 1) decreasing interference between devices and 2) improving power efficiency. We identify a third motivation for utilizing directional antennas: pushing the range limitations of full-duplex wireless communication. A characterization of full-duplex performance in the context of a base station transmitting to one device while receiving from another is presented. In this scenario, the base station can exploit directional diversity by using directional antennas to achieve additional passive suppression of the self-interference. The characterization shows that at 10 m distance and with 12 dBm transmit power the gains over half-duplex are as high as 90 and no lower than 60 as long as the directional antennas at the base station are separated by 45 or more. At 15 m distance the gains are no lower than 40 for separations of 90 and larger. Passive suppression via directional antennas also allows full-duplex to achieve significant gains over half-duplex even without resorting to the use of extra hardware for performing RF cancellation as has been required in the previous work.