In Band Full Duplex (IBFD) Technology for Next Generation Wireless Networks: A Survey in Cellular Networks

Next-Generation(NextG)wireless communication networks with their widespread applications require high data rates,seamless connectivity and high quality of service(QoS).To cope up with an unprecedented rise of data hungry applications,users demand more spectral resources imposing a limitation on available wireless spectrum.One of the potential solutions to address the spectrum scarce issue is to incorporate in band full duplex(IBFD)or full duplex(FD)paradigm in next generation networks including 5G new radio(NR).Recently,FD has gained the research interest in cellular networks for its potential to double the wireless link capacity and enhancing spectral efficiency(SE).In half duplex(HD)cellular networks,base stations(BSs)can either perform uplink(UL)or downlink(DL)transmission at a particular time instant leading to reduced throughput levels.Due to the advancement in the self interference reduction(SIR)techniques,full duplex base stations(FD-BSs)can be employed to allow simultaneous UL and DL transmissions at the same time–frequency resources as compared to its HD counterpart.It ideally achieves twice the throughput without any additional complexity at user-equipment(UE).This paper covers a detailed survey on FD cellular networks.A series of SIR approaches,UE-UE mitigation techniques are summarized.Various existing MAC protocols and antenna architectures for FD cellular networks are outlined.An overview of security aspects for FD in cellular networks is also presented.Lastly,various open issues and possible research directions are brought up for FD cellular networks.

Secure Performance Analysis and Optimization for FD-NOMA Vehicular Communications

Vehicle-to-vehicle(V2V)communication appeals to increasing research interest as a result of its applications to provide safety information as well as infotainment services.The increasing demand of transmit rates and various requirements of quality of services(QoS)in vehicular communication scenarios call for the integration of V2V communication systems and potential techniques in the future wireless communications,such as full duplex(FD)and non-orthogonal multiple access(NOMA)which enhance spectral efficiency and provide massive connectivity.However,the large amount of data transmission and user connectivity give rise to the concern of security issues and personal privacy.In order to analyze the security performance of V2V communications,we introduce a cooperative NOMA V2V system model with an FD relay.This paper focuses on the security performance of the FD-NOMA based V2V system on the physical layer perspective.We first derive several analytical results of the ergodic secrecy capacity.Then,we propose a secrecy sum rate optimization scheme utilizing the instantaneous channel state information(CSI),which is formulated as a non-convex optimization problem.Based on the differential structure of the non-convex constraints,the original problem is approximated and solved by a series of convex optimization problems.Simulation results validate the analytical results and the effectiveness of the secrecy sum rate optimization algorithm.

基于FD-NOMA的无人机通信系统容量分析

为了提高无人机与地面用户的通信质量,提出了一种基于全双工和非正交多址接入技术的无人机通信系统模型,并分析了城市和郊区两种场景下该系统模型的遍历容量。首先,推导出两种场景下该系统模型的精确容量表达式;然后,通过引入Q函数和利用截断方法解决了式中指数积分函数的计算问题,得到了容量的近似闭式表达式,并在城市场景下,采用取系数因子的方法得到了更精确的容量近似闭式表达式;最后,仿真和数值结果表明,莱斯因子对系统容量存在一定影响,增加无人机数量或非正交多址接入功率向量都可以获得更好的容量性能。

Time-Hopping Sequence Design for Virtual Full Duplex via Rapid On-Off-Division Duplex

To achieve virtual full-duplex(VFD)communication using half-duplex radios,the rapid on-off-division(RODD)technique has been proposed in recent years.The time-hopping(TH)sequence is critical to controlling self-interference introduced in the paradigm.By constructing the collision model with a symbol level time scale,the periodic collision correlation function properties are introduced as the performance metric for the TH sequence in the RODD system.To achieve the best VFD performance,an optimization-based method for TH sequence design is proposed.In addition,the conventional TH frame structure design for RODD system is improved.Numerical simulations are presented to demonstrate that the proposed approach can significantly increase system performance.Results indicate that the TH sequence design is very effective for the RODD system.

Performance of Nth Worst Full-Duplex Relay Selection over Nakagami-M Fading Channels

The performance analysis of Nth worst relay selection for the full-duplex (FD) mode over Nakagami-m fading channels is studied. We assume the relay employs the amplify-and-forward (AF) protocol. The closed-form expres-sions for the outage performance in terms of the received signal-to-noise ratio cumulative distribution function are derived. In the high signal-to-noise ratio regime, asymptotic outage probability is also investigated. Based on these expressions, the effect of several important network parameters, i.e., the number of relays and the order of selected relay, as well as the quality of the relay links, source-relay links, relay-destination links, are analytically characterized. Finally, numerical results are provided to verify and illustrate our mathematical analysis.

二重荧光RT-LAMP鉴别检测禽呼肠孤病毒和鸡滑液囊支原体

本研究旨在建立一套通过添加荧光探针FD,反应后可使用成像仪直接观测结果的鉴别检测禽呼肠孤病毒(ARV)和鸡滑液囊支原体(MS)的二重荧光RT-LAMP检测方法。根据ARV和MS的保守基因片段,设计了2套LAMP引物,并各添加1条FD荧光探针,2条FD探针分别标记CY5和6-FAM荧光基团。结果:ARV阳性对照在成像仪下发出红色荧光,MS阳性对照发出绿色荧光,双重模板经过图像融合后为黄色荧光;特异性结果显示,该二重荧光RT-LAMP检测方法仅能扩增ARV和MS两种病原,对其他常见病原如鸡毒支原体(MG)、禽流感病毒(AIV)、新城疫病毒(NDV)等无扩增反应;敏感性结果显示,该二重荧光RT-LAMP检测方法对ARV和MS的最低检测量分别为1.7×10^(2)copies和1.9×10^(2)copies;使用该方法检测40份临床样品,检出率与本实验室前期建立的二重荧光RT-PCR检测结果相同。综上,该二重荧光RT-LAMP检测方法可特异、敏感地鉴别检测ARV和MS,通过添加FD荧光探针和成像仪观测结果,为不同条件的实验室提供了新的检测手段。

一种抑制相位噪声的多通道变时延下变频全双工收发方法

相位噪声会限制全双工(FD)收发机的自干扰抑制能力,恶化有用信号解调性能,即使全双工收发机采用发射机、接收机共用本振的结构,也无法消除相位噪声的限制作用。为了降低多径自干扰(SI)分量中相位噪声的影响,该文提出一种多通道变时延下变频全双工收发方法,具体包括可以补偿相位噪声的全双工收发机设计和能够抑制残余相位噪声的自干扰抑制算法。多通道变时延下变频全双工收发机采用多条通道接收同一天线的信号,各接收本振信号为经过不同延时调整的发射本振信号,可以在下变频时补偿多径自干扰中的相位噪声。自干扰抑制算法利用不同接收信号估计相位噪声参数,进一步降低残余相位噪声的影响。此外,该文推导了这种全双工收发方法的自干扰抑制能力,并给出了其随发射功率、接收通道数量的变化关系。分析与仿真结果表明,当接收通道数量高于自干扰信道强径数量时,多通道变时延下变频全双工接收方法不受相位噪声影响。

Integrated photonic RF self-interference cancellation on a silicon platform for full-duplex communication

In-band full-duplex(IBFD) technology can double the spectrum utilization efficiency for wireless communications,and increase the data transmission rate of B5G and 6G networks and satellite communications. RF self-interference is the major challenge for the application of IBFD technology, which must be resolved. Compared with the conventional electronic method, the photonic self-interference cancellation(PSIC) technique has the advantages of wide bandwidth, high amplitude and time delay tuning precision, and immunity to electromagnetic interference.Integrating the PSIC system on chip can effectively reduce the size, weight, and power consumption and meet the application requirement, especially for mobile terminals and small satellite payloads. In this paper, the silicon integrated PSIC chip is presented first and demonstrated for IBFD communication. The integrated PSIC chip comprises function units including phase modulation, time delay and amplitude tuning, sideband filtering, and photodetection, which complete the matching conditions for RF self-interference cancellation. Over the wide frequency range of C, X, Ku, and K bands, from 5 GHz to 25 GHz, a cancellation depth of more than 20 dB is achieved with the narrowest bandwidth of 140 MHz. A maximum bandwidth of 630 MHz is obtained at a center frequency of10 GHz. The full-duplex communication experiment at Ku-band by using the PSIC chip is carried out. Cancellation depths of 24.9 dB and 26.6 dB are measured for a bandwidth of 100 MHz at central frequencies of 12.4 GHz and14.2 GHz, respectively, and the signal of interest(SOI) with 16-quadrature amplitude modulation is recovered successfully. The factors affecting the cancellation depth and maximum interference to the SOI ratio are investigated in detail. The performances of the integrated PSIC system including link gain, noise figure, receiving sensitivity, and spurious free dynamic range are characterized.

基于加权MMSE方法的中继发射波束成形器设计

针对一个全双工(Full Duplex, FD)双向通信系统提出了中继发射波束形成器的设计问题.该系统的两个源结点配备多根天线,附近的每个中继结点配备两根天线,一根用于传输,另一根用于接收.中继处在有限的发射功率和使用迫零归零技术下,设计了两种具有迭代线性复杂度的中继波束成形器:最小化两个源结点加权均方误差和最大化较小源结点的信噪比.通过对加权总和传输速率和平均运行时间的仿真,数值实验验证了改进加权最小均方误差波束成形器的有效性和高效性.

A 220 GHz Frequency-Division Multiplexing Wireless Link with High Data Rate

With the development of wireless communication,the 6G mobile communication technology has received wide attention.As one of the key technologies of 6G,terahertz(THz)communication technology has the characteristics of ultra-high bandwidth,high security and low environmental noise.In this paper,a THz duplexer with a half-wavelength coupling structure and a sub-harmonic mixer operating at 216 GHz and 204 GHz are designed and measured.Based on these key devices,a 220 GHz frequency-division multiplexing communication system is proposed,with a real-time data rate of 10.4 Gbit/s for one channel and a transmission distance of 15 m.The measured constellation diagram of two receivers is clearly visible,the signal-to-noise ratio(SNR)is higher than 22 dB,and the bit error ratio(BER)is less than 10^(−8).Furthermore,the high definition(HD)4K video can also be transmitted in real time without stutter.

同时同频全双工LTE射频自干扰抑制能力分析及实验验证

同时同频全双工本地发射信号会对本地接收信号产生强自干扰,为了使信号能够通过射频接收通道及模数转换器件,需要在射频前端进行自干扰抑制。在自干扰为直射路径的条件下,该文采用直接射频耦合法,对长期演进(LTE)同时同频全双工自干扰抑制进行实验测试;分析推导了自干扰功率、带宽及线缆、幅度、相位调整误差对射频自干扰抑制能力的影响;得到了射频自干扰抑制能力的闭合表达式。分析表明对于20 MHz带宽,-10 dBm接收功率的LTE射频自干扰信号,理论上能抑制54 dB的射频自干扰,而实验测试结果表明能抑制51.2 dB。

基于带内回程的全双工大规模MIMO异构网覆盖分析

在大规模多输入多输出(MIMO)系统中,带内全双工无线回程方案能够有效复用无线电接入频谱,大幅提高网络性能。为此,基于该方案构建大规模MIMO异构蜂窝网络模型,并假设网络元素分别服从独立齐次泊松点过程,利用随机几何理论分别研究宏蜂窝下行和小蜂窝上行链路信号干扰噪声比(SINR)的覆盖概率,分析不同参数对覆盖性能的影响。仿真结果表明,带内全双工无线回程方案能够有效提高系统频谱效率,但不能改善宏蜂窝和小蜂窝网络的SINR覆盖概率。

全双工大规模MIMO AF中继系统频谱与能量效率研究

为提高移动通信系统的能量与频谱效率,基于放大转发协议,提出一种多用户全双工大规模多入多出中继协作方案。对频谱和能量效率进行研究,获得系统中每一对用户间各态历经速率下界的封闭解析解以及系统的频谱、能量效率。分析系统在不同能量分配场景下对环路干扰的抑制效果和渐近性能。实验结果表明,当中继收或发天线数足够大时,系统能有效地消除小规模衰落和多用户干扰,其渐近频谱效率和能量效率将达到一饱和稳定值。当采用信源发功率固定、中继发功率与中继发天线数成反比的功率分配方案时,系统可有效地抑制环路干扰。

全双工无线携能通信速率最大化波束赋形研究

针对全双工无线携能通信系统,提出了一种基于系统和速率最大化准则的波束赋形联合优化方案。该方案以系统和速率最大化为目标,在保证上行/下行链路的最大发射功率约束及最小能量收获需求的同时,实现了信息速率和频谱效率的同步改善。由于速率问题为非凸问题,首先采用半定松弛及一阶泰勒近似方法将其转换为凸优化问题,然后结合基于逐次凸近似的迭代算法分别求解最优的信息波束赋形矢量和能量波束赋形矢量。仿真结果表明,所提方案相比传统方案性能更优,实现了系统和速率的有效提高。

I/Q失衡影响下无人机多向全双工中继NOMA传输系统性能分析

无人机(UAV)具备高灵活性、强适应性和高机动性等优势,能够为6G网络提供便捷有效的辅助通信方案。为提高UAV通信系统的频谱效率,让所有用户彼此间在更少的时隙内完成信息交互,该文提出一种全双工(FD)多向中继非正交多址接入(NOMA)(FD NOMA MWRN)传输方案,考虑收发端都存在同相/正交(I/Q)失衡的情况,对系统的传输率和能量效率进行分析。仿真结果表明:相比半双工(HD),全双工技术可以实现频谱利用率的翻倍;所提方案比正交多址接入(OMA)方案更具性能优势,且不受用户数量的影响,传输消耗的时隙数始终为1;I/Q失衡会限制系统传输率,UAV的工作高度也对其起到一定的约束作用。

全双工协作中继网络的遍历容量分析

为了对无线网络开展合理设计,就存在直达通信链路的多节点全双工协作中继网络(FD-CRNs)进行了研究。首先,在同时考虑网络内节点的互干扰与全双工(FD)节点进行自干扰消除后的残余自干扰的情况下,基于Nakagami-m衰落就中继节点,分别采用放大转发与解码转发协议的不同场景对遍历容量展开了分析。接着,通过将求解遍历容量转化为求解接收信干噪比的原点矩,求得遍历容量的近似闭合表达式。最后,通过仿真分析了不同中继转发协议、Nakagami-m衰落参数、残余自干扰、互干扰、节点传输功率等不同因素对遍历容量的影响。仿真结果表明,提升节点的发射功率能一定程度提高遍历容量,解码转发协议抗干扰的性能优于放大转发协议。当其他通信参数一定时,中继节点采用解码转发协议时具有更好的容量性能表现。

全双工无线供能物联网的物理层安全性能分析

面对干扰和窃听,传统的安全信息传输大都基于密钥加密的方法,在面向动态变化无线网络环境时会产生对称性密码系统的密钥分配、非对称性密码系统的高计算复杂度等问题。而快速增长的无线业务流量和物联网类型的海量设备接入,会引起计算复杂度的进一步提升和能量开销的激增。针对此问题,提出一种基于物理层安全技术的全双工无线供能物联网的安全通信方法,利用噪声和无线信道随机性来限制窃听者接收信息量。该方法首先基于信息论对全双工无线供能物联网安全容量进行分析,然后根据安全容量的分析模型推导得到了安全中断概率(SOP)的闭合表达式。最后,考虑到噪声、干扰机干扰、空间互干扰,以及残余自干扰等因素对安全容量的影响,提出一种全双工无线供能物联网安全波束成形方法,该方法通过降低联合干扰来增加发送和接收端的互信息量,提高全双工无线功能物联网的安全容量。通过蒙特卡罗仿真验证了推导结果的准确性,仿真结果表明,在安全容量和SOP指标上,全双工无线供能物联网比传统半双工无线功能物联网有较大性能增益。

Full Duplex Communications for Next Generation Cellular Networks:The Capacity Gain

Full duplex communication highly improves spectrum efficiency of a wireless communication link.However, when it is applied to a cellular network, the capacity gain from this technology remains unknown. The reason is that full duplex communication changes the aggregate interference experienced by each communication link in cellular networks. In this paper, the capacity gain from full duplex communication is studied for cellular networks of 4G and beyond, where the same frequency channel is adopted in each cell. A two-layer Poisson point process(PPP) is adopted to model the network topology, and stochastic geometry is employed to derive the coverage probability and the average capacity of typical link in a cellular network. On the basis of these derived parameters, the capacity gain from full duplex communication is determined. Numerical results reveal that without mutual interference cancellation(MIC), the capacity gain is small under various power levels; with perfect MIC at base stations, the capacity gain can exceed 60%; with imperfect MIC at base stations, the capacity gain decreases quickly even with a slight drop of MIC performance.

复式住宅火灾危害性探讨

为准确衡量实际火灾烟气危害,提出一种综合考虑温度、能见度、烟气毒性的火灾烟气危害评价模型HVCHT。以云南地区复式住宅为例,基于FDS进行数值模拟。结果表明:烟气在35s时对隔层人员产生危害性,高温在200s时对2号和3号门的人员造成伤害,CO毒性在整个火灾过程中不具备致命性,火灾前期能见度成为人员能否及时疏散的关键因素;通过HVCHT模型得出在火灾中后期烟气温度所占危害性权重逐步增加,从42%上升至63%。

Research on the novel asymmetric frequency division duplex technique

This article introduces a novel duplex transmission technique-asymmetric frequency division duplex （AFDD）. One of the characteristics in future mobile systems is asymmetric characteristic caused by service requirement and electromagnetic radiation, AFDD is designed to adapt to the new asymmetric characteristics. The AFDD puts forward a novel adaptive frequency-allocation scheme in downlink and uplink. Combining AFDD with code division multiple access （CDMA） communication system, it is proven that AFDD improves the capacity and coverage of the system compare with FDD CDMA system.