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Journal of Semiconductors 2024年第1期45卷 22-32页

作者： Yongran Yi Dixian Zhao Jiajun Zhang Peng Gu Chenyu Xu Yuan Chai Huiqi Liu xiaohu you National Mobile Communication Research Laboratory Southeast UniversityNanjing 211189China Purple Mountain Laboratories Nanjing 211111China Chengdu Xphased Technology Company Ltd. Chengdu 610041China

This article presents an 8-element dual-polarized phased-array transceiver(TRX)front-end IC for millimeter-wave(mm-Wave)5G new radio(NR).Power enhancement technologies for power amplifiers(PA)in mm-Wave 5G phased-array TRX are discussed.A four-stage wideband high-power class-AB PA with distributed-active-transformer(DAT)power combining and multi-stage second-harmonic traps is proposed,ensuring the mitigated amplitude-to-phase(AM-PM)distortions across wide carrier frequencies without degrading transmitting(TX)power,gain and efficiency.TX and receiving(RX)switching is achieved by a matching network co-designed on-chip T/R switch.In each TRX element,6-bit 360°phase shifting and 6-bit 31.5-dB gain tuning are respectively achieved by the digital-controlled vector-modulated phase shifter(VMPS)and differential attenuator(ATT).Fabricated in 65-nm bulk complementary metal oxide semiconductor(CMOS),the proposed TRX demonstrates the measured peak TX/RX gains of 25.5/21.3 dB,covering the 24−29.5 GHz band.The measured peak TX OP1dB and power-added efficiency(PAE)are 20.8 dBm and 21.1%,respectively.The measured minimum RX NF is 4.1 dB.The TRX achieves an output power of 11.0−12.4 dBm and error vector magnitude(EVM)of 5%with 400-MHz 5G NR FR2 OFDM 64-QAM signals across 24−29.5 GHz,covering 3GPP 5G NR FR2 operating bands of n257,n258,and n261.

关键词： fifth-generation(5G) power amplifier millimeter-wave transceiver phased-array

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Research on user pairing algorithm for LTE femtocell uplink

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Science China(Information Sciences) 2014年第8期57卷 96-105页

作者： WANG Jie XU Chen you xiaohu National Mobile Communications Research Laboratory Southeast University

In this article,a new simulated annealing based bit error rate pairing scheduling(SA-BPS)algorithm for LTE femtocell uplink virtual multiple input multiple output(V-MIMO)systems is proposed,which uses Round Robin(RR)criterion to decide the first user,and simulated annealing(SA)algorithm with objective function of bit error rate(BER)is suggested to decide the pairing users.The SA-BPS is considered not only to be used for inner layer user pairing within femtocell user equipments(HUEs)to increase spectrum efficiency,but also to be used for cross layer user pairing between HUEs and macrocell user equipments(MUEs)to cancel the cross layer interference from MUEs to HUEs.As a growth control coefficient is used in SA-BPS to control the growth of average BER of users in the pairing group,rapid user BER deterioration can be prevented by adopting a proper coefficient.Simulation results show that,the SA-BPS outperforms RPS,DPS,and the conventional SA algorithm in terms of BER performance,whether used for inner layer user pairing or cross layer user pairing.Also,the mode switching signal to interference ratio(SIR)threshold between inner and cross layer user pairing are obtained by simulation in three cross layer interference power distribution scenarios.

关键词： user pairing femtocell simulated annealing V-MIMO bit error rate

Low-complexity optimal spatial channel pairing for AF-based multi-pair two-way relay networks

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Science China(Information Sciences) 2014年第10期57卷 46-55页

作者： SHU Feng CHEN Yu you xiaohu LU JinHui School of Electronic and Optical Engineering Nanjing University of Science and Technology National Mobile Communications Research Laboratory Southeast University Ministerial Key Laboratory of JGMT Nanjing University of Science and Technology

This paper considers a multi-pair two-way relay system with multi-antenna users and proposes a low-complexity optimal spatial channel pairing(SCP) strategy at the relay station(RS) for such a system. The proposed SCP scheme, following the BD-like beamformer at RS, pairs the uplink spatial subchannels of each user pair with the corresponding downlink spatial subchannels by maximizing sum-rate(Max-SR). Furthermore, a new mathematical inequality(arrangement inequalities of a product) is developed and applied to obtain sufficient and necessary conditions for achieving Max-SR-SCP. This also yields a simple low-complexity implementation of the proposed SCP in contrast to the NP-hard complexity of the original Max-SR-SCP problem. Simulation results illustrate that the proposed Max-SR-SCP achieves substantial sum-rate gains over other pairing schemes.

关键词： multipair two-way relay spatial channel pairing maximizing sum-rate arrangement inequalities of product relaying station

Energy-efficient resource allocation for OFDMA relay systems with imperfect CSIT

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Science China(Information Sciences) 2015年第8期58卷 131-143页

作者： WANG XiaoMing ZHENG FuChun ZHU PengCheng MENG Chao you xiaohu National Mobile Communications Research Laboratory Southeast University School of Systems Engineering University of Reading

In this paper, we propose an energy-efficient resource allocation scheme for the downlink of decodeand-forward relay-assisted orthogonal frequency division multiple access systems. The resource allocation is designed based on imperfect channel state information at the transmitter. We jointly optimize the power allocation, data rate allocation, and subcarrier allocation to maximize the system energy efficiency(EE). We formulate the EE problem as a probabilistic mixed non-convex optimization problem, in which the individual power constraints and the outage probability requirements are considered. An iterative algorithm based on bisection method is given to transform the optimization problem into a standard concave form. Also, we consider a proportional fairness design for the EE maximization problem. Simulation results illustrate the effectiveness of the proposed algorithm.

关键词： energy efficiency relay systems OFDMA decode-and-forward imperfect CSIT

ACK-based adaptive backoff for random access protocols

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Science China(Information Sciences) 2015年第4期58卷 37-50页

作者： YANG Yang SONG GuanNan WEI Kun ZHANG WuXiong you xiaohu Shanghai Institute of Microsystem and Information Technology Chinese Academy of Sciences Shanghai Research Center for Wireless Communications Key Laboratory of Wireless Sensor Network & Communication Chinese Academy of Sciences National Mobile Communications Research Laboratory Southeast University

In contention-based networks, ALOHA and CSMA are the most popular random access protocols,wherein a station transmits packets after a certain delay according to a particular backoff policy, such as binary exponential backoff(BEB). When a contention-based network is heavily loaded, system performance, in terms of transmission success rate and throughput, degrades dramatically under random backoff policies without considering the backoff choices of the neighborhood. To alleviate this problem, we propose and verify in this paper a highly efficient backoff policy, namely "ACK-based adaptive backoff "(AAB), which takes into account the total number of successful packet transmissions(with ACKs) among neighboring stations in determining a station’s subsequent backoff period before its next packet(re)transmission. By doing this, AAB can effectively reduce the overall packet collisions under heavy-loaded conditions, even with hidden-stations. On comparing with BEB and its modified policy, multiple increase linear decrease(MILD), AAB can achieve about 17% and10% performance gains of transmission success rate under CSMA protocol in a network with 20 stations with new packet arrival rate of 0.9, and 43% and 16% performance gains of energy efficiency respectively when the former two protocols reach their saturated points.

关键词： backoff policy contention-based networks medium access control(MAC) energy efficiency green communications

Three novel opportunistic scheduling algorithms in CoMP-CSB scenario

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Science China(Information Sciences) 2013年第8期56卷 250-261页

作者： WANG Hao LIU Nan WU Ping PAN ZhiWen you xiaohu National Mobile Communications Research Laboratory School of Information Science and EngineeringSoutheast University Signal and System at Department of Engineering Sciences Uppsala University

Coordinated scheduling/beamforming(CSB),which belongs to the coordinated multi-point(CoMP) transmission,has received lots of attention recently due to its great potential to mitigate inter-cell interference(ICI) and to increase the cell-edge throughput,and meanwhile it only requires limited base station cooperation and is easy to implement.However,to the best of our knowledge,there are no effective scheduling algorithms with low complexity and overhead in CoMP-CSB scenario as yet.Thus,in this paper,we propose three novel opportunistic scheduling algorithms in CoMP-CSB scenario.All of them jointly consider the intended channel condition of the scheduled user from its serving cell and the orthogonality between the intended channel and the corresponding interference channels to concurrently scheduled users in nearby cells,thus exploiting multi-user diversity(MUD) and mitigating ICI at the same time.Algorithm 1 cooperatively chooses the most orthogonal user pair within a candidate user set in which all users have a large local channel feedback,while Algorithm 2 concurrently schedules the user pair with the largest ratio between the local channel feedbacks and the aforementioned orthogonality within the same candidate user set.Algorithm 3 performs in the way similar to the proportional fairness scheduling,while making a proper modification for its usage in CoMP-CSB scenario.The performance of the proposed scheduling algorithms are evaluated through simulation.Results show that,they all can significantly enhance the received signal to interference plus noise ratio(SINR) with relatively good fairness guarantee,thus achieving larger throughputs and utilities than several well-known scheduling algorithms.Algorithm 2 even outperforms Algorithm 1 when the aforementioned candidate user set is big enough in size and has a bit more overhead/complexity.Furthermore,Algorithms 3 is the best one among all the three proposed algorithms,but it requires more overhead/complexity than Algorithm 1 and 2.Finally,we give the optimal param

关键词： coordinated multi-point(CoMP) coordinated scheduling/beamforming(CSB) inter-cell interference(ICI) multi-user diversity(MUD) opportunistic scheduling.

QoS and channel state aware load balancing in 3GPP LTE multi-cell networks

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Science China(Information Sciences) 2013年第4期56卷 91-102页

作者： LI ZhiHang WANG Hao PAN ZhiWen LIU Nan you xiaohu National Mobile Communications Research Laboratory School of Information Science and EngineeringSoutheast University

In this paper,we investigate the load balancing problem with the consideration of different qualityof-service(QoS) and channel state in 3GPP long term evolution(LTE) multi-cell networks.Load imbalance among nearby cells often causes inefficient utilization of the system resources.Then in overloaded cells,users cannot get satisfied services for short resources,while in idle cells,there is plenty of unoccupied resources.However,switching users only for load balancing with no consideration of channel state often results in aggressive handover of users,which may occupy too many resources in their target cells and deteriorate the network efficiency.Thus,how to efficiently perform load balancing with the consideration of channel state becomes an important issue.Meanwhile,LTE network aims to serve users with different QoS requirements,which should be taken into account when performing load balancing.Thus we propose a multi-objective optimization problem,whose objectives are load balancing index and network average load for users with QoS requirements and a unified utility function for users without QoS requirements.The constraints are physical resource limits and users’ QoS demands.Then we analyze its complexity and propose a practical algorithm,load balancing,with the consideration of different QoS requirements and channel state services(LBQC).Extensive simulations are conducted.The results show that the proposed algorithm can approximate the optimal algorithm efficiently,and leads to significantly better performances than load balancing with no consideration of channel state,e.g.a lower new call blocking rate with a fewer system resources occupation for users with QoS requirements,a higher cell edge throughput and total throughput for users without QoS requirements.

关键词： load balancing channel state quality of service(QoS) multi-objective optimization problem total utility

Transmission capacity maximization for LED array-assisted multiuser VLC systems

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Science China(Information Sciences) 2015年第8期58卷 117-130页

作者： KONG Lei SHEN Hong XU Wei ZHANG Hua ZHAO ChunMing you xiaohu National Mobile Communications Research Laboratory Southeast University

In this paper, we present a light-emitting diode(LED) array-assisted visible light communication(VLC) system. Considering the requirements of illumination, the human eye safety, and the energy saving,we optimize the optical power allocation(PA) to maximize the transmission capacity of the overall system.Specifically, we discuss two typical scenarios where the LED array in each room serves multiple users either simultaneously or in a round-robin manner. The problem corresponding to the first case turns out to be nonconvex whose globally optimal solution is hard to obtain. To address this difficult problem, we first adopt the famous gradient projection algorithm to obtain a locally optimal solution, then we employ powerful convex relaxation techniques, and achieve a high-quality solution. While for the round-robin case, we are able to derive an optimal solution in closed form by virtue of Karush-Kuhn-Tucker conditions. Interestingly, the derived closedform solution follows a water-filling pattern with both square root and two-side clipping operations, which differs from the conventional water-filling-like PA in radiofrequency channels. Numerical results depict the performance advantage provided by the proposed PA strategies under various settings.

关键词： light-emitting diodes visible light communication power allocation multiuser transmission convex relaxation

Hybrid interference alignment and power allocation for multi-user interference MIMO channels

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Science China(Information Sciences) 2013年第4期56卷 19-27页

作者： SHU Feng you xiaohu WANG Mao HAN YuBing LI Yang SHENG WeiXing Institute of Wireless Communication and Sensor Network EEOTNanjing University of Science and Technology National Mobile Communications Research Laboratory Southeast University Department of Electrical Engineering University of Texas at DallasTX 75080-3021TexasUSA

This paper proposes a hybrid interference alignment scheme which combines maximizing signal-toleakage-noise ratio(Max-SLNR) at transmitter and maximizing signal-to-interference-noise ratio(Max-SINR) at receiver.The proposed scheme gives the same sum rate as the existing method using Max-SINR at both transmitter and receiver by avoiding the operation of reversing channel,thus it provides a simpler solution.Furthermore,two power allocation procedures are devised based on game theory and water filling.The gain of these schemes over equal power allocation increases to 2 bit/s/Hz in correlated fading channels as large-scale fading becomes significant.Additionally,user fairness is solved by introducing weighting factors.

关键词： interference alignment power allocation sum rate Max-SLNR Max-SINR

Lifetime maximization routing with network coding in wireless multihop networks

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Science China(Information Sciences) 2013年第2期56卷 26-40页

作者： DING LiangHui WU Ping WANG Hao PAN ZhiWen you xiaohu Institute of Image Communication and Network Engineering Shanghai Jiao Tong University Signals and Systems Department of Engineering Sciences Uppsala University National Mobile Communication Research Laboratory Southeast University

In this paper, we consider the lifetime maximization routing with network coding in wireless mul- tihop networks. We first show that lifetime maximization with network coding is different from pure routing, throughput maximization with network coding and energy minimization with network coding. Then we formulate lifetime maximization problems in three different cases of (i) no network coding, (ii) two-way network coding, and (iii) overhearing network coding. To solve these problems, we use flow augmenting routing (FA) for the first case, and then extend the FA with network coding (FANC) by using energy minimized one-hop network coding. After that, we investigate the influence of parameters of FANC, evaluate the performance of FANC with two-way and overhearing network coding schemes and compare it with that without network coding under two different power control models, namely, protocol and physical ones. The results show that the lifetime can be improved significantly by using network coding, and the performance gain of network coding decreases with the increase of flow asymmetry and the power control ability.

关键词： network coding lifetime maximization linear programming flow augmenting routing wireless multihop networks