Yafeng Wang

Beijing University of Posts and Telecommunications | BUPT · School of Information and Communication Engineering (SICE)

In this study, the authors consider multi-user millimetre wave (mmWave) multiple-input multiple-output (MIMO) downlink communications for multi-carrier scenarios, e.g. orthogonal frequency-division multiplexing (OFDM) a common analogue precoder and combiner for the transmitter and receiver to maximise spectral efficiency is the main challenge for m...

Due to high hardware costs for digital beamforming, hybrid beamforming (HBF) is widely employed in millimeter wave (mmWave) communications systems. However, the number of radio frequency (RF) chains in the analog part of HBF is far less than that of antennas, which causes a serious dimensiondeficient problem. In order to overcome this problem, this...

We consider the channel estimation of millimeter wave (mmWave) multiple-input multiple-output (MIMO) systems, where both the transmitter and receiver adopt hybrid beamforming structure. Due to the spatial sparsity of the mmWave channel, it can be reconstructed by estimating the direction and gain of the paths. Leveraging this feature, we propose a...

The end-to-end throughput in multi-hop OFDM relay systems can be increased by incorporating sub-channel pairing (SCP) at the relay nodes. This helps in achieving high data rate requirements for live streaming applications. In real-time applications the physical layer configuration both static and dynamic is of significant importance and the end-to-...

In this paper, we propose a hybrid synchronous algorithm based on the combination of distributed and centralized algorithm. First of all, we put forward the concept of local cluster and generalized local cluster. The cluster is a collection of synchronous UE meeting certain conditions and has a center UE. Through this mechanism, we can finish many...

In this paper, we consider the two-hop MIMO interference network, where T source-destination pairs communicate via T×K relays selected from G alternative relays. Based on optimal relay selection, each source-destination pair selected K relays to transmit data streams. In the first time slot, the source node transmits data steams to the selected rel...

In the cognitive radio networks, the spectrum handoff scheme directly determines the system performance. That's to say a handoff scheme that cannot fully uses the information of users and channels will not provide the best choice. In this paper, a spectrum handoff scheme based on comprehensive cost is proposed. By jointly computing multiple factors...

Wireless network coding for multi-hop two-way relay channels (MH-TRC) has been proven to achieve a significantly improved network throughput than non- network coding (Non-NC) schemes. Our previous work showed that the multi-hop compute-and-forward (MH- CPF) scheme for the MH-TRC with fixed two transmission time intervals was unable to outperform No...

Under the more practical assumption that transmitters have no knowledge of the channel state information (CSI) but the channel distribution information (CDI), this paper examines the diversity-multiplexing trade-off (DMT) of two classes of cooperative protocols, namely, the amplify-and-forward (AF) and decode-and-forward (DF) protocols, with a thre...

JPEG 2000 is one of the most popular image compression standards offering significant performance advantages over previous image standards. High computational complexity of the JPEG 2000 algorithms makes it necessary to employ methods that overcomes the bottlenecks of the system and hence an efficient solution is imperative. One such crucial algori...

In traditional cellular networks, the capacity of downlink channels is limited by inter-cell interference (ICI). Basestation cooperation is a promising technique which yields large performance improvements by mitigating or eliminating ICI. However, many existing cooperation methods are far from practical due to intensive computational complexity. I...

In this paper, an unequal error protection (UEP) scheme based on hierarchical quadrature amplitude modulation (HQAM) for three-dimensional (3-D) video transmission is proposed. The proposed scheme exploits unique characteristics of the color plus depth map stereoscopic video, where the color sequence has a more significant impact on the reconstruct...

This paper focuses on the influence of beamforming on the interference distribution of wireless communications systems. Through comparing broadcast beamforming and adaptive beamforming, some significant conclusions have been drawn. First, for most users the gain of adaptive beamforming as opposed to broadcast beamforming is noticeable in terms of b...

Relay is becoming one of the most desirable techniques proposed in LTE-Advanced systems to improve the capacity and coverage. However, with the introduction of relays, users accessing to the relays need to use two links, i.e., the enhanced Node B (eNB) to relay node (RN) link also known as the backhaul link and the RN to User Equipment (UE) link al...

Recently, Coordinated Multi-Point (CoMP) transmission/Reception technology is introduced into the fourth-generation cellular mobile communication system. Time-division duplex (TDD) system is more suitable to apply CoMP when joint processing is needed because it can easily get the channel information through channel reciprocity. Actually, a crucial...

We consider a problem of optimizing multi-cell downlink throughput in multiple-input single-output (MISO) beamforming with single user per sub-channel in the wireless communication system. Previous work based on the generalization of uplink-downlink duality has already reformulated the maximum achievable downlink throughput into dual uplink through...

In the cognitive radio network [1], the spectrum access mechanism determines the spectrum utilization and the system performance. In this paper, we set up a cognitive radio network scenario with finite primary users and finite secondary users as our simulation model environment. We define a new way by probability anticipation to help secondary user...

Relay networks are subject to two different types of interferences, i.e., inter-cell interference and intra-cell interference. As the inter-cell interference has been well addressed in the literature, this paper is concentrated on intra-cell interference cooperation. An interference graph based interference coordination scheme is proposed to manage...

TD-SCDMA, which has been widely used in China, provides better experience for mobile users than GSM did. However, weak coverage remains one of the most important problems in the current network as it used to be in GSM. One way to address the problem is through network optimization. Traditional approaches of network optimization exhaustively search...

Collaborative transmission among evolved Node-Bs (eNBs) is one of the promising techniques for LTE-Advanced to provide broader coverage and higher spectral efficiency. The interference among multi-cell transmission can be mitigated by joint precoding, such as multi-cell block diagonalization (BD) at cooperative eNBs. The major difference between mu...

In this paper, system RoT and a novel intercell interference control scheme for TD-SCDMA HSUPA (High-Speed Uplink Packet Access) based on system RoT is presented. The scheme controls the user admission and the resource distribution according to the information of users' geometry. System simulation results proves that this scheme improves the system...

Multi-user multi-input and multi-output based on block diagonalization algorithm can eliminate the multi-user interference, but in fact the existence of the non-ideal factors lead to the interference can not be cancelled completely. In this paper we study the performance of the 3GPP long term evolution system based on BD algorithm and propose a low...

Diversity is an effective technique to enhance link quality and increasing network capacity. In this paper, we propose a generalized distributed turbo codes (DTC)-based coded cooperation protocol for two-hop relay networks with an arbitrary number of relays. This scheme aims at achieving improved diversity over the classical coded cooperation metho...

Abstract-Single and Multi-layer adaptive eigen based beamforming (EBB) has been proved to be a promising method to achieve the tradeoff between diversity and spatial multiplexing. But the CQI in multi-layer mode is calculated according to the CQI in single-layer mode. Lack of accurate multi-layer CQI will induce performance loss when implementing l...

Block diagonalization (BD) algorithm is an efficient precoding technique for multiuser multiple-input multiple-output (MU-MIMO) system. In previous researches, BD precoding was mostly realized based on the singular value decomposition (SVD). However, in the cooperative transmission scenario where the dimension of channel matrix is significantly enl...

Cooperative communications enable single antenna mobiles in a multi-user environment to share their antennas and form a virtual multiple antenna array that allows them to achieve transmit diversity. In order to achieve improved diversity over the classical coded cooperation method in fading channels, we consider a coded cooperation diversity strate...

In practical use, data traffic has a feature of high-burst in wireless network, which means that the serve request of a user is not continuous. With full buffer traffic model, network operators can give evaluations on the peak data rate and the least data rate of heavy load network. However, rather than the peak data rate and the least data rate, w...

A cross-layer packet scheduling algorithm is proposed for multi-user MIMO-OFDMA systems with the mixed services, such as Real-Time (RT) and Non-Real-Time (NRT) services. The proposed scheduling algorithm is based on the channel state information of physical layer and user queuing delay of Medium Access Control (MAC) sub-layer, and constructs the co...

In this paper, we propose a novel semidistributed algorithm with low overhead and complexity for multi-user cooperative wireless networks with opportunistic relaying. The source is required to satisfy its minimum rate requirement with a feasible relay and help another source as a relay. The optimal solution can be obtained by exhaustive search with...

In this paper, we develop and analyze several inter-cell interference modeling methods for cellular network. The models can analyze multiple interfering signals under different fading scenarios. Incoherent addition of summing multiple interfering signals is assumed. We propose an approximate method that uses the generalized Gram-Charlier series to...

The investigation of inter-cell interference mitigation techniques is a key area in wireless communications. Coordinated multiple points (CoMP) transmission/reception is a candidate technique for interference cancellation in 3GPP LTE-Advanced system. However, the coordination scheme in CoMP remains a key research problem to be solved, which will ha...

This paper investigates a novel relaying strategy for cooperative networks over Nakagami-m fading channel, namely selection incremental relaying (SIR), which combines selection relaying (SR) with incremental relaying (IR) based on decode-and-forward (DF). The closed-form expression for the outage probabilities of both single relay and opportunistic...

Antenna gain mismatch between transmitter and receiver circuits has been regarded as an obstacle for exploit- ing channel reciprocity between uplink and downlink channels in time-division duplex (TDD) multiple-input multiple-output (MIMO) systems. To the best knowledge of the authors, little work to date has been on about the impact of antenna mism...

The virtual MIMO (V-MIMO) and coordinated multi- point transmission (CoMP) are adopted by the LTE system to extend the uplink spectral efficiency. V-MIMO makes use of spatial multiplexing to increase system throughput while CoMP by means of mitigating inter cell interference (ICI) significantly achieve the same effect. In this paper, we present an...

Coordinated multi-point (CoMP) transmission is a promising technique to suppress inter-cell interference (ICI) in LTE-Advanced system. With perfect channel state information (CSI) at the transmitter, joint beamforming methods can be used to completely cancel ICI and significantly improve the spectrum efficiency. However, in FDD system, the transmit...

Reckon for the considerable beamforming gain, eigen-based beamforming (EBB) has been proved to be a promising case to ensure cell edge link robustness. For simplicity, both spatial multiplexing gain and beamforming gain can be obtained with conventional rank adaptive EBB scheme, however, former researches suggest that it doesn't work well at cell e...

CoMP (Coordinated Multiple Points) is an effective technique to deal with ICI (Inter-Cell Interference), which is the main constraint for the performance of LTE-Advanced (Long Term Evolution) system. Through coordination among cells, ICI can be largely avoided even mitigated and thus the cell edge as well as the average performance will be improved...

This paper utilizes an adaptive modulation and coding (AMC) scheme and compares the performance of adaptation between single-user multiple input multiple output (SU-MIMO) and multi-user (MU) MIMO with that of SU-MIMO. In long term evolution (LTE), every UE only needs to feed back SU-MIMO rank 1 channel quality indicator (CQI) which could get feedba...

This paper presents a feature comparison between the 3rd Generation Partnership Project (3GPP) Long Term Evolution (LTE) Release 8 and Institute of Electrical and Electronics Engineers (IEEE) 802.16m and preliminary system performance comparison. As Orthogonal Frequency Division Multiple Access (OFDMA) mobile broadband air interfaces, LTE and IEEE...

Multi-cell cooperation has been regarded as a promising technique of the future cellular wireless network to achieve higher transmission rate and better QoS (quality of service) performance. Cooperation among base stations can be classified into two categories: centralized and distributed cooperation. In this work, we mainly consider efficient and...

Incremental selection amplify-and-forward relaying (ISAF) has the best performance of outage probability among relaying strategies and has been identified as the best protocol. This paper proposes to jointly optimize power allocation (PA) and best-relay position based on cooperative diversity for ISAF in order to minimize outage probability. The cl...

In LTE downlink multiple-input multiple-output (MIMO), eigen based beamforming (EBB) is a promising approach for single-user scenario, while block diagonalization based beamforming (BDBF) eliminates intra-cell interferences significantly for multi-user scenario. However, both of them neglect inter-cell interferences which may lead system performanc...

One of the most challenging problems in high-data-rate wireless transmission is to reduce inter-symbol interference (ISI) resulted from the time dispersion caused by multi-path propagation. To solve this problem, equalization is introduced. Generally, efficient decision feedback equalizer (DFE) holds better performance than linear equalizer for the...

In the cooperative system with a large number of users, the base station may select a subset of users to serve in order to maximize the total throughput. The brute-force search for the optimal user set, however, is computationally prohibitive. We propose a clustering algorithm for cooperative communication systems, whose objective is to increase th...

In this paper, we propose a new approach for the design of a wireless portable vibration acquisition and analysis instrument. The system can achieve high-speed synchronous data acquisition at the sample speed of 10k samples per second per channel. The system employs Wireless LAN technology to achieve data transmission up to 54 Mbps. A remote signal...

In this paper, a field-programmable gate array (FPGA) based enhanced architecture of the arithmetic coder is proposed, which processes two symbols per clock cycle as compared to the conventional architecture that processes only one symbol per clock. The input to the arithmetic coder is from the bit-plane coder, which generates more than two context...

As one of the key technologies in TD-LTE-Advanced downlink system, MIMO-OFDMA (Multi-Input and Multi-Output Orthogonal Frequency Division Multiplexing Access) achieves high system throughput by using multiple antennas at both the transmitter and receiver while eliminating intra-cell interference by utilizing closely-spaced orthogonal sub-carriers....

The wireless extension of the JPEG 2000 standard formally known as JPWL is the newest international standard for still image compression. Different from all previous standards, this new standard was created specifically for wireless imaging applications. This paper examines the error resilience performance of the JPEG, JPEG 2000 and JPWL standards...

Due to the flexibility and freedom of the P2P e-commerce environment, peers often make transactions with other unknown peers, the trust evaluation becomes critical. Traditionally the trust evaluation model is based on feedback mechanism, which only depends on transactions number neglecting transaction amount, etc. This may lead to the transaction r...

In order to avoid the resource inefficiency of all-participated cooperation in wireless amplify-and-forward relay networks, a novel relay selection scheme based on the channel gain of the source-relay and relay-destination links is proposed. A condition is introduced to maximize the upper bound of the overall received signal-to-noise ratio (SNR). T...

Coordinated scheduling is a hot topic recently. Inter-cell interference is crucial to the improvement of system throughput, especially in OFDMA system. In this work, the optimization of beamforming in multiple-input single-output (MISO) downlink system is considered. The uplink-downlink duality has been widely used in this sort of research. By the...

LTE-Advanced extends the number of transmit antennas of evolved NodeB (eNB) up to 8, which will provide substantial spatial degrees of freedom. However, the user is usually equipped with a small number of antennas due to space constraints. Thus, multi-user beamforming (MU-BF) was proposed to dramatically boost the spectrum efficiency by transmittin...

Coordinated Multi-Point (CoMP) Transmission/Rec-eption technology has shown to improve the system performance. In Time-division duplex system, it can easily obtain channel information by the channel reciprocity. However, a crucial point to realize the channel reciprocity is the antenna calibration problem. This paper aims at analyzing the impact of...

The inherent multicast nature of the wireless medium can be exploited over two hop networks paves a way for Physical layer multicasting. The system performance gain can be achieved through multicast diversity achieved with dual amplify-and-forward (AF) Relay schemes. The dual AF relay multicast scheme is proposed in this paper for cooperative and n...

A novel channel estimation algorithm for sounding reference signal in DFT-spread OFDM (DFT-S OFDM) system is proposed, which can estimate the channel response with high efficiency. According to the MSE metric between the estimated channel response and the real one, the simulation result shows that the intra-cell interference is neglectable while th...

LTE-Advanced system based on orthogonal frequency division multiplexing (OFDM) can eliminate intra-cell interference since data are carried on the orthogonal subcarriers; however, it can not mitigate inter-cell interference (ICI) which affects the performance severely. Therefore, coordinated multiple point (CoMP) reception scheme was proposed to re...

After relaying technology is introduced into the cellular system, many research fields emerge. Among them, resource allocation strategy for distributed and centralized scheduling is an important topic. This paper analyzes and compares the differences between these two scheduling modes, including both system performance and signaling overhead. Two p...

Many applications of mobile ad hoc networks (MANETs) adopt hierarchical structure for the scalability and simplify of management. Clustering is the most popular method to impose a hierarchical structure in MANETs. As a newly proposed weighing based clustering algorithm, the weighted clustering algorithm (WCA) has improved performance compared with...

In cellular networks, the relay selection scheme for a given user is generally determined by the base station in a centralized manner. But the feedback for achieving every channel gain can cause a lot of burden to the system. In order to overcome this shortcoming, we propose a threshold-based relay selection scheme. In the proposed scheme, the feas...

The QoS of VoIP service in TDD-LTE uplink is subject to a series of restrictive factors, such as strong inter-cell interference, tight delay budget, less retransmission times, etc. This paper studies different scheduling and link adaptation schemes for VoIP users in TDD-LTE uplink and makes analysis of the corresponding simulation results. To furth...

With enough channel state information feedback, the close-loop multiple-input multiple-output (MIMO) yields large improvements in the system performance. Usually, it is divided into two main areas. One is codebook based precoding (CBP), and the other is non-codebook based precoding (NBP). For the channel reciprocity property, the eigen-based beamfo...

In this paper, we propose a new relay selection scheme based on the channel gain of the source-to-relay and relay-to-destination links to maximize the upper bound on the overall received signal-to-noise ratio (SNR). In order to reduce the complexity of the scheme, we assume that each of the selected relays is allocated identical power. The total po...

User cooperation is employed to explore the inherent distributed spatial diversity priority of wireless network. Nodes based rather than linked based protocol is employed and the broadcast nature of radio network is considered by user cooperation. However cooperative partner selection might be difficult especially for nomadic cooperative networks a...

Fixed relay, which has been taken into consideration for beyond-3G cellular networks, is a promising technique to provide high data rate coverage in a cost-effective manner. In this paper, we study the capacity and optimal configurations of two-hop relay downlink system. First, we summarize two typical resource allocation schemes of the two hops on...

To further improve and satisfy the spectral efficiency requirements addressed in LTE-Advanced system, in this paper, a Coordinated Multi-Cell MU-MIMO scheme is proposed to achieve this goal, especially to enhance the cell-edge user(the 5% of user throughput) throughput substantially. In our proposed cooperative scheme, we adopt multi-cell block dia...

For the channel reciprocity property, Eigen-based Beamforming (EBB) has been attracting more and more attentions in LTE-Advanced system. In this paper, single user beamforming with rank adaptation and multi-user beamforming using block diagonal algorithm are studied to make full use of the spatial multiplexing gain. In addition, power control and p...

We consider the resource allocation of centralized and distributed scheduling in the two-hop relaying cellular system. The limited spectrum resource is one of the obstacles which conflicts with the evolution of being wider coverage and larger capacity in the wireless system. In this paper, system performance and signaling overhead are analyzed and...

The use of multicasting over multi-hop networks seems an attractive new way to provide support to real-time applications like video streaming. In this paper, we proposed a 2-hop Dual Amplify-and-Forward (DAF) relay scheme. In this scheme, only the intermediate nodes (relay nodes) can cooperate with each other and there is no cooperation between tra...

In this paper, a scheme of multiple cells downlink joint transmitting for OFDMA system is introduced. The system and cell edge spectrum efficiency gain from the joint transmission is analyzed. The main factor to get the gain is the geography area selection of joint transmitting. Moreover, multiple users' joint transmitting provides the more signifi...

Bi-dimensional Markov chain model based on cooperative medium access control (MAC) of wireless local area networks (WLAN) is considered to reflect system performance accurately. Two basic factors that affect the analysis results are station retry limits and non-saturated transmit probability. A uniform solution considering both factors is proposed....

In the DFT-spread-OFDM system, the traditional frequency estimation scheme can accurately estimate half of channel frequency responses (on the odd-indexed sub-carriers) and yet the other half (on the even-indexed sub-carriers) can only be made out of approximation or interpolation. It is because that the long block used for data-transmission is dou...

This paper investigates the performance of VoIP service in 3G-LTE system and IEEE 802.16m system both in TDD mode, and compares their different system characteristics in details. Thereafter semi-persistent scheduling, dynamic scheduling and link adaptation schemes involved are presented. Finally, this paper demonstrates different VoIP capacities of...

User cooperation enables single antenna terminals to benefit from spatial diversity by partnering with other users to create a virtual transmit antenna array. A promising form of cooperation is called coded cooperation which integrates cooperation with channel coding, showing great performance gains. In this paper, we examine the performance of cod...

This paper analyzes the performance bound of variable gain relaying over non-identical Nakagami-m fading channel, and the closed-form expressions for average bit error probability (ABEP) of binary phase shift keying (BPSK)modulation and multiple amplitude modulation (M-AM) are derived. Numerical and simulation results show that the deduced performa...

This paper analyzes the performance measures of amplify-and-forward (AF) relaying over non-identical Nakagami-m fading channel. The exact probability density functions (PDFs) of total signal-to-noise ratio (SNR) for variable gain relaying and fixed gain relaying are deduced, and the theoretical formulas of moment generating function (MGF) and momen...

LTE-advanced system which based on orthogonal frequency division multiplexing (OFDM) can eliminate intra-cell interference but still can not mitigate inter-cell interference (ICI). In this paper, we propose a novel cooperative multi-cell multiple-input multiple-output (MIMO) scheme for LTE-advanced system to reduce ICI and improve the cell capacity...

Cyclic Delay Diversity (CDD) is a simple and efficient space-time diversity technique. It can be used in OFDM and DFT-Spread-OFDM. The traditional CDD has low complexity and system overhead, however, also has some limitations on performance and is sensitive to propagation environment. In this paper, two improved CDD scheme including open-loop and c...

In this paper, we have proposed a prototype biometrics authentication system based upon fingerprint recognition. The major functional blocks of the proposed authentication system are presented in details. A simple but effective algorithm is proposed to detect and remove false minutia, which is able to considerably improve the system performance. Th...

We address the problem of frequency reuse schemes in the downlink of the fixed two-hop orthogonal frequency division multiple access (OFDMA) cellular relaying networks. There has been little work on specific frequency reuse schemes for this system in the literatures, although this is the key element for realizing the potential capacity and coverage...

We compare the outage performance by applying transmit antenna selection strategies to amplify-and-forward protocol in the MIMO relaying scenario. Although antenna selection is a suboptimal form of beamforming, it enjoys the advantages of tractable optimization and low feedback overhead. Specifically, by combining transmit antenna selection strateg...

This paper derives the tight performance bound for average bit error probability (ABEP) of binary phase shift keying (BPSK) modulation and multiple amplitude modulation (M-AM), using variable gain relaying, over non-identical Nakagami-m fading channel. Additionally, we present other performance measures including approximate moments and amounts of...

Recently, cooperative sensing which can enhance the sensing performance becomes popular in the design of cognitive radio (CR) networks. CR networks need reliable information exchange to conduct cooperative sensing,but it is difficult to transmit information for CR networks without licensed band over the air interface. In this paper, we propose to u...

Recently, cooperative sensing which can enhance the sensing performance becomes popular in the design of cognitive radio (CR) networks. CR networks need reliable information exchange to conduct cooperative sensing, but it is difficult to transmit information for CR networks without licensed band over the air interface. In this paper, we propose to...

Fixed relay as a candidate solution in the cellular system attracts more and more attention due to its improvements of coverage and capacity. In this paper, we make our study on the optimal configurations of two-hop relay downlink system. Based on former works, two typical resource allocation schemes of the two hops are considered on the assumption...

In this paper, an improved stopping criterion for irregular LDPC decoding is proposed. This scheme considers the decoding property of irregular LDPC codes. When the lowest degree variable nodes reach stable state, the decoder gets the final decoding result. Therefore, the improved criterion is based on the convergence of the mean magnitude of the l...