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Hopping control channel MAC protocol for opportunistic spectrum access networks

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The Journal of china Universities of posts and telecommunications 2010年第6期17卷 65-71页

作者： FU Jing-tuan,JI Hong,MAO Xu key laboratory of universal wireless communications,ministry of education,beijing university of posts and telecommunications,beijing 100876,china key laboratory of universal wireless communications Ministry of Education Beijing University of Posts and Telecommunications Beijing 100876 China

Opportunistic spectrum access （OSA） is considered as a promising approach to mitigate spectrum scarcity by allowing unlicensed users to exploit spectrum opportunities in licensed frequency bands. Derived from the existing channel-hopping multiple access （CHMA） protocol,we introduce a hopping control channel medium access control （MAC） protocol in the context of OSA networks. In our proposed protocol,all nodes in the network follow a common channel-hopping sequence; every frequency channel can be used as control channel and data channel. Considering primary users＇ occupancy of the channel,we use a primary user （PU） detection model to calculate the channel availability for unlicensed users＇ access. Then,a discrete Markov chain analytical model is applied to describe the channel states and deduce the system throughput. Through simulation,we present numerical results to demonstrate the throughput performance of our protocol and thus validate our work.

关键词： channel hopping MAC protocol OSA Markov chain

Bandwidth allocation and admission control scheme based on Nash bargaining solution for WiMAX systems

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The Journal of china Universities of posts and telecommunications 2010年第2期17卷 53-58页

作者： CAI Dao-jin ,JI Hong,LI Xi key laboratory of universal wireless communications,ministry of education,beijing university of posts and telecommunications,beijing 100876,china key laboratory of universal wireless communications Ministry of Education Beijing University of Posts and Telecommunications Beijing 100876 China

Development of fair and efficient bandwidth allocation and admission control schemes is one of the key issues in the design of IEEE 802.16 broadband wireless access systems in time division multiple access （TDMA） mode. In this article, the problem of bandwidth allocation and admission control is formulated as a Nash bargaining model. The nash bargaining solution （NBS） derived from the cooperative game is adopted to maximize the spectrum utilization. Analysis and simulation results show that there is a unique Pareto optimal bandwidth allocation solution by using NBS among various flows. Furthermore, maximum utility of the system can also be maintained by using the admission control policy with different number of connections and variable channel qualities. The total throughput of the proposed scheme is close to the maximal one, while significantly improving fairness compared to the existing solutions.

关键词： NBS game theory bandwidth allocation admission control IEEE 802.16

Cross layer scheduling for real-time traffic in multiuser MIMO-OFDMA systems

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The Journal of china Universities of posts and telecommunications 2009年第3期16卷 24-29页

作者： SUN Qiao-yun,TIAN Hui,DONG Kun,ZHANG Ping key laboratory of universal wireless communications,ministry of education,beijing university of posts and telecommunications,beijing 100876,china key laboratory of universal wireless communications Ministry of Education Beijing University of Posts and Telecommunications Beijing 100876 China

A novel cross layer scheduling algorithm is proposed for real-time （RT） traffic in multiuser downlink multiple-input multiple-output orthogonal frequency division multiple access （MIMO-OFDMA） wireless systems. The algorithm dynamically allocates resources in space, time and frequency domain based on channel state information （CSI）, users＇ quality of service （QoS） requirements and queue state information （QSI）. To provide higher data rate and spectrum efficiency, adaptive modulation and coding （AMC） is employed. The proposed algorithm can improve cell throughput and increase the number of users that can be supported while guaranteeing users＇ QoS requirements and fairness among all users. Simulation results indicate that the proposed algorithm can achieve superior performance.

关键词： MIMO-OFDMA cross layer QoS AMC

Emergency access mechanism in IEEE 802.15.4 for wireless body area sensor networks

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The Journal of china Universities of posts and telecommunications 2009年第6期16卷 24-31页

作者： GUO Yan-yan,KANG Gui-xia,CAO Yu,ZHANG Ping key laboratory of universal wireless communications,ministry of education,beijing university of posts and telecommunications,beijing 100876,china key laboratory of universal wireless communications Ministry of Education Beijing University of Posts and Telecommunications Beijing 100876 China

IEEE 802.15.4 protocol has attracted much attention in research and industrial communities as candidate technology for wireless body area sensor networks（WBASNs）.IEEE 802.15.4 supports the exclusive use of a wireless channel through guaranteed time slot（GTS）.However,on one hand,bandwidth underutilization rate may be lower because of the variance between the guaranteed bandwidth and the arrival *** the other hand,the waiting time for transmitting emergency notification is getting longer when the GTSs assigned to the nodes increase in *** solve these problems,in this article,a new scheme is proposed to reduce transmission delay for the alarm notification in emergent *** results are presented to validate the efficiency of the proposed scheme by comparing it with the medium access control（MAC） protocol of IEEE 802.15.4.

关键词： WBASN GTS IEEE 802.15.4 emergency mechanism

RPPK modulation with high data rates

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Science china(Information Sciences) 2010年第2期53卷 344-354页

作者： LI Bin , ZHOU Zheng & ZOU WeiXia key laboratory of universal wireless communications, ministry of education wireless Network laboratory, beijing university of posts and telecommunications, beijing 100876, china key laboratory of universal wireless communications Ministry of Education Beijing University of Posts and Telecommunications Beijing China wireless Network laboratory Beijing University of Posts and Telecommunications Beijing China

With the development of communication technology, the precious frequency spectrum is becoming more and more crowded. Exploiting the particular filter with zero group delay, ultra narrow band (UNB) modulation is intended for acquiring the high frequency efficiency. Unfortunately, this UNB filter is confronted with great challenges from the classical communication theories. The validation on its realization is also difficult. This paper proposes a novel UNB modulation, namely random pulse position keying (RPPK). It is demonstrated from analysis that there is no inessential discrete spectral line in modulated signal’s power density spectrum (PDS), and the UNB filter has been successfully avoided. Consequently, RPPK is rather explicit in theory and simple in implementation. As is shown by the simulation, the frequency utilization of RPPK can even reach 100 bits/s/Hz. Its optimum receiving performance is slightly inferior to BPSK, yet is much superior to that of other UNB modulations such as VMSK/2. Moreover, multi-access and confidentiality are additional benefits to UNB users.

关键词： UNB modulation frequency utilization efficiency RPPK PDS

An improved dynamic user equipment power saving mechanism for LTE system and performance analysis

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Science china(Information Sciences) 2010年第10期53卷 2075-2086页

作者： XU HaiBo, TIAN Hui , HUANG Bo & ZHANG Ping key laboratory of universal wireless communications, ministry of education beijing university of posts and telecommunications, beijing 100876, china key laboratory of universal wireless communications Ministry of Education Beijing University of Posts and Telecommunications Beijing China

In order to minimize the power consumption of user equipments (UEs), and further to support various services and transmissions of large amount of data, the power saving mechanisms have been investigated for most remarkable wireless systems. In this paper, an improved dynamic discontinuous reception (D-DRX) scheme is presented for LTE system, which is able to adaptively adjust the inactivity timer and the sleep period of UEs’ receivers. Moreover, theoretical analysis based on the Markov chain is provided for the D-DRX scheme. Several numerical examples quantitatively show that the D-DRX scheme can capture various packet arrival patterns and scheduling behaviors of system to make a better tradeoff between power saving and packet delay by considering the length of packet queue.

关键词： power saving DRX Markov chain LTE-advanced

A novel adaptive spectrum forming filter:Application in cognitive ultra-wideband

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Science china(Information Sciences) 2010年第12期53卷 2584-2599页

作者： LI Bin ,ZHOU Zheng & ZOU WeiXia key lab of universal wireless communications,MOE.wireless Network lab,beijing university of posts and telecommunications,beijing 100876,china key lab of universal wireless communications MOE. Wireless Network Lab Beijing University of Posts and Telecommunications Beijing China

Ultra wideband impulse radio(UWB-IR) has important applications in high data rate communications,high precision positioning and penetrating target *** with cognitive radio(CR),UWB can also greatly alleviate the current spectrum ***,the existing UWB waveforms are faced with two *** spectrum utilization of UWB signal is rather low,which reduces the communication ***,it appears difficult for UWB-IR to avoid spectrum collision with other incumbent *** UWB will inevitably interfere other legal wireless *** by these considerations,we model the UWB waveform design into an interpolation *** on radial basis function neural network,a novel UWB pulse is presented in this *** UWB pulse is then realized though reasonable simplification on the already proposed theoretical *** designed UWB pulses can adaptively track the external spectral environment where UWB devices work and reconfigure its emission spectrum according to the state of primer users without any modification on *** frequency utilization is maximized when there is no active primary *** adequate spectrum avoidance has also been achieved without much spectrum utilization degradation within the non-primary *** and analysis show that our UWB-IR pulse is much superior to the other existing UWB signals in the frequency utilization,spectrum avoidance and in the transmission performance.

关键词： UWB-IR cognitive radio pulse design RBF network spectrum efficiency spectrum avoidance

On the bounds of frequency-selective channel capacity with doubly correlated geometrical MIMO channel model

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The Journal of china Universities of posts and telecommunications 2010年第2期17卷 8-13页

作者： LI Yong-hua , Lü Tie-jun, WU Xiao-fei, ZHANG Lin key laboratory of universal wireless communications, ministry of education, beijing university of posts and telecommunications, beijing 100876, china key laboratory of universal wireless communications Ministry of Education Beijing University of Posts and Telecommunications Beijing 100876 China

The multi-input multi-output （MIMO） technology plays an important role in link transmissions. This article considers the general case for the ergodic capacity in doubly correlated frequency-selective MIMO channel. In the study, the geometrical MIMO channel model is presented. Based on the formula of MIMO ergodic capacity, the capacity limits are studied with arbitrary finite number of antennas in the frequency-selective MIMO channel. It first derives the exact expressions for the upper bound and lower bound in doubly correlated MIMO channel. The results for the single-ended correlation and independent identically distributed （i.i.d.） MIMO channel are also obtained as special cases. Then the simple expressions of the capacity bounds are attained at high SNR. Finally, results are provided by Monte Carlo simulations to verify the tightness of the derived bounds.

关键词： MIMO correlation capacity bounds

Spectral efficient half-duplex relaying with interference suppression

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The Journal of china Universities of posts and telecommunications 2010年第6期17卷 19-24页

作者： LI Xing-zheng,LIU Yuan-an,XIE Gang,CHANG Ling-jun,HAN Xiao key laboratory of universal wireless communications,ministry of education,beijing university of posts and telecommunications,beijing 100876,china key laboratory of universal wireless communications Ministry of Education Beijing University of Posts and Telecommunications Beijing 100876 China

Two-hop relaying systems suffer spectral efficiency loss due to the half-duplex property of relays. This paper proposes an efficient relaying protocol which can recover the spectral efficiency loss but still work with half-duplex relays. However,there exists inter-relay interference which degrades the performance of the protocol. With this consideration,a power control policy is derived to suppress the interference using game theory,and then an algorithm is given to facilitate distributed implementation. Furthermore,impact of deploying more destination antennas on performance of the relaying protocol is investigated. Simulation results show that,with the power control policy,the proposed relaying protocol can achieve high spectral efficiency.

关键词： relaying protocol distributed power control cooperative communication decode-and-forward relay game theory