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Communications and Networking in China (CHINACOM), 2010 5th International ICST Conference on

Date 25-27 Aug. 2010

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Displaying Results 1 - 25 of 208
  • [Title page]

    Publication Year: 2010 , Page(s): 1
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  • ChinaCom 2010 - greetings from the general chairs

    Publication Year: 2010 , Page(s): 1 - 3
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  • International Advisory Committee

    Publication Year: 2010 , Page(s): 1 - 4
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  • Keynote speakers

    Publication Year: 2010 , Page(s): 1 - 3
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (65 KB)  

    Provides an abstract for each of the keynote presentations and a brief professional biography of each presenter. The complete presentations were not made available for publication as part of the conference proceedings. View full abstract»

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  • Tutorials

    Publication Year: 2010 , Page(s): 1 - 3
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  • Table of contents

    Publication Year: 2010 , Page(s): 1 - 18
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  • WCN track

    Publication Year: 2010 , Page(s): 1
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  • User grouping based on large scale channel information in multi-cell downlink cooperative multi-antenna systems

    Publication Year: 2010 , Page(s): 1 - 5
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (173 KB) |  | HTML iconHTML  

    In this paper, we study low feedback user grouping in downlink cooperative transmission multi-antenna systems. Users in the same group are served on the same frequency and time resource by multiple cooperative BSs using the zero-forcing precoder. We first derive the user's average received signal to interference and noise ratio (SINR). It shows that each user's SINR is an increasing function of the large scale signal to interference ratio (SIR) of users in neighbor cells, which can be obtained using the large scale channel information. We then propose a novel fair user grouping algorithm based on the large scale SIR. Simulation results show that our algorithm achieves better cell edge throughput compared with existing methods with minor reduction of cell throughput. View full abstract»

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  • Multi-source relay networks exploiting cooperative network coding

    Publication Year: 2010 , Page(s): 1 - 5
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (300 KB) |  | HTML iconHTML  

    In this paper, we develop effective multi-source relay schemes which, by exploiting cooperative network coding, are designed to achieve a high diversity gain and coding efficiency. Key to the proposed schemes lies in two ingredients: (1) Utilization of the high-capacity channels between closely spaced intra-cluster nodes to enable efficient information exchange among these nodes; (2) Proper distributed network coding that provides high diversity gain. Outage probability analysis and numerical results are provided and evidently demonstrate higher diversity gain and coding efficiency that the proposed schemes achieve compared to other comparable network coding schemes. View full abstract»

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  • Minimum Conflict Degree Channel Assignment in multi-rate multi-channel wireless networks

    Publication Year: 2010 , Page(s): 1 - 5
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (1204 KB) |  | HTML iconHTML  

    In this paper, the conflict degree of multi-rate link pairs based on SINR model in co-channel has been analyzed. We suggest five conflict types for link pairs, and verify the associated effects on data rate links of each type in random topology network. To maximize the network throughput, we further propose a simple and efficient algorithm called Minimum Conflict Degree Channel Assignment (Min-CD CA). Novel metrics are also proposed to assess the conflict degree of each link and overall network. Our simulation results show that the proposed metrics are more appropriate than a widely used metric, fractional network interference, in multi-rate multi-channel wireless networks. The simulation results also show that our algorithm performs better than the minimum interference greedy CA algorithm. View full abstract»

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  • Location-aware routing for Delay Tolerant Networks

    Publication Year: 2010 , Page(s): 1 - 5
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (175 KB) |  | HTML iconHTML  

    In this paper, we sought to understand the reasons causing failures and delays of message delivery in Delay Tolerant Networks (DTN), and to use this understanding for improving the network. By studying two real-world datasets, we found that node isolation is prevalent, which largely accounts for the inefficiencies in DTN's message delivery. In addition, by analyzing nodes' contact-location relationship, we found that individual and system-wide key locations exist and their existence suggests potential improvements. Motivated by our observations, we designed a location aware routing scheme for DTN networks. With simulation-based experiments, we compared our proposal with other representative DTN routing schemes, and showed that with the awareness of the location information, our solution can deliver more messages within shorter delays, therefore improves the network intensively. View full abstract»

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  • Joint session admission control scheme in integrated WLAN and 3G networks

    Publication Year: 2010 , Page(s): 1 - 5
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (116 KB) |  | HTML iconHTML  

    As heterogeneous wireless networks are deployed and users need more flexible mobility services, there has been a lot of research work about interworking mechanism between widely deployed 3G network and rapidly boarded WLAN (wireless local area network). On the other side, TD-SCDMA (time division-synchronous code division multiple access), which combines all the advantage of the TDD (time-division deplex) with CDMA (code-division multiple access), is one of the three main standards of third-generation mobile radio system, and is newly commer-cialized in China. It is expected to provide enough mobility and higher data rate. So the study of the integration between WLAN and TD-SCDMA will be attractive. In this paper, we propose an efficient joint session admission control scheme that maximize overall network revenue with Qos (quality of service) constraints over both the WLAN and the TD-SCDMA cellular networks. Simulation results illustrate that the overall network revenue earned in the proposed scheme is significant larger than that when the individual networks are optimized independently. View full abstract»

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  • Joint channel estimation for downlink base station cooperative transmission exploiting channel asymmetry

    Publication Year: 2010 , Page(s): 1 - 5
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (201 KB) |  | HTML iconHTML  

    In this paper, we study uplink joint channel estimation for downlink base station cooperative transmission orthogonal frequency division multiplexing systems. We present three linear estimators which jointly estimates the channel coefficients from users in different cells with minimum mean square error (MSE), robust design and least square criterion, then we analyze their performance. We find that due to the asymmetric feature of the multi-cell channels in cooperative transmission systems, the MSE for different links with three joint estimators differ. When the channel energy information is exploited for channel estimation, the cross channels that experience large attenuation have smaller estimation MSEs than the local channels, and using non-orthogonal training sequences among users in different cells leads to minor performance loss. This is in contrast to the traditional understanding. To reduce the complexity of the estimators when non-orthogonal training sequences are used, we also present an interference cancelation based estimator. Both the channel estimation errors and the throughput of the cooperative transmission system are simulated to verify our analysis. View full abstract»

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  • Iterative symbol-by-symbol decoding of LDPC codes and constellation mapping for multilevel modulation

    Publication Year: 2010 , Page(s): 1 - 4
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (350 KB) |  | HTML iconHTML  

    Iterative probabilistic decoding of binary low-density parity-check (LDPC) codes have been studied extensively. Non-binary LDPC codes have recently attracted an increasing attention. Most of the existing non-binary codes are built over GF(2q), and decoding methods developed for binary LDPC codes cannot be used directly with multilevel modulations. In this paper, we first extend the binary parity-check codes to the case with multiple symbols over modular arithmetic. Then, we develop a sum-product algorithm to decode this new type of codes at the symbol level. Finally, we propose an effective constellation mapping method for multilevel modulations. Error performances of this type of codes with 4-PAM, 4-PSK, and 16-PSK modulations over AWGN channels are provided. Compared with uncoded systems, the coding gain of a medium-size regular LDPC code of rate 8/9 with 4-PAM and 4-PSK modulations is about 5 dB. With 16-PSK and an appropriate constellation mapping at a code rate 3/4, the proposed code's performance is comparable to that of trellis codes. View full abstract»

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  • Interference impact on throughput performance of Bluetooth scatternets under different traffic loads

    Publication Year: 2010 , Page(s): 1 - 5
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (620 KB) |  | HTML iconHTML  

    Multiple Bluetooth piconets are likely to co-exist in a physical environment, supporting many wireless applications. An independently operating Bluetooth piconet will inevitably encounter mutual interference from collocated piconets, which results in individual piconet and overall scatternet performance degradation. In this paper, the throughput performance of Bluetooth piconet is studied and evaluated as the number of interfering piconets is increased considering that the frequency hopping mechanism in Bluetooth piconets is not a totally random process. Several different simulations were performed with varying inter-piconet time offset in order to represent the effects of different packet sizes, symmetric / asymmetric transmission, synchronized / unsynchronized data packets, and different traffic loads with non equal probabilities of collision for different packet sizes. Results proved that certain packets sizes can achieve higher throughput depending on type, size, and number of interferers. Throughput improvement may be achieved in the presence of interference by changing the packet size in the piconet. It was also verified that an optimum traffic load could be reached to achieve maximum throughput for each number of piconets. View full abstract»

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  • Inter-cell relaying and base station cooperation in cellular uplink systems

    Publication Year: 2010 , Page(s): 1 - 5
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (161 KB) |  | HTML iconHTML  

    Joint decoding at the base stations is investigated as a means to improve the uplink/downlink throughput of current cellular systems over fading channels. In this paper, the multi-cell relay-assisted time-division uplink system, i.e. one active user per time slot per cell with a relay serving that user, is studied. A linear mesh network is considered in which a single user per-cell communicates to a local base station via a dedicated relay. Base station cooperation through multi-cell decoding, where each cell has a single relay that amplifies and forwards the desired transmission signals to the base station. All the base stations in the mesh network collaboratively decode the signals received at each. The key contribution of this paper is compare the ergodic sum-rate in single-cell processing with multi-cell processing, under the system model, separately. View full abstract»

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  • Fast reservation list-to-send MAC protocol in wireless networks

    Publication Year: 2010 , Page(s): 1 - 5
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (378 KB) |  | HTML iconHTML  

    Fast reservation list-to-send (FRLS) medium access control (MAC) protocol is proposed to apply to wireless networks with long propagation delay. In the protocol, a central control node (CCN) is applied to allocate the channel resources of two channels, and all the nodes transmit packets over the two channels without collision. Packet train transmission mechanism ensures that a number of packets are transmitted continuously with small guard interval and just a one-way propagation delay. Once a node successfully reserves the channel resources for a communication session, it can transmit the whole message without the need of any other reservations, which gain high utilization of the channels. Moreover, CCN can provide uniform time benchmark to make the network working in an asynchronous fashion. Simulation results show that FRLS protocol outperforms centralized scheduling-based MAC (CSMAC) protocol in terms of throughput, average packet access delay and average packet dropping rate, and effectively resolves low channel utilization problem due to long propagation delay. View full abstract»

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  • Estimation of channel temporal auto-correlation and coherence time based on propagation paths

    Publication Year: 2010 , Page(s): 1 - 5
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (1246 KB) |  | HTML iconHTML  

    In this contribution, we investigate the applicability of using multiple propagation paths to estimate the temporal auto-correlation function and the coherence time of wireless propagation channels. The Space-Alternating Generalized Expectation-maximization (SAGE) algorithm is applied for extracting the paths from measurement data. It is found that the channel auto-correlation function and coherence time computed based on the path parameters are biased. A simple method is proposed for correction of the biases. Experimental investigations are conducted to evaluate the effectiveness of the method. View full abstract»

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  • Novel filter banks based wireless microphone detection in IEEE 802.22 WRAN

    Publication Year: 2010 , Page(s): 1 - 5
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (828 KB) |  | HTML iconHTML  

    The primary task in any cognitive radio (CR) network is to dynamically explore the spectrum and determine spectrum band that can be used without causing interference to other users. In this paper, we propose a multistage filter banks to sense the spectrum band. Compared with the conventional filter banks, our proposed method has low complexity but high detection precision. The proposed scheme has been analyzed and tested through simulations on wireless microphone detection in IEEE 802.22 WRAN. View full abstract»

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  • On a low-complexity subblock partitioning sequence for PAPR reduction of OFDM system

    Publication Year: 2010 , Page(s): 1 - 5
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (1648 KB) |  | HTML iconHTML  

    Conventional partial transmit sequence (PTS) orthogonal frequency division multiplexing (OFDM) system requires high hardware or high algorithm computational complexity to reduce peak to average power ratio (PAPR) so that signal distortion and power can be reduced during transmission. The Lim's PTS OFDM system is applied to this paper in the beginning with the aim at reducing hardware complexity. Since the emphasis of this paper is placed on subblock partitioning method, we then employ linear subblock partitioning method and realize the multiplications and the additions of radix-2 inverse fast Fourier transform (IFFT) butterfly diagram with linear characterization. We find that the complementary cumulative distribution function (CCDF) curve of linear subblock partitioning is close to that of non-linear subblock partitioning, and therefore our method can yield the same performance with more hardware complexity reduction. View full abstract»

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  • Two high-rate space-time codes for three and four transmit antennas with good diversity-multiplexing tradeoffs

    Publication Year: 2010 , Page(s): 1 - 5
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (116 KB) |  | HTML iconHTML  

    In this work, we present two high-rate quasi-orthogonal space-time coding (STC) schemes for three and four transmit antennas which are designed in conjunction with the serial interference cancellation (SIC) based receiver. The symbols of the proposed STCs are of judiciously designed diversity order which can be effectively exploited by the SIC based receiver to cancel interference as well as to obtain diversity gain. The proposed STC schemes' amicable quasi-orthogonal structures lend themselves to efficient low-complexity linear decoding. Simulation results show that the proposed STC schemes achieve better diversity-multiplexing tradeoffs than the existing conventional schemes. View full abstract»

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  • Throughput maximization for opportunistic spectrum access via transmission probability scheduling scheme

    Publication Year: 2010 , Page(s): 1 - 6
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (134 KB) |  | HTML iconHTML  

    In this paper, we propose a novel transmission probability scheduling scheme for opportunistic spectrum access in cognitive radio networks. With the proposed scheme, the secondary user's throughput over a single channel is maximized while collision probability perceived by the primary user is constrained under a required threshold since the secondary user optimally schedules its transmission probabilities during the primary user's idle period. Moreover, we deeply study the maximum achievable throughput of the secondary user when the idle period of the primary user is different distribution to analyze the performance of the proposed transmission probability scheduling scheme. In a practical communication systems, where primary user's traffic pattern and parameters are unknown and the secondary user's spectrum sensing is imperfect, a novel predictor, which is based on hidden Markov model, is also proposed to predict the future channel states and to enable the transmission probability scheduling for the secondary user. Conducted simulations show that the proposed transmission probability scheduling scheme and predictor are effective and can offer good system performances. View full abstract»

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  • Spectral gap filling in cognitive networks: A cooperative game-theoretic approach

    Publication Year: 2010 , Page(s): 1 - 6
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (215 KB) |  | HTML iconHTML  

    An optimal joint channel selection and power control scheme is investigated in a cognitive network context, where the cognitive network is composed by multiple cognitive interference channels. Here, we take the fairness among multiple secondary users (SUs) and Pareto optimality measured by the capacity maximization into consideration. The complex cooperation and competition relationship among multiple SUs and primary users (PUs) is described with the refined signal-to-interference plus noise (SINR) definition. According to the Nash axioms from the Nash bargaining cooperative game, the newly built utility function is formulated, and the spectral gap-filling problem is formulated as cognitive capacity Nash product maximization (CCNPM). To improve the centralized algorithm design in in the cooperative game theory framework, we employ the dual decomposition technique to achieve the distributed bargaining approaches. The proposed approaches are with low implementation complexities and the little information exchange. View full abstract»

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  • Sensor selection for collaborative spectrum sensing using SVD-QR

    Publication Year: 2010 , Page(s): 1 - 5
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (151 KB) |  | HTML iconHTML  

    Collaborative spectrum sensing enables opportunistic unlicensed access to the unused portions of the licensed spectrum. In this paper, we propose an effective sensor selection scheme for collaborative spectrum sensing over shadow fading channel using SVD-QR decomposition. Since shadow fading is correlated for closely spaced sensors, it is desired to select fewer independent sensors to reduce battery consumption and save bandwidth, while still adopting adequate sensors to make the sensing performance satisfied. The proposed scheme can reduce the redundancy in cognitive radio networks and does not rely on the position information of sensors. The simulation results illustrate that the SVD-QR algorithm outperforms correlation measure based selection method for spectrum sensing. View full abstract»

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  • Resource allocation and scheduling in MIMO-OFDMA with time-varying channel and bursty arrivals

    Publication Year: 2010 , Page(s): 1 - 5
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (609 KB) |  | HTML iconHTML  

    A cross-layer resource allocation and scheduling scheme in the downlink of MIMO-OFDMA systems is proposed to provide quality of service (QoS) guarantees to real-time traffics and non-real-time traffics in case of heavy-traffic. The proposed algorithm aims to maximize the efficient system throughput with the constraints of packet error rate, delay, packets dropping rate and buffer size. At the medium access control (MAC) layer, the proposed algorithm dynamically assigns subcarriers to the highest priority user based on the channel state information (CSI) and the queue state information (QSI). After initial subcarrier assignment, the subcarrier re-assignment is applied to approve the system performance. At the physical (PHY) layer, a low complexity rate-and-power adaptation scheme is used to the predetermined subcarriers. It is demonstrated in the numerical results that the proposed algorithm significantly improves the system performance in terms of system throughput and packet loss rate. View full abstract»

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