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Communication Technology and Application (ICCTA 2011), IET International Conference on

Date 14-16 Oct. 2011

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Displaying Results 1 - 25 of 218
  • Title page

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  • Contents

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  • Cognitive wireless networks: Challenges and opportunities

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    Considering the challenges of network heterogeneity and spectrum inefficient usage, the future wireless networks should have the intelligent network information awareness, flexible spectrum management, dynamic network reconfiguration abilities. The concept of cognitive wireless network (CWN) has been proposed that aims at improving radio resources utilization by taking advantage of unused licensed spectrum with proper interference mitigation techniques. This speech will focus on the key technologies in CWN, including wideband spectrum sensing, multi-domain cognitive database and dynamic spectrum management techniques. The cognitive radio based TD-LTE testbeds will also be introduced briefly based on the national funded “973” project. Furthermore, an open discussion of the challenges and opportunities in CWN from regulators, operators, equipment vendors and users are discussed. At last, the related CWN standards of ITU-R, IEEE and CCSA are introduced briefly. View full abstract»

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  • Deployment strategies of LTE of DOCOMO and challenges for future mobile

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    In the mobile NW, rapid growth of data traffic observed in not only China and Japan, but also in world widely. Increasing of smart-phones and attraction of video-contents are current origin of the data traffic growth. In near future, tethering and M2M communications are also going to make the traffic increase. Requirement to our mobile NW to be with larger capacity is very strong and urgent. View full abstract»

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  • M2M communications

    Page(s): 2
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    Machine to Machine communications (M2M, also known as Internet of Things (IoT)) aims to enable interactions between smart objects ranging from sensors to actuators and robots and smart meters…, with or without human intervention. It has its origin in control and data acquisition systems. Recent developments in areas such as wireless communications, sensing and actuation have given it a new impetus. Furthermore, the number of connected devices is poised to grow exponentially in the coming years. As a results, IoT will usher a wide range of smart applications and services to cope with many of the challenges and the needs that we face in our daily lives. It represents intelligent end-to-end systems that enable smart solutions and as such it covers a diverse range of technologies, including sensing, communications, networking, computing, information processing, and intelligent control technologies, and so on. To make IoT a reality, significant research needs to be conducted within and across these technological aspects. In this talk, an overview of M2M communication architecture with the focus on applications is first given. Then some of standardization activities in the world are introduced. In the third part, the major communications and networking technologies ((IEEE 802.15.4, Zigbee, 6LoWPAN) for M2M are discussed. It also includes the new applications layer protocols being developed (e.g, IETF CoAP). In the final part, some research directions and concerns are listed. View full abstract»

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  • Communications - a rapidly changing world

    Page(s): 2
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    Probably the most influential recent change affecting how we use communications has been the iPhone - and this change has been as significant as the introduction of the fax or the mobile phone itself. View full abstract»

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  • The European Framework Programmes for Co-financing R&D - the last opportunities in FP7 (2007–2013) and initial plans for FP8

    Page(s): 3
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    This talk will be introducing the European Framework Program and the Co-financing R&D supporting policies. Prof. Potts will talk about the end of the FP7 and initial plan of the FP8. View full abstract»

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  • Field trials of DVB-T sensing for TV White Spaces

    Page(s): 3
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    The use of TV White Space spectrum on a secondary, unlicensed basis has been of great interest in academia, industry and regulatory bodies worldwide. Proposed applications have included residential data transfer and content streaming, and rural broadband. In the US, the FCC has published rules for unlicenced devices in the TV bands, while in the UK, Ofcom has released statements on the subject. Central to these regulatory requirements is the constraint that all unlicenced devices must operate as secondary users and cause no interference to primary users. We study autonomous spectrum sensing as a means of avoiding interference. Using this technique, a device uses its own receiver to decide if a particular channel is available or not by listening from transmissions from primary users. A particular challenge is the well-known ‘hidden node’ problem in which a device is shielded from a transmitter but not a receiver that would suffer from interference. To guarantee protection to primary users under these circumstances requires very low sensing thresholds and the FCC (−115 dBm) and Ofcom (−120 dBm) have both proposed levels that are below the noise floor. View full abstract»

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  • Where next for cognitive radio?

    Page(s): 4
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    The FCC issued its first Report and Order in September 2001 on Software-Defined Radio. It commissioned a follow-on inquiry on SDR security issues and another on the potential for unlicensed usage of TV spectrum, facilitated by software radio technology. Spectrum managers in Europe, USA and Asia held a regulators forum in the UK in September 2003, which reviewed SDR approaches and the potential regulatory actions required of national spectrum managers. View full abstract»

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  • Challenges in cognitive radio research: Primary radio aware spectrum sensing, medium access, and routing

    Page(s): 4
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    In this talk, after a brief introduction of the cognitive radio (CR) technology, we focus on several important technical aspects of CR research. Based on my previous CR-related research work, we mainly cover three issues: spectrum sensing, medium access, and routing, which correspond to the traditional three system layers: PHY, MAC, and Network layers. Here the difference from traditional layered network research is the primary radio (PR) awareness in all our design considerations. Throughout the talk, we will focus on how to detect PR existence in spectrum sensing, how to protect PR transmissions in medium access, and how to even help PR packet delivery in routing. For each of the three subjects and also from a system-wide perspective, we will conclude the talk by discussing the open problems remained to challenge us in the future years. View full abstract»

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  • Using TV White Space for interference mitigation in LTE Femtocell Networks

    Page(s): 5 - 9
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    The traditional Femtocell shares the same licensed frequency band with Macrocell, thus introducing cross-tier interference. Interference mitigation between the Femtocell and Macrocell is considered to be one of the major challenges in Femtocells Network. In this paper, the released TV spectrum by the digital switchover named TV White Space (TVWS) is proposed to reduce the interference for the LTE Femtocell Network. Based on the combination of cognitive sensing and TVWS, a novel resource allocation scheme is applied to mitigate the interference that Macro users are suffering from nearby Femtocells. A single cell Long Term Evolution (LTE) Femtocell simulator is established to demonstrate the system performance. The cases with traditional resource allocation scheme and the proposed scheme are compared and analysed. View full abstract»

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  • On intelligent V-BLAST detection algorithm with D-S theory in correlated MIMO channel

    Page(s): 10 - 14
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    In this paper, a novel signal detection scheme is proposed for correlated multiple input multiple output(MIMO) system based on Dempster-Shafer (D-S) evidence theory. The geometrical MIMO model is used for the correlated MIMO system. The focal-element-set (FES) is used to describe the uncertainty for the decision statistics, and the corresponding basic-probability-assignment (BPA) of FES is the likelihood measure, which act as the soft-decisions for the receiver signals. The detection is called intelligent deductions, in which the uncertainty can be mitigated during combining the soft information sources from all received spatial signals, leading to the performance improvement for MIMO system. Simulation results verify that the proposed MIMO detection algorithm outperforms conventional MIMO detection schemes in both independent and correlated MIMO channel. View full abstract»

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  • Synchronization for MIMO-OFDM systems based on preamble signals

    Page(s): 15 - 18
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    An accurate technique for timing and frequency synchronization of multiple-input multiple-output (MIMO) orthogonal frequency division multiplexing (OFDM) systems is proposed in this paper. A new preamble signal which adapts to the MIMO-OFDM synchronization, is derived based on GCL sequences. The carrier frequency offset (CFO) estimation is obtained through taking double correlation operations on the preamble signal, and used in the timing synchronization to gain accurate time estimation. From analysis, it is shown that at the same SNR, the proposed method can reduce the BER and the frame transmission BER of the system compared to the conventional method. View full abstract»

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  • A high speed turbo decoder implementation for CPU-based SDR system

    Page(s): 19 - 23
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    More and more CPU-based SDR systems appear in recent two years. Such system requires high speed real-time signal processing. In this paper, we present our effort on the speed optimization of Turbo decoder, the most computation-demanding module in all baseband modules. We jointly consider the algorithm parallelism and the processor architecture. Single Instruction Multiple Data (SIMD) instruction is used for software implementation. The evaluation results show that this proposed design can achieve a maximum of 124 Mbps throughput for single Soft Input Soft Output (SISO) module with Max-Log-MAP algorithm. View full abstract»

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  • Design of a novel ultra-wideband microstrip antenna with a frequency notch characteristic

    Page(s): 24 - 28
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    The ultra-wideband (UWB) wireless communication has become a hotspot in current researches, which faces new challenges at the same time. One novel ultra-wideband microstrip antenna is proposed, and a U-shaped slot is cut in the radiation patch to obtain the band-notch function, and the results are simulated by using electromagnetic simulation software CST MWS (CST microwave studio). Experimental results show that the VSWR in the frequency band from 3.05 to 13.8 GHz is always less than 2, which covers the band FCC (Federal Communications Commission) proposed. Meanwhile, the antenna achieves relative stability and good omni-directional radiation performance, which meets the request to antenna in ultra-wideband communication very well. The antenna also has a band-notched function in the frequency range of 3.14-4.0GHz and 5.13-5.83 GHz. Thus, the potential interference between ultra-wideband systems, WIMAX and WLAN system can be inhibited. View full abstract»

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  • Robust joint beamforming for MIMO Broadcast system with limited feedback

    Page(s): 29 - 34
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    In Multiple-In Multiple-Out (MIMO) Broadcast systems with limited feedback, when receivers are equipped with multiple antennas, the so-called quantization error of channel direction matrix was unavoidably introduced. This quantization error will result in the reduction of system capacity since it was referenced in the beamforming design. In this paper, we proposed a robust beamforming method based on MMSE, which considers the statistical characteristics of the quantization error for channel direction matrix. Simulation results show that the proposed method effectively enhanced system capacity, reduced bit error rate (BER), as well as mitigated the Plateau Effect. View full abstract»

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  • New coordinated beamforming scheme for multi-cell multi-user MIMO systems

    Page(s): 35 - 40
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    As the development of next-generation wireless broadband cellular networks, base station (BS) cooperation has become a promising tool to increase the per-cell spectral efficiency as well as cell-edge user throughput. In this paper, we introduce a new multi-cell cooperation strategy, where each cooperating BS simultaneously serves two co-channel users, one from the cell edge and the other from the cell center. Three distributed coordinated beamforming schemes together with user pairing for the considered cooperative multi-cell multi-user MIMO system are proposed. Simulation results show that the signa- to-leakage-and-noise ratio (SLNR) based scheme and the ZF-SLNR scheme are able to considerably improve both the system total throughput and edge user throughput. View full abstract»

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  • An approximate formula for WER of turbo-like codes and its application

    Page(s): 41 - 44
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    By using radius of decision region, an approximate formula for word error rate (WER) of Turbo-like codes is presented in [1]. The approximate formula has a simple form of Gaussian Q-function with multiple arguments including the signal to noise ratio (SNR), the code length, and two parameters determined by the code structure and the decoding algorithm. This formula makes it possible to theoretically analyze the performance of turbo-like codes over fading channels. In this paper, we apply the formula to evaluate the WER of LDPC code over block fading channels. Simulation results show that the theoretical analysis matches well with the Monte Carlo simulation for both Rician and Nakagami-m fading channels. View full abstract»

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  • A novel Coordinated Beamforming scheme based on local feedback and Quantization based Combining in downlink CoMP system

    Page(s): 45 - 49
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    In this paper we propose a novel limited feedback scheme based on local limited feedback combined with SLNR precoding and Quantization-based-Combining (QBC) in downlink Coordinated-Beamforming (CB) systems. The channels of serving cell and coordinated cells are quantized based on QBC technology. Due to more accurate channel quantization, the proposed scheme achieves considerable improvement over the conventional scheme which uses global feedback. Moreover, since inter-user shadowing correlation produces additional Inter-Cell-Interference (ICI) in a practical system, its influence is assessed in this paper. This work is seldom performed before by other literatures, to the best of our knowledge. View full abstract»

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  • Effective channel estimation for sparse multipath OFDM systems

    Page(s): 50 - 54
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    Coherent detection and demodulation need channel state information at receivers for orthogonal frequency division multiplexing systems. Conventional channel estimations, such as least squares (LS), are widely adopted under the assumption of rich multipath. Recently, numerous physical measurements have verified that many wireless multipath channels encountered in practice tend to exhibit sparse structures. Exploiting the inherent sparsity, a novel channel estimation method based on compressive sensing is proposed, which reduces the number of pilots so as to improve the bandwidth efficiency. Simulation results confirm that the proposed method has a 5-dB lower mean square error in channel estimation when compared to the conventional approach. In addition, the complexity of the proposed method is acceptable. View full abstract»

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  • A joint scheduling and precoding scheme based on sum chord distance in MU-MIMO system with limited feedback

    Page(s): 55 - 59
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    In this paper, we propose a joint scheduling and precoding scheme in MU-MIMO downlink channel with limited feedback. Each user feeds back the index which indicates the channel direction in a predefined codebook and one scalar denoting the quantization error. With the feedback information, the base station schedules the first user with the minimal quantization error. And then it schedules the users with the metric based on the sum of two chord distances. Compared with the traditional joint scheduling and precoding based on ZF-CI, our proposed scheme can restrain the performance loss caused by quantization error and reduce the feedback. Further, the sum rate is greatly improved as SNR increases. Simulation results are exhibited to verify its effectiveness. View full abstract»

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  • An iterative multiuser detection with frequency-domain equalization for relay-assisted SFBC single-carrier systems

    Page(s): 60 - 65
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    In this paper, an iterative multiuser detection scheme for relay-assisted space-frequency block code (SFBC) single-carrier systems with frequency-domain equalization is proposed. In practical mobile applications, relay-assisted SFBC in SC-FDE suffers performance degradation from double-selective (time and frequency selective) channels, resulting in a deviation from the basic assumption of Alamouti codeword. In the proposed algorithm, diagonalized SFBC decoding, soft multi-user interference (MUI) cancellation and soft inter-symbol interference (ISI) cancellation with minimum mean-square error (MMSE) filtering were performed iteratively to suppress interferences. An approximate implementation for complexity reduction with little performance loss was also proposed. The bit error rate (BER) performances and extrinsic information transfer (EXIT) charts were presented for Rayleigh fading channels. Simulation results show that our proposed algorithm outperforms other existing ones in severely double-selective channels without increasing computational complexity. View full abstract»

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  • A new beamforming for 60GHz wireless system with an adaptive approach

    Page(s): 66 - 70
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    In this paper, we propose a type of beamforming technique for orthogonal frequency division multiplexing (OFDM) based wireless personal area networks (WPANs) based on blocks idea. In order to compromise between performance and computational complexity, the proposed scheme divides all the subcarriers into blocks, then utilizes the similarity of adjacent blocks, and decides whether to carry out first order perturbation compensation (FOPC) or eigenvalue based beamforming (EBB) algorithm. Simulation results indicate that FOPC-EBB algorithm with blocking operation can achieve better effect in reducing the complexity. View full abstract»

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  • On complexity of sphere decoding with novel sphere radius determining method

    Page(s): 71 - 75
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    In this article a non-heuristic sphere radius determining method for sphere decoding is developed so that the sphere radius could be properly chosen to restrict the complexity as much as possible without incurring evident performance loss. A special bound of symbol error ratio performance of maximum likelihood detection is formulated which can serve as a lower bound in low signal to noise ratio (SNR) region. Thus the sphere radius determining method can be presented with a SNR dependent probability employing the bound. Then a modification of radius determining method is introduced using a compress factor suppressing the sphere radius in low SNR region to make the expected complexity tolerable. The expected complexity analysis is performed based on the expected number of all visited nodes for all search levels. Finally, simulation results show the effectiveness of the proposed sphere radius determining method within the whole SNR region. View full abstract»

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  • Analyze and design receiving system of UV communication

    Page(s): 76 - 80
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    The architecture of UV receiver system is analyzed and the functional modules are described. Two different treatment methods and application conditions are discussed according to the two output types of PMT, analog sampling and photon counting methods. The factors affecting the BER are analyzed in theory as the key, and have been verified by the practical test. A designed prototype achieves the voice communication, and lays a good foundation for the further research in UV communication. View full abstract»

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