中国邮电高校学报(英文版), 2009, 16 (3). doi： 10.1016/S1005-8885(08)60217-4
摘要 ( 2117 ) PDF (366 KB)( 408 )
This article covers laser configurations, design and experiments of photonic microelectromechanical systems (MEMS) tunable laser sources. Three different types of MEMS tunable lasers such as MEMS coupled-cavity lasers, injection-locked laser systems and dual-wavelength tunable lasers are demonstrated as examples of natural synergy of MEMS with photonics. The expansion and penetration of the MEMS technology to silicon optoelectronic creates on-chip optical systems at an unprecedented scale of integration. While producing better integration with robustness and compactness, MEMS improves the functionalities and specifications of laser chips. Additionally, MEMS tunable lasers are featured with small size, high tuning speed, wide tuning range and CMOS compatible integration, which broaden their applications to many fields.
卞银兵, FENG Guang-zeng
中国邮电高校学报(英文版), 2009, 16 (3). doi： 10.1016/S1005-8885(08)60218-6
摘要 ( 2079 ) PDF (158 KB)( 386 )
To improve error-correcting performance, an iterative concatenated soft decoding algorithm for reed-solomon (RS) codes is presented in this article. This algorithm brings both complexity as well as advantages in performance over presently popular soft decoding algorithms. The proposed algorithm consists of two powerful soft decoding techniques, adaptive belief propagation (ABP) and box and match algorithm (BMA), which are serially concatenated by the accumulated log-likelihood ratio (ALLR). Simulation results show that, compared with ABP and ABP-BMA algorithms, the proposed algorithm can bring more decoding gains and a better tradeoff between the decoding performance and complexity.
中国邮电高校学报(英文版), 2009, 16 (3). doi： 10.1016/S1005-8885(08)60219-8
摘要 ( 2240 ) PDF (229 KB)( 383 )
This article proposes a new space-time cooperative diversity scheme called full feedback-based cooperative diversity scheme (FFBCD). In contrast to the conventional adaptive space-time cooperative diversity schemes that utilize the feedback from only the destination node, the new scheme utilizes the feedback from both the destination node and the cooperation node. With the feedback from the destination node, the occasional successful reception of the destination node in the information distribution stage can be detected, thus avoiding unnecessary retransmissions in the information delivery stage. The feedback from the cooperation node indicates the receiving state of the cooperation node in the information distribution stage, and the source node and the cooperation node will not perform cooperative retransmission during the information delivery stage unless the cooperation node is received successfully in the information distribution stage. In this way the new scheme can reduce the number of transmission attempt and improve the channel utilization. The expressions of the average number of transmission attempt are given. Numerical approximations and simulation results both show that the new scheme performs better than the non-cooperative scheme and the conventional adaptive space-time cooperative diversity scheme.
颜智,王文博,汪剑锋, ZHENG Kan
中国邮电高校学报(英文版), 2009, 16 (3). doi： 10.1016/S1005-8885(08)60220-4
摘要 ( 2832 ) PDF (252 KB)( 374 )
In this article, the authors consider joint design of a linear precoder and power allocation for uplink multiuser multiple input multiple output (MIMO) communication systems with limited feedback to improve the bit error rate (BER) performance for all users. Precoder selection from the codebook set is directly based on the exact BER performance, instead of other suboptimal criteria, to achieve the optimal precoder matrix, but closed-form expressions may not exist in the view of power allocation based directly on the BER criterion. From this perspective, the authors propose the joint transmitter optimization algorithm for the consideration of precoder design, with total power constraint for asymptotic MBER (AMBER) criterion. In this AMBER criterion, a closed-form solution has been derived for power allocation with an optimal precoder. The simulation results show that the proposed joint design algorithm can achieve a much better performance than precoding with uniform power allocation and only consideration of power allocation.
张炎炎,张建华, HUANG Jiang-chun, ZHANG Ping
中国邮电高校学报(英文版), 2009, 16 (3). doi： 10.1016/S1005-8885(08)60221-6
摘要 ( 2042 ) PDF (237 KB)( 435 )
In orthogonal frequency division multiplexing (OFDM) systems, time and frequency synchronization are two critical elements for guaranteeing the orthogonality of OFDM subcarriers. Conventionally, with the employment of pseudonoise (PN) sequences in preamble design, the preamble information is not fully utilized in both symbol timing offset acquisition and carrier frequency offset estimation. In this article, a new synchronization algorithm is proposed for jointly optimizing the time and frequency synchronization. This algorithm uses polynomial sequences as synchronization preamble instead of PN sequences. Theoretical analysis and simulation results indicate that the proposed algorithm is much more accurate and reliable than other existing methods.
中国邮电高校学报(英文版), 2009, 16 (3). doi： 10.1016/S1005-8885(08)60222-8
摘要 ( 3167 ) PDF (253 KB)( 404 )
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.
杨春萍, LI Dao-ben
中国邮电高校学报(英文版), 2009, 16 (3). doi： 10.1016/S1005-8885(08)60223-X
摘要 ( 1967 ) PDF (230 KB)( 377 )
A novel high spectrum efficiency channel encoding method called overlapped code division multiplexing (OvCDM) is presented. It is a convolutional encoding method with code rate greater than 1. Compared with traditional coded modulation (CM) technologies, OvCDM emphasizes the constrain relation between encoded codes. It is actually a blind modulation. The simulation results in the additive white Gaussian noise (AWGN) channel indicate that OvCDM can significantly improve spectrum efficiency of mobile communications systems. Meanwhile, the proposed OvCDM can ensure high decoding performance.
中国邮电高校学报(英文版), 2009, 16 (3). doi： 10.1016/S1005-8885(08)60224-1
摘要 ( 2035 ) PDF (307 KB)( 451 )
One critical issue for routing in mobile Ad-hoc networks (MANETs) is how to select a reliable path that can last longer because mobility may cause frequent breakdown in radio links. A novel routing mechanism based on link lifetime estimation is proposed in this article. In this mechanism, the node’s received signal strength is obtained continuously by using Newton interpolation polynomial, and by method of middle value and interception, the reference points are selected to estimate the link lifetime. With the constraint of link lifetime and hop counts, the source nodes set up the route hop by hop. The simulations show that link lifetime can be predicted regardless of mobility pattern. Moreover, the route discovery times and packet drop ratio can be reduced by the proposed mechanism, and thus improving the performance of MANETs.
潘沛生, ZHENG Bao-yu
中国邮电高校学报(英文版), 2009, 16 (3). doi： 10.1016/S1005-8885(08)60225-3
摘要 ( 2265 ) PDF (333 KB)( 503 )
Multiple-input multiple-output (MIMO) systems can be combined with orthogonal frequency division multiplexing (OFDM) systems to improve the capacity and quality of wireless communications. In this article, a channel estimation technique in both space and frequency domain for MIMO-OFDM systems is proposed. It is shown that the proposed scheme with space-frequency pilot tones achieve optimal minimum mean square error (MMSE) channel estimation. Simulation results indicate that the proposed method achieves good performance.
中国邮电高校学报(英文版), 2009, 16 (3). doi： 10.1016/S1005-8885(08)60226-5
摘要 ( 2118 ) PDF (278 KB)( 384 )
A new blind (non-data-aided) synchronization algorithm based on direct-sequence (DS) codes is proposed for ultra-wideband (UWB) systems. The proposed approach fully exploits prior knowledge of DS codes and bypasses channel estimation. The real-time acquisition is achieved using integrating-and-dumping (I&D) operation and DS codes matching filter. Because of pseudo randomicity and periodicity of DS codes, both the speed and the accuracy of synchronization are improved significantly. A lower bound on the acquisition probability of the proposed approach is also derived. Simulations confirm performance improvement of the proposed algorithm relative to existing alternatives in terms of acquisition probability, normalized mean square error (NMSE), and bit error rate (BER).
中国邮电高校学报(英文版), 2009, 16 (3). doi： 10.1016/S1005-8885(08)60227-7
摘要 ( 2998 ) PDF (168 KB)( 457 )
This article studies the problem of constructing optimal layered multicast with network coding for heterogeneous networks. Based on the flexibility of layered source coding, a global-favorable optimization scheme is proposed, which maximizes the aggregate throughput of heterogeneous sink nodes for layered multicast with network coding by determining the optimal bit rates of the layers. To solve this global-favorable optimization scheme, especially in the large-scale heterogeneous networks, a new problem-specific genetic algorithm (GA) is further proposed. It not only searches efficiently for the optimal allocation of layer bit rates, but also guarantees the validity of candidate solutions in the whole evolutionary process. Simulation results demonstrate that this new GA-based optimization scheme could obtain efficiently the optimal or satisfactorily near-optimal bit rates for layered multicast with network coding, even in the large-scale heterogeneous networks.
李立,刘元安,LIU Kai-ming, 马晓雷, YANG Ming
中国邮电高校学报(英文版), 2009, 16 (3). doi： 10.1016/S1005-8885(08)60228-9
摘要 ( 2919 ) PDF (373 KB)( 512 )
This article proposes a novel grid resource allocation model, in which the users and the grid service providers participate in the combinatorial double auction for the resource allocation. To obtain the detailed resource allocation status and the price information, a novel pricing algorithm is designed for the allocation model. Simulation results demonstrate that the proposed algorithm completes the resource allocation and pricing efficiently, and exhibits incentive compatible characteristic. Moreover, users with the higher average price and providers with the lower average price get compensation during the pricing process.
中国邮电高校学报(英文版), 2009, 16 (3). doi： 10.1016/S1005-8885(08)60229-0
摘要 ( 2065 ) PDF (155 KB)( 349 )
Peer-to-peer (P2P) computing technology has been widely used on the Internet to exchange data. However, it occupies much network bandwidth, and thus greatly influences traditional business on the Internet. Besides, problems about free-riders and ‘tragedy of the commons’ in the P2P environment estrange from it P2P users who constantly contribute to the network with quality resources. This article proposes a new P2P network traffic control mechanism based on global evaluation values. It aims to help individual users to avoid peak traffic time as much as possible, ease network congestion and protect traditional business on the Internet, as well as differentiating priority grades of peers according to their contributions and stimulating them to share their valuable resources actively. This article first analyzes the current state of network traffic, and then elaborates on P2P network traffic control policies and proposes the peer’s priority level differentiation mechanism based on global evaluation values. Finally, after the testing results and analysis of the proposed P2P network traffic control mechanism are discussed, conclusions are drawn.
中国邮电高校学报(英文版), 2009, 16 (3). doi： 10.1016/S1005-8885(08)60230-7
摘要 ( 2685 ) PDF (277 KB)( 372 )
This article proposes algorithms to determine an optimal choice of the reed Solomon forward error correction (FEC) code parameters (n,k) to mitigate the effects of packet loss on multimedia traffic caused by buffer overflow at a wireless base station. A network model is developed that takes into account traffic arrival rates, channel loss characteristics, the capacity of the buffer at the base station, and FEC parameters. For Poisson distributed traffic, the theory of recurrent linear equations is applied to develop a new closed form solution of low complexity of the Markov model for the buffer occupancy. For constant bit rate (CBR) traffic, an iterative procedure is developed to compute the packet loss probabilities after FEC recovery.
中国邮电高校学报(英文版), 2009, 16 (3). doi： 10.1016/S1005-8885(08)60231-9
摘要 ( 1949 ) PDF (123 KB)( 479 )
Classification of network traffic using port-based or payload-based analysis is becoming increasingly difficult when many applications use dynamic port numbers, masquerading techniques, and encryption to avoid detection. In this article, an approach is presented for online traffic classification relying on the observation of the first n packets of a transmission control protocol (TCP) connection. Its key idea is to utilize the properties of the observed first ten packets of a TCP connection and Bayesian network method to build a classifier. This classifier can classify TCP flows dynamically as packets pass through it by deciding whether a TCP flow belongs to a given application. The experimental results show that the proposed approach performs well in online internet traffic classification and that it is superior to naïve Bayesian method.
中国邮电高校学报(英文版), 2009, 16 (3). doi： 10.1016/S1005-8885(08)60232-0
摘要 ( 2957 ) PDF (391 KB)( 493 )
A low-power and low-cost advanced encryption standard (AES) coprocessor is proposed for Zigbee system-on-a-chip (SoC) design. The cost and power consumption of the proposed AES coprocessor are reduced considerably by optimizing the architectures of SubBytes/InvSubBytes and MixColumns/InvMixColumns, integrating the encryption and decryption procedures together by the method of resource sharing, and using the hierarchical power management strategy based on finite state machine (FSM) and clock gating (CG) technologies. Based on SMIC 0.18 complementary metal oxide semiconductor (CMOS) technology, the scale of the AES coprocessor is only about 10.5 kgate, the corresponding power consumption is 69.1 , and the throughput is 32 Mb/s, which is reasonable and sufficient for Zigbee system. Compared with other designs, the proposed architecture consumes less power and fewer hardware resources, which is conducive to the Zigbee system and other portable devices.
中国邮电高校学报(英文版), 2009, 16 (3). doi：
摘要 ( 1891 ) PDF (428 KB)( 406 )
Video signal processing needs high signal-to-noise ratio (SNR) in high-speed time delay and integration charge coupled devices (TDICCD). To solve this problem, this article first analyzes the characteristics of the output video signal of a new type of high-speed TDICCD and its operation principle. Then it studies the correlation double sample (CDS) method of reducing noise. Following that a synthesized processing method is proposed, including correlation double sample, programmable gain control, line calibration and digital offset control, etc. Among the methods, XRD98L59 is a video signal processor for the charge coupled device (CCD). Application of this processor to one kind of high-speed TDICCD with eight output ports achieves perfect video images. The experiment result indicates that the SNR of the images reaches about 50 dB. The video signal processing for high-speed multi-channel TDICCD is implemented, which meets the required project index.
李恩玲,王雪,宋林红,苑永霞, YU Fa-da, LIU Man-cang
中国邮电高校学报(英文版), 2009, 16 (3). doi： 10.1016/S1005-8885(08)60234-4
摘要 ( 2197 ) PDF (496 KB)( 502 )
A voltage controlled oscillator (VCO) module is designed, which can be used for the third generation mobile communication (3G) system. The circuit is simulated by spectre radio frequency (RF) by TSMC 0.25 μm CMOS process. During the simulation, the performance parameters of the designed VCO are as follows: tuning range 1.804 GHz–2.039 GHz, phase noise 136.457 dBc/Hz @1 MHz, 146.045 dBc/Hz@3 MHz, supply voltage 2.5 V, voltage output rate of 0.8 V–2.6 V, power consumption 25 mW. The layout of the related circuit is drawn by the Virtuoso Layout Editor.
中国邮电高校学报(英文版), 2009, 16 (3). doi： 10.1016/S1005-8885(08)60235-6
摘要 ( 2698 ) PDF (229 KB)( 487 )
As one of the most promising next-generation access network techniques, the user-oriented Ethernet passive optical network (EPON) should pay more attention to its quality of service (QoS). However, now the EPON adopts mostly differentiated services model (Diffserv) that only provides quality control on traffic aggregation, whereas, the quality of user session cannot be guaranteed when the network is overloaded with substantial connections. This article proposes to apply integrated services model (Intserv) in Diffserv-based EPON, which uses per-flow processing to guarantee QoS. In the simulation, a framework of combined Diffserv and Intserv model is employed in an EPON system, with a dynamic bandwidth allocation algorithm that adapts to it. The simulation results demonstrate that the EPON system with the combined models can provide more flexible, various control for user-oriented service quality.
中国邮电高校学报(英文版), 2009, 16 (3). doi： 10.1016/S1005-8885(08)60236-8
摘要 ( 2707 ) PDF (240 KB)( 372 )
The security, efficiency, transmission distance and error rate are important parameters of a quantum key distribution scheme. In this article, the former two parameters are focused on. To reach high efficiency, an unsymmetrical quantum key distribution scheme that employs Greenberger-Horne-Zeilinger (GHZ) triplet states and dense coding mechanism is proposed, in which a GHZ triplet state can be used to share two bits of classical information. The proposed scheme can be employed in a noisy or lossy quantum channel. In addition, a general approach to security analysis against general individual attacks is presented.
钱建发, MA Wen-ping
中国邮电高校学报(英文版), 2009, 16 (3). doi： 10.1016/S1005-8885(08)60237-X
摘要 ( 1995 ) PDF (133 KB)( 476 )
The problem of Gray image of constacyclic code over finite chain ring is studied. A Gray map between codes over a finite chain ring and a finite field is defined. The Gray image of a linear constacyclic code over the finite chain ring is proved to be a distance invariant quasi-cyclic code over the finite field. It is shown that every code over the finite field, which is the Gray image of a cyclic code over the finite chain ring, is equivalent to a quasi-cyclic code.
中国邮电高校学报(英文版), 2009, 16 (3). doi： 10.1016/S1005-8885(08)60238-1
摘要 ( 1935 ) PDF (176 KB)( 373 )
This article proposes a model combination method to enhance the discriminability of the generative model. Generative and discriminative models have different optimization objectives and have their own advantages and drawbacks. The method proposed in this article intends to strike a balance between the two models mentioned above. It extracts the discriminative parameter from the generative model and generates a new model based on a multi-model combination. The weight for combining is determined by the ratio of the inter-variance to the intra-variance of the classes. The higher the ratio is, the greater the weight is, and the more discriminative the model will be. Experiments on speech recognition demonstrate that the performance of the new model outperforms the model trained with the traditional generative method.