Afshin S. Daryoush
中国邮电高校学报(英文版), 2009, 16 (4). doi： 10.1016/S1005-8885(08)60239-3
摘要 ( 2389 ) PDF (439 KB)( 381 )
Stable opto-electronic oscillators (OEOs) are realized using long fiber delay lines and changes in the index of refraction of high quality factor delay line results in temperature sensitivity of OEOs. Temperature sensitivity of various OEOs is measured to compare index of refraction variation of standard (SMF-28) and photonic crystal fiber (PCF). Both hollow-core (HC) and solid-core (SC) versions of PCF are quantified. SC-PCF exhibited a factor of three reductions in the rate of index of refraction change (about +4.7 ppm/°C) with temperature over SMF-28 (about 12 ppm/°C) based OEO. Although HC-PCF have a greater attenuation per unit length, but those fibers have demonstrated a negative rate of change (about 0.6 ppm/°C) in the effective index of refraction with temperature and prospect of thermal stability in the OEO using passive techniques is great when a combination of HC-PCF and SMF-28 are employed as fiber delay lines.
YU Xian-bin,<SPAN style=
中国邮电高校学报(英文版), 2009, 16 (4). doi： 10.1016/S1005-8885(08)60240-X
摘要 ( 2975 ) PDF (439 KB)( 524 )
We firstly review the efforts in the literature on ultra-wideband (UWB)-over-fiber systems. Secondly, we present experimental results on photonic generation of high-speed UWB signals by both direct modulation and external optical injecting an uncooled semiconductor laser. Furthermore, we introduce the use of digital signal processing (DSP) technology to receive the generated UWB signal at 781.25 Mbit/s. Error-free transmission is achieved.
中国邮电高校学报(英文版), 2009, 16 (4). doi： 10.1016/S1005-8885(08)60241-1
摘要 ( 2627 ) PDF (439 KB)( 404 )
Lithium niobate (LiNbO3) is a useful photonic material for its electro-optic and nonlinear optical properties. In this paper, I will report developments of LiNbO3 based optical devices for fiber communication, including high-performance modulators and high efficiency wavelength converters.
中国邮电高校学报(英文版), 2009, 16 (4). doi： 10.1016/S1005-8885(08)60242-3
摘要 ( 2646 ) PDF (282 KB)( 438 )
In recent years, 10 Gbit/s Ethernet passive optical networks (10G EPON) have been gaining considerable interests because of its high bandwidth capability. To ensure smooth transition from 1 Gbit/s to 10 Gbit/s equipment and to avoid a significant one-time investment into such a cost-sensitive market, coexistence of gigabit Ethernet passive optical networks (GEPON) and 10G EPON system are necessary. In this article, coexistence system architecture and a novel bandwidth allocation algorithm called weight-optimized dynamic bandwidth allocation for coexistence EPON (WOCE-DBA) for the system is proposed. The simulation results show that this algorithm can guarantee fair bandwidth sharing among different optical network unit (ONU) groups, without ignoring the inter-ONU and intra-ONU fairness. Most importantly, it can flexibly adapt to the system composition variations and save efforts needed to modify the bandwidth scheduling mechanism during the migration process from GEPON to 10G EPON.
中国邮电高校学报(英文版), 2009, 16 (4). doi： 10.1016/S1005-8885(08)60243-5
摘要 ( 1882 ) PDF (412 KB)( 378 )
This article proposes a new fault location mechanism in optical network. In this mechanism, a network alarm packet format with time-stamp is introduced to implement fast restoration. In locating the fault, the existing schemes are usually complex and inaccessible when solving the multifailure location problem. For multifailures, the proposed mechanism using time-stamps is more efficient in locating the fault and decreasing computational complexity.
中国邮电高校学报(英文版), 2009, 16 (4). doi： 10.1016/S1005-8885(08)60244-7
摘要 ( 2720 ) PDF (242 KB)( 394 )
In this article, the performance of a novel radio resource management (RRM) strategy for voice over IP (VoIP) service will be evaluated in low code rate (LCR) time duplex high speed downlink packet access (TD-HSDPA) system. This novel RRM strategy is studied from the aspects of scheduling algorithm and time slot assignment algorithm. As VoIP is delay sensitive service, the delay based proportional fair (DBPF) scheduler is proposed in this article. Smart antenna (SA), which is adopted in LCR TD-HSDPA, can obtain spatial information from the direction of arrival (DOA) estimation. To exploit this spatial information further, a dynamic time slot allocation (DTA) algorithm is introduced to cooperate with the DBPF scheduler. The performance of the round robin (RR), proportional fair (PF) with the random time slot allocation (RTA) algorithm will be given to demonstrate the benefits of this novel DBPF with DTA RRM strategy. The system level simulation results prove that the performance of this novel RRM strategy is the best of all the RRM strategies.
中国邮电高校学报(英文版), 2009, 16 (4). doi： 10.1016/S1005-8885(08)60245-9
摘要 ( 2517 ) PDF (245 KB)( 469 )
IEEE 802.16e is currently the latest broadband wireless access standard designed to support mobility. In mobile networks, how to control energy consumption is one of the most important issues for battery-powered mobile stations. The standard proposes an energy saving mechanism named ‘sleep mode’ for conserving the power of mobile stations. According to the operation principle of the sleep mode for downlink traffic in the type I power saving class, considering the self-similar nature of massive multimedia data in wireless networks, a discrete-time batch arrival GeomX/G/1 queuing model with a close-down time and multiple vacations is built. The batch size is supposed to be Pareto distributed. By employing an embedded Markov chain method, the average queue length and the average sojourn time of the system model are derived. Correspondingly, the performance measures are obtained of the energy saving rate and the average packet delay time for the sleep mode in the IEEE 802.16e. The numerical results demonstrate the dependency relationships between the system performance measures and the system parameters with different offered loads and different self-similar degrees. Furthermore, a cost model is developed to determine the optimum length of the close-down time for minimizing the total system cost.
中国邮电高校学报(英文版), 2009, 16 (4). doi： 10.1016/S1005-8885(08)60246-0
摘要 ( 2017 ) PDF (168 KB)( 401 )
Opportunistic routing takes advantage of the broadcast nature of wireless communications by forwarding data through a set of opportunistic paths instead of one ‘best’ path in traditional routing. However, using the global scheduling opportunistic scheme like the existing opportunistic routing protocol (ExOR) would consume considerable transmission latency and energy in large-scale wireless topologies. In this article, a graph partitioning algorithm is proposed, namely, minimum cut with laplacians (MCL), to divide the Ad-hoc network topology into subgraphs with minimized edge cuts across them. Then the existing opportunistic routing can be applied locally in each subgraph. In this way, forwarders in different subgraphs can transmit simultaneously, and each node only needs to maintain a local forwarder list instead of a global one. The simulations show that using MCL scheme in the opportunistic routing can reduce the end-to-end delay by about 49%, and increase the life time of the wireless node by about 39%.
中国邮电高校学报(英文版), 2009, 16 (4). doi： 10.1016/S1005-8885(08)60247-2
摘要 ( 3340 ) PDF (275 KB)( 636 )
In radio frequency identification (RFID) systems, tag collision arbitration is a significant issue for fast tag identification. This article proposes a novel tag anti-collision algorithm called framed slotted ALOHA with grouping tactic and binary selection (GB-FSA). The novelty of GB-FSA algorithm is that the reader uses binary tree algorithm to identify the tags according to the collided slot counters information. Furthermore, to save slots, tags are randomly divided into several groups based on the number of collided binary bits in the identification codes (IDs) of tags, and then only the number of the first group of tags is estimated. Performance analysis and simulation results show that the GB-FSA algorithm improves the identification efficiency by 9.9%–16.3% compared to other ALOHA-based tag anti-collision algorithms when the number of tags is 1 000.
中国邮电高校学报(英文版), 2009, 16 (4). doi： 10.1016/S1005-8885(08)60248-4
摘要 ( 1957 ) PDF (284 KB)( 464 )
This article develops a discrete time dynamic feedback model of a congestion control system for a simple network with TCP Westwood (TCPW) connections and a single bottleneck link with random early detection (RED) gateway. By using this model, the nonlinear dynamics of the TCPW/RED network are analyzed and its parameter sensitivities are studied. It is shown that periodic doubling bifurcation occurs when the RED control parameters or other parameters are varied. By theoretical analysis, the fixed point, the critical value of parameters and the nature of the bifurcation are determined. Moreover, by using bifurcation diagrams and Lyapunov exponent, the result of theoretical analysis is validated and the bifurcation and chaotic phenomena are numerically studied of the congestion control system with TCPW connections and RED gateway.
王晓军, 李养群, 吴晓妹, 闵丽娟
中国邮电高校学报(英文版), 2009, 16 (4). doi： 10.1016/S1005-8885(08)60249-6
摘要 ( 2033 ) PDF (259 KB)( 395 )
Composite Web services provide promising prospects for conducting cross-organizational Web service transactions. Such transactions generally require longer processing time and manipulate financially critical data. To efficiently manage these Web services transactions, isolation is commonly relaxed, but inconsistency will be caused by concurrently executing isolation-relaxing transactions. This article proposes an extension to the WS-Business Activity Protocol, which ensures the consistent executions of isolation-relaxing Web service transactions, and which is based on transaction dependency graphs distributed over multiple nodes. Furthermore, this article presents several algorithms implementing the protocol, and introduces the implement of a prototype system.
中国邮电高校学报(英文版), 2009, 16 (4). doi： 10.1016/S1005-8885(08)60250-2
摘要 ( 2102 ) PDF (196 KB)( 507 )
A new load balancing algorithm named dynamic weighed random (DWR) algorithm for the session initiation protocol (SIP) application server cluster is proposed. It uses weighted hashing random algorithm that supports dialog in the SIP protocol to distribute messages. The weight of each server is dynamic adaptive with feedback mechanism. DWR insures that the cluster is balanced, and it performs better than the limited resource vector (LRV) algorithm and minimum sessions first (MSF) algorithm.
中国邮电高校学报(英文版), 2009, 16 (4). doi： 10.1016/S1005-8885(08)60251-4
摘要 ( 1915 ) PDF (247 KB)( 363 )
In this article, two novel Tomlinson-Harashima precoding (THP) algorithms are proposed at the downlink broadcast channel of multi-user multiple-input multiple-output (MIMO) systems. The optimality criterion is the minimization of the bit error rate (BER) at the receiver with a constraint on the overall transmitted power. In these algorithms, transmit power allocation (TPA) matrix is introduced to the traditional THP algorithms as part of the precoding matrix. This leads to a power loading operation based on substreams signal to interference-plus-noise ratio (SINR) and results in improvement of the error rate performance compared with traditional THP algorithms. When the precoding loss factor is considered, further performance improvement is achieved by the enhanced algorithm.
中国邮电高校学报(英文版), 2009, 16 (4). doi： 10.1016/S1005-8885(08)60252-6
摘要 ( 2951 ) PDF (371 KB)( 384 )
The performance of singular value decomposition (SVD)-based multiple-input multiple-output (MIMO) with adaptive modulation (AM) is dependent on the accuracy of the channel state information (CSI) at the transmitter and the receiver. However, for a time-varying channel, the CSI obtained at the transmitter or the receiver is incorrect owing to an inherent delay or error. A typical system employing SVD suffers degradation in capacity when outdated CSI is used to transmit data. This article first addresses the adaptive modulation MIMO system designed under perfect CSI assumption. Based on that, two scenarios of outdated CSI are investigated and analyzed. The effect of imperfect CSI on the system performance is focused on and a simple post processing SNR (pSNR) adjustment design is proposed on AM system in the two scenarios for reducing degradation in average spectral efficiency (ASE). Simulation results show that these designs provide good performance in an adaptive way, and enable the adaptive MIMO system considerably more to be robust against CSI imperfection.
中国邮电高校学报(英文版), 2009, 16 (4). doi： 10.1016/S1005-8885(08)60253-8
摘要 ( 3024 ) PDF (334 KB)( 484 )
An optimized Chord protocol is proposed to solve the convergence problem for separated Chord rings over mobile Ad-hoc networks (MANETs). This protocol exploits the information of topological neighbors in routing layer by utilizing a cross-layer design, and periodically detects whether there is any neighbor node that belongs to an alien Chord ring by sending detecting packets. The detection will be confirmed and then the corresponding predecessor node will be found out to initialize convergence of the Chord rings. Theoretical analysis and experiment results show that the proposed algorithm can detect separated Chord rings and implement the convergence process efficiently, and that a significant improvement in the successful lookup ratio is also achieved at an acceptable overhead for the system maintenance. Moreover, the proposed protocol can ensure the stability and scalability of the system.
中国邮电高校学报(英文版), 2009, 16 (4). doi： 10.1016/S1005-8885(08)60254-X
摘要 ( 3067 ) PDF (179 KB)( 408 )
A novel adaptive power loading algorithm with the constraint of target overall bit error rate (BER) for orthogonal frequency division multiplexing (OFDM) systems is proposed in this article. The proposed algorithm aims to minimize the required transmit power with fixed data rate and uniform (nonadaptive) bit allocation, while guaranteeing the target overall BER. The power loading is based on the unequal-BER (UBER) strategy that allows unequal mean BERs on different subcarriers. The closed-form expressions for optimal BER and power distributions are derived in this article. Simulation results indicate the superiority of the proposed algorithm in terms of BER performance and algorithmic complexity.
中国邮电高校学报(英文版), 2009, 16 (4). doi： 10.1016/S1005-8885(08)60255-1
摘要 ( 2026 ) PDF (219 KB)( 378 )
A simple but effective relay-selection and power-allocation scheme is proposed to maximize the lifetime of decode-and-forward (DF) cooperative networks under the constraint that only the mean channel gain information is available at the transmitters. The new scheme takes both channel state information (CSI) and residual energy information (REI) into consideration. To evaluate the performance of the proposed scheme, three typical relay-selection and power-allocation schemes, i.e., maximum residual energy (MRE), minimum transmit power (MTP) and equal transmit power (ETP) are considered. Simulation results show that the proposed scheme outperforms the MRE and the MTP in lifetime duration and outage probability, while needing much less signal overhead compared with the ETP.
中国邮电高校学报(英文版), 2009, 16 (4). doi： 10.1016/S1005-8885(08)60256-3
摘要 ( 1946 ) PDF (371 KB)( 389 )
In a hybrid wired-cum-wireless network environment, packet loss may happen because of congestion or wireless link errors. Therefore, differentiating the cause is important for helping transport protocols take actions to control congestion only when the loss is caused by congestion. In this article, an end-to-end loss differentiation mechanism is proposed to improve the transmission performance of transmission control protocol (TCP)-friendly rate control (TFRC) protocol. Its key design is the introduction of the outstanding machine learning algorithm – the support vector machine (SVM) into the network domain to perform multi-metric joint loss differentiation. The SVM is characterized by using end-to-end indicators for input, such as the relative one-way trip time and the inter-arrival time of packets fore-and-aft the loss, while requiring no support from intermediate network apparatus. Simulations are carried out to evaluate the loss differentiation algorithm with various network configurations, such as with different competing flows, wireless loss rate and queue size. The results show that the proposed classifier is effective under most scenarios, and that its performance is superior to the ZigZag, mBiaz and spike (ZBS) scheme.
中国邮电高校学报(英文版), 2009, 16 (4). doi： email@example.com
摘要 ( 2751 ) PDF (130 KB)( 386 )
Several geometric sequences have very low linear complexities when considered as sequences over GF(p), such as the binary sequences of period constructed by Chan and Games [1–2] (q is a prime power pm, p is an odd prime) with the maximal possible linear complexity when considered as sequences over GF(2). This indicates that binary sequences with high GF(2) linear complexities LC2 and low GF(p)-linear complexities LCp are not secure for use in stream ciphers. In this article, several lower bounds on the GF(p)-linear complexities of binary sequences is proved and the results are applied to the GF(p)-linear complexities of Blum-Blum-Shub, self-shrinking, and de Bruijn sequences. A lower bound on the number of the binary sequences with LC2 > LCp is also presented.
中国邮电高校学报(英文版), 2009, 16 (4). doi： 10.1016/S1005-8885(08)60258-7
摘要 ( 2639 ) PDF (182 KB)( 670 )
Proxy signature is an important cryptographic primitive and has been suggested in numerous applications. The revocation of delegated rights is an essential issue of the proxy signature schemes. In this article, a security model of proxy signature schemes with fast revocation is formalized. Under the formal security framework, a proxy signature scheme with fast revocation based on bilinear pairings is proposed. A security mediator (SEM), which is an on-line partially trusted server, is introduced to examine whether a proxy signer signs according to the warrant or he/she exists in the revocation list. Moreover, the proxy signer must cooperate with the SEM to generate a valid proxy signature, thus the proposed scheme has the property of fast revocation. The proposed scheme is provably secure based on the computational Diffie-Hellman (CDH) intractability assumption without relying on the random oracles, and satisfies all the security requirements for a secure proxy signature.
中国邮电高校学报(英文版), 2009, 16 (4). doi： 10.1016/S1005-8885(08)60259-9
摘要 ( 2631 ) PDF (240 KB)( 418 )
Recent progress in home networks enhances the application of broadband power line communication (BPL) since it does not require any installation of new communication lines or outlets. However, high-density distribution of BPL devices may bring down the access quality. Besides, the electromagnetic field radiating from the power line may cause interference with other radio systems. Thus, the objective of this study is to investigate the impact of cumulative interference in BPL systems, especially focused on indoor environment. A 2-D model describing the BPL transmission activity is proposed. Based on transmission characteristics of the main networks, it takes into account the coexistence effect of the BPL devices. The maximum acceptable density of BPL devices and the radiation field are finally determined.