Dedicated Short Range Communication System Research Articles

Performance enhancement of the DSRC system using frequency-domain equalization for 5.9 GHz DSRC applications

This paper proposes the use of equalization concepts in frequency domain that exploit the frequency domain channel matrix to combat inter-carrier interference (ICI) instead of inter-symbol interference (ISI) in 5.9 GHz Dedicated Short Range Communications (DSRC) systems. The physical layer (PHY) of DSRC is currently being developed by work group of IEEE 802.11p. The conventional system currently assumes static channel characteristics. Channel tracking schemes were investigated and the Viterbi-aided channel estimation scheme was proposed for DSRC systems that did not explicitly exploit the ICI components caused by the time-varying channels. The performance of the DSRC system is investigated for a time-varying channel using a conventional DSRC model, a decision-directed (Viterbi-aided) channel estimation model, and the frequency-domain equalization design. It is shown that the DSRC system with the frequency-domain equalization achieves a considerable performance enhancement compared to both the conventional and the Viterbi-aided channel estimation schemes in terms of both packet error rate (PER) and bit error rate (BER) at relatively high and low velocities.

Circularly polarized H‐shaped microstrip‐array antenna with a T‐slot for DSRC system roadside equipment

AbstractThis article describes the design of a novel circularly polarized H‐shaped microstrip‐array antenna with a T‐slot for dedicated short‐range communication (DSRC) system roadside equipment (RSE: 5.850–5.925 GHz). The antenna system needs a correct radiation pattern, at the assigned communication area, without interference from the other radio wave propagation. The proposed antenna is designed to reduce the side lobe level (SLL) by using the proper distance for patch array and multilayer substrates for DSRC RSE. H‐shaped patches are used for circular polarization (RHCP or LHCP) with a T‐slot. The measured bandwidth of the fabricated antenna is from 5.830 to 5.939 GHz when the return loss < −10 dB. The measured axial ratio (RHCP) is 1.25–2.02 dB and gain is 15.62–15.94 dBi. The experimental 3‐dB beam width (HPBW) in the E‐plane and H‐plane are 22.52° and 24.11° at 5.91 GHz, respectively. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 1545–1548, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24369

Performance and Reliability of DSRC Vehicular Safety Communication: A Formal Analysis

IEEE- and ASTM-adopted dedicated short range communications (DSRC) standard toward 802.11p is a key enabling technology for the next generation of vehicular safety communication. Broadcasting of safety messages is one of the fundamental services in DSRC. There have been numerous publications addressing design and analysis of such broadcast ad hoc system based on the simulations. For the first time, an analytical model is proposed in this paper to evaluate performance and reliability of IEEE 802.11a-based vehicle-to-vehicle (V2V) safety-related broadcast services in DSRC system on highway. The proposed model takes two safety services with different priorities, nonsaturated message arrival, hidden terminal problem, fading transmission channel, transmission range, IEEE 802.11 backoff counter process, and highly mobile vehicles on highway into account. Based on the solutions to the proposed analytic model, closed-form expressions of channel throughput, transmission delay, and packet reception rates are derived. From the obtained numerical results under various offered traffic and network parameters, new insights and enhancement suggestions are given.

Performance Improvement of the DSRC System Using a Novel S and Π-Decision Demapper

Based on the constellation diagram of the different modulations, a novel S and Π-decision rule is designed for the analog demapper of the orthogonal frequency-division multiplexing (OFDM) systems. The dedicated short-range communications (DSRC) system is chosen as an OFDM platform to compare the performance among the proposed S and Π-decision decoder, hard-decision and soft-decision decoders. Simulation results demonstrate that both the complexity and performance of S and Π-decision demapper used for M-ary quad-rature amplitude modulation (QAM) OFDM system can be greatly improved. The number of decisions be-tween the received symbol and constellation points can be simplified to look up table times for M-ary QAM OFDM system.

ITS용 2층형 전파 흡수체(유전체/자성체) 설계 및 경사 입사 흡수 특성 해석

5.8 GHz의 DSRC(Dedicated Short Range Communication) 시스템을 사용하는 ITS(Intelligent Transport System)에 전자파 환경 문제가 발생하면서 광각 경사 입사 대책용 전파 흡수체의 사용이 요구된다. 5.8 GHz 주파수에서 경사 입사된 전파에 대해 낮은 반사 손실을 보이는 2층형의 전파 흡수체(유전 복합 재료/자성 복합 재료)를 설계하였다. 흡수층에는 iron flake를 filler로 사용하였다. 임피던스 정합 기능의 표면층에는 유전상수가 낮은 carbon black을 사용하였다. 각 층의 sheet는 일반적인 세라믹 혼합물 제조 공정에 의해 제작되었고, 지지재로는 가황고무를 사용하였다. 전송 선로 이론에 근거하여 TE(Transverse Electric)와 TM(Transverse Magnetic) 편파에 대해 입사각을 변화시키며 반사 손실을 계산하였고, 자유공간법에 의해 반사 전력을 실측하였다. 입사각 <TEX>$55^{\circ}$</TEX>까지 낮은 반사 손실(-10 dB 이하)을 갖는 2층형 흡수체가 설계되었다. 자유공간법에 의한 반사 전력의 실측치가 이론적 계산치와 비슷한 값을 보여 설계 방법의 타당성을 입증할 수 있었다. Advanced microwave absorbers for wide oblique incidence angles are required in many applications including wireless communication or vehicle identification in ITS(Intelligent Transport System) where 5.8 GHz DSRC(Dedicated Short Range Communication) system is applied. In this study, two-layered microwave absorber(with a laminate structure of dielectric/magnetic composites) has been designed for the achievement of low reflection coefficient over wide incidence angles at 5.8 GHz. Iron flake particles are used as the filler in the absorbing layer, and the magnetic composite sheet exhibits high magnetic loss due to ferromagnetic resonance in gigahertz frequencies. The surface layer of low dielectric constant containing small amount of carbon black is used as the impedance transformer. On the basis of transmission line theory, the reflection loss has been calculated for the two-layer structure with variation of incident angles for both TE(Transverse Electric) and TM(Transverse Magnetic) polarizations. At the optimum thickness of the composite layers, a low value of reflection loss(less than -10 dB) has been predicted for wide incidence angles up to <TEX>$55^{\circ}$</TEX> which is in good agreement with the measured value determined by free-space measurement.

Performance of DSRC systems using conventional channel estimation at high velocities

In this paper, we present a study of the dedicated short range communications (DSRC) receiver performance under varying signal to noise ratio, velocity, symbol durations and packet lengths. Conventional channel estimation, which is used in IEEE 802.11a, assumes static channel characteristics for the entire packet duration. That is found to be infeasible for high velocity DSRC applications. Simulation results show that the packet-error-rate increases with the increase in relative velocity. Viterbi decoding substantially improves the performance, but the sensitivity to Doppler shift still exists. Analysis and simulation results show that extending the symbol duration or increasing packet length results in an increase of the packet-error-rate. These results may serve as benchmarks for future DSRC channel estimation methods.

Analysis of EM Environment for DSRC System on Express Highway with Wave Absorbers on Sidewalls and Pavement

Electromagnetic (EM) wave absorbers have been used for improving the EM environment of an electronic toll collection (ETC) system on an express highway or a wireless local area network (LAN) system in an indoor environment. In this paper, an efficient multi-ray propagation model, which uses 3D geometry and image techniques to trace multiple signal rays from transmitter to receiver, is employed to analyze the EM environment of a dedicated short-range communication (DSRC) system on an express highway. The validity of the model employed is discussed by the comparison with the results obtained by an experiment on the highways. The analysis shows that the possible undesired communications between onboard equipment that acts as a receiver and DSRC beacon which transmits the radio signals, is improved by increasing the EM wave-absorption capability of the sidewalls and the pavement of the highway. Another advantage of the employed model is that it is effective for investigating the location of wave absorbers to be set up on the highway, and it takes only a fraction of a minute for computation.

LMMSE 등화기법을 적용한 OFDM-DSRC 시스템의 성능분석

무선 다중경로 채널에서 데이터를 고속으로 전송할 경우, 신호는 페이딩, 심볼간 간섭 등의 영향으로 높은 에러율을 갖게 된다. 그러므로 현재 개발된 DSRC(dedicated short-range communication) 시스템의 변복조 방식은 1 Mbps이상의 데이터 서비스가 어려울 것으로 예상되므로 새로운 채널등화 기법 및 개선된 변복조 방식이 요구된다. OFDM(orthogonal frequency division multiplexing) 방식은 보호간격의 삽입을 통하여 ISI를 방지할 수 있으므로 고속 데이터 전송에 적합하다. 그러나 보호기간이 OFDM 방식에서의 각각의 심볼주기에 사용되는 채널지연 확산보다 길어지므로 채널활용의 효율성에서 상당한 손실이 야기된다. 그러므로 등화기를 고속의 데이터 전송율과 긴 채널 지연확산 조건을 가지는 ITS(intelligent transport system)에 적용하기 위해서는 ISI(inter symbol interference)를 제거할 필요가 있다. 본 논문에서는 OFDM-DSRC 시스템을 위한 채널 등화기를 설계하였으며, 다중경로 페이딩 환경에서 컴퓨터 시뮬레이션을 통해 그 성능을 분석하였다. The signal in wireless multi-path channel is affected by fading and ISI because of high data rate transmission, so the signal has the high error rate. The present modulation and demodulation method of DSRC system can not expect sufficient for providing data service over 1 Mbps, so the channel equalization and advanced modulation and demodulation methods are required. OFDM is generally known as an effective technique for high data rate transmission system, since it can prevent ISI by inserting a guard interval. However, a guard interval longer than channel delay spread has to be used in each OFDM symbol period, thus resulting a considerable loss in the efficiency of channel utilization Therefore the equalizer is necessary to cancel ISI to accommodate advanced ITS service with higher bit rate and longer channel delay spread condition In this paper, the channel equalizer for the OFDM -DSRC system was designed and its performance in a multi-path fading environment was evaluated with computer simulation.

Design of a double‐looped monopole array antenna for a DSRC system roadside base station

AbstractThe antenna system for a dedicated short‐range communication (DSRC) system must have pattern characteristics that satisfy the system's specifications. Also, the antenna system needs to have good space efficiency for mounting on a roadside base station. The proposed antenna has the traveling‐wave structure of a double‐looped monopole array. The Wilkinson power divider is used for the in‐phase feeding of the array. The designed antenna system's performance is suitable for the DSRC system. © 2003 Wiley Periodicals, Inc. Microwave Opt Technol Lett 37: 74–77, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10829

Impact of Security/AAA on Intelligent Transport Systems

On-demand type DSRC (Dedicated Short Range Communication) system is one of the future target RVC (Road-to-Vehicle Communication) system in ITS (Intelligent Transport Systems). This paper investigates the permissible range of contents download volume focusing on the duration time of vehicle passage thought a spot and the download time of contents in addition to authentication process time. It is clarified that the most priority technical issue is the realization of the real-time characteristics in the On-demand type DSRC system.

Performance Evaluation of the Physical Layer of the DSRC Operating in 5.8 GHz Frequency Band

In this paper, the theoretical as well as experimental results of BER characteristics of three different modulation schemes, ASK, FSK and BPSK, in a multi-path Rician channel are addressed. These BER characteristics are analyzed as a function of E b / N o and the power ratio of the line of sight (LOS) component to the Rayleigh scattered component The theoretical as well as computer simulation results shows the ASK is the most suitable modulation scheme for the dedicated short range communication (DSRC) in terms of implemental cost and system complexity. The decision feedback equalizer is proved to be very effective in canceling the multi-path interference in the DSRC channel environment. The simulation result of the equalized ASK, reveals the performance enhancement achievable with decision feedback (DFE) equalizer for the first generation DSRC system. The multi-ray DSRC channel model is also provided to predict the received carrier power and fluctuation, which are quite dependent on the surroundings of a cell.

Applications of Wireless Communication Technologies for Intelligent Transport Systems

The DSRC (Dedicated Short Range Communication) system based on the wireless communication technologies is essential to provide ITS (Intelligent Transport Systems) services using the information and...

Analysis of International Border Clearance Technologies

Dedicated Short Range Communication (DSRC) technology was implemented at land-border ports to support the International Trade Data System’s (ITDS’s) vision of nonstop paperless border processing. Subsequent evaluation concluded that the implemented DSRC systems inadequately supported the ITDS objectives. Consequently, alternative technologies were assessed that could support multimodal border processing. Alternative technologies considered are divided into two main categories: ( a) short-range systems that include laser, radio frequency, and automated teller machine (ATM) technologies and ( b) wide-area systems that include cellular telephony, radio data network services, and satellite communications. The names of the companies proposing technologies still in development were withheld. The data indicate that several widely used and off-the-shelf technologies, such as Qualcomm, Type II transponders, and ATM systems, are capable of only partially supporting the functional requirements of ITDS border processing. A proposal that combines cellular and radio-frequency technology, which came closest to satisfying the ITDS requirements, is still new and untested. It was found that short-range technology is inadequate for supporting sea and air transportation modes. Wide-area systems are costlier and are incapable of supporting lane discrimination and automatic decision and exit notification at land-border ports without the support of other on-board short-range automatic vehicle identification devices. On the basis of the findings, the solution that combines cellular and radio-frequency technology seems to address most of the ITDS border processing requirements and may merit further consideration.