The design and evaluation of Inter-Vehicle Communication (IVC) protocols rely much on the accurate and efficient computational simulations. For simulations of Medium Access Control (MAC) and higher layers, the modeling work of underlying Physical layer (PHY) and wireless channel has impacts both on the computational efficiency of simulations and on the correctness of results. In this contribution, we discuss the modeling issues of the inter-vehicle wireless channel in highway scenarios and the packet error performance of Dedicated Short Range Communications (DSRC) PHY, which works at the newly allocated 5.9GHz Intelligent Transportation System (ITS) frequency band. A computationally efficient yet accurate enough error modeling approach used in our MAC layer simulator WARP2 is presented in this paper, together with simulation results. Both weaknesses and potential improvements of the proposed approach are discussed also in this work.

Abstract

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MIMO (Multiple Input -Multiple output) systems apply multiple antennas to increase signal to noise ratio (SNR), reduce interference and/or send multiple streams simultaneously over a single channel. Besides increasing the data rate of the physical layer (PHY), benefits can be achieved with cross-layer optimization approach exploiting the layered structure of the channel.In this paper we focus on MIMO schemes with multiplexing and/or diversity gain and present a link model for system level simulations. The model maps total SNR to achievable link level throughput, both per spatial subchannel and cumulative. The model can be combined with an arbitrary coding and modulation scheme and is abstract enough to be applied to any system protocol, fulfilling the given conditions about channel propagation characteristics.

IEEE 802.11a/e has become a worldwide wireless local area network (W-LAN) standard, with a rapid development. Many proposals have been made for its further expansion, and some of them focus on multicarrier code division multiple access (MC-CDMA), a novel, high capacity, multicarrier modulation scheme. In this paper we present an analysis of the error models for radio transmissions in such systems. An accurate model of the channel is necessary for the performance evaluation of the protocol by means of computer simulations. Focusing on the estimation of the signal to interference and noise ratio (SINR) at the detector and on the calculation of a packet error ratio (PER), in this contribution we discuss a modeling approach which allows an efficient calculation of frame transmissions over a MC-CDMA shared radio channel.