Doppler Shift Compensation Schemes in VANETs

Abstract

Over the last decade vehicle-to-vehicle (V2V) communication has received a lot of attention as it is a crucial issue in intravehicle communication as well as in Intelligent Transportation System (ITS). In ITS the focus is placed on integration of communication between mobile and fixed infrastructure to execute road safety as well as nonsafety information dissemination. The safety application such as emergence alerts lays emphasis on low-latency packet delivery rate (PDR), whereas multimedia and infotainment call for high data rates at low bit error rate (BER). The nonsafety information includes multimedia streaming for traffic information and infotainment applications such as playing audio content, utilizing navigation for driving, and accessing Internet. A lot of vehicular ad hoc network (VANET) research has focused on specific areas including channel multiplexing, antenna diversity, and Doppler shift compensation schemes in an attempt to optimize BER performance. Despite this effort few surveys have been conducted to highlight the state-of-the-art collection on Doppler shift compensation schemes. Driven by this cause we survey some of the recent research activities in Doppler shift compensation schemes and highlight challenges and solutions as a stock-taking exercise. Moreover, we present open issues to be further investigated in order to address the challenges of Doppler shift in VANETs.

Doppler Shift Estimation and Compensation in High Speed MIMO-OFDM VANETs

“…The processed (L + 1)(Q + 1) symbols are a reduction from the full matrix contents. This is a big saving in terms of computational resources such as memory space and processing time, compared to the conventional method which processes M 2 symbols, M being the FFT size [2], [4], [12], [26]. Moreover, the zero off-diagonal entries cancel the out-of-band noise coefficients to enhance BER performance.…”

“…This section provides the performance evaluation of the pilot assisted general complex exponential basis expansion modelling (BEM) based DFS estimation and compensation method in a moderately high speed MIMO-OFDM VANET [22], [23]. The simulation was conducted with the number of sub-carriers set to be M = 1024 and the length of the cyclic prefix (CP) was M/8.…”

“…The increased speed causes increased channel fading rate and increased DFS, thus lowering the performance at high speed. In Figure 5, the non-compensated [2], iterative LCR [4] and proposed BEM methods are compared in two vehicular speed regimes (below and above HS, respectively).…”

“…Recently, Intelligent Transportation System (ITS) applications which promise safety and comfort of drivers on the roads have attracted attention of many researchers. The emergence of the ITS applications have witnessed an increased research interest toward estimating and compensating the DFS in low to medium speed (typically, below 120 km/h) VANETs [2]. As such, several methods have been proposed including the Error Vector Magnitude (EVM) methods [2], [26] and the one-tap split phasor least mean square (LMS) algorithm [3].…”

Social Internet of Vehicles for Smart Cities

“…Another problem that the communication between moving vehicles has arises when the receiver and the source are moving towards different directions. The problem that is called Doppler shift has attracted much attention, and many solutions have been proposed [79]. The authors in [80] identified the key factors that affect the delivery of warning messages between vehicles, which are the radio propagation model, the density of vehicles and the roadmap.…”