In the context of fully distributed systems, we consider a scenario densely populated with wireless nodes which are equipped with simultaneous wireless information and power transfer (SWIPT) capabilities and can act as relays between a source and a destination. In this scenario, the probability of finding a node able to provide a useful contribution to the quality of the link tends to be high and can be exploited adopting a suitable relay selection scheme. Assuming nodes distributed following a Poisson point process and communicating only with source and destination to ensure the scalability of the system, we consider two well-known relay selection schemes, which are typically used as performance benchmarks, and derive an analytical framework to investigate the performance of the source-destination link in terms of outage probability. In our analysis we include, through the use of a simple but effective model, the non-linear effects of the energy harvesting circuitry of the devices and introduce a simple signaling mechanism between source, SWIPT nodes and destination to identify the most suitable relay among the various SWIPT devices. The impact of multiple access during the phase of relay selection is also modeled and investigated.

This paper investigates the performance limit of position estimation in a three dimensional (3D) molecular diffusion environment. Specifically, we consider a realistic molecular transmission process based on chemical-physical laws and a Poisson distribution of the received molecules. We derive a closed form expression of the Cramér-Rao Bound as a function of the system parameters, such as the number of molecules, the estimation time, the distance of the target, the constant reaction rate and the reagents concentration showing how they impact the localization estimation.

Future automated driving relies on two pillars, (i) ultra-low-latency and reliable communications, and (ii) accurate positioning information. In particular, the knowledge of vehicle positions is becoming fundamental with the increase of the automation level, allowing autonomous navigation of the environment. Today’s positioning techniques cannot provide the accuracy, robustness, and latency required for stringent applications, like platooning, where vehicles are expected to travel at extremely short distances. In this paper, we leverage vehicle-to-everything (V2X) sidelink communication for localization purposes, capitalizing on the near-field propagation attributes of signals generated utilizing high carrier frequencies and/or large antenna arrays. Consequently, a receiving vehicle can accurately determine the transmitting vehicle’s location through V2X sidelink packet reception, obviating the need for supplementary reference nodes or stringent synchronization. Fundamental limits on localization accuracy are derived to characterize the positioning performance in vehicular contexts. A case study based on 5G new radio (NR) V2X sidelink shows how this technique is extremely promising and capable of providing high accuracy, low latency, high update rate, and high availability of position information in realistic vehicular scenarios.

Connectivity and automation are increasingly getting importance in the automotive industry, which is observing a radical change from vehicles driven by humans to fully automated and remotely controlled ones. The test and validation of all the related devices and applications is thus becoming a crucial aspect; this is raising the interest on hardware-in-the-loop (HiL) platforms which reduce the need for complicated field trials, thus limiting the costs and delay added to the process. With reference to the test and validation of vehicle-to-everything (V2X) communications aspects, and assuming either sidelink LTE/5G-V2X or IEEE 802.11p/bd technologies, in this work we focus on the real-time HiL simulation of the information exchanged by one vehicle under test and the surrounding, simulated, objects. Such exchange must be reproduced in a time-efficient manner, with elaborations done fast enough to allow testing the applications in real-time. More precisely, we discuss the simulation of non-ideal positioning and channel propagation taking into account current impairments. We also provide details on optimization solutions that allowed us to trade-off minor loss in accuracy with a significant reduction of the computation time burden, reaching up to more than one order of magnitude speed increase in our experiments.

Current vehicular communication technologies were designed for a so-called phase 1, where cars needed to advise of their presence. Several projects, research activities and field tests have proved their effectiveness to this scope. But entering the phase 2, where awareness needs to be improved with non-connected objects and vulnerable road users, and even more with phases 3 and 4, where also coordination is foreseen, the spectrum scarcity becomes a critical issue. In this work, we provide an overview of various 5G and beyond solutions currently under investigation that will be needed to tackle the challenge. We first recall the undergoing activities at the access layer aimed to satisfy capacity and bandwidth demands. We then discuss the role that emerging networking paradigms can play to improve vehicular data dissemination, while preventing congestion and better exploiting resources. Finally, we give a look into edge computing and machine learning techniques that will be determinant to efficiently process and mine the massive amounts of sensor data.

Most of the applications envisaged for the forthcoming connected vehicles are based on the broadcasting by each vehicle of periodic messages describing its characteristics, state, and actions. Such messages are denoted as cooperative awareness messages (CAMs) in the ETSI standardization. From a communication perspective, the success of CAM delivery is thus a particularly important aspect to evaluate and the obvious method to address large scale scenarios consists in performing simulations. Normally, given that the relevance of the information is related to the distance between communicating vehicles, output metrics are restricted to a given range. However, no attention is typically posed on the relative positions and movements of the vehicles, which could be, for example, on parallel roads. In this work, we propose a novel method to identify and neglect those transmissions that are not really meaningful, based only on the position and direction of the vehicles. Particular emphasis is laid on the efficiency of the methodology for possible large-scale simulations. The described approach is evaluated in a complex urban scenario, where hundreds of vehicles are equipped with either LTE-V2V or IEEE 802.11p. Results show that, in the considered cases, even less than half of the transmissions could be meaningful and that neglecting those that are not relevant significantly impacts on the quality of the investigated application.

We investigate a dual-user scenario where sources transmit their messages to the destinations by means of relays in an amplify-and-forward two-hop mechanism. In this scenario, the presence of co- channel interference requires the design of a suitable relay selection algorithm to minimize outage events. To this aim, we present a relay selection algorithm specifically tailored for amplify-and-forward relaying. The performance of the relay selection mechanism is evaluated analytically, in terms of outage probability, under the assumption that relay nodes are distributed according to a homogeneous Poisson point process. Numerical results show that the proposed algorithm outperforms a conventional one, based only on the measurement of the power received from the desired transmitters.

On the path to zero fatalities on the roadways, all vehicles have to periodically broadcast cooperative awareness messages (CAMs) in a timely and reliable manner, even in areas of high traffic density. The carrier senses multiple access with collision avoidance (CSMA/CA) scheme of IEEE 802.11, the de-facto standard for vehicular communications, is known to offer no reliability to broadcast packets that cannot be acknowledged, and to poorly perform at high network load due to collisions and interference. In this paper, an enhanced CSMA/CA protocol is analyzed for vehicular networks, which improves the CAM timeliness and reliability by leveraging full-duplex (FD) transceivers on board. FD devices can listen to the channel while transmitting, thus making collision detection viable. A FD vehicle can detect a CAM collision while sending, promptly abort the packet and retransmit it later. Results achieved through an analytical model under mathematically tractable assumptions, and through extensive system-level simulations in a complex urban environment, show the effectiveness of the protocol to cope with direct collisions, especially in high traffic areas, paving the way towards the realization of cooperative automated driving.

Vehicle-to-everything (V2X) communications may radically change the transportation system allowing a real-time and highly reliable exchange of information, which can be processed by vehicles in the neighborhood or by the road-side infrastructure to enable safety, mobility and environmental applications. In this context, 3GPP-based cellular networks, and especially long term evolution (LTE), are offering progressively higher performance and enabling a wider set of operations. To this aim, vehicle-to-vehicle (V2V) has been recently added as a new feature to LTE, but the usage of radio resources still needs to be optimized and is subject of extensive research activities. In this work, we focus on autonomous V2V resource reselection schemes, which allow communications also in out-of-coverage areas, we propose MAP-RP, a reselection procedure based on the embedding of a map of resources, as detected by each receiving vehicle, in the broadcasted packet, and we compare it to two sensing-based benchmark algorithms found in the literature. Results are achieved through simulations performed on a realistic highway scenario and demonstrate that the proposed solution guarantees a lower update delay and allows to achieve up to 20% of improvement in terms of packet reception ratio, with respect to the best-performing benchmark algorithm.

Current wireless access technologies cannot satisfy all the requirements of future vehicular networks, and 5G could provide a solution to the actual limitations enabling super-fast, reliable, and low latency connections. The road to 5G vehicular networks can be considered opened by the Release 14 of Long Term Evolution (LTE), which enables vehicle-to-vehicle (V2V) communications also out of coverage of the eNodeB. This work firstly focuses on radio access of actual and next generation vehicular networks, by highlighting the main limitations and potentialities. Then, it focuses on beaconing for cooperative awareness and compares the performance of LTE when adopted in different fashions, from the actual legacy solution in vehicle-to-infrastructure (V2I) mode to future potential alternatives, such as LTE-V2V, LTE-V2V with short subframe and LTE-V2V with full duplex (FD) radios. Performance results are provided in terms of medium access efficiency and success probability of resource allocation, and show the potential advantages of future solutions, especially those provided by LTE-V2V with FD radios.

Resource allocation is a challenging issue in multiuser wireless systems. Since users are not all in the same conditions and do not achieve the same performance given the same amount of resources, resource allocation must typically deal with the following two conflicting objectives: on the one hand, the overall performance should be maximized, tending to prioritize few users in better conditions, and on the other hand, fairness among users should be maximized, consequently reducing the overall performance. Identifying the compromise that is somehow optimum is all but simple and this aspect is normally worsened by the absence of a curve describing how the maximum performance varies changing the accepted level of fairness. To cover this gap, in this paper, we propose a unified and general mathematical formulation of the optimal performance versus fairness tradeoff in multiuser wireless communication systems. Differently from the existing literature, our approach is based on the generalized Lagrange method and adopts general definitions for both performance and fairness. Besides the exact solving equations describing how the maximum performance varies with fairness, we also derive a simpler lower bound with reduced computational cost. Example results are provided for two case studies, respectively, concerning linear and logarithmic dependence of performance on resources.

In this paper, we consider a multi-user scenario where an arbitrary number of sources transmit their messages to the intended destinations by means of relays in a decode-and-forward two-hop mechanism. To minimize the interference generated in the scenario, two opportunistic relay selection mechanisms are proposed and investigated. The performance of the two selection mechanisms is analytically evaluated, in terms of outage probability and average achievable rate, under the assumption that relay nodes are distributed according to a Poisson point process. Asymptotical analysis is also presented for infinite node density. Numerical results show that the selection of the relays has a significant impact on the amount of interference generated and a suitable choice can improve the overall performance.

In a near future, vehicles will be equipped with wireless communications technologies to periodically broadcast information to their neighbors on their position and speed. The messages carrying such information, normally denoted as beacons, will reduce the probability of accidents and improve the safety of drivers and passengers. The main candidate technologies for this scope today are IEEE 802.11p and LTE-Advanced with device-to-device communications (LTE-D2D), which is now evolving into vehicle-to-vehicle communications features (LTE-V2V). The aim of this paper is thus to compare the performance in terms of scalability of these two technologies when used for beacon transmission. The comparison is made analytically, through the definition of common scenario and metrics.

We consider a multi-user scenario where sources transmit their messages to the destinations by means of a two-hop mechanism. To minimize the interference generated in the scenario, a simple opportunistic relay selection mechanism is investigated. The performance of the scenario is evaluated using some results of the stochastic geometry under the assumption that relay nodes are distributed according to a Poisson point process. Results show that, when the relay density is sufficiently high, a suitable choice of the relay leads to a limited amount of interference generated during source-relay and relay-destination transmissions.

Vehicular ad hoc networks (VANETs) drive new challenging research issues at different layers of the protocol pillar, from physical to application. Focusing on the medium access layer, one of the most promising and not yet fully explored option is the adoption of orthogonal frequency division multiple access (OFDMA). Besides guaranteeing high spectral efficiency and effective resource allocation, it relies at the physical layer on orthogonal frequency division multiplexing, which allows repetitions of the same signals to be opportunistically combined at the receiver even if they are not perfectly synchronized. Exploiting this property, here we suggest and discuss the use of OFDMA for alert message flooding in VANETs to increase reliability and resource usage efficiency. The achievable benefit and the potential drawback (in terms of high delivery delay) are here assessed through a simple yet realistic model that allows to compare, in highway scenarios, OFDMA with carrier sensing multiple access/collision avoidance, currently adopted by IEEE 802.11p for distributed communications in high mobility scenarios.

Optimal resource allocation is an outstanding issue in wireless communication systems. In this work we focus on the ever challenging optimization of the tradeoff between throughput and fairness. Specifically, we propose a novel framework to analytically derive the maximum average throughput versus fairness under the assumptions that the throughput of each user i) increases if more resources are allocated to him and ii) depends on how many resources and not which resources are allocated. We achieve a general formulation of the tradeoff optimization problem and we also derive and validate a closed form solution in those scenarios where throughput linearly depends on resources, which cover several realistic cases. Besides these valuable results, the framework also lays solid basis toward a more general solution.

Vehicular ad hoc networks (VANETs) based on IEEE 802.11p are moving new safety and traffic applications beyond the present limitations given by infrastructures. However, due to the high variability in time and position of nodes, the medium access control layer of IEEE 802.11p, which is based on carrier sensing multiple access with collision avoidance (CSMA/CA), could lead to severe performance degradation in terms of delivery delay and delivery ratio as the node density increases. Because of its higher efficiency, we propose the use of orthogonal frequency division multiple access (OFDMA) as access technique in VANETs, discussing and evaluating i) its feasibility, ii) the challenges posed by the distributed allocation of resources, and iii) its performance in terms of resource allocation efficiency (specifically, delivery rate and delivery delay) when compared to CSMA/CA. Results, obtained by means of simulations that jointly take into account realistic road maps, vehicular traffic, and the whole network architecture from the application down to the physical layer, show that OFDMA allows up to four times higher delivery rate and that it also guarantees lower delivery delay in heavy loaded network conditions.

When energy is harnessed by wireless nodes from renewable sources, its availability becomes uncertain and its use for communications must be carefully designed. While the optimal power allocation has been derived in previous works when energy availability is fully (a priori) known, practical algorithms are needed when only causal and statistical information is available. In this paper, we study the optimal transmission policy when only the statistical distribution of the energy arrival intervals is known and no information is available on the amount of energy that will be harnessed. We firstly obtain an exact solution for the case of a step-wise transmission power profile. This result is then extended to the time-continuous case. Within energy arrival intervals, the obtained power profile is shown to be non increasing as a function of time and non decreasing as a function of the residual energy. Numerical results are finally provided focusing on an exponentially distributed energy arrival process as a case study.

Routing strategies deeply affect the performance of wireless ad hoc networks, in terms of coverage, interference, and delay. In this work, we investigate the impact of different routing strategies on the overall amount of interference generated in a distributed ad hoc network with power control. To this end, we derive an analytical model for the evaluation of the performance in terms of mean value and variance of the interference when signal level power control is adopted and different routing strategies, based on long-hop and short-hop relay selections schemes, are considered. This model allows us to quantify the performance of the overall network in terms of interference, average number of hops and path efficiency. Numerical results have been also verified by simulations.

Considering vehicles as sensors for traffic and pollution information is a new paradigm to monitor the environment and to open the way to an efficient smart navigation. In this work we focus on the uplink acquisition of traffic information from vehicles toward a remote control center. With the increase in the number of vehicles equipped with on board units (OBUs) enabling cellular transmissions, this service is leading to higher loads for the cellular network itself and, consequently, to higher costs. In this paper we discuss the opportunity to take advantage of vehicle-to-vehicle (V2V) and vehicle-to-roadside communications in addition to vehicle-to-infrastructure cellular transmissions. The objective is twofold: to investigate the potential reduction of data transmitted over the cellular networks and to verify the potential transmission delay reduction, by sharing and aggregating information through V2V communications. Results are obtained through an integrated simulation platform jointly taking into account both realistic vehicular environments and wireless network communication aspects.

Real time information to vehicular users is proposing new challenging questions to which wireless systems designers are called to answer. Nowadays many vehicles are already equipped with devices able to connect to cellular networks, and to transmit and receive in real time traffic information through vehicle-to-infrastructure (V2I) communication. Focusing on the uplink transmission of real time measurements, this is leading to high costs in terms of network load and billing. In this work we discuss the opportunity to take advantage of vehicle-to-vehicle (V2V) in addition to V2I communications to reduce the amount of data to be transmitted from vehicles to a remote control center, and thus also to reduce the resulting costs for transmissions over the cellular networks. Having in mind to allow a first understanding of the achievable advantages, we propose a simple mathematical model through which we discuss how many vehicles are necessary to guarantee an useful V2V communication and which are the advantages in terms of network load and, consequently, costs reductions for the V2I network.

Relay assisted communications exploit cooperative diversity to efficiently extend area coverage or improve the performance in wireless channels. We propose a mathematical framework to analyze the frame error probability (FEP) at the destination depending on distributed coding, nodes spatial distribution, and power allocation among source and relay nodes. We evaluate the impact of cooperative links characterization on the overall FEP at the destination by considering simple approximations on the link FEP which depend on the signal-to-noise ratio and diversity. We consider a number of power allocation techniques such as uniform, ideal power control, outage-optimal, and FEP-optimal. Results are given for a case study in which pragmatic space-time codes are employed as distributed coding technique. Analytical results are confirmed by simulations that are given to serve as a benchmark for the considered cases. The framework enables the system designer to allocate power and individuate the best relay position to minimize the FEP.

Real time traffic information systems represent a growing sector of the wireless communication industries. To provide traffic information to drivers in a short term, cellular systems represent the answer: on the one hand many vehicles are equipped with global positioning system (GPS) navigators integrating cellular devices; on the other a large percentage of people has smart phones integrating advanced positioning systems. In this paper we aim at evaluating the feasibility of real time traffic information transmission to drivers by exploiting the universal mobile telecommunication system (UMTS) as the enabling technology. In particular, we compare the performance in the downlink of a urban scenario of the UMTS adopted in unicast and multicast mode, in terms of service feasibility and impact on the capacity left for other services. Results, performed through a simulation platform integrating a vehicular simulator tool together with a UMTS network simulator, will show which between unicast and multicast has to be preferred as a function of the considered environment.

Link adaptation (LA) has been demonstrated to be a very effective technique to improve transmission reliability in wireless communication systems subject to fading channel fluctuations. Due to the diffusion in commercial systems, LA techniques should take into account realistic channel models, low complexity algorithms, and application requirements. In this work, after analyzing the adaptive modulation and coding (AMC) performance for progressive images transmission, we propose a modified AMC technique that jointly takes into account both the channel variations and the progressive nature of the encoded bitstream. Since different priorities are assigned to the bits by the source encoder, an unequal error protection AMC method, that enhances transmission reliability for high priority bits, is necessary. Rather than increasing the complexity of the channel coding and modulation techniques, we adopt classical AMC methods optimizing the thresholds for the selection of opportunist modulation and coding schemes. The results show that the proposed technique is robust even with non-ideal channel state information.

The high flexibility of ad hoc wireless networks plays an important role in the design of future wireless generation. In this work, we consider an ad hoc network with nodes communicating the one with each other using multi-hop. Nodes use signal level power control to adjust the amount of transmitted power. The objective of this work is to quantity the amount of interference generated in the network as a function of the relay selection scheme considered. The effectiveness of the power control in reducing the level of interference is also investigated.

Intelligent transportation systems (ITS) make use of wireless communication technologies to provide traffic efficiency and road safety without altering the existing road infrastructure. To really impact on traffic management, ITS should act in real-time, requiring updated traffic information; hence, the collection of small amounts of information frequently transmitted from a high number of vehicles is needed. Cellular systems represent the most suitable technological solution to achieve this service, since they do not require any further installation of network infrastructures. However, they were designed for different applications: voice, web browsing or e-mailing. In this paper we aim at discussing the feasibility of frequent acquisition of small amount of data from vehicles through the universal mobile telecommunication system (UMTS), and at investigating its impact on the services already provided by the network. Numerical results are obtained by means of simulations, paying particular attention to realistic scenarios, both in terms of wireless systems and users mobility.

Efficient mobility management is an issue of vast economic importance for its consequences on urban and suburban mobility. In this context, telecommunications are gaining a key role, allowing to increase people safety, traffic efficiency, and travel comfort. To investigate the telecommunication systems behavior in new infomobility scenarios, advanced simulations tools are needed jointly taking into account realistic road traffic mobility and telecommunication networks protocols in all their aspects. In this paper we discuss the architecture of a complex and complete simulation platform we are developing on the behalf of the Italian project PEGASUS: the choice of traffic simulators, the network simulation and their interface will be presented and described.

Equalization techniques are considered in multi carrier-code division multiple access (MC-CDMA) systems to efficiently combine subcarriers contribution and improve the performance. In this paper we analytically investigate a combined equalization technique which consists in performing both pre- equalization at the transmitter and post-equalization at the receiver, by exploiting channel knowledge at both sides. To keep the framework as much general as possible, a parametric partial combining (PC) technique is considered. The analytical framework proposed allows the derivation of the bit error probability in correlated block fading channels and its dependence on the number of subcarriers, the number of active users, the mean signal-to-noise ratio (SNR) averaged over small-scale fading and, above all, the PC parameters, thus allowing the derivation of optimal equalization technique depending on fading levels.

Multi carrier code-division multiple access (MC-CDMA) is considered for beyond third generation wireless systems for its effectiveness in the presence of both multipath fading and interference. This paper analyzes MC-CDMA systems adopting an adaptive detection technique based on threshold orthogonality restoring combining (TORC). The mathematical framework here developed allows the evaluation of both the bit error probability and the bit error outage in downlink with perfect and imperfect channel state information and the derivation of the TORC threshold that optimizes the performance. The optimal threshold is analytically derived as a function of the number of subcarriers, the number of active users, and the mean signal-to-noise ratio. This enables an adaptive variation of the threshold following slow processes fluctuations. Numerical results show very good performance of TORC with optimal threshold comparing with others combining techniques with perfect and imperfect channel estimation. Results are shown both in uncorrelated Rayleigh fading as well as in time and frequency correlated fading channels.

In this paper we analytically evaluate the downlink performance of a multi-carrier code division multiple access (MC-CDMA) system by employing partial combining when multiple antennas at the transmitter or at the receiver are considered. It is known that for single reception/transmission, the partial combining technique depends on a parameter which can be optimized as a function of the number of subcarrier, the number of active users and the SNR improving the performance with respect to other classical techniques (such as maximal ratio combining, equal gain combining, or orthogonality restoring combining). In this paper we extend the analysis considering also multiple antennas aiming at showing how the spatial diversity affects the performance as a function of the partial combining parameter.

Abstract This paper investigates the impact of diversity reception on the performance of Bluetooth (BT) packet transmission in wireless channels with fast fading and shadowing and in the presence of IEEE802.11g interference. In particular, selection diversity (SD) technique is considered and the adoption of this technique results in a coverage extension evaluated in the paper. We first derive a tight parametric exponential approximation for the instantaneous bit error probability (BEP) in additive white Gaussian noise (AWGN); then, from this expression, we derive the mean block error probability (BLEP) in Ricean fading channel by adopting a simple SD scheme. The analysis is then extended to the evaluation of the mean packet error probability (PEP) and the coverage probability (Pcov). In particular, the impact of the diversity order on the BLEP, PEP, andPcovis shown. Copyright © 2007 John Wiley & Sons, Ltd.

This paper addresses the performance evaluation of multi-carrier code division multiple access systems both at physical and TCP levels. A partial equalization technique improving the performance at physical layer in the presence of interference is investigated and its impact on the performance at upper layer is studied. The results are obtained through an integrated simulation platform carefully reproducing all main aspects affecting the quality of service perceived by the final user. Works of this nature enable a deep investigation of the real gain perceived by the user provided by proper signal processing techniques at the physical level.

In this work the performances of a multi-carrier code division multiple access (MC-CDMA) system are analytically evaluated when a threshold orthogonality restoring combining (TORC) detector is adopted at the receiver of the downlink and not perfect channel state information (CSI) is provided. The analytical framework here proposed allows the derivation of the bit error probability (BEP) expression and its dependence on the number of sub-carriers, the number of active users, the mean signal-to-noise ratio (SNR) averaged over fast fading, the threshold of the detector and the variance of the channel estimation errors. Moreover, the dependence of the threshold on the channel estimation error is evaluated, providing the optimum value of the threshold minimizing the BEP as a function of the channel estimation error variance.

This paper addresses the performance evaluation of multi-carrier code division multiple access systems. A partial equalization technique depending on a parameter adapted to different conditions such as the number of sub-carriers, the number of active users and the mean signal-to-noise ratio is evaluated for the down-link. We analytically derive the performance of this system and the value of the equalization parameter that maximizes the performance. The partial equalization technique is shown to have the same complexity of the well known maximal ratio combining, equal gain combining and orthogonality restoring combining techniques, with significative performance improvement. Analytical results are compared with simulations showing a perfect agreement

In this work we propose an analytical framework aiming at studying the coexistence issue between Bluetooth (BT) and IEEE802.11g in fading channels. With the goal to improve the BT performance in the presence of interference, we consider a non coherent selection diversity (SD) scheme at the receiver side. In fact, due to its simplicity, the SD scheme is fully compliant with the low-cost requirement of BT equipped devices. Through the analysis, we derive the BT performance in terms of packet error probability averaged over Ricean fading when IEEE802.11g acts as interferer, taking into account all physical and medium access control (MAC) aspects. Results show the performance improvement and the reduction of the minimum coexistence distance due to the adoption of the simple SD receiving scheme

The paper address the coexistence of Bluetooth (BT) and IEEE802.11g systems. The interference on BT is analytically evaluated as well as the performance when diversity reception in Ricean fading is considered. We firstly derive the expression of the mean block error probability in the presence of interference, then we extend the analysis to the mean packet error probability and to the coexistence distance. Due to multiple receiving antennas, results show the not negligible performance improvement and the reduction of the minimum coexistence distance.

The work deals with the impact evaluation of an intelligent transportation system (ITS) based on the GPRS (general packet radio service) technology to alert vehicles approaching an accident. The last ten years saw an unexpected increasing of wireless communication technologies, first for circuit switching services, then also for packet switching applications. This kind of technologies can now be used not only for communication issues. Here we show the application of the GPRS wireless technology to ITS in a realistic scenario to promptly alert vehicles approaching difficult and unexpected situations such as accidents and queues. The aim of this work is to show the validity of a GPRS radio system on board in order to provide warning services to vehicles near an imminent crash situation on a highway. The great advantage of the proposed solution is the adoption of the well known and spread GPRS infrastructure to improve safety on roads. Numerical results, obtained by means of a simulation tool implementing realistic traffic models, show the great improvement, in term of safety, derived by the use of an embedded alerting system

This paper investigates the impact of diversity reception techniques on the performance of Bluetooth (BT) packet transmission in fading channels. We firstly derive a tight parametric exponential approximation for the bit error probability in additive white Gaussian noise depending on GFSK modulation parameters according to the BT standard. Then, from this expression we derive the mean block error probability (BLEP) for DH packets transmission in Rayleigh fading channel by adopting different diversity reception techniques, such as selection diversity and maximal ratio combining (MRC). In particular, the impact of the diversity order and combining techniques on the BLEP is shown. For the MRC technique, we also obtain a tight bound on the BLEP. Furthermore, we extend the results for MRC to Nakagami-m fading and we obtain the parameters of exponential approximation for a general GFSK modulation, although out of BT standard, showing their impact on both the performance and spectrum.

The performance in terms of the mean packet error probability (PEP) in a Rayleigh fading channel with thermal noise is analytically derived for a Bluetooth transmission interfered by IEEE 802.11b. The methodology proposed carefully takes PHY as well MAC aspects into account. Simulations are used to verify methodology assumptions. Moreover, we derive the coexistence domain, in terms of relative distances between the two systems, for a fixed quality of service, i.e., a target mean PEP.