At present, WLANs supporting broadband multimedia communication are being developed and standardized around the world. Standards include HIPERLAN/2, defined by ETSI BRAN, 802.11a, IEEE, HiSWANa MMAC. These systems provide channel adaptive data rates up to 54 Mb/s (in a 20 MHz spacing) in 5 GHz radio band. An overview of HIPERLAN/2 802.11a standards is presented together with software simulated physical layer performance results for each transmission modes. Furthermore, differences between...

A novel approach to provide unequal error protection (UEP) using rateless codes over erasure channels, named Expanding Window Fountain (EWF) codes, is developed and discussed. EWF use a windowing technique rather than weighted (non-uniform) selection of input symbols achieve UEP property. The introduces additional parameters in the code design, making it more general flexible approach. Furthermore, provides better performance scheme, which confirmed both theoretically experimentally.

We consider a cognitive radio system with one secondary user (SU) accessing multiple channels via periodic sensing and spectrum handoff. propose an optimal access mechanism such that the average energy cost of SU, which includes consumed by sensing, channel switching, data transmission, is minimized, whereas constraints on reliability throughput, delay transmission are satisfied. Optimality achieved jointly considering two fundamental tradeoffs involved in minimization, i.e.,...

Low delay and high reliability of safety broadcast messages are critical to future intelligent transport systems (ITS). The main objective this paper is propose a novel system model satisfy the latency requirements vehicle-to-vehicle (V2V) applications. Second, using proposed model, comprehensive performance evaluation conducted under different technologies (cellular IEEE 802.11p) for vehicle densities in rural urban scenarios based on realistic system-level simulator. further improved by...

At present, WLANs supporting broadband multimedia communications are being developed and deployed around the world. Standards include HIPERLAN/2 defined by ETSI BRAN 802.11 family IEEE. These systems provide channel adaptive data rates up to 54 Mb/s (in a 20 MHz spacing) over short ranges 200 m. The standard also specifies flexible radio access network that can be used with variety of core networks, including UMTS. It is likely will become an important complementary technology 3G cellular...

The feasibility of coexistence between radar and a communication system is investigated under log-normal shadowing conditions. A key element that enables sensing receiver to detect the presence prevent transmissions when interference may occur. Initial studies where each terminal does its own decision-making shows while bandsharing possible, stringent requirements, efficiency can be limited. Analytical simulation results illustrate cooperative leads an improved detection range, higher...

This paper explores the potential gain of joint diversity in both frequency domain and time which can be exploited to achieve spectral efficiency gains whilst simultaneously facilitating QoS/fairness an OFDMA system (particularly 3GPP Long Term Evolution (LTE)). The performance several time-frequency schedulers is investigated. Simulation results show that significantly superior compared a more conventional (only) proportional fair scheduler. schemes promising throughput while meeting...

This letter considers transmit precoding schemes based on the maximum signal-to-leakage-and-noise ratio (SLNR) in multiuser MIMO systems with single-antenna receivers. The closed-form solution of SLNR design is generally given form eigenvector associated to eigenvalue. In this letter, analytic expressions SLNR-based solutions and resulting are derived for a generic power allocation (GPA). shown be function user-allocated an arbitrary phase shift. Under equal (EPA), scheme equivalent minimum...

In this study, multi‐user (MU) underwater acoustic communication is investigated using massive multiple‐input multiple‐output (MIMO) orthogonal frequency division multiplexing (OFDM)‐based time space modulation (OTFS) systems. The performance of a 4‐user scenario evaluated over simulated 1 km vertically‐configured time‐varying channel (UAC) in terms bit error rate and maximum achievable rate. Considering 64‐QAM frequency‐domain pilot‐based estimation, it shown that the vehicles employing...

Radio access network (RAN) technologies continue to evolve, with Open RAN gaining the most recent momentum. In O-RAN specifications, intelligent controllers (RICs) are software-defined orchestration and automation functions for management of RAN. This article introduces principles machine learning (ML), in particular, reinforcement (RL) applications stack. Furthermore, we review state-of-the-art research wireless networks cast it onto framework hierarchy architecture. We provide a taxonomy...

Expectations and requirements for future wireless communication systems continue to grow evolve. Thus, recently, the third generation partnership project (3GPP) has considered long term evolution (LTE) of 3G - also known as super ensure its competitiveness in future. It is generally assumed that downlink new air interface would be OFDMA based some form hybrid ARQ (HARQ) might employed. This paper aims evaluate performance various HARQ schemes over currently proposed 3GPP LTE specification....

In this contribution, we consider design of distributed LT codes, i.e., independent rateless encodings multiple sources which communicate to a common relay, where relay is able combine incoming packets from the and forwards them receivers. We provide density evolution formulae for allow us formulate code problem prove equivalence performance codes with related parameters in asymptotic regime. Furthermore, demonstrate that allowing coding apparatus at both may advantageous only relay.

In this paper, an advanced site-specific image-based ray-tracing model is developed that enables multielement outdoor propagation analysis to be performed in dense urban environments. Sophisticated optimization techniques, such as preprocessing the environment database using object partitioning, visibility determination, diffraction image tree precalculation, and parallel processing are used improve run-time efficiency. Wideband multiple-input-multiple-output (MIMO) predictions (including...

This paper introduces a novel 128-element sub-6 GHz Massive MIMO (Multiple-Input Multiple-Output) testbed being developed by the University of Bristol in collaboration with National Instruments and Lund as part BIO (Bristol is Open) city testbed. Distributed systems avoid large single-piece antenna facets their associated windage problems also offer greater spatial diversity, but node synchronization phase alignment becomes more challenging. Simulated network performance co-located 3D...

This paper studies a WiFi indoor localisation technique based on using deep learning model and its transfer strategies. We take CSI packets collected via the standard channel sounding as training dataset verify CNN subsets in three experimental environments. achieve accuracy of 46.55 cm an ideal (6.5m × 2.5m) office with no obstacles, 58.30 102.8 sports hall (40 35m). Then, we evaluate ability proposed to different The results show that, for trained model, feature extraction layers can be...

In this paper channel estimation techniques for a mobile fourth generation coherent orthogonal frequency division multiplexing (OFDM) system are proposed. Coherent detection dictates that per-subband estimate of the response is generated each OFDM symbol. This achieved by inserting pilot symbols amongst data in modulation grid. With suitable interpolation, at all intermediate can be generated. A number methods with different patterns and interpolation examined range UTRA specified...

The demand for broadband mobile services continues to grow. Conventional high-speed solutions are based on wired-access technologies such as digital subscriber line (DSL). This type of solution is difficult deploy in remote rural areas, and furthermore it lacks support terminal mobility. Mobile wireless access (BWA) offers a flexible cost-effective these problems. In recent years the WiMax standard has emerged harmonise wide variety different BWA technologies. first version was IEEE...

Recently, the development and requirement for ultra-high data rate wireless communication applications has increased dramatically. The 60 GHz millimeter-wave technology is getting increasing attention, IEEE 802.11 Task Group AD making standardization efforts multi-gigabit communications on both physical (PHY) medium access control (MAC) layers. This paper presents a performance evaluation of PHY MAC layers 802.1 lad. Packet error throughput are presented different modes, theoretical analyzed...

This article presents a comprehensive review of the principles and characteristics 3D channel models. We propose framework for extension widely used 2D 3GPP/ ITU generic model. describe main components challenges newly proposed model motivations that lie behind them. models specify multipath elevation angles as well azimuth (or horizontal plane) angles. enables evaluation MIMO techniques such FD per user beamforming. also provide state-of-the-art on evolution The ends with discussion impact...

Recently there has been strong interest in extending MEMO signal processing from the azimuth dimension to include elevation plane. However, many channel models, such as 3GPP/ITU model, focus on two dimensional propagation, i.e. propagation plane only. The assumption of 2D may lead inaccurate estimation capacity, spatial correlation and system level performance environments where distribution angles is significant. In this paper, we implement a 3D extension model by adding angle statistics...

Orthogonal Time Frequency Space (OTFS) is a recently proposed modulation scheme for doubly-dispersive channels in which symbol multiplexing and processing performed the Doppler-delay domain, rather than conventional time-frequency domain. In this paper, performance of OTFS compared to orthogonal frequency division (OFDM) line-of-sight mobility automotive channels. Ray launching used simulate channel two different dynamic 3D vehicle infrastructure transmission environments, using Kirchhoff...

This work focuses on the throughput analysis of IEEE 802.11 medium access control (MAC). In standard, main scheme is called distributed coordination function (DCF) and basis for other schemes, such as point (PCF) enhanced DCF (EDCF) new 802.11e MAC. Since MAC does not support quality service (QoS), currently working final draft an version known 802.11e. this QoS differentiations are supported. The delay performance DCF/PCF presented different packet lengths numbers users. Throughput...