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Periodic packet transmission in fading channel is an important issue in wireless networks, where the nodes can save energy, as it is powered by batteries. In mobile radio communication system, communication takes place over time-varying channels. This time variation is called as fading. Fading is the direct result of multi-path propagation where radio waves propagate along different paths before arriving...
The paper describes the transmission of BPSK signals in an OFDM system with 64-point IFFT at transmitter and FFT at receiver. The channel over which transmission will take place is ISI Rayleigh fading channel given by 2 tap channel model with path delay [0, 0.5] μs. The sampling frequency of OFDM is to be kept at 20MHz. Cyclic prefix for OFDM is calculated for improving bandwidth efficiency of the...
We consider the problem of energy-efficient point-to-point transmission of delay-sensitive data (e.g. multimedia data) over a fading channel. We propose a rigorous and unified framework for simultaneously utilizing both physical-layer centric and system-level techniques to minimize energy consumption, under delay constraints, in the presence of stochastic and unknown traffic and channel conditions...
Opportunistic Dynamic Spectrum Access (DSA) systems are emerging as a key to enable the Department of Defense (DoD) to meet its technology requirements for access to the electromagnetic spectrum. One of the main goals of DSA is to protect incumbent spectrum users from interference that could be caused by DSA emitters. One of the ways to accomplish this is through spectrum sensing as means to enable...
In this paper, we propose to use the Discrete-Time Rake receiver for Cooperative DS-CDMA systems. We compare the Bit Error Rate (BER) performance of the Continuous Time, Discrete Time and Decorrelating Discrete Time Rake receivers (CTR, DTR, DDTR) using Decode and Forward (DF) relaying. The former receiver is the most used and consists in combining the output of correlators locked on the most significant...
With the extensive deployment of 802.11 wireless local area networks (WLANs) and the need for better quality of service (QoS), the 802.11e MAC with service differentiation was developed. Analysing the effect of fading, shadowing and near-far effect on the performance of 802.11 is a fundamental consideration in practical situations since the wireless channels are errorprone.This paper develops a p-persistent...
This paper examines the capacity of a time division duplex (TDD) multiple input single output (MISO) beamforming system with channel estimation error and delay over the time varying fading channel. In TDD system, the base station estimates the channel state information (CSI) at transmitter based on uplink pilots and then uses it to generate the beamforming vector in the downlink transmission. Because...
This paper investigates the downlink system level performance for Layer-3 (L3) and Layer-1 (L1) relays with orthogonal frequency division multiple access (OFDMA) used in LTE-Advanced. Various practical factors are taken into account in the evaluations such as the processing delay and upper-bound of the amplifier gain of the L1 relay, capacity limitation of the backhaul channels, and empty buffer status...
In this paper, we introduce several technologies to adapt orthogonal frequency division multiple access (OFDMA) scheme to satellite environments. Maximizing the commonalities with the terrestrial system is one of the most important factors for cost-effective service delivery, which will finally bring successful deployment of the system. For this purpose, we adopt an orthogonal frequency division multiplexing...
In this paper we present parametrization for pathloss regarding the wideband car-to-car channel at 5.7 GHz. Furthermore, we investigate the power decay of delay-resolved multipath components, categorized in LOS and NLOS paths, and discuss the results. The results show relatively high pathloss exponents and a strong dependency of the exponent on the LOS path, which carries the main part of signal power...
Coordination between two or more multiple access channel (MAC) receivers can enlarge the achievable rate region of the whole system. This paper focuses on coordination by sharing the codebooks of the users between the receivers of MACs. We first define the achievable rate region of the time invariant multiple coordinated MAC (MCMAC) and subsequently derive its achievable rate region. We later express...
Multi-site measurements for urban macro cells at 2.66 GHz are performed with three base stations and one mobile station. In order to analyze the correlation properties of large scale parameters, we split up the routes into subsets, where it can be assumed that wide-sense stationarity (WSS) applies. The autocorrelation distance and correlation properties of large scale parameters for each link are...
Inside a tunnel, electromagnetic wave propagation differs strongly from the well understood "open-air" situation. The characterization of the tunnel environment is crucial for deploying vehicular communication systems. In this paper we evaluate vehicle-to-vehicle (V2V) radio channel measurements inside a tunnel. We estimate the time-varying root mean square (rms) delay and Doppler spreads,...
In this work an opportunistic scheduling scheme is presented and analyzed for a multiuser system. The objective of the proposed scheme is to minimize the system transmit energy in the presence of a hard deadline delay constraint for the individual packets. In the large system limit, the scheme is modeled and analyzed in the scenario when arriving packets have associated deadlines which vary from packet...
Deterministic network calculus (DNC) is not suitable for deriving performance guarantees for wireless networks due to their inherently random behaviors. In this paper, we develop a method for Quality of Service (QoS) analysis of wireless channels subject to Rayleigh fading based on stochastic network calculus. We provide closed-form stochastic service curve for the Rayleigh fading channel. With this...
One of the key technologies introduced in LTE-Advanced in order to increase the capacity is carrier aggregation (CA). Based on this scheme, continuous and non-continuous sub-bands are aggregated in order to achieve larger bandwidth. Such a new technique introduces various challenges in both system aspect and the modeling of the wireless channel. In particular, the traditional channel models that was...
We consider an energy harvesting wireless system where data is stored in a data buffer and energy is harvested from various sources and stored in an energy buffer. The transmitter tries to minimize a delay criterion, e.g., average delay in the data buffer or probability of overflow, subject to the hard power constraints imposed by the available energy. We show that if the average rate of data arrival...
This paper presents the performance analysis of a realistic Smart Utility Network (SUN) system with low duty signaling design. The main focus of this paper is to evaluate the performance of the SUN system based on the specifications in an on-going industrial standardization activity, the IEEE 802.15.4g. For this purpose, a theoretical framework is constructed to model the transceiver with low duty...
In this paper, we consider a single-user secure data communication system. Data packets arriving at the transmitter are enqueued at a data queue to be transmitted to the receiver over a block fading channel, securely from an eavesdropper that listens to the transmitter over another independent block fading channel. We address two separate problems, both of which involve the maximization of a long-term...
The law of the time to transmit a packet from a node to its intended receiver, in a wireless network with randomly deployed, multiple-antennas equipped nodes, whose communication is impaired by fading and interference, is investigated. SINR-based coverage at the physical layer is assumed, and the useful signal strength is shaped through either cooperative or non-cooperative beamforming. In particular,...
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