Density Of Successful Transmissions Research Articles

Stochastic Geometry Analysis of Individual Carrier Sense Threshold Adaptation in IEEE 802.11ax WLANs

This paper discusses the impact of spatial reuse and carrier sense threshold (CST) optimization on the performance of wireless local area networks using stochastic geometry analysis. The adjustment of the CST is a promising approach to improve spatial reuse, and has been proposed for the IEEE 802.11ax standard. Considering the situation where each access point (AP) individually adjusts its CST based on the individual received power, this paper derives the probability of transmission success and the density of successful transmissions (DST). The evaluation results of these metrics reveal that the optimal setting is to increase the CST linearly (in terms of dB) with respect to the average received signal power. Because the maximization of the DST causes unfairness from the viewpoint of success of transmission, the maximization of the product of the transmission success probabilities is proposed to improve the performance of the entire system and restrain unfairness. Using the trend of the optimal CST function, the impact of the density of APs on the optimal CST function is determined. Moreover, individual CST adjustment is found to improve spatial reuse compared with identical adjustment, i.e., setting the CST of all APs to an identical value.

On The Modeling and Analysis of Uplink and Downlink IEEE 802.11ax Wi-Fi With LTE in Unlicensed Spectrum

The growing demand on data to enhance the user experience has motivated research toward increasing the efficiency of spectrum utilization by extending cellular technology, such as LTE, toward unlicensed bands. In order to study the fair coexistence of LTE and Wi-Fi, we consider the IEEE 802.11ax Wi-Fi standard, where we use stochastic geometry to model and analyze the coexistence of LTE with simultaneous uplink and downlink IEEE 802.11ax transmissions. Mainly, we consider LTE with continuous transmissions (no protocol change), LTE with discontinuous transmissions (LTE-U), and licensed-assisted access (LAA) coexistence mechanisms. In addition, we focus on single unlicensed frequency band transmissions, where the locations of Wi-Fi access points, Wi-Fi stations (users), and LTE eNodeBs (eNBs) are modeled as three independent homogeneous Poisson point processes. Then, we derive analytical expressions for a set of performance metrics, which are the medium access probability, signal-to-interference-plus-noise ratio coverage probability, density of successful transmissions, and Shannon throughput probability for both uplink and downlink of IEEE 802.11ax in addition to LTE. Our analysis quantifies both single-user and multi-user operation modes of the IEEE802.11ax and show that LTE-U or LAA can be a good neighbor for IEEE 802.11ax for different traffic types.

Transmission capacity analysis for linear VANET under physical model

In this study, the transmission capacity of VANETs in a highway scenario is analysed on the basis of a 1D line model and the carrier sense multiple access with collision avoidance (CSMA/CA) protocol. We describe the CSMA/CA protocol used in IEEE802.11p from the perspective of the geometric relationship amongst simultaneous transmitters. The desired channel and interfering channels are assumed to experience the same amount of path-loss and Rayleigh fading. On the basis of the proposed model, we analyse the attempted transmission probability of each road segment and the maximum intensity of active transmitters, including their theoretical values. Then, we employ the physical model to obtain the outage probability and derive the upper bound of the transmission capacity of a VANET, which is defined as the average spatial density of successful transmissions in the network. Simulation results indicate that the theoretical value offers a good bound on network capacity.

Modeling and Analyzing the Coexistence of Wi-Fi and LTE in Unlicensed Spectrum

We leverage stochastic geometry to characterize key performance metrics for neighboring Wi-Fi and LTE networks in unlicensed spectrum. Our analysis focuses on a single unlicensed frequency band, where the locations for the Wi-Fi access points and LTE eNodeBs are modeled as two independent homogeneous Poisson point processes. Three LTE coexistence mechanisms are investigated: 1) LTE with continuous transmission and no protocol modifications; 2) LTE with discontinuous transmission; and 3) LTE with listen-before-talk and random back-off. For each scenario, we derive the medium access probability, the signal-to-interference-plus-noise ratio coverage probability, the density of successful transmissions (DST), and the rate coverage probability for both Wi-Fi and LTE. Compared with the baseline scenario where one Wi-Fi network coexists with an additional Wi-Fi network, our results show that Wi-Fi performance is severely degraded when LTE transmits continuously. However, LTE is able to improve the DST and rate coverage probability of Wi-Fi while maintaining acceptable data rate performance when it adopts one or more of the following coexistence features: a shorter transmission duty cycle, lower channel access priority, or more sensitive clear channel assessment thresholds.