Exploiting an Optimal Delay-Collision Tradeoff in CSMA-Based High-Dense Wireless Systems

Abstract : A novel carrier sense multiple access strategy with collision avoidance (CSMA/CA) balancing contention probability and channel access time is proposed. The approach can be applied to any context where the computational simplicity of the MAC must be preferred to the complexity of the channel access strategy. Our MAC, called Delay-Collision CSMA (DC-CSMA), is a slotted nonpersistent CSMA/CA with nonuniform contention probability distribution, designed to reduce at the same time latency of contenders and preserve a high successful access probability. An utility function aiming at equalizing the effects of these two performance metrics is introduced, and the related theoretical properties and optimal distribution are derived. DC-CSMA is insensitive to the number of contenders and very robust with respect to contention window size, packet length, and impairments such as frame synchronization errors and hidden terminals, and it does not require any adaptive tuning to optimize its performance. Current technologies such as WSN, RFID, IoT devices can benefit from such a simple access technique. The numerical evaluation has been led out considering latency, successful probability and throughput, and DC-CSMA has been compared with other classical strategies such as CSMA with uniformly distributed contention probability, CSMA/p* and Sift distribution.
 EXISTING SYSTEM :
 ? We expect the provided information lead the researchers in academia and industry to understand the limitations of the existing works and promote a change of thinking for early adoption of energy harvesting techniques within the IoT paradigm. ? We extensively review the already existing energy-aware MAC protocols to develop a categorization that identifies the various dimensions of proposed MAC additions to enable the concurrent use of energy harvesting. ? We contribute with an analysis of the functionalities and characteristics of existing energy harvesters and their suitability for the wireless communication technologies in the IoT paradigm. ? There are numerous existing MAC protocols in the literature, where each of them has distinct benefits and drawbacks.
 DISADVANTAGE :
 ? To protect these transmissions, they employ a busytone signaling to prevent hidden terminal problem. ? Some studies have added some fields to the RTS/CTS mechanism to communicate with other nodes in the network by informing them of the chosen mode and transmission duration to prevent hidden and exposed terminal problems. ? This problem can be formulated as a multi-objective optimization to maximize rate and queue serving and minimize the delay of high priority traffic which are conflicting with each other. ? These proposed algorithms jointly consider both subcarrier and power allocation problems and aim to maximize certain sum utility for scheduling in OFDMA networks.
 PROPOSED SYSTEM :
 • The proposed energy harvesting MAC classification was built based on the adopted optimization techniques in designing the protocols, such as load balancing, contention reduction, or wake-up time awareness. • This method proposes a CSMA-based mechanism with two different approaches for ultra-low power networks. • The proposed energy model is designed based on the random nature of the channel access method, where due to the three aforementioned characteristics, the number of collisions and consequently re-transmissions are reduced. • However, in both subcategories, the missing energy-related parameter among the proposed MAC protocols is load balancing.
 ADVANTAGE :
 ? The protocol retains the performance of an underwater acoustic network with higher energy efficiency in half-duplex communications and efficiently increase the performance in full-duplex scenarios. ? However, the performance of carrier-sense multiple access with collision avoidance (CSMA/CA), the standardized medium access control (MAC) protocol for wireless local area networks (WLAN), degrades with increasing number of stations. ? In addition, adaptive selection of optimal CW size based on different measured criteria in the network has been shown to improve the performance of CSMA/CA. ? We introduced a distributed reservation mechanism for ECA, termed ECA-DR, based on which stations can collaboratively achieve higher network performance.

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