Throughput-Delay Tradeoff in Coupled Queues in Wireless Networks Priority and Concurrent Transmissions Regimes
Abstract : This paper investigates the performance of a wireless network that consists of two pairs of transmitter-receiver sharing the same channel, modeled using two coupled queues. In this analysis, we use the power metric P , defined as the ratio of throughput and mean delay, to understand the compromise between these two metrics. We show that, when the users’ transmit power levels are adjusted to maximize P , two transmission regimes emerge. When the coupling degree between the queues is strong, but the traffic is not heavy, there will be plenty of opportunities for non-concurrent transmissions. Our analysis shows that, in this case, the best strategy is to prioritize one user over the other through appropriate transmit powers adjustment and to use the highest modulation order available. On the other hand, for heavy traffic, none of the users should be prioritized, and there is an optimum combination of robust modulation orders and transmit power ratio to achieve the best performance.
? When a large number of M2M devices attempts to access the PRACH, an outage condition may occur; furthermore, traffic prioritization is regulated only through age-based power ramping, which drives the network even faster towards the outage condition.
? In this article, we describe an overlay network that allows a massive number of M2M devices to coexist with H2H traffic and access the network without going through the full LTE handshake.
? The proposed architecture used the RTS/CTS mechanism for accessing the medium in the WLAN, which caused overload in the network and coexistence issues.
? Networks that support M2M traffic must provide broad coverage, but also message reliability and limited delay.
? To protect these transmissions, they employ a busytone signaling to prevent hidden terminal problem.
? Bidirectional full-duplex mode can mitigate hidden node problem since STAs around the transmitter and receiver listen to their transmissions and refrain to transmit simultaneously.
? 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.
• It was proposed in that LTE supports reliable data transmission with high data rates for real-time health messages over large coverage areas.
• An overlay network for M2M traffic was proposed that dedicates a portion of PRACH resources to M2M traffic.
• The super frame structure of the proposed Priority-based Machine-to-Machine (PM2M) overlay network.
• A different scheme has been recently proposed that tries to resolve collisions and, presumably, improve performance by reassigning a subset of available preambles to calls that failed an access attempt.
• The base station can apply a suitable polling scheme (also known as pull-based scheme) to differentiate between UEs.
? We develop innovative access mechanisms, scheduling techniques, and architectures, and with simulations, measure the performance of networks working with these protocols based on the popular metrics of throughput, delay, and jitter among others.
? However, in dense scenarios, performance of EDCA severely degrades with increasing number of contenders and resultant collisions.
? 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.
? These criteria include access mechanism, number of activated FD modes, network type, traffic type, inter-symbol interference (ISI) consideration, key features, and performance metrics to evaluate their work.
|