P-persistent Carrier Sense Multiple Access Research Articles

Content-Based Wake-Up for Top-k Query in Wireless Sensor Networks

This article proposes content-based wake-up control for top- k query in wireless sensor networks, where the sink attempts to collect information on top- k nodes or top- k values from sensor nodes employing wake-up receivers. The wake-up procedure is designed with a goal of waking up only the subset of nodes which have the relevant data observations to construct the desired top- k set. This prevents the sensors with less relevant data from waking up and wasting energy. Assuming p-persistent carrier sense multiple access (CSMA) as the medium access protocol, the proposed scheme is analyzed theoretically in terms of data collection delay and total energy consumption. The performance of the proposed wake-up control is examined over a wide variety of parameters with practical considerations and compared to the conventional identity (ID)-based wake-up (IDWu) such as unicast wake-up (UCWu) and broadcast wake-up (BCWu). The obtained numerical results show that the proposed CDCoWu outperforms IDWu in terms of data collection delay and energy consumption for the maximum ratio of top-data to number of sensor nodes ranging from 0.1 to 0.5 when the number of sensor nodes is equal to or more than 20.

Delay and Reliability Analysis of p-Persistent Carrier Sense Multiple Access for Multi-Event Industrial Wireless Sensor Networks

In industrial environments various events can concurrently occur and may require different quality of service (QoS) provision based on different priority levels. To reduce the chances of collision and to improve efficiency in multi-event occurrence, Carrier Sense Multiple Access (CSMA) is a preferable choice for Medium Access Control (MAC) protocols. However, it also increases the overall delay. In this paper, a Priority MAC protocol for Multi-Event industrial wireless sensor networks (PMME) is proposed. In PMME, use of different p values/sequences is proposed to enable multi-priority operation, which can be optimized to suit different operational classes within industrial applications including emergency, regulatory control, supervisory control, open-loop control, alerting and monitoring systems. In this work, novel mathematical model as well as simulations are presented to validate the accuracy and performance of the proposed protocol. Mathematical analysis shows that the proposed PMME can prioritize data packets effectively while ensuring ultra-reliable and low latency communications for high priority nodes. Simulations in Castalia verify that PMME with different p values/sequences notably reduces packet delay for all four priority classes. The PMME also returns a high packet success rate compared to other two well-known priority enabled MAC protocols, QoS aware energy-efficient (QAEE) and multi-priority based QoS (MPQ), in multi-event industrial wireless sensor networks.

H ∞ filtering for multi‐rate multi‐sensor systems with randomly occurring sensor saturations under the p ‐persistent CSMA protocol

In this study, the $H_{\infty }$H∞ filtering problem is studied for a class of discrete networked multi-rate multi-sensor systems with randomly occurring sensor saturations under the p-persistent carrier sense multiple access (CSMA) protocol. A set of mutually independent Bernoulli distributed white sequences is introduced to characterise the random occurrence of the sensor saturations. The p-persistent CSMA protocol is employed to decide which sensor is allowed to transmit its measurement to the filter at a certain time instant. By using the lifting technique, the multi-rate system is converted to a single-rate one for convenient analysis. The main purpose of the addressed problem is to design an $H_{\infty }$H∞ filter such that the filtering error dynamics is exponentially mean-square stable and the $H_{\infty }$H∞ performance requirement is satisfied simultaneously. Sufficient conditions are established on the existence of the desired $H_{\infty }$H∞ filters and the corresponding filter gains are then characterised by resorting to the feasibility of certain matrix inequalities. Finally, a numerical example is given to illustrate the effectiveness of the proposed filtering scheme.

Non-Uniform Time-Step Deep Q-Network for Carrier-Sense Multiple Access in Heterogeneous Wireless Networks

This paper investigates a new class of carrier-sense multiple access (CSMA) protocols that employ deep reinforcement learning (DRL) techniques, referred to as carrier-sense deep-reinforcement learning multiple access (CS-DLMA). The goal of CS-DLMA is to enable efficient and equitable spectrum sharing among a group of co-located heterogeneous wireless networks. Existing CSMA protocols, such as the medium access control (MAC) protocol of WiFi, are designed for a homogeneous network in which all nodes adopt the same protocol. Such protocols suffer from severe performance degradation in a heterogeneous environment where there are nodes adopting other MAC protocols. CS-DLMA aims to circumvent this problem by making use of DRL. In particular, this paper adopts α-fairness as the general objective of CS-DLMA. With α-fairness, CS-DLMA can achieve a range of different objectives (e.g., maximizing sum throughput, achieving proportional fairness, or achieving max-min fairness) when coexisting with other MACs by changing the value of α. A salient feature of CS-DLMA is that it can achieve these objectives without knowing the coexisting MACs through a learning process based on DRL. The underpinning DRL technique in CS-DLMA is deep Q-network (DQN). However, the conventional DQN algorithms are not suitable for CS-DLMA due to their uniform time-step assumption. In CSMA protocols, time steps are non-uniform in that the time duration required for carrier sensing is smaller than the duration of data transmission. This paper introduces a non-uniform time-step formulation of DQN to address this issue. Our simulation results show that CS-DLMA can achieve the general α-fairness objective when coexisting with TDMA, ALOHA, and WiFi protocols by adjusting its own transmission strategy. Interestingly, we also find that CS-DLMA is more Pareto efficient than other CSMA protocols, e.g., p-persistent CSMA, when coexisting with WiFi. Although this paper focuses on the use of our non-uniform time-step DQN formulation in wireless networking, we believe this new DQN formulation can also find use in other domains.

A multi-state Q-learning based CSMA MAC protocol for wireless networks

Due to the shared nature of wireless channels, competition among the nodes to access media is inevitable. P-persistent carrier sense multiple access (CSMA) is a medium access control scheme widely ...

Performance analysis of opportunistic CSMA schemes in cognitive radio networks

In this paper, we consider underlay cognitive radio (CR) networks where an amount of interference caused by secondary stations (STAs) has to be kept below a predefined level, which is called interference temperature. We propose opportunistic p-persistent carrier sense multiple access schemes for the CR networks, which opportunistically exploit wireless channel conditions in transmitting data to the secondary access point. We also devise an adaptive interference-level control technique to further improve quality-of-service of a primary network by limiting the excessive interference due to collisions among STAs. The performances of the proposed schemes are mathematically analyzed, and they are validated with extensive computer simulations. The simulation results show that the proposed schemes achieve near optimal throughput of the secondary network while they are backward-compatible to the conventional p-persistent CSMA scheme.

A study of a wire–wireless hybrid NoC architecture with an energy-proportional multicast scheme for energy efficiency

The efficiency of interconnect network-on-chip (NoC) design significantly affects the thermal and energy-consumption problems. The wireless interconnect NoC (WiNoC) design provides a promising NoC architecture for multicast in chip multiprocessor (CMP) as compared with fully wired NoC. However, wireless routers (WRs) cost a larger area size as well as larger energy consumption than wired routers do. In this paper, we study a 2-tier wire–wireless hybrid NoC (WHNoC) architecture in an (NS)-processing-element (PE) CMP where N PEs use wires to connect with a wireless-enabled hub forming a star topology subnet and S wireless-enabled hubs form a fully connected WiNoC, named sWHNoC. We first investigate the performance of slotted p-persistent carrier sense multiple access (CSMA) protocol on the fully connected WiNoC. To greatly reduce the energy consumption of WiNoC, we propose an energy-proportional multicast scheme (EMS) by using a power-gating (PG) technique to switch off non-member WRs during the period of multicast transmission. A comprehensive comparison of the star-ring WHNoC, the mesh-based WHNoC, and the proposed sWHNoC is studied. Detailed analyses of the energy consumption of sWHNoC are presented. The correctness of analysis is validated by using Orion 2.0 simulator. Based on our investigation, the sWHNoC with the slotted p-persistent CSMA and the EMS will significantly reduce the energy consumption as well as the transmission latency in CMP.

Delay analysis of carrier sense multiple access with collision resolution

To improve the efficiency of carrier sense multiple access (CSMA)-based medium access control (MAC) protocols, CSMA with collision resolution (CSMA/CR) has been proposed. In the CSMA/CR, a transmitting station can detect a collision by employing additional sensing after the start of a data transmission and then resolve the next collision that might occur by broadcasting a jam signal during a collision detection (CD) period. In this paper, we analyze the delay of a CSMA/CR based on a generic p-persistent CSMA model and obtain the minimum achievable delay of the CSMA/CR by finding the optimal length of the CD period according to the number of contending stations. Through this delay analysis, we also investigate the throughput-delay characteristics of the CSMA/CR protocol according to various parameters. Analysis and simulation results show that the CSMA/CR has a considerably lower delay and its throughput-delay characteristic is significantly improved than the conventional CSMA/CA and wireless CSMA/CD protocols.

Performance analysis of network coding‐based content distribution in vehicularad‐hocnetworks

The authors investigate the content distribution among the vehicles of a cluster in a vehicular ad-hoc network, exploiting network coding. The vehicles collaborate to disseminate the coded data packets, received from a roadside info-station based on IEEE 802.11 medium access control (MAC) protocol. Two types of network coding are considered: random linear network coding (RLNC) over a large finite field and random XORed network coding (RXNC). An analytical model is proposed to address the effect of random access MAC as well as the correlation among received coded packets on the performance of content distribution. First, a p-persistent carrier sense multiple access approximation for IEEE 802.11 MAC is adopted, to derive the expected amount of time necessary to deliver the whole information (a data file) to the vehicles, that is, content distribution delay, based on RLNC. Second, the content distribution delay for RXNC is investigated. In this respect, the authors determine the probability of a newly received packet to be innovative for RXNC and characterise the probability that all nodes succeed to retrieve the data file, that is, content delivery ratio. Finally, the success of content distribution process for erasure channels is assessed.

Toward a Coherent Theory of CSMA and Aloha

Aloha and Carrier Sense Multiple Access (CSMA) are two representative random-access protocols. Despite their simplicity in concept, the performance analysis of Aloha and CSMA networks has long been known as notoriously difficult. Numerous models and analytical approaches have been proposed in the past four decades. Yet how to integrate them into a coherent theory remains an open challenge. Toward this end, a unified analytical framework was recently proposed in , based on which a comprehensive study of throughput, delay and stability performance of Aloha networks was presented. In this paper, the framework is further extended to CSMA networks. The analysis shows that both CSMA and Aloha have the same bi-stable property, and the performance of both networks critically depends on the selection of backoff parameters. Different from Aloha, however, substantial gains can be achieved in CSMA networks by reducing the mini-slot length a and the collision-detection time x. The maximum throughput with CSMA is derived as an explicit function of a and x, and shown to be higher than that with Aloha if a <; e1/ϵ - 1≈0.445. With a small mini-slot length a, CSMA networks are also found to be more robust than Aloha networks thanks to larger stable regions of backoff parameters. To demonstrate how to properly tune the backoff parameters to stabilize the network, the complete stable region of the initial transmission probability q0 is characterized, and illustrated via the example of p-persistent CSMA with the cutoff phase K=0. The optimal values of q0 to maximize the network throughput and to minimize the first and second moments of access delay are also obtained, which shed important light on practical network control and optimization.

Throughput Upper-Bound of Slotted CSMA Systems with Unsaturated Finite Population

In this paper we propose a new Markovian model for p-persistent carrier sense multiple access (CSMA) systems with a finite population of unsaturated single-buffered terminals. Focused on the distribution of the number of backlogged terminals in the steady state, our model allows the optimal persistent probability p from the number of backlogged terminals, which enables us to determine the throughput upper-bound (or mean access delay lower-bound) of slotted CSMA systems. We compare the performance of slotted CSMA systems with binary exponential backoff (BEB) algorithm and with p-persistent protocol against the throughput upper-bound and examine the stability of these systems. We show how closely slotted CSMA systems with BEB algorithm or p-persistent protocol approaches the throughput upper-bound in accordance with the minimum contention window size or the persistent probability p. Further, we propose a generalized Bertsekas' (backoff) algorithm (GBA) based on backlog size estimation, which is a generalization of the existing algorithm proposed by Bertsekas, in order to achieve the throughout upper-bound. Our study shows that in slotted CSMA systems, the access fairness of BEB algorithm is worse than those of p-persistent protocol and GBA algorithm, while the BEB and GBA algorithms show throughput performance close to optimality.

Learning-based p-persistent CSMA for secondary users of cognitive radio networks

In this paper, we consider learning-based p-persistent carrier sense multiple access (CSMA) for cognitive radio secondary users (SUs) when the primary user (PU) operates with the conventional CSMA/CA scheme. The learning algorithms are applied to tune the value of p to balance the channel idle time and collision costs due to both the PU and the SUs sharing the same wireless channel. Our proposal comprises two steps: first, the Q-learning scheme is used to adjust the transmission probability p when the PU has imperfect sensing. Then, for the multiple SUs’ case, a mixed strategy access policy is executed to solve the fairness problem in media access control (MAC). Our proposed scheme can maximise the SUs’ throughput and ensure protection of the performance of the PU, as well.

Achieving service differentiation in IEEE 802.11e enhanced distributed channel access systems

The IEEE 802.11e standard allows for contention-based quality of service (QoS) provisioning using enhanced distributed channel access (EDCA). By tuning the contention parameters for EDCA, the system can adapt to changes in the network scenario. The benefits of this adaptation include the ability to maximise the system capacity while also achieving the service differentiation necessary to provide QoS. The use of fixed sized contention windows is one simple and effective way to improve EDCA performance and this can be modelled as p-persistent carrier-sense multiple access (CSMA). In this study a straightforward throughput and delay analysis is provided for p-persistent CSMA that can be easily applied to an EDCA system within the rules of the current 802.11 standard. Several versions of the analysis are provided to show how further parameters of EDCA can also be included and their effects on system performance are shown. These further parameters include transmission opportunities, internal collision resolution, AIFS differentiation and retry limits. Any number and combination of these further parameters can be included at the same time making this new form of analysis extremely flexible as well as accurate to model a wide variety of EDCA system scenarios.

Average Channel Utilization of CSMA With Geometric Distribution Under Varying Workload

Performance analysis of fixed-size contention window carrier sense multiple-access (CSMA) protocol with geometric distribution for slot selection probability is addressed in the paper. This MAC scheme, called Sift, was initially proposed for large-scale event-driven wireless sensor networks. The goal of the present paper is to evaluate the standard performance measures (throughput, protocol capacity, collision rate, and mean access delay) for geometrically distributed CSMA both in the context of data-centric dense sensor networks and node-centric industrial automation systems. The analytical approach based on the stochastic analysis has been applied. To demonstrate how the protocol is able to cope with bursty traffic, the average throughput defined over a specified workload range has been introduced and examined. Using the average throughput as the performance criterion, the geometric CSMA has been compared to conventional CSMA schemes with uniform distribution. The latter are represented by the classical p-persistent CSMA and the predictive p-persistent CSMA used in LonWorks control networks. It is shown that G-CSMA is overload-tolerant event-driven MAC protocol since the average throughput may be kept on high level in wide range of workload if the shape of geometric distribution is well chosen.

Throughput maximization by utilizing multi-user diversity in slow-fading random access channels

In slow-fading uplink channels, carrier-sense multiple-access (CSMA) has been a popular random-access method, although it can have increased the throughput by using channel state information (CSI) acquired from a downlink training signal and electromagnetic reciprocity. To improve the throughput by using the CSI, this paper presents a random- access scheme that achieves multi-user diversity, called opportunistic p-persistent CSMA (OpCSMA). A user using OpCSMA sends a packet in a slot if the user's CSI exceeds the threshold assigned to the slot. The thresholds diminish with time to prioritize users having good CSI, while being designed to maintain the same persistency as the conventional CSMA, thus enabling backward compatibility. OpCSMA is mathematically shown to significantly increase the throughput compared with conventional CSMA, when the infinite-user model is used to model the variation of the number of users. As the expected number of users increases, the expected sum-rate of the OpCSMA approaches that using a centralized scheduler, which is the theoretical upper bound.