Traffic Class Prioritization-Based Slotted-CSMA/CA for IEEE 802.15.4 MAC in Intra-WBANs

Abstract

This paper proposes an improved Traffic Class Prioritization based Carrier Sense Multiple Access/Collision Avoidance (TCP-CSMA/CA) scheme for prioritized channel access to heterogenous-natured Bio-Medical Sensor Nodes (BMSNs) for IEEE 802.15.4 Medium Access Control (MAC) in intra-Wireless Body Area Networks (WBANs). The main advantage of the scheme is to provide prioritized channel access to heterogeneous-natured BMSNs of different traffic classes with reduced packet delivery delay, packet loss, and energy consumption, and improved throughput and packet delivery ratio (PDR). The prioritized channel access is achieved by assigning a distinct, minimized and prioritized backoff period range to each traffic class in every backoff during contention. In TCP-CSMA/CA, the BMSNs are distributed among four traffic classes based on the existing patient’s data classification. The Backoff Exponent (BE) starts from 1 to remove the repetition of the backoff period range in the third, fourth, and fifth backoffs. Five moderately designed backoff period ranges are proposed to assign a distinct, minimized, and prioritized backoff period range to each traffic class in every backoff during contention. A comprehensive verification using NS-2 was carried out to determine the performance of the TCP-CSMA/CA in terms of packet delivery delay, throughput, PDR, packet loss ratio (PLR) and energy consumption. The results prove that the proposed TCP-CSMA/CA scheme performs better than the IEEE 802.15.4 based PLA-MAC, eMC-MAC, and PG-MAC as it achieves a 47% decrease in the packet delivery delay and a 63% increase in the PDR.

Optimized backoff scheme for prioritized data in wireless sensor networks: A class of service approach

“…The IEEE 802.15.4 standard provides no platform to address data heterogeneity or data priority [9,12]. One of the crucial operational requirements of WSN is to handle data of different heterogeneity like real-time and non-real-time data.…”

“…The timing operation of an ongoing transaction must elapse before a next queued node begins its transaction. A unit BP is a constant given as aUnitBackoffPeriod = 20 Symbols equivalent to 0.32 millisecond (or 320μs), subsequently equivalent to 80 bits [9,24]. This is the smallest possible time a node can wait before Clear Channel Assessment (CCA) [24,25] is performed.…”

“…TCP-CSMA/CA was proposed by Farhan Masud et al in their work [9]. Nodes/traffic are classified and prioritized in the order of data importance.…”

“…slotted beacon-enabled mode [9,24]. In this mode, nodes randomly select BP or waiting time from the range of computed backoff time-slots using Eq 1, where 2 BE −1 is known as the BEB algorithm.…”

“…Contiki OS provides an efficient simulation environment for WSN with detailed statistical parameters. The Unit Disk Graph Medium (UDGM), with distance loss propagation model, was adopted with Constant Bit Rate (CBR) traffic model which is most suitable for resource-constrained devices generating data at a constant rate [20,29] with maximum frame size set to 127 bytes, which include 25 bytes of MAC Header and 102 bytes of payload [9,17] operating within the standard operational carrier frequency of 2.4 GHz and channel data rate of 250 kbps [4,9] (see Table 5).…”