IEEE 802.15.4

—In this paper, error correction is introduced to the Bluetooth Low Energy (BLE) and IEEE 802.15.4 standards by utilising data redundancy provided by Cyclic Redundancy Check (CRC) codes used by both protocols to detect erroneous packets. A scenario with an energy-constrained transmitter and a constraint-free infrastructure is assumed which enables additional signal processing at the receiving side, keeping the transmitter intact. CRC error correction is achieved using a novel approach of applying iterative decoding techniques. The proposed methods are evaluated based both on simulated and real packets. It is shown that by enabling CRC error correction, up to 2.5 dB of the SNR gain can be achieved, while up to 35% of real corrupted packets can be corrected, at no extra cost for the transmitter. This results in potential range extension and longer battery life caused by a reduced number of retransmissions.

This paper investigates the performance of high rate IEEE 802.15.4 UWB PHY schemes. Evaluation takes place over office, residential and outdoor IEEE channel models via Monte-Carlo simulation. Special attention is given to the highest rate (27.24 Mbps) scheme that suffers from intersymbol interference (ISI) over NLOS outdoor and residential channels. Optimum bit-to-symbol mapping (OBM), ISI cancellation and MLSE techniques are proposed and evaluated in conjunction with RAKE reception. Significant gains are attained with the proposed enhancements while keeping complexity low. On the other hand, the coverage range of high rate schemes is estimated for a given BEP. It is deduced that 27.24 Mbps and 6.81 Mbps schemes are well applicable to all LOS channels. However, the maximum allowable transmission power deteriorates range in NLOS cases. Overall, high rate schemes are shown to deserve more attention in the context of high rate sensor applications.

Zigbee technology has been developed for short range wireless sensor networks and it follows IEEE 802.15.4 standard. For such sensors, several considerations should be taken including; low data rate and less design complexity in order to achieve efficient performance considering to the transceiver systems. This research focuses on implementing a digital transceiver system for Zigbee sensor based on IEEE 802.15.4. The system is implemented using offset quadrature phase shift keying (OQPSK) modulation technique with half sine pulse-shaping method. Direct conversion scheme has been used in the design of Zigbee receiver in order to fulfill the requirements mentioned above. System performance is analyzed considering to BER when it encountered adaptive white Gaussian noise (AWGN), besides showing the effect of using direct sequence spread spectrum (DSSS) technique. 1. INTRODUCTION Due to the advances in wireless communications and electronics over the last few years, the development of networks of low-cost, low-power, and multi-functional sensors received an increasing attention. These sensors are small in size and able to sense, process data, and communicate with each other over an RF (radio frequency) channel. A sensor network is designed to detect events or phenomena, collect and process data, and transmit sensed information for the intended users [1], [2].These networks have the potential of interfacing the physical world with the virtual (computing) world in an unprecedented scale and provide practical usefulness in developing a large number of applications, including the protection of civil infrastructures [3], habitat monitoring, precision agriculture, toxic gas detection, supply chain management, and health care [4]. Zigbee is considered one of wireless sensor devices operates under IEEE 802.15.4 standard. This standard has been introduces by Zigbee Alliance [5]. Zigbee standard was created to address the market need for cost-effective, standard-based wireless networking solutions that support low data rates transceivers, low power consumption [6], security, and reliability through wireless personal area networks (WPANs) [7]. Zigbee technology can be worked within three various frequency bands according to the geographical coverage area. In Europe, 868-868.6 MHz (868 MHz) is used, in Northern America 902-928 MHz (915 MHz), while the 2.4 GHz is used all over the world, and it depends on unlicensed Industrial, Scientific and Medical(ISM) radio bands [8]. It is known that the wireless medium is influenced by real time conditions such as signals interference, doppler shift, and path loss; where these parameters have the effect of degrading wireless transmission performance [9]. Hence, it is quite important to provide a transceiver system that could be able

In this paper, we present a new concept of ZigBee backbone by utilizing ZigBee technology for the use of low-rate wireless medium-distance link. The backbone is mainly used for connecting sensor devices around the backbone location to the gateway device. Non-beacon enabled ZigBee operation mode is considered in this backbone with ring topology enhanced by dual-hop coverage setting. We present an analytical model to evaluate the performance of the backbone in term of its success transmission probability and suggest the optimal backbone configuration. The accuracy of the model is confirmed using computer-based simulation.

This paper describes the design, implementation, and testing of a wireless sensor and actuator network for monitoring the energy use of electric appliances in a home environment. The network includes energy measurement nodes and a central server, where the nodes read the energy use of connected appliance, and wirelessly report their readings to the central server for processing. The server displays the readings from
these nodes via a user visual interface in real time. Through this system, users can easily understand their
electricity usage patterns and adapt their behaviour to reduce their energy consumption and costs.
Moreover, users are able to remotely power on/off individual devices to actively control the power use of
certain appliances. The system allows for inexpensive monitoring of home energy use and illustrates a
practical way to control the energy consumption through user interaction.

IEEE 802.15.4-based devices networks known by the name of LR-WPAN (Low Rate Wireless Personal Area Network) are characterized by low computation, memory and storage space, and they do not possess an infrastructure. This makes them dynamic and easy to deploy, but in the other hand, this makes them very vulnerable to security issues, as they are low energy so they cant implement current security solutions, and they are deployed in non-secure environments that makes them susceptible to eavesdropping attacks. Most proposed solutions draw out the security of the bootstrapping and commissioning phases as the percentage of existing of an intruder in this time is very low. In this paper, we propose a security model for LR-WPANs based on symmetric cryptography, which takes into account securing the bootstrapping phase, with an analysis of the effectiveness of this proposal and the measures of its implementation.

This paper proposes an improvement for beacon enabled IEEE 802.15.4 medium access control (MAC) protocol for better energy consumption, reliability and synchronization among the sensors. First, we suggest an improved model over the existing beacon enabled IEEE 802.15.4. The modified IEEE 802.15.4 MAC protocol is modeled through a Markov chain using retry limits, acknowledgements and a new parameter namely `number of sleep slots'. Second, in beacon superframe structure there is an inactive period, which is used by sensors during sleep mode; the random sleep time for each sensor reduces the reliability of the network. We have proposed an optimized sleep time which divides the inactive period into number of slots in which the sensor utilizes a single slot in the sleep mode and then returns to the idle state. Third, sensors are synchronized by periodic transmission of beacon superframe from personal area network (PAN) coordinator. We have modified this by an adaptive synchronization method. We have simulated our suggested model in ns 2.34 to test the performance. The performance of our model is compared with the existing model for different performance metrics as reliability, data packet collision probability, data transmission failure probability and energy consumption of the sensors.