IEEE 802.15.4 is a standard used for low rate personal area networks (PANs). It offers device level connectivity in applications with limited ower and relaxed throughput requirements. Devices with IEEE 802.15.4 technology can be used in many potential applications, such as home networking, industry/environments monitoring, healthcare equipments, etc, due to its extremely low power features. Although the superframe beacons play the key role in synchronizing channel access in IEEE 802.15.4, they are sources for energy inefficiency. This research focuses on exploring how to optimize the beacons, and designing novel schemes to distribute the information that are supposed to be delivered to a subset of PAN devices. In this work, an acknowledgement based scheme is proposed to reduce the energy consumption in the distribution of guaranteed time slot (GTS) descriptors. Based on the observation that the superframe beacon frame has global impact on all PAN devices, an energy-efficient channel reservation scheme is presented to deliver the information (GTS descriptors and pending addresses). In addition, the problem of channel underutilization is studied in the contention free period. To address the problem, a new GTS allocation scheme is proposed to improve the bandwidth utilization.

Wireless Sensor Networks (WSN) are used in many applications, for example industrial applications, automatic control applications, monitoring applications, to name but a few. Although WSN can employ different standards in order to achieve short range wireless communication, the mainstream of the market is toadopt the low-power, low-rate IEEE 802.15.4 standard. However, this standard does not specify any block codes on the Physical layer (PHY) and the MAC sublayer. Reliability and energy efficiency are two important metrics used to evaluate the WSN performance. In order to enhance the reliability of the WSN performance, schemes such as Forward Error Correction (FEC) and HybridAutomatic Repeat-reQuest (HARQ) can be introduced on the PHY and MACsublayer when transmitting signals. However, this will reduce the energy efficiency of the WSN. In order to investigate what does affect the reliability and energy efficiency, this thesis has been conducted with the assistance of Matlab simulations, which simulate different transmission schemes proposed by the authors. Based on the simulations, both the reliability and energy efficiency can be evaluated and the results are illustrated for both metrics. The objective of this thesis is to determine a scheme that is able to meet these metric requirements.

IEEE 802.15.4 is a standard defined for wireless sensor network applications with limited power and relaxed throughput needs. The devices transmit data during two periods: Contention Access Period (CAP) by accessing the channel using CSMA/CA and Contention Free Period (CFP), which consists of Guaranteed Time Slots (GTS) allocated to individual devices by the network coordinator. The GTS is used by devices for cyclic data transmission and the coordinator can allocate GTS to a maximum of only seven devices. In this work, we have proposed two algorithms for an efficient GTS allocation. The first algorithm is focused on improving the bandwidth utilization of devices, while the second algorithm uses traffic arrival information of devices to allow sharing of GTS slots between more than seven devices. The proposed schemes were tested through simulations and the results show that the new GTS allocation schemes perform better than the original IEEE 802.15.4 standard.

This thesis will investigate the possibilities to wireless communicate within time critical applications with the radio protocol IEEE 802.15.4. IEEE 802.15.4 is a very quick protocol so the delays and jitter can be ignored in a small network. The thesis handles the question: Is it possible to split a CAN-bus and send the data via radio to the other side of the CAN-bus? The big problems with this are: • Will it be treated like a transparent link and not disturb the original functionality? • How does a system which is split up by radio treat new nodes on the bus? • What will be the maximum speed and the maximum utilization factor for the split up bus? • What new suitable protocols can be implemented on a higher level to get the split bus to work? This is modeled and discussed, real measurement from a radio link is used in the model to see if it’s possible. The radio communication will satisfy the demands from the company regarding their application. With an efficient error handling and a smart transmission protocol the application can be a very smart way of sending CAN-data via radio. / Denna rapport undersöker möjligheterna med att kommunicera trådlöst i tidskritiska applikationer med hjälp av radioprotokollet IEEE 802.15.4. IEEE 802.15.4 är ett väldigt snabbt protokoll så jitter och fördröjningen i sändningarna kan försummas för så små nätverk som tas upp i denna uppsats. Går det att bryta en CAN-buss och koppla in denna radiolänk så att den uppfattas som transparent? Många problem kommer att dyka upp om detta görs, några av dem är dessa: • Hur behandlar ett system nya noder som kopplas in om CAN-bussen är uppdelad? • Vilken är den maximala hastigheten och utnyttjandefaktor som kan uppnås av den delade CAN-bussen? • Måste ett överliggande protokoll användas för att sköta om datatrafiken mellan bussarna? Detta modelleras och diskuteras efter det att de uppmätta mätvärdena har samlats in och analyserats. Det som framkom var att det fungerar väldigt bra, data kommer fram i tid och felen i radiosändningarna är väldigt små. Med en väl genomtänkt felhantering och ett likaså genomtänkt omsändningsprotokoll kommer detta att fungera väldigt bra beroende på avstånd och antennval.

The main purpose of this thesis is to estimate the signal arrival time in low rate wireless personal area network systems. In a dense multipath environment, the generalized maximum-likelihood (GML) algorithm can be used for the time-of-arrival (TOA) estimation. Nevertheless, the GML algorithm is very time-consuming and usually takes a long period of time, and sometimes fails to converge. Hence, a simplified scheme that would improve the algorithm is investigated. In the simplified scheme, the search is executed in a sequential form. Two threshold parameters are determined for the stop condition in the algorithm. One threshold is on the arrival time of estimated path, while the other is on the fading amplitude of estimated path. The determination of thresholds can be based on the minimum error probability, which is defined as the sum of the false alarm probability and the missing probability. Root-mean-square error statistics are used to improve the thresholds setting. In this scheme, candidate pairs of thresholds are evaluated in each appropriate range. To solve the problem that the root-mean-square error value for each pair of thresholds is calculated, the simulated annealing is adopted for searching the best threshold pair. The problem that all possible solutions in a large range must be evaluated can be solved by simulated annealing. From the simulation results, it is seen that, while the signal-to-noise ratio is larger or equal to 4dB, the proposed scheme can achieve better performance than the root-mean-square error statistics scheme.

<p>This thesis will investigate the possibilities to wireless communicate within time critical applications with the radio protocol IEEE 802.15.4.</p><p>IEEE 802.15.4 is a very quick protocol so the delays and jitter can be ignored in a small network.</p><p>The thesis handles the question: Is it possible to split a CAN-bus and send the data via radio to the other side of the CAN-bus?</p><p>The big problems with this are:</p><p>• Will it be treated like a transparent link and not disturb the original functionality?</p><p>• How does a system which is split up by radio treat new nodes on the bus?</p><p>• What will be the maximum speed and the maximum utilization factor for the split up bus?</p><p>• What new suitable protocols can be implemented on a higher level to get the split bus to work?</p><p>This is modeled and discussed, real measurement from a radio link is used in the model to see if it’s possible.</p><p>The radio communication will satisfy the demands from the company regarding their application. With an efficient error handling and a smart transmission protocol the application can be a very smart way of sending CAN-data via radio.</p> / <p>Denna rapport undersöker möjligheterna med att kommunicera trådlöst i</p><p>tidskritiska applikationer med hjälp av radioprotokollet IEEE 802.15.4.</p><p>IEEE 802.15.4 är ett väldigt snabbt protokoll så jitter och fördröjningen i sändningarna kan försummas för så små nätverk som tas upp i denna uppsats.</p><p>Går det att bryta en CAN-buss och koppla in denna radiolänk så att den</p><p>uppfattas som transparent?</p><p>Många problem kommer att dyka upp om detta görs, några av dem är dessa:</p><p>• Hur behandlar ett system nya noder som kopplas in om CAN-bussen är uppdelad?</p><p>• Vilken är den maximala hastigheten och utnyttjandefaktor som kan uppnås av den delade CAN-bussen?</p><p>• Måste ett överliggande protokoll användas för att sköta om datatrafiken mellan bussarna?</p><p>Detta modelleras och diskuteras efter det att de uppmätta mätvärdena har samlats in och analyserats.</p><p>Det som framkom var att det fungerar väldigt bra, data kommer fram i tid och felen i radiosändningarna är väldigt små. Med en väl genomtänkt felhantering och ett likaså genomtänkt omsändningsprotokoll kommer detta att fungera väldigt bra beroende på avstånd och antennval.</p>

<p><!--st1\:*{behavior:url(#ieooui) } --><!--[endif]--> <!-- /* Font Definitions */ @font-face {font-family:Garamond; panose-1:2 2 4 4 3 3 1 1 8 3; mso-font-charset:0; mso-generic-font-family:roman; mso-font-pitch:variable; mso-font-signature:647 0 0 0 159 0;} /* Style Definitions */ p.MsoNormal, li.MsoNormal, div.MsoNormal {mso-style-parent:""; margin:0cm; margin-bottom:.0001pt; mso-pagination:widow-orphan; mso-layout-grid-align:none; punctuation-wrap:simple; text-autospace:none; font-size:12.0pt; mso-bidi-font-size:10.0pt; font-family:"Times New Roman"; mso-fareast-font-family:"Times New Roman"; mso-ansi-language:EN-GB; mso-fareast-language:EN-US;} @page Section1 {size:612.0pt 792.0pt; margin:70.85pt 70.85pt 70.85pt 70.85pt; mso-header-margin:36.0pt; mso-footer-margin:36.0pt; mso-paper-source:0;} div.Section1 {page:Section1;} --></p><p>To implement a utility wireless sensor network, investigation of different wireless protocols has been performed. The protocols are Bluetooth, Wi-Fi, IEEE 802.15.4 and Zigbee. Consecutively literature studies have made it comprehensible to understand the function of the protocols that are suitable for development of wireless sensor networks. The importance of low cost, low power, reliable and high-quality properties for long distances are significant. IEEE 802.15.4 and Zigbee protocol are proper to implement as a wireless sensor network.</p><p> </p><p>To reduce the human efforts in the configuration of the system, a comfortable method is implemented to facilitate the procedure. The applied method is based on an automatic configuration of the system. The configuration and the decision taking are implemented in the software. The system is designed to avoid interference to other wireless networks with the possibilities of reconfiguration.</p><p>A uniform hardware and software design with separate functions of the system decided by a subsequent command for configuration is preferable. This imposes an advantage that increases the flexible potential of the system when a uniform solution is implemented.</p><p> </p><p>To support the basic communication principles and control of the system, a buffer implementation has been introduced. The functionality of decision taking is distributed, configured by system commands from the host system. Detecting of system commands requires a properly operating buffer management. In consideration to the power consumption in reference to battery utilizations, the settings of RF-module and microcontroller have a powerful impact to reduce the power consumption. All possibilities of hibernates and avoidance of unnecessarily transmitting, should be deactivated to minimize the power consumption.</p><p> </p>

ITC/USA 2014 Conference Proceedings / The Fiftieth Annual International Telemetering Conference and Technical Exhibition / October 20-23, 2014 / Town and Country Resort & Convention Center, San Diego, CA / The wireless acquisition system LISA has been designed for mechanical phenomenon analysis onboard aircrafts. It has been in use for more than one year now. This paper describes the organization of this equipment and the experiences related by first users.

Zigbee is a relatively new wireless mesh networking standard with emphasis on low cost and energy conservation. It is intended to be used in wireless monitoring and control applications such as sensors and remotely operated switches where the end devices are battery powered. Because it is a recent technology there is not sufficient understanding on how network architecture and configuration affect power consumption of the battery powered devices. This research investigates the power consumption and delivery ratio of Zigbee wireless mesh and star networks for a single sink real time monitoring system at varying traffic rates and the beacon and non beacon mode operation of its underlying standard IEEE 802.15.4 in the star network architecture. To evaluate the performance of Zigbee, the network operation was simulated using the simulation tool NS-2. NS-2 is capable of simulating the entire network operation including traffic generation and energy consumption of each node in the network. After first running the simulation it was obvious that there were problems in the configuration of the simulator as well as some unexpected behaviour. After performing several modifications to the simulator the results improved significantly. To validate the operation of the simulator and to give insight on the operation of Zigbee, a real Zigbee wireless network was constructed and the same experiments that were conducted on the simulator were repeated on the Zigbee network. The research showed that the modified simulator produced good results that were close to the experimental results. It was found that the non beacon mode of operation had the lowest power consumption and best delivery ratio at all tested traffic rates. The operation of Zigbee mesh and star networks were compared to the results for IEEE 802.15.4 star networks in non beacon mode which revealed that the extra routing traffic sent by the Zigbee networking layers does contribute significantly to the power consumption, however even with the extra routing traffic, power consumption is still so low that it the battery life of the device would be limited by the shelf life of the battery, not by the energy consumption of the device. This research has successfully achieved its objectives and identified areas for future development. The simulator model for NS-2 could be improved to further increase the accuracy of the results as well as include the Zigbee routing layers and the experimental results could be improved by a more accurate power consumption data acquisition method.

Medium access control (MAC) plays a vital role in satisfying the varied quality of service (QoS) requirements in wireless networks. Many MAC solutions have been proposed for these networks, and performance evaluation, optimization and enhancement of these MAC protocols is needed. In this thesis, we focus on the analysis and optimization of MAC protocols for some recently emerged wireless technologies targeted at low-rate and multimedia applications.