Wireless sensor networks consist of many small sensor nodes with sensing, computation, and wireless communications capabilities. Recently, there have been numerous research results in the power consumption for routing protocol. Routing protocols in WSNs might difference depending on the application and network architecture. This paper focuses on reducing the power consumption for routing protocol of wireless sensor networks too. We present a routing protocol called ACRP. sensor nodes will organize many clusters voluntarily. Cluster heads will distribute time slot to the sensor nodes in the same cluster and sensor nodes will transmit data to cluster head in it¡¦s time slot. After the data had been aggregated by cluster heads, they will send the aggregated data to base station through the routing path that had been established. In addition, in order to lengthen the living time of wireless sensor network, the base station will periodically adjust the amount of sensor nodes in all clusters according to the cluster information.

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Wireless sensor networks suffer from limited power resources. Therefore, managing the energy constraints and exploring new ways to minimize the power consumption during the operation of the nodes are critical issues. Conventional MAC protocols deal with this problem without considering the internal properties of the sensor nodes’ batteries. However, recent studies about battery modeling and behaviour showed that the pulsed discharge mechanism and the charge recovery effect may have a significant impact on wireless communication in terms of power saving. In this thesis we propose two battery-aware MAC protocols that take benefit of these factors to save more energy and to prolong the lifetime of the nodes/network without affecting the throughput. In both protocols we measure the remaining battery capacity of the node and use that measurement in the back-off scheme. The first protocol gives the nodes with higher remaining battery capacity more priority to access the medium, while the other one provides more medium access priority to the nodes with lower remaining battery capacity. The objective is to investigate, through simulations, which protocol reduces the power consumption of the nodes, improve the lifetime of the network, and compare the results with the CSMA-CA protocol.

There has been growing interest in the Mobile WSN applications where mobility is the fundamental characteristic of the sensor nodes. Mobility poses many challenges to the routing protocols used in such applications. In this thesis we evaluate the performance of Collection Tree Protocol as applied in mobile WSN scenarios. The simulation study shows CTP performs poorly in mobile scenario because of the frequent tree re-generation resulting from node movements. We compare Collection Tree Protocol with reactive ad hoc network routing protocols. The simulation results show that collection tree protocol performs better than reactive MANET protocols in terms of data delivery ratio and control overhead under low traffic rates. The end-to-end delay obtained in case of reactive protocols is also higher compared to that obtained when using CTP, which is due to their route discovery process. This thesis presents an improved data collection protocol Fixed Node Aided CTP based on the analysis of CTP. The protocol introduces the concept of fixed aided routing into CTP. It is shown that our enhanced CTP outperforms CTP in terms of data delivery ratio and control overhead chosen as performance metrics. / UOIT

Wireless sensor networks suffer from limited power resources. Therefore, managing the energy constraints and exploring new ways to minimize the power consumption during the operation of the nodes are critical issues. Conventional MAC protocols deal with this problem without considering the internal properties of the sensor nodes’ batteries. However, recent studies about battery modeling and behaviour showed that the pulsed discharge mechanism and the charge recovery effect may have a significant impact on wireless communication in terms of power saving. In this thesis we propose two battery-aware MAC protocols that take benefit of these factors to save more energy and to prolong the lifetime of the nodes/network without affecting the throughput. In both protocols we measure the remaining battery capacity of the node and use that measurement in the back-off scheme. The first protocol gives the nodes with higher remaining battery capacity more priority to access the medium, while the other one provides more medium access priority to the nodes with lower remaining battery capacity. The objective is to investigate, through simulations, which protocol reduces the power consumption of the nodes, improve the lifetime of the network, and compare the results with the CSMA-CA protocol.

Wireless sensor networks(WSNs) are different to traditional networks and are highly dependent on applications, thus traditional routing protocols cannot be applied efficiently to the networks. As the variability of both the application and the network architecture, the majority of the attention, therefore, has been given to the routing protocols. This work surveys and evaluates state-of-the-art routing protocols based on many factors including energy efficiency, delay andcomplexity, and presents several classifications for the various approaches pursued. Additionally, more attention is paid to several routing protocols and their advantages and disadvantages and, indeed, this work implements two of selected protocols, LEACH and THVRG, on the OPNET, and compares them in many aspects based on a large amount of experimental data. The survey also provides a valuable framework for comparing new and existing routing protocols. According to the evaluation for the performance of the routing protocols, this thesis provides assistance in relation to further improving the performance in relation to routing protocols. Finally, future research strategies and trends in relation to routing technology in wireless sensor networks are also provided.

Recent technological advancements are enabling the vision of pervasive or ubiquitous computing to become a reality. Service discovery is vital in such a computing paradigm, where a great number of devices and software components collaborate unobtrusively and provide numerous services. Current service-discovery protocols do not make use of contextual information in discovering services, and as a result, fail to provide the most appropriate and relevant services for users. In addition, current protocols rely on keyword-based search techniques and do not consider the semantic description of services. Thus, they suffer from poor precision and recall. To address the need for a discovery architecture that supports the envisioned scenarios of pervasive computing, we propose a context-aware service-discovery protocol that exploits meaningful contextual information, either static or dynamic, to provide users with the most suitable and relevant services. The architecture relies on a shared, ontology-based, semantic representation of services and context to enhance precision and recall, and to enable knowledge sharing, capability-based search, autonomous reasoning, and semantic matchmaking. Furthermore, the architecture facilitates a dynamic service-selection mechanism to filter and rank matching services, based on their dynamic contextual attributes, which further enhances the discovery process and saves users time and effort. Our empirical results indicate the effectiveness and feasibility of the proposed architecture.

Vehicular communication has been an emerging topic among current wireless research. The vehicular communication can be classified to Inter-Vehicle Communication (IVC) and Road-to-Vehicle Communication (RVC). IVC and RVC support applications mainly on two aspects: safety applications aiming to reduce dangers on the road, and data applications aiming to provide information and entertainment to people on traveling. Vehicles nearby form Vehicular Ad hoc Networks (VANETs) without any fixed infrastructures. Due to the characteristics of vehicular networks such as quickly changing and unstable network topology, IVC has special requirements to the network protocols. Several MAC protocols have been appeared or improved based on previous work for IVC. But these protocols are designed either for QoS guaranteed data service or for reliable message broadcast. There is not a protocol including both application requirements and inexpensive to implement as well. MAC protocol for vehicular communication hasn’t been finalized. In this thesis, an overlay token ring protocol (OTRP) is proposed which can work on MAC layer with broadcast function and taking into the IVC features into consideration. In OTRP, vehicles are grouped to overlapped rings with a token passed in each ring as the sole right for transmission. The ring is dynamically updated in a distributed manner based on smart algorithm at each node. OTRP provides bounded delay by assigning maximum token holding time for each node. It also reduces collisions by decreasing the number of contention nodes by times of ring size. Fair and high throughput is obtained as well. Furthermore, it provides reliable and prompt broadcast of emergency messages by pre-emptively transmitting while applying the token as an acknowledgement. The time nodes reliably receive the message is within limit. Theoretical analysis is provided and simulation results are given to evaluate the performance of OTRP under saturated traffic conditions both in safety and data applications.

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.

In this thesis a distributed, dynamic, load aware, joint power and frequency allocation protocol for 4G networks along with system-level simulated results are presented. In all cellular networks, a key limiting factor for throughput is inter-cell interference, especially at the cell edges. Several methods have been proposed and adopted in each mobile network generation to cancel or suppress its effects, whereas each method has its drawbacks in terms of receiver complexity or additional control nodes. However, the proposed protocol presented here does not impose any architectural changes.  In 4G networks such as LTE, the choice of OFDMA for the air interface has paved the way for selective frequency and power allocation in the available spectrum. Taking advantage of this opportunity, fractional frequency reuse (FFR) has been proposed in OFDMA based mobile networks in order to reduce the throughput loss at the cell edges due to inter-cell interference. In FFR, center users lose part of available spectrum that is dedicated to the edge users.  Our protocol aims to minimize this loss of center users incurred by FFR, at the cost of minimal degradation at the edges. An eNodeB, only when overloaded, requests its neighbours’ edge band to be used for its center users at a reduced power level. This is done via small message exchange between the eNodeBs. The neighbors of the overloaded eNodeBs solve a small local knapsack problem to decide whether band lending is feasible or not. A distinguishing feature of this protocol is the power level adjustment for the borrowed band, which is mutually decided by the borrower and lender. The band is released when it is not needed or it is causing unacceptable loss to the lender. The implementation is done in a Matlab based LTE system level simulator. For the implementation of our protocol in the simulator, starting point was implementation of FFR-3 functionality, a prerequisite and a baseline for comparison with our protocol. Results are compared among three different setups of re-use1, FFR-3 and our protocol by varying number of overloaded eNodeBs for various numbers of scenarios and the comparison is made based on the center users’ throughput, edge users’ throughput. An estimation of time and protocol overhead is also presented. We have observed center users’ throughput gain up to 46%, at the cost of 9% edge users’ throughput loss, when compared to the classic FFR-3 scheme. The overall system throughput goes up to 26 % in heavily loaded scenario.   The utility of the protocol for an LTE system is evident from the results, which is supported by the dynamic and decentralized nature of the protocol. This ensures better utilization of spectrum, by temporarily allocating more bandwidth where it is needed more.