| The rapid development of Internet technology is changing every aspect of human life. Wireless body area network(WBAN) as an important branch of the Internet of things, is playing an important role in personal health, remote medical treatment, individual equipment, identification and aerospace fields. Especially in terms of personal health, the emergence of more lightweight and miniaturization sensor devices makes sensors implanted in human body possible. At present, the wireless body area network is still in the early stage of development and faces a series of technical problems at the same time more to contain the huge opportunity. Therefore, it attracts a large number of scholars and the industry committed to wireless body area network research.Due to the limitation of sensor’s size and placement, how to use energy from the sensor battery energy efficiently is one of the important research direction of wireless body area network. In recent years, scholars at home and abroad have studied the source code, sleep mechanism, media access layer algorithm and routing algorithm, the energy efficiency of sensor, and made a series of breakthrough progress. However, most of the research are assumed the body in a static posture(standing up or lying down), few research on the human body in motion. When the body is in a static posture, the sensor node location does not change. The wireless network structure of wireless body area network is stable and algorithm design is easy implementation. However, the algorithm has limitations in human body motion. Therefore, further study of energy efficient algorithm under movement posture in wireless body area network, has important theoretical and practical significance.When the human body is in motion, the position of the sensor nodes and network structure of wireless body area network has dynamic and time-varying characteristics. This paper starts from medium access protocol design of energy-efficient technology in WBAN and selects the body walking in constant speed to study for filling the blank of the field. It is also the foundation for the future more complicated motion research. In this paper, the research idea is as follows:First of all, this paper concerns that the process of people walking at a constant speed consists of successive frames of video; Then, with the concept of key frames in video processing field, this paper removes the redundant information of video and selects specific static posture to represent this process; Finally, the original static protocol is applied to the selected posture. In this paper, the main work is as follows:First, this paper analyzes and simulates of the four existing efficient protocol under the human standing posture: pure conservative protocol, pure opportunistic protocol, max-min protocol, dynamic protocol for lifetime maximization(DPLM). This paper points out the deficiency of existing protocols and expounds limitations of the existing protocol.Second, this paper applies the idea of the key frames to wireless body area network, and aims at resolving the efficiency of the network under human body in motion. This paper deduces posture recognition function, posture information matrix and path loss model under human walking posture and redefines energy efficient function of the wireless body area network, and designs suitable protocols under human walking posture.Third, this paper analyzes the node position influence on wireless body area network lifetime, and deduces the optimal placement of coordinator, and the enumeration method is used to solve the deduced formula.Fourth, this paper puts forward the energy efficient model for wireless body area network under human walking posture. The model specifies the coordinator location, and joins the sleep mechanism. The model improves the sensor node energy utilization to a great extent.This paper is the research of energy efficiency problems on specific posture for wireless body area network, and it provides reference for more complex human postures. |
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