| dc.description.abstract | With the advance of science and technology, various wireless communication network technologies have been developed in succession to satisfy different demands of the modern people. However, making a balance or compromise between new and old wireless communication network technologies becomes a serious problem because different wireless network technologies may correspond to different frameworks and specifications. For this purpose, improving wireless communication network technologies without violating the existing technologies shall be a desirable way.
Machine to Machine (M2M) wireless communication networks, which allow different devices to communicate and exchange data with each other without the need of (or with the need of only a limited amount of) human to machine interactions, have been developed in recent years. In order to accomplish the modern M2M wireless communication networks, most of wireless communication network service providers promote the concept of M2M to gain extensive benefits from such innovative services.
Wireless communication networks, which are established according to the conventional wireless communication network frameworks, are all designed on the basis of human to human (H2H) behaviors and demands. Besides, when wireless devices have not synchronized with the communication system, they must contend with each other through a random access mechanism to gain an opportunity for uplink transmission. However, the M2M communications are different to contemporary mobile network communication services as it involves a very large number of communication terminals with little traffic requirement, many technical issues and system impacts have to be tackled in order to realize the M2M communications on existing wireless communication networks.
Under the framework of the Long Term Evolution (LTE) system of the 3rd Generation Partnership Project (3GPP), a user equipment (UE) and the serving evolved Node B (eNB) must perform at least the following steps when it desires to upload data to the serving eNB: (1) the UE selects one of sixty-four preambles for transmitting an uplink transmission request to the eNB; (2) the eNB replies a relevant message to the UE in response to the preamble; (3) the UE transmits an uplink bandwidth request to the eNB in response to the relevant message; and (4) the eNB makes a schedule to allow the UE to upload data.
Under the framework of the LTE system of 3GPP, the sixty-four preambles are shared by individual UEs, and once one of the preambles is chosen by multiple UEs, it would cause a collision. When such a collision occurs, the UEs must wait for a backoff time before they can transmit an uplink transmission request to the eNB again. Unfortunately, when M2M wireless devices are integrated into an existing H2H wireless communication network, all M2M wireless devices will share the sixty-four preambles with the existing H2H wireless devices. Consequently, the integrated wireless communication network would suffer from a serious blocking rate of uplink data transmissions from either the M2M wireless devices or the H2H wireless devices.
According to previous discussions, it is an urgent requirement to overcome the collision problem effectively without violating the existing wireless communication network framework. This thesis focuses on the serious collision problem and proposes a self-adaptive persistent contention scheme for scheduling based M2M devices which report data in a periodical manner. In order to make the most effective way to operate the next generation communication system, the proposed scheme not only solves the congestion impact on the legacy devices but also optimizes the uplink bandwidth utilization and contention of M2M devices without violating the existing wireless communication network framework.
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