A Study Of Wireless Access Based On MAC Layer Protocol In EPON

With the popularization of Internet and emergence of large number of digital multimedia services, the demand for broadband services has kept rising. The abundant facts confirm that Ethernet Passive Optical fiber access Network (EPON) is the best solution of the "last mile". Although EPON is unable to provide adequate long-distance bandwidth, it can give end-user flexible wireless access methods such as Wireless Local Area Network (WLAN) which becomes a noticeable study field. The integration of optical communication and wireless communication to achieve broadband wireless access will become the most competitive solution. The demand for flexible wireless access method make broadband wireless access become trend of future access method. At the same time, the extension of the EPON MAC layer frame function can not only be combined with the advantage of PON structure, but also achieve flexible wireless access which is of important significance to popularization and application.This paper mainly analyzed and discussed the Protocol of EPON MAC ( Media Access Control) , compared EPON MAC protocol frame format with WLAN MAC. After studying the contents of the MAC protocol frame in EPON, WLAN wireless MAC frame is added to the EPON MAC which further encapsulates 802.11 MAC PDU frames suitable for wireless transmission, thus displayed peculiar features under PON architecture. During the completion of the work and the main results are as follows:(1)From the viewpoint of hierarchical structure, the architecture and operational principle of EPON is analyzed. According to such features, the content of MAC layer, frame format and content of MPCP are discussed and corresponding functions are realized.(2)The mature and widely used CSMA/CA algorithm for IEEE 802.11 MAC and basic distributed coordination function (DCF) is respectively discussed in terms of content, frame format and performance indicator of MAC protocol. (3) Starting from the MAC layer protocol, a contrastive study of functions of EPON and WLAN MAC layer protocol is made. Then the wireless access control frame referring to WLAN MAC is encapsulated to EPON MAC to achieve communication with upper layer protocols of EPON and also utilize IEEE 802.11 MAC protocol to achieve the integration of EPON optical fiber and WLAN wireless access.(4) OPNET simulation software is used to establish model of EPON, simulate the proposed EPON MAC layer protocol. Relevant performance indicators are also compared and discussed. Experimental results show that the wireless access function of EPON MAC can both achieve the optical broadband access of PON system and advantages of WLAN flexible access which has the certain application value of engineering.