As the increase of requirement for communication services, people pay more attention to the improvement of short distance networks. Currently, the data rate required for local area networks has increased to over 1 Gbps .On this condition, the optical fiber becomes the cheap wedding gown dresses perfect medium. Due to it can support high data rate and small attenuation .Fiber to home, fiber to desk is the inevitable tendency in communications. Optical fibers can be custom made prom dresses categorized by the number of guide mode. That is single-mode fiber and multimode fiber. Due to the relative low costs of multimode fiber, the usage of multimode fiber is very common in short distance networks. Through analysis and simulation, we know that the frequency response of the sell discount wedding dresses multimode fiber at low frequencies decreases monotonically, and in high frequency range, the frequency response does not fall off but becomes relatively flat. Since OFDM can be used to overcome the blog new shirts 2010 effect of frequency selectivity in the dispersive multimode fiber , it just can be used in the high frequency region with flat frequency response .But, the performance of the system will be effected by the deep nulls in the channel. How to solve the effect of the nulls on system is the key point of making OFDM multimode fiber communication technology come true. And the adaptive modulation technology is one of the effectively method to solve the deep nulls in the channel. Studying and finding a adaptive modulation algorithm suitable for the multimode fiber channel is just the major work of this paper.To simulate the adaptive modulation algorithm in the multimode fiber, a new channel model which is fit for simulation is proposed. Based on deeply studying current adaptive modulation algorithm of improving communication system and combining OFDM multimode optical fiber communication features, In order to make comparisons with other adaptive modulation algorithms, the dissertation uses the current optimization algorithm to the system of OFDM multimode fiber communication.
http://www.oddworldforums.net
http://www.johnbridge.com/vbulletin
http://bleachasylum.com
