Loading...

Analysis and Improvement of QoS in Optical CDMA Networks Using Cross Layer Design Concepts

Hosseini, Ahmad Reza | 2012

532 Viewed
  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 43248 (05)
  4. University: Sharif University of Technology
  5. Department: Electrical Engineering
  6. Advisor(s): Pakravan, Mohammad Reza
  7. Abstract:
  8. According to the rapid growing in communication devices, users need higher rates for their usages. Fiber optics is one the major choices to support such rates. One of the simplest and cheapest networks is Local Area Network (LAN) as a Passive Optical Network (PON). In these networks, some computers are locally connected to a passive optical device and communicate through it. Multiple access to a shared channel is an important task in such a network. In this thesis, Code Division Multiple Access (CDMA) is used and a new algorithm for Multiple Access Control Sublayer (MAC) based on scheduling will be developed to improve Quality of Service (QoS) and stabilize the network.
    In the scheduling protocol, the transmitter changes the time of sending the packet, so that its packet will be received successfully and also it won’t disturb the other packets. The first step is to estimate the channel state, which is neglected in many researches but here a new all-optical algorithm is developed for both estimating channel state and deciding the moment of sending according to the estimation. Some other parameters should be determined in the algorithm such as packet length and retransmission time which are adjusted as a function of fixed parameters including number of users and the distance between the splitter and the users based on simulations.
    As is shown, using this algorithm will increase the maximum normalized throughput of the network to 0.75 which is really more than the maximum throughput reached in previous researches (0.4). Also other QoS parameters like delay and jitter are improved. It should be noted that implementing this algorithm is not complicated than other researches.
    At the end of the thesis, it is shown that different classes of service could be supported in the network by just a little changing the parameters of the algorithm. The results are all derived using simulation in MATLAB and the strength of the proposed algorithm is shown
  9. Keywords:
  10. Code Devision Multiple Access (CDMA) ; Scheduling Technique ; Service Quality ; Cross Layer Design ; Optical Local Area Network (OLAN) ; Multiple Access Control (MAC)Sublayer

 Digital Object List

 Bookmark

No TOC