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|Title: ||Performance analysis of Multi-channel Aloha (MCA) and Multi-channel Slotted Aloha (MCSA) schemes for optical fiber network|
|Other Titles: ||Duo pin dao chun Aloha ji fen duan Aloha ying yong yu guang xian wang luo shi de biao xian fen xi|
多頻道純 Aloha 及分段 Aloha 應用於光纖網絡時的表現分析
|Authors: ||Yuen, Man Hon ( 袁文瀚)|
|Department: ||Department of Electronic Engineering|
|Degree: ||Master of Philosophy|
|Issue Date: ||2011|
|Publisher: ||City University of Hong Kong|
|Subjects: ||Optical fiber communication.|
|Notes: ||CityU Call Number: TK5103.592.F52 Y83 2011|
xx, 160 leaves : ill. (some col.) 30 cm.
Thesis (M.Phil.)--City University of Hong Kong, 2011.
Includes bibliographical references (leaves 116-118)
|Abstract: ||Advances in optical fiber technology have facilitated transmission of large volumes
of data at different wavelengths in the same fiber network using wavelength division
multiplexing (WDM). We are interested in analyzing the performance of a Multi-channel Multiple Access Scheme for WDM optical fiber networks. In this thesis, we propose to use the Aloha scheme as the multiaccess protocol because optical fiber
provides huge volumes of bandwidth that are often far larger than user requirements.
The advantage of low efficiency Aloha schemes is their low cost and simple structure.
Performance of single-channel and multi-channel Aloha and Slotted Aloha schemes
with variable packet length is analyzed using a simple closed-loop model. The analytical model assumes a perfect environment where transmission can fail only if
packet collision occurs. Analysis parameters include collision probability, throughput, packet rate, and end-to-end delay. Analysis results are verified by some discrete
C event simulation results supported at 95% confidence interval (C.I.). Most of the
analysis results are very close to those produced by simulation programs employing
binary exponential backoff (16 windows size) as the retransmission scheme.
Analysis and simulation results have provided many interesting findings. The external packet arrival rate or packet rate is proportional to the number of available
channels with the same collision probability. Collision probability decreases as the
number of available channels increases, if external packet arrival rate remains constant. Several states are defined such as steep period, turning period and flat period
to describe the shape of these curves. The middle point of the turning period is
recommended as the most effective choice because the performance improvement is
not great after this point and the required number of channels is not large. Although
these values vary in different situations, most of them are about 0:15, a little bit
smaller than the "threshold collision probability" of 0:2.
Throughput increases along with increase in external packet arrival rate until it
reaches the maximum point. After the maximum point, the trend changes from
increasing to decreasing and finally it becomes zero. Throughput is proportional to the number of available channels while the utilization improves slightly or remains
the same after the number of available channels is increased.
End-to-end delay increases slowly until the external packet arrival rate reaches the
corresponding arrival rate of "threshold collision probability" and then there is a
steep upward slope after the arrival rate exceeds the threshold value.
Binary exponential backoff schemes have been shown to have better performance
than fixed retransmission probability approach and random selection of one interval for a fixed period approach. Either "BEB16" or "BEB32" are suggested to be
used as retransmission schemes of multi-channel Aloha and Slotted Aloha schemes
because their overall performance in simulation are the best and close to analysis
results. In addition, Aloha scheme is proposed to be applied in short average packet
length distribution while long average packet length distribution must choose Slotted Aloha scheme. For medium average packet length distribution, both schemes
are applicable; the selection criterion depends on the cost or the performance.|
|Online Catalog Link: ||http://lib.cityu.edu.hk/record=b4086777|
|Appears in Collections:||EE - Master of Philosophy |
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