Sittichivapak, Suvepon

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Performance analysis of multi-user detection of slow frequency hopping multicarrier DS-CDMA over nakagami fading channels
(2003-01-01)
Promasa, Priwann
;
Sittiwatjanaiand, Pisako
;
Sittichivapak, Suvepon
We propose a new multi-user detection of slow frequency hopping multicarrier direct- sequence code division multiple access technique (Multi-user detection of SFW MC DS-CDMA). The frequency hopping pattern are controlled by asset of constantweight code. Consequently, multirate communication can be implemented by selecting the correspandence set of constant-weight code. We assume the system operates in multipaths fading environment and a decorrelating receiver structure, The receiver has an explicit knowledge of the associzted ftequencyhopping (FH) pattems invoked. The system's performance is evaluated using Nakagami fading channels with numerical method. Furtlmmore the performance of the Multi-user detection of SFWMC DS-CDMA system is compared to the conventional Multi-user detection of direct-sequence code division multiple access system ( Multi-user detection of DSCDMA).
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Performance analysis on the controllable Slotted DS-CDMA with an allocating buffer for collided traffic
(2005-01-01)
Asavaruk, Seri
;
Sittichivapak, Suvepon
;
Varakulsiripunth, Ruttikorn
;
Kato, Yasushi
;
Shiratori, Norio
This paper presents an analysis of the Slotted DS-CDMA system with modified node components in order to construct a load control structure in which the service rates of each node can be dynamically adapted without using feedback information. In contrast to the traditional Slotted DS-CDMA which is widely represented with single queue, prior emphasis of the approach is laid on the usage of an additional queue which is applied to manage the collided packet traffic while its queue size is also used as a load control parameter. Semi-Markov process is applied to describe the statistic behavior of the system in steady state. Trade-offs between two major performance parameters, i.e., delay and throughput, are presented and compared with those of the traditional system. Results obtained from the simulation and numerical analysis using queuing concept are compared. With these results, an advantage performance for group packets is shown, and we finally extend the concept based on the obtained results to describe a simple algorithm using one way control message as the tool to alleviate the stability problem. Copyright © 2005 The Institute of Electronics, Information and Communication Engineers.
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Throughput/delay analysis of spectrally phase-encoded optical CDMA over WDM networks
(2008-12-01)
Puntsri, K.
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Sittichivapak, S.
;
Shalaby, H. M.H.
This paper presents a performance analysis of spectrally phase-encoded optical CDMA over WDM networks. Random access protocol is adopted to assign wavelengths. The discrete time Markov chain model is used to build analytical model of multi-channel random access protocol. We measure several performance characteristics, namely, steady-state throughput and average packet delay time. Additionally, the efficiencies of the system, which are based on both the processing gain and the number of WDM wavelengths, are considered. Exponential retransmission is used for solving packet collision problems. In our numerical results, system performance is given in terms of both average throughput and delay time. copyright © 2008 IEICE.
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Performance of multiuser detection combining with multicarrier on nakagami fading channels for DS/CDMA transmission systems
(2003-01-01)
Kothirani, Apinya
;
Sirimak, Thanest
;
Sittichivapak, Suvepon
This paper combines multiuser detection and multicamer signaling technique for direct sequence code division multiple access system (DSKDMA). These techniques are analyzed in multipath fading environment. - The receiver provides a decorrelating detector for each carrier and the outputs of the correlators are combined with a maximal-ratio combiner. The system perfomnce is evaluated over nakagami fading channels in the presence of partial band interference with numerical method. The system performance of multiuser detection combining multi-camer DS/CDMA with the conventional single-carrier decorrelating detector was also compared.
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Performance analysis of SPE-OCDMA over WDM networks
(2008-10-06)
Puntsri, K.
;
Sittichivapak, S.
;
Shalaby, H. M.H.
This paper presents a performance analysis of SPE-OCDMA (spectrally phase-encoded optical CDMA) over WDM networks. The discrete time Markov chain model is used to build analytical model of multi-channel random access Slotted Aloha. The number of WDM wavelength is corresponded to multichannel Slotted Aloha. We measure several performance characteristics, namely, steady-state throughput and average packet delay time. Additionally, the efficiencies of the system, which are based on both the processing gain and the number of WDM wavelengths, are considered. Additionally, exponential retransmission is used for solving packet collision problems. In our numerical results, system performance is given in terms of both average throughput and delay time. ©2008 IEEE.
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Enhancement of data transmission in OFDM-WLAN system using transmit diversity method
(2003-07-14)
Jitrangsri, T.
;
Sittichivapak, S.
Currently, the OFDM-WLAN system becomes the interesting topic since wireless technology is very successful at present. Although the advantage of wireless system is the moveable terminal but wireless channel itself needs more advanced techniques to combat the effect of multipath, as the data is transmitted through the channel. Diversity technique is considered to be one of the method to improve efficiency of data tranmission in physical layer. In this paper we present the applying of transmit diversity to the OFDM-WLAN system. The Space Time Diversity (STD) is simulated, compared with Maximal Ratio Combining (MRC). The simulation result shows that STD can improve efficiency of the system by decreasing Packet Error Rate (PER) as well as MRC.
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Sittichivapak, Suvepon

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