Tawil Paungma

Mobile Internet navigation system

This paper presents a mobile Internet navigation system (MINS) which can provide traffic-condition acquisition and monitoring convenience for mobile phone users by using the wireless application protocol (WAP) format. This system operates in two ways. Firstly, mobile phone users can access the network to request road traffic information from the database of the server. This feature is useful to a user in planning the optimum route to a destination. Secondly, the user can monitor real time traffic information on the screen of the mobile phone. The traffic information includes quantity of cars for both main roads and their branch roads. These data are collected from sensors at all locations and are relayed to the clients computer by the traffic controller via the Internet and are stored at the database in the server. This system enables mobile phone users to acquire real time traffic condition data from the server for deciding the optimum road route in their travels.

Proposal of Improved PTS Method for OFDM Signal

The major drawback of orthogonal frequency division multiplexing (OFDM) is a large Peak-to-Average Power Ratio (PAPR). To overcome the PAPR problem, many PAPR reduction methods have been proposed. Partial Transmit Sequence (PTS) method is a well known method to reduce the PAPR statistics of an OFDM signal. The PTS method can reduce the PAPR by controlling the multiplied weighting factor of subblock both data sub carrier and clusters. The PTS method can improve PAPR reduction performance very well as increasing a number of weighting factors and clusters. However, the number of side information is proportionally increasing as increased number of weighting factors or/and clutters, which are required to inform the side information to the receiver for recovering the original data. In this paper, we propose the new weighting factor which can improve the PAPR reduction performance better than conventional PTS method. The proposed method doesnpsilat have any additional number of side information and system complexity. The proposed method can achieve both a better PAPR performance and BER performance with keeping the same number of side information when compare with the conventional PTS method. This paper presents various computer simulation results to verify the effectiveness of proposed method in the multi-path fading channel.

Proposal of Clipping and Inter-Modulation Noise Mitigation Method for OFDM Signal in Non-linear Channel

One of the disadvantages of using OFDM is the larger peak to averaged power ratio (PAPR) of the time domain signal as compared with the conventional single carrier transmission method. The OFDM signal with larger PAPR will cause the undesirable spectrum regrowth and the larger degradation of bit error rate (BER) performance both due to the inter-modulation products occurring in the non-linear amplifier at the transmitter. The clipping method in conjunction with the Decision Aided Reconstruction (DAR) method is well known as one of the solutions to improve the BER performance with keeping the better PAPR performance. However, the DAR method is proposed to mitigate only the clipping noise and not for the inter-modulation noise. In this paper, we propose the Improved DAR (IDAR) method, which can mitigate both the clipping noise and inter-modulation noise on the basis of DAR method. The proposed method enables the efficient usage of transmission power amplifier at the transmitter with keeping the better PAPR and BER performances. This paper presents various computer simulation results to verify the performance of proposed IDAR method in the non-linear channel.

PAPR Reduction Method for OFDM Signal by Using Dummy Sub-carriers

One of the disadvantages of using OFDM is the larger peak to averaged power ratio (PAPR) in its time domain signal. The larger PAPR signal would course the fatal degradation of bit error rate performance (BER) due to the inter-modulation noise in the non-linear channel. This paper proposes an improved DSI (Dummy Sequence Insertion) method, which can achieve the better PAPR and BER performances. The feature of proposed method is to optimize the phase of each dummy sub-carrier so as to reduce the PAPR performance by changing all predetermined phase coefficients in the time domain signal, which is calculated for data sub-carriers and dummy sub-carriers separately. To achieve the better PAPR performance, this paper also proposes to employ the time-frequency domain swapping algorithm for fine adjustment of phase coefficient of the dummy subcarriers, which can achieve the less complexity of processing and achieves the better PAPR and BER performances than those for the conventional DSI method. This paper presents various computer simulation results to verify the effectiveness of proposed method as comparing with the conventional methods in the non-linear channel.

Proposal of Simple PAPR Reduction Method for OFDM Signal by Using Dummy Sub-Carriers

One of the disadvantages of using OFDM is the larger peak to averaged power ratio (PAPR) in its time domain signal. The larger PAPR signal would course the fatal degradation of bit error rate performance (BER) due to the inter-modulation noise in the non-linear channel. This paper proposes an improved DSI (Dummy Sequence Insertion) method, which can achieve the better PAPR and BER performances. The feature of proposed method is to optimize the phase of each dummy sub-carrier so as to reduce the PAPR performance by changing all predetermined phase coefficients in the time domain signal, which is calculated for data sub-carriers and dummy sub-carriers separately. To achieve the better PAPR performance, this paper also proposes to employ the time-frequency domain swapping algorithm for fine adjustment of phase coefficient of the dummy subcarriers, which can achieve the less complexity of processing and achieves the better PAPR and BER performances than those for the conventional DSI method. This paper presents various computer simulation results to verify the effectiveness of proposed method as comparing with the conventional methods in the non-linear channel.

Improved PTS Method with New Weighting Factor Technique for OFDM Signal

Partial Transmit Sequence (PTS) method is a well - known method which can reduce the peak-to-average ratio (PAPR) for an OFDM signal. A major drawback of PTS method is its higher computation complexity due to the necessity of larger number of inverse fast Fourier transforms (IFFT). The PTS method with low computation complexity, called decomposition PTS sub-blocking was proposed [1] which employs the radix-*- inverse fast Fourier transform (IFFT) for the signals at the middle stages of an TV-point radix-*- IFFT and decimation in frequency (DIF) domain. This method (DIF-IFFT) can reduce the computation complexity relatively while providing PAPR reduction similar to other PTS techniques. On the other hand, PTS method can improve PAPR reduction performance very well as increasing a number of weighting factors and clusters. However, the size of side information proportionally increases as increasing the number of weighting factors or/and clutters, which are required to inform the side information to the receiver for recovering the original data. In this paper, we propose the new weighting factor technique in conjunction with D-PTS sub-blocking technique which can improve both the PAPR performance and computation complexity without any increasing of side information.

Proposal of improved PTS method for OFDM signal in the multi-path fading channel

The major drawback of orthogonal frequency division multiplexing (OFDM) is a large Peak-to-Average Power Ratio (PAPR). To overcome the PAPR problem, many PAPR reduction methods have been proposed. Partial Transmit Sequence (PTS) method is a well known method to reduce the PAPR statistics of an OFDM signal. The PTS method can reduce the PAPR by controlling the multiplied weighting factor of subblock both data sub carrier and clusters. The PTS method can improve PAPR reduction performance very well as increasing a number of weighting factors and clusters. However, the number of side information is proportionally increasing as increased number of weighting factors or/and clutters, which are required to inform the side information to the receiver for recovering the original data. In this paper, we propose the new weighting factor which can improve the PAPR reduction performance better than conventional PTS method. The proposed method doesnpsilat have any additional number of side information and system complexity. The proposed method can achieve both a better PAPR performance and BER performance with keeping the same number of side information when compare with the conventional PTS method. This paper presents various computer simulation results to verify the effectiveness of proposed method in the multi-path fading channel.

Proposal of D-PTS method with non-uniform weighting factor for PAPR reduction in OFDM systems

Partial Transmit Sequence (PTS) method is a well - known method which can reduce the peak-to-average ratio (PAPR) for an OFDM signal. A major drawback of PTS method is its higher computation complexity due to the necessity of larger number of inverse fast Fourier transforms (IFFT). The PTS method with low computation complexity, called decomposition PTS (D-PTS) sub-blocking was proposed [1] which employs the radix-r IFFT for the signals at the middle stages of an N-point radix-r IFFT and decimation in frequency (DIF) domain. This method can reduce the computation complexity relatively while providing PAPR reduction similar to other PTS techniques. On the other hand, PTS method can improve PAPR reduction performance very well as increasing a number of weighting factors and clusters. However, the size of side information proportionally increases as increasing the number of weighting factors or/and clusters, which are required to inform the side information to the receiver for recovering the original data. In this paper, we propose the non-uniform weighting factor technique in conjunction with D-PTS sub-blocking technique which can improve both the PAPR performance and computation complexity without any increasing of side information.

PAPR Reduction of OFDM Signal by Use of DSI Method with Time-Frequency Domain Swapping Algorithm

SUMMARY The main disadvantage of orthogonal frequency divisionmultiplexing (OFDM) is the high time domain PAPR. The larger PAPRsignal would fatallydegrade BER performance in non-linear channels. Thispaper proposes an improved DSI method, which can achieve better PAPRand BER performances in the non-linear channel with less computationcomplexity than the conventional DSI method. The feature of proposedmethod is to employ the time-frequency domain swapping algorithm inthe determination of frequency data for dummy sub-carriers. This paperpresents various computer simulation results to verify the effectiveness ofproposed DSI method. key words: OFDM, PAPR, dummy sub-carriers, non-linear amplifier 1. Introduction The OFDM technique has been received a lot of attentionespecially in the field of wireless communications becauseof its efficient usage of frequency bandwidth and robustnessto multi-path fading. One of the limitations of using OFDMtechnique is the larger peak to averaged power ratio (PAPR)of its time domain signal [1]. The larger PAPR signal wouldcause the severe degradation of bit error rate (BER) perfor-mance due to the inter-modulation noise occurring in thenon-linear amplifier.To overcome the PAPR problem in OFDM systems,various PAPR reduction methods for OFDM signal havebeen proposed including the selected mapping method(SLM) [2], partial transmit sequence method (PTS) [3] anddummy sequence insertion method (DSI) [4]. All of thesemethods improve the PAPR performance by controlling thephase of data or dummy sub-carriers. The SLM and PTSmethods control the phase of data sub-carriers and the DSImethod controls the phase of dummy sub-carriers. First twomethods are required to inform the phase information con-trolled for the data sub-carriers to the receiver as the sideinformation. Since the side information is required to trans-mit separately from the data information through the data orcontrol channels with the higher signal quality for the cor-rect demodulation of data information at the receiver, the

Proposal of QAM-OFDM System with IDAR Method for Non-Linear Satellite Channel

The future satellite communication systems are required to support the higher transmission data rate for providing multimedia services by employing the efficient modulation method such as multi-level QAM. However, the employment of conventional single carrier transmission method with multi-level QAM would cause the fatal degradation of signal quality due to the non-linear amplifiers located at the Earth station and satellite. To overcome this problem, this paper proposes the multi-level QAM-OFDM technique with IDAR method designed for satellite channel. In the IDAR method, the characteristics of non-linear amplifiers are required to be known at the receiver. This paper also proposes the estimation method for the characteristics of the non-linear amplifiers by using low PAPR preamble symbols. Various computer simulations are conducted in this paper to verify the effectiveness of proposed method in the non-linear satellite channel