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One of the digital modulation methods is wavelet packet modulation (WPM). This modulation method is a multiplex transmission method in which the time and frequency division regions in the transmission frame can be rather flexibly modified. In this paper, a digital communication system is studied that can adaptively carry out transmission by using W...
Contexts in source publication
Context 1
... code is extended to match the MSM frame of 16 symbols in Fig. 7, so that the code length is extended to 16. Then, in order not to lose the class structure of the subband, the code shown in Fig. 9, which has a class structure with S1 as an apex, is obtained. This code is called Code 1. Here, c 1 to c 4 are the parity check bits for S1 to S5 and are given by The code characteristics are listed in Table 1. This code is adapted from the configuration in Fig. 8 as S 11 S 21 S 31 S 41 S 51 , S 11 S 21 S 31 S 41 S 52 , . . . , S 11 S ...
Context 2
... maximum likelihood decoding is performed, metrics are computed from S1 toward S5. Since the code in Fig. 9 has a class structure, the number of states increases exponentially for the class of S. For S1 and S2, there are 4 states, S3 has 8 states, and S4 has 32 states. However, convergence is attained at S5 because this is a block code using a parity check bit. Parallel paths occur for unencoded portions l3 and l4. There are four for each ...
Citations
... The WPM packet construction as shown in Fig. 2 where the time-frequency resolution changes stepwise is called as MSM (multi-scale modulation). In MSM, the baseband signal {c (0) k }, i.e., wavelet composed signal, is obtained from wavelet reconstruction algorithm as [5] ...
Wavelet packet modulation (WPM) using the discrete wavelet transform is a multiplexing transmission method in which data is assigned to wavelet subbands having different time and frequency resolutions. The WPM keeps data transmission throughput even in tone and impulse interference environments that cannot be achieved with conventional multiplexing methods such as TDM (Time division multiplexing) or OFDM (Orthogonal frequency division multiplexing). In this paper, we propose an effective multicarrier transmission method of WPM for wireless mobile communications. First, the transmission characteristics of WPM in fading environments are minutely investigated. Then, taking the advantage of the WPM and the OFDM that has an equalizing technique in multipath fading environments, we propose a multimode transmission method using them. The adaptive transmission in those fading and interference environments is achieved by using the multimode transmission. Their transmission performances are evaluated by computer simulations.
The performance of WPM over the mobile satellite channel is presented and analyzed. The theory analysis and the simulation results show that the orthogonality of WPM can help the system be robust to the multipath effect and the extend period of WPM symbols can decrease the frequency selective fading of the system. The simulation result demonstrates that the performance of mobile satellite communication system using WPM is dependent on the support length of the wavelets, therefore a ratio decreasing algorithm is proposed in this study to improve the performance by weakening the support length effect. The simulation result shows that the better performance can be achieved by using proposed method.
The wavelet synthesis wave is able to set up the scale freely. So it is possible to use it as UWB transmission wave by compressing time. The possibility of the application to UWB was shown by the following characteristics of the wavelet and some figures of the transmission waveform and spectrum after band restriction. Also, we evaluated the BER characteristic that used Haar as the mother wavelet by computer simulation.
