Abstract-The effect of the companding process on QAM signals has been under investigation for the past several years. The compander, included in the PCM telephone network to improve voice performance, has an unusual affect on digital QAM data signals which are transmitted over the same channel. The quantization noise, generated by the companding process which is multiplicative (and asymmetric), degrades the detectability performance of the outermost points of the QAM constellation more than that of the inner points. The combined effect of the companding noise and the inherent white gaussian noise of the system, leads us to a re-examination of signal constellation design. In this paper we investigate the detectability performance of a number of candidates for signal constellations including, a typical rectangular QAM constellation, the same constellation with the addition of a smear-desmear operation, and two new improved QAM constellation designs with two-dimensional warpi
標(biāo)簽： investigation Abstract-The companding the
上傳時間： 2013-12-20
上傳用戶：英雄
ofdm信道特性 Channel transmission simulator Channel transmission simulator ％ ％ inputs: ％ sig2 - noise variance ％ Mt - number of Tx antennas ％ Mr - number of Rx antennas ％ x - vector of complex input symbols (for MIMO, this is a matrix, where each column ％ is the value of the antenna outputs at a single time instance) ％ H - frequency selective channel - represented in block-Toeplitz form for MIMO transmission ％ N - number of symbols transmitted in OFDM frame ％ ％ outputs: ％ y - vector of channel outputs (matrix for MIMO again, just like x matrix) ％ create noise vector sequence (each row is a different antenna, each column is a ％ different time index) note: noise is spatially and temporally white
標(biāo)簽： transmission simulator Channel inputs
上傳時間： 2016-07-22
上傳用戶：kelimu
Process a binary data stream using a communication system that consists of a baseband modulator, channel, and demodulator. Compute the system s bit error rate (BER). Also, display the transmitted and received signals in a scatter plot.
標(biāo)簽： communication modulator baseband consists
上傳時間： 2017-01-08
上傳用戶：ardager
MPEG-4 標(biāo)準(zhǔn)文檔 access to visual objects in natural and synthetic moving pictures and associated natural or synthetic sound for various applications such as digital storage media, internet, various forms of wired or wireless communication etc. The use of ISO/IEC 14496 means that motion video can be manipulated as a form of computer data and can be stored on various storage media, transmitted and received over existing and future networks and distributed on existing and future broadcast channels.
標(biāo)簽： associated and synthetic pictures
上傳時間： 2017-04-15
上傳用戶：TRIFCT
GNU_Radio GNU radio is a free/open-source software toolkit for and the content is controlled by a handful of organizations. Cell building software radios, in which software defines the phones are a great convenience, but the features your phone transmitted waveforms and demodulates the received supports are determined by the operator s interests, not yours. waveforms. Software radio is the technique of getting code A centralized system limits the rate of innovation. Instead of as close to the antenna as possible. It turns radio hardware cell phones being second-class citizens, usable only if problems into software problems.
標(biāo)簽： open-source GNU_Radio software toolkit
上傳時間： 2017-06-27
上傳用戶：拔絲土豆
Digital Modulation Techniques are those echniques through which we convert digital signals into analog signal which can be transmitted through transmission medium...this program demostrate some of the basics techniques
標(biāo)簽： Modulation Techniques echniques Digital
上傳時間： 2013-12-23
上傳用戶：wyc199288
The 4.0 kbit/s speech codec described in this paper is based on a Frequency Domain Interpolative (FDI) coding technique, which belongs to the class of prototype waveform Interpolation (PWI) coding techniques. The codec also has an integrated voice activity detector (VAD) and a noise reduction capability. The input signal is subjected to LPC analysis and the prediction residual is separated into a slowly evolving waveform (SEW) and a rapidly evolving waveform (REW) components. The SEW magnitude component is quantized using a hierarchical predictive vector quantization approach. The REW magnitude is quantized using a gain and a sub-band based shape. SEW and REW phases are derived at the decoder using a phase model, based on a transmitted measure of voice periodicity. The spectral (LSP) parameters are quantized using a combination of scalar and vector quantizers. The 4.0 kbits/s coder has an algorithmic delay of 60 ms and an estimated floating point complexity of 21.5 MIPS. The performance of this coder has been evaluated using in-house MOS tests under various conditions such as background noise. channel errors, self-tandem. and DTX mode of operation, and has been shown to be statistically equivalent to ITU-T (3.729 8 kbps codec across all conditions tested.
標(biāo)簽： frequency-domain interpolation performance Design kbit_s speech coder based and of
上傳時間： 2018-04-08
上傳用戶：kilohorse
Mobile communication devices like smart phones or tablet PCs enable us to consume information at every location and at every time. The rapid development of new applications and new services and the demand to access data in real time create an increasing throughput demand. The data have to be transmitted reliably to ensure the desired quality of service. Furthermore, an improved utilization of the bandwidth is desired to reduce the cost of transmission.
標(biāo)簽： Architectures Processing Baseband Signal for
上傳時間： 2020-05-26
上傳用戶：shancjb
Cognitive radio has emerged as a promising technology for maximizing the utiliza- tion of the limited radio bandwidth while accommodating the increasing amount of services and applications in wireless networks. A cognitive radio (CR) transceiver is able to adapt to the dynamic radio environment and the network parameters to maximize the utilization of the limited radio resources while providing flexibility in wireless access. The key features of a CR transceiver are awareness of the radio envi- ronment (in terms of spectrum usage, power spectral density of transmitted/received signals, wireless protocol signaling) and intelligence.
標(biāo)簽： Cognitive Wireless Network
上傳時間： 2020-05-26
上傳用戶：shancjb
OSCILLATORS are key building blocks in integrated transceivers. In wired and wireless communication terminals, the receiver front-end selects, amplifies and converts the desired high-frequency signal to baseband. At baseband the signal can then be converted into the digital domain for further data processing and demodula- tion. The transmitter front-end converts an analog baseband signal to a suitable high- frequency signal that can be transmitted over the wired or wireless channel.
標(biāo)簽： High-Frequency Oscillator Design
上傳時間： 2020-05-27
上傳用戶：shancjb
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