Multicarrier modulation

Large bandwidth penalty since the subcarriers can’t have perfectly rectangular pulse shapes and still be time-limited. Very high quality (expensive) low pass filters will be required to maintain the orthogonality of the subcarriers at the receiver.

27p nhq_khtn 07-11-2013 53 3   Download

The properties of Convolutional codes. We introduced interleaving as a means to combat bursty errors by making the channel seem uncorrelated. We also studied “Concatenated codes” that simply consist of inner and outer codes. They can provide the required performance at a lower complexity.

36p doanhung_dtvtk10 24-03-2013 70 6   Download

How decoding is performed for Convolutional codes? What is a Maximum likelihood decoder? What are soft decisions and hard decisions? How does the Viterbi algorithm work?The demodulator makes a firm or hard decision whether one or zero was transmitted and provides no other information for the decoder such as how reliable the decision is.

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Another class of linear codes, known as Convolutional codes. We studied the structure of the encoder and different ways for representing it.What are the state diagram and trellis representation of the code? How the decoding is performed for Convolutional codes? What is a Maximum likelihood decoder? What are the soft decisions and hard decisions? How does the Viterbi algorithm work?

28p doanhung_dtvtk10 24-03-2013 54 4   Download

Another class of linear codes, known as Convolutional codes. We study the structure of the encoder. We study different ways for representing the encoder.Convolutional codes offer an approach to error control coding substantially different from that of block codes. A convolutional encoder: encodes the entire data stream, into a single codeword. does not need to segment the data stream into blocks of fixed size (Convolutional codes are often forced to block structure by periodic truncation). is a machine with memory.

20p doanhung_dtvtk10 24-03-2013 48 4   Download

Evaluating the average probability of symbol error for different bandpass modulation schemes Comparing different modulation schemes based on their error performances.Transforming signals to improve communications performance by increasing the robustness against channel impairments (noise, interference, fading, ...)

43p doanhung_dtvtk10 24-03-2013 57 4   Download

Some bandpass modulation schemes MPAM, MPSK, MFSK, MQAM How to perform coherent and noncoherent detection.How to calculate the average probability of symbol error for different modulation schemes that we studied? How to compare different modulation schemes based on their error performances?

25p doanhung_dtvtk10 24-03-2013 71 4   Download

Another source of error due to filtering effect of the system: Intersymbol. interference (ISI) The techniques to reduce ISI. Pulse shaping to achieve zero ISI at the sampling time. Equalization to combat the filtering effect of the channel.Some bandpass modulation schemes used in DCS for transmitting information oer channel. MPAM, MPSK, MFSK, MQAM How to detect the transmitted information at the receiver. Coherent detection. Noncoherent detection.

27p doanhung_dtvtk10 24-03-2013 56 5   Download

Signal detection in AWGN channels Minimum distance detector. Maximum likelihood. Average probability of symbol error. Union bound on error probability. Upper bound on error probability based on the minimum distance.ISI in the detection process due to the filtering effects of the system Overall equivalent system transfer function

30p doanhung_dtvtk10 24-03-2013 66 6   Download

Given the observation vector , perform a mapping from to an estimate of the transmitted symbol, , such that the average probability of error in the decision is minimized.Signal vector is deterministic. Elements of noise vector are i.i.d Gaussian random variables with zeromean and variance . The noise vector pdf is

21p doanhung_dtvtk10 24-03-2013 61 5   Download

Receiver structure Impact of AWGN and ISI on the transmitted signal. Optimum filter to maximize SNR. Matched filter receiver and Correlator receiver.Demodulation and sampling: Waveform recovery and preparing the receivedl signal for detection: Improving the signal power to the noise power (SNR) using matched filter Reducing ISI using equalizerl Sampling the recovered waveform. Detection: Estimate the transmitted symbol based on the received sample

23p doanhung_dtvtk10 24-03-2013 64 8   Download

Transforming the information source to a form compatible with a digital system. Sampling. Aliasing. Quantization Uniform and non-uniform. Baseband modulation. Binary pulse modulation. M-ary pulse modulation. M-PAM (M-ary Pulse amplitude modulation).Assuming real time transmission and equal energy per transmission data bit for binary-PAM and 4-ary PAM

22p doanhung_dtvtk10 24-03-2013 70 8   Download

Important features of digital communication systems Some basic concepts and definitions such as as signal classification, spectral density, random process, linear systems and signal bandwidth.The first important step in any DCS: Transforming the information source to a form compatible with a digital syst

22p doanhung_dtvtk10 24-03-2013 76 8   Download

Communications is a process by which information is exchanged between individuals through a common system of symbols, signs, or behaviour “It is about communication between people; the rest is technology” Communication systems are reliable, economical and efficient means of communications Public switched telephone network (PSTN), mobile telephone communication (GSM, 3G, 4G...), broadcast radio or television, navigation systems, ... The course is aiming at introducing fundamental issues required for understanding and designing a (digital) communication system...

28p doanhung_dtvtk10 24-03-2013 81 7   Download

Tuyển tập báo cáo các nghiên cứu khoa học quốc tế ngành hóa học dành cho các bạn yêu hóa học tham khảo đề tài: Optimized Irregular Low-Density Parity-Check Codes for Multicarrier Modulations over Frequency-Selective Channels

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Tuyển tập báo cáo các nghiên cứu khoa học quốc tế ngành hóa học dành cho các bạn yêu hóa học tham khảo đề tài: Research Article Channel Equalization in Filter Bank Based Multicarrier Modulation for Wireless

18p dauphong20 10-03-2012 40 4   Download

Bài giảng "Truyền thông không dây - Giới thiệu" do Đặng Lê Khoa biên soạn trình bày các nội dung về: Giới thiệu hệ thống DCS (Digital Communication system); kênh truyền (Channel); định dạng và điều chế dải gốc (Formatting & Baseband modulation); bộ cân bằng, phân tập, và đan xen (Equalization, Diversity & Interleaving); mã hóa kênh (Channel coding); điều chế đa sóng mang (Multicarrier modulation); các kỹ thuật đa truy cập (Multiple Access Techniques); giới thiệu một số chuẩn trong truyền thông không dây.

7p nhq_khtn 12-03-2011 314 57   Download