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Modulation and Demodulation. Introduction. A communication system that sends information between two locations consists of a transmitter, channel, and receiver as illustrated in Figure 1. The channel refers to the physical medium carrying the information signal (voice, video, data etc.) from one location to another.
Dec 23, 2021 · Definition. Modulation is a process of mixing a signal with a sinusoid to produce a new signal. This new signal, conceivably, will have certain benefits over an un-modulated signal. Mixing of low frequency signal with high frequency carrier signal is called modulation.
- Signal Retrieval and Communication
- Major Events
- Block Diagram of a Communication System
- Components of Block Diagram
- Channel Characteristics
- Characteristics
- Traffic offloading
- Spectrum extension
- Major Issues
- Characteristics
- Systems Analysis Techniques
- Probabilistic Approaches to System Optimization
Theory of systems for the conveyance of information Characteristics of communication systems Uncertainty Noise and “information” (deterministic vs probabilistic) Keep in mind: Signal retrieval problem Communication (only particular type of signal retrieval problem) Usually two resources to consider Bandwidth vs. Power
Innovations in microelectronics, signal processing, information theory have led to the proliferation of communication systems Major Events Major Events Which OSI Layer Will We Focus On?
Keep in mind that this is only a model! Can we make it simpler? More complicated? Consequences?
Input transducer Messages Analog or digital Message conversion E.g. speech voltage variations Transmitter Couple the message to the channel Modulation, filtering, amplification, and coupling Modulation For the ease of radiation To reduce noise and interference For channel assignment For multiplexing or transmission of several messages over a sing...
Channel Signal degradation (convolutive noise) Additive “noise” Sensor noise, thermal noise, interference (e.g. MUI, jammer, ...) Receiver Demodulation, amplification Output transducer Loudspeaker, tape recorder, PCs, CRT, LCD, etc. Channel Characteristics Additive noise sources (usu. less troublesome) Internal noise Noise generated by components w...
Large frequency reuse factor Performance enhanced by increasing spectrum efficiency
(alternative means for communications) WiFi offload, D2D, etc. Dense urban Shopping mall Non-orthogonal multiple access controller Massive MIMO, advanced receiver Multiple access technologies with Tx-Rx cooperative interference cancellation Current capacity
Existing cellular bands Home/office Cellular network assists local area radio access New cellular concept for cost/energy efficient dense deployment Very wide Super wide Hybrid access using coverage and capacity spectrum bands frequency
Effective backhaul design Mitigating relay to macrocell interference
Wired backhaul User-deployed Closed/open/hybrid access
Time and frequency domain analyses Looking at things from different perspective Modulation and communication theories Modulation theory employs time and frequency domain analyses to analyze and design systems for modulating and demodulating of information-bearing signals Analysis of interfering signals on system performance, and design of systems t...
As seen earlier, proper modeling of (additive and convolutive) noise (incl. interference) is important Probabilistic models are often used Why? Design Optimal design is crucial Many “optimal” design are not optimal – depends on perspective How do we do it? (We are engineers, this is important!) Statistical signal detection and estimation theory Wi...
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Showcasing the essential principles behind modern communication systems, this accessi-ble undergraduate textbook provides a solid introduction to the foundations of communi-cation theory. Carefully selected topics introduce students to the most important and fundamental con-
The idea of layering in communication systems is to break up communication functions into a string of separate layers as illustrated in Figure 1.2. Each layer consists of an input module at the input end of a communcation system and a ‘peer’ output module at the other end. The input module at layer i processes the information received
A two-node, one-way communication system consists of the channel that conveys the waves, together with a modulator and a demodulator. All communications systems can be regarded as aggregates of these basic two-node units.
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6.1 Introduction. Digital modulation (or channel encoding) is the process of converting an input sequence of bits into a waveform suitable for transmission over a communication channel. Demodulation (channel decoding) is the corresponding process at the receiver of converting the received waveform into a (perhaps noisy) replica of the input bit ...
