Adaptive equalization compensating for channel distortions in a 16-QAM comms link
Based on the core VisSim engine, VisSim/Comm) is used for the modeling and simulating end-to-end communication systems at the signal or physical level. With a full complement of communication blocks and a powerful, time-domain simulation engine, VisSim/Comm provides fast and accurate solutions for analog, digital, and mixed-mode communication system designs. The communication block set includes RF, UWB, Bluetooth, 802.x, Turbo Codes, Costas loop, PLL, VCO, BPSK, QPSK, DQPSK, QAM, BER, Eye Diagram, Viterbi, Reed-Solomon and much more. VisSim/Comm was rebadged as "Commsim" by Electronic Workbench and sold by them for a number of years.
Typical Data Communication Link Simulation
Using VisSim/Comm, you can freely move among the stages of model construction, simulation, optimization, and validation. This tightly integrated development platform allows you to simulate and view signal waveforms at any stage of the communication system chain. And all modeling and simulation tasks can be completed without writing a line of code. In short, VisSim/Comm makes it easy to build, modify and maintain even the most complex system models. Ericsson Inc., a leading developer and manufacturer of cellular and PCS consumer electronics, has been using VisSim/Comm for years in their research and development efforts.
Transmitter and Receiver Models
Communication system design can be divided into two categories: transmitter design and receiver design. VisSim/Comm lets you build both transmitter and receiver models, from a first principles perspective, by simply selecting and connecting predefined blocks. You can construct a wide range of models including analog, digital and mixed mode designs, and quickly simulate their behavior. The VisSim/Comm block set provides a variety of modulators and demodulators, including standard analog, PSK, QAM and differential formats. Full support is also provided for the design of phase locked loops, including loop filter and VCO elements.
Encoders and RF Components
For designs where encoding is required, VisSim/Comm supports both conventional coding techniques (convolutional, Reed-Solomon, trellis-based) as well as more advanced methods such as the UMTS or LTE Turbo Codes. In addition, for designs that require the modeling of RF components, VisSim/Comm provides models for amplifiers, mixers, splitters, attenuators, couplers, and switches, including noise figure and nonlinear effects.
Channel Distortion Fading and Echos
VisSim/Comm includes a variety of predefined channel models supporting both fixed and mobile service scenarios. Included are fading, multipath, bandlimited, and Gaussian noise models:
- AWGN (real and complex, scalar and vector)
- Binary Symmetric
- Jakes Mobile
- Rummler and standard Multipath
- Propagation loss
- Rice/Rayleigh Fading
- Saleh-Valenzuela (real and complex)
- TWTA (calculated and table lookup)
You can modify VisSim/Comm block parameters to suit their specific system. You can also create custom models by forming new compound blocks or developing custom blocks using the built-in VisSim block wizard.