Introduction
Over the past two decades, a major transistion has occurred from analog modulation to digital modulation techniques in communication systems. Moreover, while communication systems were initially established as voice networks, they now have to accomodate computer data as well as multimedia content. And, as more and more users join the communication network the need for efficient use of available bandwidth in the RF spectrum becomes even more important. Especially given that every service provider has to pack much data as possible - into the alloted RF bandwidth - to meet establishment expenses and recurring spectrum license fees.
Digital modulation techniques provide more information carrying capacity, better quality communication, data security and RF spectrum sharing to accomodate more services when compared to analog modulation. All modern communication systems and gadgets today use various forms of digital modulation techniques, such as PSK, MSK, QAM as well multiplexing techniques such as TDMA and CDMA, to pack more in the available RF bandwidth.
Digital modulations are often expressed in terms of I (in-phase) and Q (quadrature) signals, and all modern digital communication systems and gadgets have three main blocks namely:
- Data processing block
- ADC and DAC conversion block
- RF block
All the blocks process the I and Q signals simultaneously, leading to the use of complex algebra and analysis in their design and implementation. This standardized and uniform approach in buliding digital communication systems or gadgets results in lower cost of development and manufacturing. The focus is also turned towards adding more features and bringing in more techniques within the available RF spectrum.
The Benchmark WiCOMM-T - the ultimate Wireless Digital communication Training Platform - is the actual implementation of modern digital communication systems with direct interface to MATLAB through the Hi-Speed USB port of a PC.
The WiCOMM-T provides maximum flexibility in learning complete digital communication system concepts, which includes digital modulation techniques, Baseband Equaliztion, Filtering concepts, and the basics of CDMA, GSM etc. MATLAB codes of all suggested experiment topics are available to users as reference. A MATLAB interface to the platform also allows users to try out other topics on their own.
Features
- Typical implementation of modern communication systems
- Interface with MATLAB
- Gives the ability to generate required signal and pass it through the transmitter and receiver providing a real life wireless digital communication system
- Comprehensive mannual - describes wide range of experiments
- Loop back options at Baseband and at IF
Experiments
Baseband Digital Communication Link (Baseband loop back)
- Rasied Cosine spectrum pulses
- Timing acquisition algorithm
- Clock tracking & slip control
- Matched filtering, Root raised cosine spectrum pulses - performance in noise
Quadrature Modulation Schemes (Baseband & IF)
- QPSK (Phase and frequency offset)
- Constellation plots
- Carrier recovery algorithm
- Carrier and Clock Tracking
Adaptive Equalization Techniques (Baseband & IF)
- Adaptive linear equaliser
- Adaptive decision feedback equaliser
- MSE convergence
- Decision aided channel tracking
GSM (Baseband)
- GMSK modulation and demodulation
- Viterbi equaliser for GSM
Basics of DS-CDMA (Baseband & IF)
- Orthogonal and non-orthogonal spreading codes
- Multipath channel estimation for RAKE reciever
- SER performance of RAKE combiner
Basics of OFDM (Baseband & IF)
- Timing and frequency synchronisation
- Channel estimation using fft processing
- Channel estimation using modified LS
- Mean Square Error Performance
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