EC 2401*** WIRELESS COMMUNICATION

Why Wireless Benefits – Mobility: Ability to communicate anywhere!! – Easier configuration, set up and lower installation cost Difficulties – Communication medium: Free space Noisy and unpredictable channel Broadcast channel, more user ->less BW per user – Higher equipment cost – Usually regulated spectrum and limited BW Techno-politic – Need backbone systems in order to function properly

Wireless Services

UNIT I SERVICES AND TECHNICAL CHALLENGES Objective: To study about different types of Wireless Services and frequency reuse. Types of Services, Requirements for the services, Multipath propagation, Spectrum Limitations, Noise and Interference limited systems, Principles of Cellular networks, Multiple Access Schemes.

TDMA FDMA CDMA

UNIT II WIRELESS PROPAGATION CHANNELS Objective: To learn propagation of em waves, type of channels and impact of channel over propagation. Propagation Mechanisms (Qualitative treatment), Propagation effects with mobile radio, Channel Classification, Link calculations, Narrowband and Wideband models.

UNIT III WIRELESS TRANSCEIVERS Objective: To study about different digital modulation techniques used in wireless communication Structure of a wireless communication link, Modulation and demodulation – Quadrature π/4-Differential Quadrature Phase Shift Keying, Offset-Quadrature  Phase Shift Keying, Phase Shift Keying, Binary Frequency Shift Keying, Minimum Shift Keying, Gaussian Minimum Shift Keying, Power spectrum and Error performance in fading channels.

Digital Fundamentals: The Sampling Theorem, Nyquist Sampling Key Digital Modulation Techniques: BPSK, OFDM, GMSK Spread Spectrum: DS-SS, FH-SS, Coding Gain, Fading Margins

UNIT IV SIGNAL PROCESSING IN WIRELESS SYSTEMS Objective: To learn error control coding techniques. Principle of Diversity, Macrodiversity, Microdiversity, Signal Combining Techniques, Transmit diversity, Equalisers- Linear and Decision Feedback equalisers, Review of Channel coding and Speech coding techniques.

The former counters the effects of time dispersion (ISI), while the latter reduces the depth and duration of the fades experienced by a receiver in a flat fading (narrowband) channel Channel Coding improves mobile communication link performance by adding redundant data bits in the transmitted message Channel coding is used by the Rx to detect or correct some (or all) of the errors introduced by the channel (Post detection technique)  Block code and convolutional code

The term equalization can be used to describe any signal processing operation that minimizes ISI [2]  Two operation modes for an adaptive equalizer: training and tracking  Three factors affect the time spanning over which an equalizer converges: equalizer algorithm, equalizer structure and time rate of change of the multipath radio channel  TDMA wireless systems are particularly well suited for equalizers

UNIT V ADVANCED TRANSCEIVER SCHEMES Objective: To study spread spectrum techniques Spread Spectrum Systems- Cellular Code Division Multiple Access Systems- Principle, Power control, Effects of multipath propagation on Code Division Multiple Access, Orthogonal Frequency Division Multiplexing – Principle, Cyclic Prefix, Transceiver implementation, Second Generation(GSM, IS–95) and Third Generation Wireless Networks and standards.

First Generation (AMPS) analog voice communication using frequency modulation. Second Generation (GSM) digital techniques and time-division multiple access (TDMA) or code-division multiple access (CDMA) Third Generation evolving from second-generation wireless systems will integrate services into one set of standards

ASSIGNMENTS? SEMINARS?