Signal Processing in Communication Systems

Contents

• Part 1: Signal detection (with ISI and noise): a review

Modulation. - PAM baseband. Nyquist criterion. PAM passband. Matched filter. - Orthogonal pulse modulation: generalized Nyquist criterion. - PAM - orthogonal pulses combination: Multicarrieer modulation. CDMA.

Minimum distance design. - Signal space. - Minimum distance based design. - Use with different modulations - isolated pulses - pulses with ISI. - Bandwidth and dimensionality.

Noise performance with minimum distance design. - Error probability: general results. - PAM probability of error. - Minimum distance performance: PAM isolated pulse. Orthogonal pulses. PAM - orthogonal pulses combination. - Minimum distance performance for PAM with ISI. - Spread spectrum.

Optimum detection. - Isolated symbol detection. - Vector signal detection. - Known signal in Gaussian noise. - Non coherent optimum detection. - PAM with ISI optimum detection. - Sequence detection: Viterbi algorithm.

Optimum and adaptive equalization. - Zero ISI criterion. - Generalized equalization methods. - Fractional space equalization. FIR equalizers. - ISI and channel capacity. - Reduced complexity equalization. Adaptive linear equalizer. - Adaptive decision feedback equalizer. - Passband equalization.

• Part 2: Some concepts of wireless communication

The wireless channel - Large and small scale fading - Physical models. Complex baseband equivalent channel. Multipath resolution - Flat and frequency selective fading - Doppler spread. Correlation over time.

Diversity - AWGN versus Rayleigh flat fading channel. Degrees of freedom - Time Diversity. Repetition coding and beyond - Antena Diversity. Receive and transmit diversity. Stpace-time codes: Alamouti - Frequency Diversity. Approaches: time domain equalization. DSSS. OFDM

Cellular systems: Multiple access and interference management - Narrowband systems and frequency reuse. - Wideband systems: CDMA (power control - interference averaging) - Wideband systems: OFDMA (in-cell orthogonality, out-of-cell interference averaging)

Capacity of Wireless Channels - AWGN channel: power and bandwidth limited regions - Slow flat fading channel. Receive diversity. Transmit diversity - Slow frequency selective channel. Waterfilling in frequency domain. Time diversity - Fast fading channel. Capacity with full CSI: waterfilling. Waterfilling vs channel inversion

• Part 3: A case of study: OFDMA synchronization techniques

Introduction - motivation. - OFDM system- Discrete model - Spectral efficiency - Characteristics - OFDM based multiple access schemes - OFDM Sensitivity to synchronization errors.

WiMAX - OFDMA basics - WIMAX OFDMA characteristics - WIMAX frame structure

Downlink time and CFO synchronization - OFDMA transmitter - Downlink synchronization tasks - Downlink acquisition (coarse synchronization) - Downlink tracking (fine synchronization)

Uplink synchronization - Uplink signal model - Synchronization estimation for different CAS (subband, interleaved, generalized) - Synchronization compensation for different CAS

Initial ranging estimation - Signal model and system description - Estimation of timing delays and CFOs.