Influence of bandwidth restriction on the signal-to-noise performance of a modulated PCM/NRZ signal, part 2

Analyzing effects of bandlimiting on performance of digital transmission corrupted by additive white Gaussian noise by averaging and series expansio

VHF command system study

Solutions are provided to specific problems arising in the GSFC VHF-PSK and VHF-FSK Command Systems in support of establishment and maintenance of Data Systems Standards. Signal structures which incorporate transmission on the uplink of a clock along with the PSK or FSK data are considered. Strategies are developed for allocating power between the clock and data, and spectral analyses are performed. Bit error probability and other probabilities pertinent to correct transmission of command messages are calculated. Biphase PCM/PM and PCM/FM are considered as candidate modulation techniques on the telemetry downlink, with application to command verification. Comparative performance of PCM/PM and PSK systems is given special attention, including implementation considerations. Gain in bit error performance due to coding is also considered

Performance of MiMo-OFDM Systems in Rayleigh Channel

Along with the development of wireless communication makes the increasing demand for obtaining quality services and better range, bandwidth-efficient and reliable system. OFDM is a multicarrier transmission technique to overcome multipath fading, which may result in intersymbol interference (ISI). On the other hand there is the antenna system with the use of multiple antennas at the transmitter and receiver that can also be overcome multipath fading,ie Multiple Input Multiple Output (MIMO) to increase channel capacity and diversity gain. MIMO techniques used in this Final adaldah Space Time Block Code. Simulation aims to simulate and analyze the MIMO OFDM technique using space-time block code against the influence of the number of subcarriers and influence user speed in AWGN channel and Rayleigh. The simulation results based on the number of subcarriers in AWGN channel, the best performance is obtained by subcarrier number 256. With BPSK and QPSK modulation obtained BER = 6 10-4 when SNR 4 dB. Simulation based on Rayleigh channel obtained when BER = 9.7 10-5 with BPSK modulation. Based on the comparison of the greater frequency doppler given doppler frequency, resulting in BER generated even greater, because the state of the canal will be getting worse

Digital transmission systems operating over high frequency radio channels

Imperial Users onl

The Gaussian assumption in second-order estimation problems in digital communications

This paper deals with the goodness of the Gaussian assumption when designing second-order blind estimation methods in the context of digital communications. The low- and high-signal-to-noise ratio (SNR) asymptotic performance of the maximum likelihood estimator - derived assuming Gaussian transmitted symbols - is compared with the performance of the optimal second-order estimator, which exploits the actual distribution of the discrete constellation. The asymptotic study concludes that the Gaussian assumption leads to the optimal second-order solution if the SNR is very low or if the symbols belong to a multilevel constellation such as quadrature-amplitude modulation (QAM) or amplitude-phase-shift keying (APSK). On the other hand, the Gaussian assumption can yield important losses at high SNR if the transmitted symbols are drawn from a constant modulus constellation such as phase-shift keying (PSK) or continuous-phase modulations (CPM). These conclusions are illustrated for the problem of direction-of-arrival (DOA) estimation of multiple digitally-modulated signals.Peer ReviewedPostprint (published version

A Method of Non-Data-Aided Carrier Recovery with Modulation Identification

A non-data aided carrier recovery technique using modulation format identification is proposed. This technique can also be interpreted as a modulation identification method that is robust against static phase and frequency offsets. The performance of the proposed technique is studied and analytical expressions derived for the mean acquisition time to detect lock in the cases of M-PSK, M=2,4,8, and 16-QAM modulation, with respect to frequency offset and signal-to-noise ratio. The results are verified with Monte Carlo simulations. The main advantage of the proposed method lies in its simpler implementation and faster lock detection, when compared to conventional methods

Analysis of Single RF Performance on MIMO-OFDM System Using Turbo Code and V-BLAST MMSE Detection

Along with the passing time and recent technology, the advancement of information technology has been increased in the wireless technology. The common methods that are used in this wireless communication are MIMO (Multiple Input Multiple Output) and OFDM (Orthogonal Frequency Division Multiplexing). MIMO is a system stands for a couple antenna on the transmitter and receiver which are working on themultipath component. While OFDM (Orthogonal Frequency Division Multiplexing) is a transmission method using multicarrier technique, dividing spectrum frequency into a couple subcarrier. The combination of MIMO and OFDM results in a high-speed transfer data system. The Single RF has reduced the USAge of RF Front-End into a bigger matrix size in the conventional MIMO system. This final project will discuss about the Single RF system of MIMO-OFDM with the V-BLAST (Vertical Bell Laboratories Space-Time) and MMSE (Minimum Mean Square Error) detectionwhich is used to remove ISI (Intersymbol Interference) combined with theTurbo Code,where theTurbo Encoder that lies on the transmitter side is also theTurbo Decoder in the receiver side. MIMO-OFDM utilizesthe Single RF (Radio Frequency) basis. The test on this final project will include a Single RF antenna on the MIMO-OFDM system, MIMO-OFDM with the V-BLAST detector and MMSE MIMO-OFDM with the Turbo Code, by using 64 QAM modulation. The expected result is the analysis performance of the Single RF on the MIMO-OFDM system using Turbo Code and V-BLAST MMSEDetection. The system will be shown on theBit Error Rate (BER) toward the Signal to Noise Ratio (SNR)

Communications terminal breadboard

A baseline design is presented of a digital communications link between an advanced manned spacecraft (AMS) and an earth terminal via an Intelsat 4 type communications satellite used as a geosynchronous orbiting relay station. The fabrication, integration, and testing of terminal elements at each end of the link are discussed. In the baseline link design, the information carrying capacity of the link was estimated for both the forward direction (earth terminal to AMS) and the return direction, based upon orbital geometry, relay satellite characteristics, terminal characteristics, and the improvement that can be achieved by the use of convolutional coding/Viterbi decoding techniques

Intersymbol and Intercarrier Interference in OFDM Transmissions through Highly Dispersive Channels

This work quantifies, for the first time, intersymbol and intercarrier interferences induced by very dispersive channels in OFDM systems. The resulting achievable data rate for \wam{suboptimal} OFDM transmissions is derived based on the computation of signal-to-interference-plus-noise ratio for arbitrary length finite duration channel impulse responses. Simulation results point to significant differences between data rates obtained via conventional formulations, for which interferences are supposed to be limited to two or three blocks, versus the data rates considering the actual channel dispersion