Signal Processing for Communication Systems
Since you have landed on this page, probably you are looking for an opportunity to write for this website. I assume that you have looked around and you know that I take this website seriously. I am committed to adding value to my readers and to you as an author. I am currently accepting guest posts from … Read more
We live in the age of smart phones that can be loaded with numerous applications to communicate with each other. What’s next ? Where do we go from here ? Students at MIT Media Labs has answered the call with a novel approach of “Physical Telepresence” that provides the ability to remotely render shapes of … Read more
In this article, the relationship between SNR-per-bit (Eb/N0) and SNR-per-symbol (Es/N0) are defined with respect to M-ary signaling schemes. Then the complex baseband model for an AWGN channel is discussed, followed by the theoretical error rates of various modulations over the additive white Gaussian noise (AWGN) channel. Finally, the complex baseband models for digital modulators … Read more
Focus of this article is to discuss the details of Gold code generator using preferred pair m-sequences, implemented using linear feedback shift registers (LFSR). Finally we plot and investigate correlation properties of the generated Gold codes. Introduction In a multi-user environment (like spread spectrum, CDMA ) large number of codes with good correlation properties, is … Read more
Auto-correlation, also called series correlation, is the correlation of a given sequence with itself as a function of time lag. Cross-correlation is a more generic term, which gives the correlation between two different sequences as a function of time lag. Given two sequences $latex x$ and $latex y$, the cross-correlation at times separated by lag … Read more
This article focused on constructing constellation for rectangular QAM modulation using Karnaugh-map walks. Exploit inherent property of Karnaugh-maps to construct Gray coded QAM constellation points. M-ary Quadrature Amplitude Modulation (M-QAM) In MQAM modulations, the information bits are encoded as variations in the amplitude and the phase of the signal. The M-QAM modulator transmits a series … Read more
As reiterated in the previous article, a MIMO system is used to increase the capacity dramatically and also to improve the quality of a communication link. Increased capacity is obtained by spatial multiplexing and increased quality is obtained by diversity techniques (Space time coding). Capacity of MIMO system over a variety of channels (AWGN, fading … Read more
Understand ergodic capacity of a SISO flat-fading system over fading channels. Model and simulate capacity curves in Matlab. Channel model In the previous post, derivation of SISO fading channel capacity was discussed. For a flat fading channel (model shown below), with the perfect knowledge of the channel at the receiver, the capacity of a SISO … Read more
As reiterated in the previous article, a MIMO system is used to increase the capacity dramatically and also to improve the quality of a communication link. Increased capacity is obtained by spatial multiplexing and increased quality is obtained by diversity techniques (Space time coding). Capacity equations of a MIMO system over a variety of channels … Read more
Two flavors of MIMO implementation – spatial multiplexing and spatial diversity – were discussed in the previous article. In that, it was mentioned that the reliability of a MIMO system is governed by diversity and the capacity of the link is governed by degrees of freedom. Channel State Information (CSI) Multiple data streams can be … Read more