Two-ray ground reflection model — path loss with LOS and ground bounce
Two-ray ground reflection: direct plus ground-reflected rays, breakpoint distance, and why path loss approaches 40 dB/decade at large range.
Hata Okumura model for outdoor propagation
Outdoor propagation models involve estimation of propagation loss over irregular terrains such as mountainous regions, simple curved earth profile, etc., with obstacles like trees and buildings. All such models predict the received signal strength at a particular distance or on a small sector. These models vary in approach, accuracy and complexity. Hata Okumura model is … Read more
Large scale propagation models – an introduction
Radio propagation models play an important role in designing a communication system for real world applications. Propagation models are instrumental in predicting the behavior of a communication system over different environments. This chapter is aimed at providing the ideas behind the simulation of some of the subtopics in large scale propagation models, such as, free … Read more
Simulate matched filter system with SRRC filtering
Pulse-shaping Lab path:Nyquist zero-ISI → Raised cosine → Matched filter + SRRC → Eye diagramsTool: RRC filter & bandwidth calculator Key focus: Let’s learn how to simulate matched filter receiver with square root raised cosine (SRRC) filter, for a pulse amplitude modulation (PAM) system. Simulation Model A basic pulse amplitude modulation (PAM) system as DSP … Read more
Precoding for partial response signaling schemes
Introduction to precoding Intersymbol interference (ISI) is a common problem in telecommunication systems, such as terrestrial television broadcasting, digital data communication systems, and cellular mobile communication systems. Dispersive effects in high-speed data transmission and multipath fading are the main reasons for ISI. To maximize the capacity, the transmission bandwidth must be extended to the entire … Read more
Partial response schemes: impulse & frequency response
Impulse response and frequency response of PR signaling schemes Consider a minimum bandwidth system in which the filter $latex H(f)$ is represented as a cascaded combination of a partial response filter $latex Q(f)$ and a minimum bandwidth filter $latex G(f)$. Since $latex G(f)$ is a brick-wall filter, the frequency response of the whole system $latex … Read more
Partial response (PR) signaling Model
Consider the generic baseband communication system model and its equivalent representation, shown in Figure 1, where the various blocks in the system are represented as filters. To have no ISI at the symbol sampling instants, the equivalent filter $latex H(f)$ should satisfy Nyquist’s first criterion. If the system is ideal and noiseless, it can be … Read more
Construction of Eye Diagrams from Signals Represented in Computer Memory
Pulse-shaping Lab path:Nyquist zero-ISI → Raised cosine → Matched filter + SRRC → Eye diagramsTool: RRC filter & bandwidth calculator In digital communications, an eye diagram (or eye pattern) is one of the most intuitive and powerful diagnostic tools for evaluating signal quality. Formed by overlapping consecutive symbol traces of a modulated signal over a … Read more
Square-root raised-cosine (SRRC) pulse shaping — matched filtering and ISI
Why SRRC is used at Tx and Rx: matched filtering, overall raised-cosine Nyquist pulse, roll-off α, and links to the RRC tool.
Raised cosine pulse shaping
Pulse-shaping Lab path:Nyquist zero-ISI → Raised cosine → Matched filter + SRRC → Eye diagramsTool: RRC filter & bandwidth calculator As mentioned earlier, the shortcomings of the sinc pulse can be addressed by making the transition band in the frequency domain less abrupt. The raised-cosine (RC) pulse comes with an adjustable transition band roll-off parameter … Read more