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Link budget

About: Link budget is a research topic. Over the lifetime, 1355 publications have been published within this topic receiving 19738 citations.


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Proceedings ArticleDOI
11 Dec 2006
TL;DR: This work proposes light-weight cooperation in sensing based on hard decisions to mitigate the sensitivity requirements on individual radios and shows that the "link budget" that system designers have to reserve for fading is a significant function of the required probability of detection.
Abstract: Cognitive Radios have been advanced as a technology for the opportunistic use of under-utilized spectrum since they are able to sense the spectrum and use frequency bands if no Primary user is detected. However, the required sensitivity is very demanding since any individual radio might face a deep fade. We propose light-weight cooperation in sensing based on hard decisions to mitigate the sensitivity requirements on individual radios. We show that the "link budget" that system designers have to reserve for fading is a significant function of the required probability of detection. Even a few cooperating users (~10-20) facing independent fades are enough to achieve practical threshold levels by drastically reducing individual detection requirements. Hard decisions perform almost as well as soft decisions in achieving these gains. Cooperative gains in a environment where shadowing is correlated, is limited by the cooperation footprint (area in which users cooperate). In essence, a few independent users are more robust than many correlated users. Unfortunately, cooperative gain is very sensitive to adversarial/failing Cognitive Radios. Radios that fail in a known way (always report the presence/absence of a Primary user) can be compensated for by censoring them. On the other hand, radios that fail in unmodeled ways or may be malicious, introduce a bound on achievable sensitivity reductions. As a rule of thumb, if we believe that 1/N users can fail in an unknown way, then the cooperation gains are limited to what is possible with N trusted users.

1,562 citations

Book
20 Sep 2005
TL;DR: In this paper, the authors present a review of the probability of propagation of electromagnetic signals in the presence of electromagnetic fields and their effects on the physical environment, as well as the link budget.
Abstract: Preface. 1. Introduction. 1.1 Frequency Designations. 1.2 Modes of Propagation. 1.3 Why Model Propagation? 1.4 Model Selection and Application. 1.4.1 Model Sources. 1.5 Summary. 2. Electromagnetics and RF Propagation. 2.1 Introduction. 2.2 The Electric Field. 2.3 The Magnetic Field. 2.4 Electromagnetic Waves. 2.5 Wave Polarization. 2.6 Propagation of Electromagnetic Waves at Material Boundaries. 2.7 Propagation Impairment. 2.8 Ground Effects on Circular Polarization. 2.9 Summary. 3. Antenna Fundamentals. 3.1 Introduction. 3.2 Antenna Parameters. 3.3 Antenna Radiation Regions. 3.4 Some Common Antennas. 3.5 Antenna Polarization. 3.6 Antenna Pointing loss. 3.7 Summary. 4. Communication Systems and the Link Budget. 4.1 Introduction. 4.2 Path Loss. 4.3 Noise. 4.4 Interference. 4.5 Detailed Link Budget. 4.6 Summary. 5. Radar Systems. 5.1 Introduction. 5.2 The Radar Range Equation. 5.3 Radar Measurements. 5.4 Clutter. 5.5 Atmospheric Impairments. 5.6 Summary. 6. Atmospheric Effects. 6.1 Introduction. 6.2 Atmospheric Refraction. 6.3 Atmospheric Attenuation. 6.4 Loss From Moisture and Precipitation. 6.5 Summary. 7. Near-Earth Propagation Models. 7.1 Introduction. 7.2 Foliage Models. 7.3 Terrain Modeling. 7.4 Propagation in Built-Up Areas. 7.5 Summary. 8. Fading and Multipath Characterization. 8.1 Introduction. 8.2 Ground-Bounce Multipath. 8.3 Large-Scale or Log-Normal Fading. 8.4 Small-Scale Fading. 8.5 Summary. 9. Indoor Propagation Modeling. 9.1 Introduction. 9.2 Interference. 9.3 The Indoor Environment. 9.4 Summary. 10. Rain Attenuation of Microwave and Millimeter Wave Signals. 10.1 Introduction. 10.2 Link Budget. 10.3 Rain Fades. 10.4 The Link Distance Chart. 10.5 Availability Curves. 10.6 Other Precipitation. 10.7 Cross-Polarization Effects. 10.8 Summary. 11. Satellite Communications. 11.1 Introduction. 11.2 Satellite Orbits. 11.3 Satellite Operating Frequency. 11.4 Satellite Path Free-Space Loss. 11.5 Atmospheric Attenuation. 11.6 Ionospheric Effects. 11.7 Rain Fades. 11.8 Antenna Considerations. 11.10 Summary. 12. RF Safety. 12.1 Introduction. 12.2 Biological Effects of RF Exposure. 12.3 CC Guidelines. 12.4 Antenna Considerations. 12.5 FCC Computations. 12.6 Station Evaluations. 12.7 Summary. Appendix A: Review of Probability for Propagation Modeling. Index.

742 citations

Proceedings ArticleDOI
18 May 1998
TL;DR: A space-time coded orthogonal frequency division multiplexing (OFDM) modulated physical layer is designed which combines coding and modulation and is attractive for delay-sensitive applications.
Abstract: There has been an increasing interest in providing high data-rate services such as video-conferencing, multimedia Internet access and wide area network over wideband wireless channels. Wideband wireless channels available in the PCS band (2 GHz) have been envisioned to be used by mobile (high Doppler) and stationary (low Doppler) units in a variety of delay spread profiles. This is a challenging task, given the limited link budget and severity of wireless environment, and calls for the development of novel robust bandwidth efficient techniques which work reliably at low SNRs. To this end, we design a space-time coded orthogonal frequency division multiplexing (OFDM) modulated physical layer. This combines coding and modulation. Space-time codes were previously proposed for narrowband wireless channels. These codes have high spectral efficiency and operate at very low SNR (within 2-3 dB of the capacity). On the other hand, OFDM has matured as a modulation scheme for wideband channels. We combine these two in a natural manner and propose a system achieving data rates of 1.5-3 Mbps over a 1 MHz bandwidth channel. This system requires 18-23 dB (resp. 9-14 dB) receive SNR at a frame error probability of 10/sup -2/ with two transmit and one receive antennas (resp. two transmit and two receive antennas). As space-time coding does not require any form of interleaving, the proposed system is attractive for delay-sensitive applications.

599 citations

Journal ArticleDOI
TL;DR: A survey of the mmWave propagation characteristics, channel modeling, and design guidelines, such as system and antenna design considerations for mmWave, including the link budget of the network, which are essential for mm Wave communication systems design is presented.
Abstract: The millimeter wave (mmWave) frequency band spanning from 30 to 300 GHz constitutes a substantial portion of the unused frequency spectrum, which is an important resource for future wireless communication systems in order to fulfill the escalating capacity demand. Given the improvements in integrated components and enhanced power efficiency at high frequencies, wireless systems can operate in the mmWave frequency band. In this paper, we present a survey of the mmWave propagation characteristics, channel modeling, and design guidelines, such as system and antenna design considerations for mmWave, including the link budget of the network, which are essential for mmWave communication systems. We commence by introducing the main channel propagation characteristics of mmWaves followed by channel modeling and design guidelines. Then, we report on the main measurement and modeling campaigns conducted in order to understand the mmWave band’s properties and present the associated channel models. We survey the different channel models focusing on the channel models available for the 28, 38, 60, and 73 GHz frequency bands. Finally, we present the mmWave channel model and its challenges in the context of mmWave communication systems design.

512 citations

Journal ArticleDOI
TL;DR: Antenna-on-chip (AoC) and antenna-in-package (AiP) solutions are studied for highly integrated millimeter-wave (mmWave) devices in wireless communications and the systems level pros and cons are highlighted from the electrical and economic perspectives for system designers.
Abstract: Antenna-on-chip (AoC) and antenna-in-package (AiP) solutions are studied for highly integrated millimeter-wave (mmWave) devices in wireless communications. First, the background, regulations, standard, and applications of 60-GHz wireless communications are briefly introduced. Then, highly integrated 60-GHz radios are overviewed as a basis for the link budget analysis to derive the antenna gain requirement. Next, in order to have deep physical insight into the AoC solution, the silicon substrate's high permittivity and low resistivity effects on the AoC efficiency are examined. It is shown that the AoC solution has low efficiency, less than 12% due to large ohmic losses and surface waves, which requires the development of techniques to improve the AoC efficiency. After that, the AiP solution and associated challenges such as how to realize low-loss interconnection between the chip and antenna are addressed. It is shown that wire-bonding interconnects, although inferior to the flip-chip, are still feasible in the 60-GHz band if proper compensation schemes are utilized. An example of the AiP solution in a low-temperature cofired ceramic (LTCC) process is presented in the 60-GHz band showing an efficiency better than 90%. A major concern with both AoC and AiP solutions is electromagnetic interference (EMI), which is also discussed. Finally, the systems level pros and cons of both AoC and AiP solutions are highlighted from the electrical and economic perspectives for system designers.

497 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
202329
202284
202161
202092
2019103
2018106