Fundamental Reform in Public Safety Communications Policy

Symposium: The Crisis in Public Safety Communications. Held at the Mercatus Center at George Mason University, December 8, 2006. The communications systems used by first responders in the U.S. are inadequate, primarily because of outdated and ineffective public policy. Fundamental reform is needed, and the upcoming digital TV transition provides an outstanding opportunity. This Article describes options available to policymakers, if they act soon

Impact of considering the ITU-R two slope propagation model in the system capacity trade-off for LTE-A HetNets with small cells

This work aims at understanding and evaluating the impact of using different path loss models in the optimization trade-off of small cell (SC) networks. In LTE-A, the more realistic propagation models are the more efficient the radio and network optimization becomes. In this work we compare four urban path loss models: the urban/vehicular and pedestrian test environment from the ITU-R M. 1255 Report as well as the two slope Micro Urban Line-of-Sight (LoS) and Non-Line-of-Sight (NLoS) from the ITU-R 2135 Report. The two-slope model considers the existence of a breakpoint in the behaviour of the path loss and yields a significantly lower throughput per square km than a traditional one-slope model if and only if cell radius is small (coverage distances, R, up to breakpoint distance divided by the reuse pattern).info:eu-repo/semantics/publishedVersio

Impact of propagation model on capacity in small-cell networks

This work evaluates the impact of different path loss models on capacity of small cell (SC) networks, including the relationship between cell size and capacity. We compare four urban path loss models: the urban/vehicular and pedestrian test environment from the ITU-R M. 1255 Report, and the two-slope Micro Urban Line-of-Sight (LoS) and Non-Line-of-Sight (NLoS) models from the ITU-R 2135 Report. We show that when using the ITU-R two-slope model that considers the existence of a break-point in the behaviour of path loss, for coverage distances, R, up to break-point distance divided by reuse factor, supported cell throughput, Rb-sup, is much lower than expected when traditional single-slope models are assumed. For Rs longer than dBP/rcc the results for Rb-sup increase with R, whereas they are steady or decrease with R when using the traditional single-slope propagation models. We conclude that the two-slope propagation model yields a significantly lower throughput per square km than a traditional one-slope model if and only if cell radius is small.info:eu-repo/semantics/publishedVersio

Impact of the propagation model on the capacity in small‐cell networks: comparison between the UHF/SHF and the millimetre wavebands

This work shows how both frequency and the election of path loss model affect estimated spectral efficiency. Six different frequency bands are considered, ranging from 2.6 GHz in the Ultra High Frequency (UHF) band to 73 GHz in the millimetre wave bands (mmWaves), using both single-slope and two-slope path-loss models. We start by comparing four ur ban path loss models for UHF: the urban/vehicular and pedestrian test environment from the ITU-R M. 1255 Report, which includes the two-slope urban micro line-of-sight (LoS) and NLoS, from the ITU-R 2135 Report. Then, we consider mmWaves taking into con26 sideration the modified Friis propagation model, followed by an analysis of the through put for the 2.6, 3.5, 28, 38, 60 and 73 GHz frequency bands. We have found that the signal to-interference-plus-noise ratio, as estimated with the more realistic two-slope model, is lower for devices that are within the break-point of the transmitter, which is a small dis tance in the UHF/SHF band. As a result, spectral efficiency is higher with mmWaves than with UHF/SHF spectrum when cell radius is under 40 meters but not when cells are larger. Consequently, mmWaves spectrum will be more valuable as cells get small. We also find that capacity as estimated with the two-slope model is considerably smaller than one would obtain with the one-slope model when cells are small but there is little difference in the models when cells are larger. Thus, as cells get smaller, the use of one slope models may underestimate the number of cells that must be deployed.info:eu-repo/semantics/acceptedVersio

Bringing Connected Vehicle Communications to Unlicensed Spectrum

69A3551747111This paper proposes an alternative strategy that could meet the needs of both connected vehicles and Wi-Fi 6 by allowing them to share spectrum under an appropriate set of coexistence rules. This could be achieved through changes in spectrum regulations, modest changes in technology for those C-V2X devices that operate in the shared band, and no changes to Wi-Fi. This would give C-V2X devices access to spectrum that is adjacent to the ITS band (which was part of the ITS band until recently), while giving Wi-Fi 6 devices the contiguous 160 MHz that they need, all without modification to devices that have already been deployed. For simplicity we talk of \u201cC-V2X\u201d in this paper, but our approach is likely to apply similarly to successors of C-V2X, starting with 5G NR-V2X [6]. Our approach also supports sharing between C-V2X and unlicensed devices other than Wi-Fi, although this may require some change in how those devices access spectrum