In this tutorial survey the principles of radio propagation in indoor environments are reviewed. The channel is modeled as a linear time-varying filter at each location in the three-dimensional space, and the properties of the filter's impulse response are described. Theoretical distributions of the sequences of arrival times, amplitudes and phases are presented. Other relevant concepts such as spatial and temporal variations of the channel, large-scale path losses, mean excess delay and RMS delay spread are explored. Propagation characteristics of the indoor and outdoor channels are compared and their major differences are outlined. Previous measurement and modeling efforts are surveyed, and areas for future research are suggested. >

The indoor radio propagation channel

Ultra-wideband millimeter-wave (mmWave) propagation measurements were conducted in the 28- and 73-GHz frequency bands in a typical indoor office environment in downtown Brooklyn, New York, on the campus of New York University. The measurements provide large-scale path loss and temporal statistics that will be useful for ultra-dense indoor wireless networks for future mmWave bands. This paper presents the details of measurements that employed a 400 Megachips-per-second broadband sliding correlator channel sounder, using rotatable highly directional horn antennas for both co-polarized and crosspolarized antenna configurations. The measurement environment was a closed-plan in-building scenario that included a line-of-sight and non-line-of-sight corridor, a hallway, a cubicle farm, and adjacent-room communication links. Well-known and new single-frequency and multi-frequency directional and omnidirectional large-scale path loss models are presented and evaluated based on more than 14 000 directional power delay profiles acquired from unique transmitter and receiver antenna pointing angle combinations. Omnidirectional path loss models, synthesized from the directional measurements, are provided for the case of arbitrary polarization coupling, aswell as for the specific cases of co-polarized and cross-polarized antenna orientations. The results show that novel large-scale path loss models provided here are simpler and more physically based compared to previous 3GPP and ITU indoor propagation models that require more model parameters and offer very little additional accuracy and lack a physical basis. Multipath time dispersion statistics formmWave systems using directional antennas are presented for co-polarization, crosspolarization, and combined-polarization scenarios, and show that the multipath root mean square delay spread can be reduced when using transmitter and receiver antenna pointing angles that result in the strongest received power. Raw omnidirectional path loss data and closed-form optimization formulas for all path loss models are given in the Appendices.

/pdf/indoor-office-wideband-millimeter-wave-propagation-4ogeybcgki.pdf

Indoor Office Wideband Millimeter-Wave Propagation Measurements and Channel Models at 28 and 73 GHz for Ultra-Dense 5G Wireless Networks

The future of third-generation wireless networking is discussed. The vision of the third generation is a single set of standards that can meet a wide range of wireless access applications. Third-generation systems, in harmony with broadband integrated services digital networks, will use shared resources to convey many information types. A single network architecture will serve its users efficiently in many environments, including moving vehicles, indoor and outdoor public areas, residences, offices, and factories. A study of a switching architecture, referred to as a cellular packet switch, and a packet transmission technique, referred to as a packet reservation multiple access is discussed. By means of a design example, it is shown how these techniques can work together to meet some of the demands of third-generation systems. >

Cellular packet communications

The single most important factor enabling the data rate increases in wireless networks over the past few decades has been densification, namely adding more base stations and access points and thus getting more spatial reuse of the spectrum. This trend is set to continue into 5G and beyond. However, at some point further densification will no longer be able to provide exponentially increasing data rates. Like the end of Moore’s Law, this will have extensive implications for the entire technology landscape, which depends ever more heavily on wireless connectivity. When and why will this happen? How might we delay this from occurring for as long as possible? These are the questions explored in this article.

Are we approaching the fundamental limits of wireless network densification

Using dynamic channel assignment (DCA) algorithms to select communications channels as needed, time-division multiple access (TDMA) or frequency-division multiple access (FDMA) systems can serve dynamic and nonuniform traffic demands without frequency planning as long as quality is sufficient and equipment is available. Here, performance issues and algorithms for DCA in a TDMA portable radio system are considered. A fixed number of traffic servers (time slots) per radio port is assumed: therefore, the system capacity is hard-limited by the equipment availability, and the DCA efficiency is compared mainly through the signal-to-interference ratio in both the uplink and downlink directions. >

Performance issues and algorithms for dynamic channel assignment

The properties of a TDMA/TDD (time-division multiple-access/time-division duplex) pico cellular cordless telephone system using decentralized dynamic channel allocation and handover are presented. The system has 16 time-division time-duplex channels (slots) per carrier, each occupying 2 MHz. The TDMA frame is 16-ms long, and each slot has bits for synchronization, signaling and data. The data speed is suited for 32-kb/s speech codecs. Procedures have been developed for efficient and quick dynamic channel allocation and handover, using the fact that one single radio can simultaneously monitor or communicate on all 16 channels. Simulations for a specific six-storeyed building indicate that 16 channels can provide wireless communication for up to 30% of the telephones, and 32 channels for up to 100% of the telephones. Tests show that no time dispersion equalizers are needed, and that antenna diversity is effective against fading dips and time dispersion. >

http://ieeexplore.ieee.org/iel2/717/971/00026046.pdf

Properties of a TDMA pico cellular office communication system

Properties of a TDMA/TDD (time-division multiple access/time-division duplex) micro or rather pico cellular cordless telephone system using decentralized dynamic channel allocation and handover are presented. The system has 16 or 8 time-division time-duplex channels (slots) per carrier, each occupying 2 MHz or 1MHz. The TDMA frame is 16 ms long and each slot has bits for synchronization, signalling, and data. The data speed is suited for 32 kb/s speech codecs. Procedures have been developed for efficient and quick dynamic channel allocation and handover, using the fact that a single radio can simultaneously monitor or communicate on all 16 or 8 time-slot channels. Simulations for a specific six storey building indicate that 16 channels can provide wireless communications for up to 30% of the telephones, and 32 channels for up to 100% of the telephones. Slot synchronization between adjacent systems is desirable, but not necessary. Tests show that no time dispersion equalizers are needed, and that antenna diversity is effective against fading dips and time dispersion. This system concept has been proposed to CEPT as a base for European Digital Cordless Telecommunications. >

Dynamic spectrum sharing between uncoordinated systems of the same kind or even between systems using different technologies is attracting an increasing interest. Closely related is also "bandwidth on demand" for different services within a system. Traditional frequency planning is more difficult and less spectrum efficient the smaller the cells become. For indoor cells the practical planning limit is definitely passed. Continuous or instant dynamic sharing makes it possible to avoid to plan the channel assignments within a system and between systems. This paper presents analysis and simulations on dynamic spectrum sharing. >

On channel definitions and rules for continuous dynamic channel selection in coexistence etiquettes for radio systems

There is increasing interest in radio in the local loop (RLL) applications due to technology advancements and the liberalisation of the telecommunications markets. The paper describes the properties of DECT RLL applications. DECT offers toll quality digital speech, voice band transparency and ISDN services. All user information is encrypted. The DECT continuous dynamic channel selection procedures provide efficient utilisation of the spectrum and avoid the need for traditional frequency planning. The maximum range for a line of sight fixed RLL subscriber unit is much larger than for a non line of sight mobile RLL pocket unit. The DECT repeater concept makes it possible to combine the longer range of fixed RLL with mobility, which gives added value to a DECT RLL solution. The rapid advent of other private and public DECT services provide a platform both for service integration and for economy of scale. Estimates on traffic capacity and ranges has been supported by simulations and field trails. >

DECT technology for radio in the local loop

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Properties of a TDMA pico cellular office communication system

Properties of a TDMA pico cellular office communication system

On channel definitions and rules for continuous dynamic channel selection in coexistence etiquettes for radio systems

DECT technology for radio in the local loop