Room electromagnetics

Abstract

In analogy with the established discipline of room acoustics various aspects of diffuse wideband microwave propagation in a room are treated. It is shown that an equivalent to Sabine's equation for reverberation time in a room is valid for the completely diffused field, depending only on the volume, the surface area and an effective absorption coefficient. An exponential decay of the power versus delay is a consequence of the assumptions. Furthermore, the concept of a reverberation distance is also valid. This is the distance from a transmit antenna where the received diffuse, randomly scattered power equals the direct line-of-sight received power, such that the diffuse power dominates for distances larger than the reverberation distance. A number of measurements in a large room support the theory with an effective absorption coefficient of 0.5. The power delay profiles around the room from a transmitter in the ceiling vary only in the first arriving part of the impulse, whereas the tail being dominated by the diffuse field has the same power level for a given delay and the same decay rate all over the room. It is also a consequence of the theory that the incident diffuse fields on an antenna are uniformly distributed in angle. λ −))) 4ΙςΩΣΡΕΠ ΨΩΙ Σϑ ΞΛΜΩ ΘΕΞΙςΜΕΠ ΜΩ ΤΙςΘΜΞΞΙΗ 4ΙςΘΜΩΩΜΣΡ ϑςΣΘ −))) ΘΨΩΞ ΦΙ ΣΦΞΕΜΡΙΗ ϑΣς ΕΠΠ ΣΞΛΙς ΨΩΙΩ ΜΡ ΕΡ] ΓΨςςΙΡΞ Σς ϑΨΞΨςΙ ΘΙΗΜΕ ΜΡΓΠΨΗΜΡΚ ςΙΤςΜΡΞΜΡΚ ςΙΤΨΦΠΜΩΛΜΡΚ ΞΛΜΩ ΘΕΞΙςΜΕΠ ϑΣς ΕΗΖΙςΞΜΩΜΡΚ Σς ΤςΣΘΣΞΜΣΡΕΠ ΤΨςΤΣΩΙΩ ΓςΙΕΞΜΡΚ ΡΙ[ ΓΣΠΠΙΓΞΜΖΙ [ΣςΟΩ ϑΣς ςΙΩΕΠΙ Σς ςΙΗΜΩΞςΜΦΨΞΜΣΡ ΞΣ ΩΙςΖΙςΩ Σς ΠΜΩΞΩ Σς ςΙΨΩΙ Σϑ ΕΡ] ΓΣΤ]ςΜΚΛΞΙΗ ΓΣΘΤΣΡΙΡΞ Σϑ ΞΛΜΩ [ΣςΟ ΜΡ ΣΞΛΙς [ΣςΟΩ 4ΨΦΠΜΩΛΙΗ ΜΡ −))) %ΡΞΙΡΡΕΩ ΕΡΗ 4ςΣΤΕΚΕΞΜΣΡ 1ΕΚΕ⊥ΜΡΙ :ΣΠ 2Σ Τ ¥ %ΤςΜΠ (3− 1%4

Reverberation Time and Power Model in Indoor Wireless Scenarios

“…It is based on theories of room electromagnetics and room acoustics [1], [11][12][13][14]. The indoor scenario is geometrically modelled as system of image rooms where each reflection is presented by a narrow bundle of rays originating from the respective image source [12], [13].…”

“…Over the last decade, studies based on room electromagnetics manage to provide more insightful physical understanding for indoor wireless channels [1][2][3][4][5][6][7]. The room electromagnetics theory [1] points out that the electromagnetic waves in indoor wireless scenarios and the acoustic waves in room acoustics share similar behaviors in various aspects.…”

“…The room electromagnetics theory [1] points out that the electromagnetic waves in indoor wireless scenarios and the acoustic waves in room acoustics share similar behaviors in various aspects. The room electromagnetics theory explains the quasi-linear decaying of Power Delay Profile (PDP) in indoor scenarios [1], [4]. In reverberation models, the PDP is interpreted as the superposition of primary component and reverberant component.…”

“…Hence, the modeling of reverberation time is of great importance, as it is a basis of reverberation models. Most reported electromagnetic reverberation time models are based on either Sabine's or Eyring's equation [1], [4][5][6][7], [11], [12]. In analogy with acoustics, it is proposed in the two equations that electromagnetic reverberation time in an indoor wireless scenario is solely dependent on three parameters that are fixed by propagation geometry and materials: volume, surface and average absorption coefficient of the environment [11][12][13][14].…”

“…Also, the small scale fading characteristics including the modeling of PDP are rarely investigated. Meanwhile, most of these studies are limited in enclosed environments like conference rooms and classrooms [1][2][3][4][5][6][7], but semi-enclosed scenarios are rarely studied. Therefore, it is highly desired to develop a novel, accurate and more general reverberation model for indoor wireless scenarios.…”