Microwave path-loss characteristics in urban LOS and NLOS environments

Abstract

To model the path-loss characteristics of microwave propagation in urban environments, we performed measurements at frequencies of 3.35, 8.45, and 15.75 GHz in metropolitan Tokyo. The actual breakpoint (BP) distance was shorter than the theoretical one because of the influence of vehicles, pedestrians, and other objects on the road. This effect can be characterized in terms,of the effective road height. We also found that the BP disappeared when the mobile-antenna height approached the effective road height. In non-line-of-sight (NLOS) areas, the corner losses and attenuation coefficients were greater than those of the UHF band. The attenuation coemcients increased with LOS distance between the base station and the corner into NLOS area. I. lntroductionMicrowave bands will likely be used for the fourthgeneration mobile-communication systems [ 11, but research still needs to be done on propagation characteristics. To model microwave path-loss characteristics. we performed measurements at the frequencies K.) of 3. 35, 8.45, and 15.75 GHz in urban environments.In line-of-sight (LOS) areas, we observed that the measured breakpoint (Rbp) was shorter than the theoretical one (R,) for all frequencies [2]. This is because of the bias of the ground level (h), which is caused by vehicles, pedestrians and other objects on the road [3]. This ground level can be referred to as the effective road height.We also found that the breakpoint (BP) disappeared when the mobile-antenna height (h,) approached h. Based on the BP characteristics in the microwave band, we give both upper-and lower-bound evaluations for the LOS path losses in urban environments.Path-loss characteristics in non-LOS (NLOS) areas have been studied for the UHF band [4] [5]. The path loss can be described with a constant attenuation coefficient, except at comers, where multipaths cause significant 'comer loss'. We compared these characteristics with those for the microwave band. Measurement DescriptionThe measurements were taken during the day in urban areas of Tokyo, where 10-to 15-story buildings line both sides of the streets. Figure 1 shows the experimental area. The base station (BS) was set up at two different locations: on a street 27-m wide (BSI) and on a street 11 -m wide (BS2). These streets were flat and straight with a LOS distance of about 1 km. The mobile station (MS) moved continuously along these streets and then turned (64 or 429 m from the BS2) onto NLOS streets whose widths were about 35 and 44 m (respectively). ElE €3 H 1.-0 in -64m -429 m Fig. 1 Measurement site in metropolitan Tohio.The transmitter of the measurement system is capable of transmitting a 10-W continuous wave in the microwave band. The transmitting BS had an antenna with a height ( h b ) of 4 m. The receiving MS was mounted on either a measuring vehicle or a handcart. A 2.7-m-high receiving

Propagation Characteristics of Ground Based Urban Communications in the Military UHF Band

“…This is consistent with observations made by other investigators at 1.8 GHz ( [3], [4] ) and has been explained by assuming that most of the energy arriving at the receiver is due to specular reflections; only those transmitted rays with specific takeoff angles at the transmitter get reflected down the side street to the NLOS receiver [3]. The second observation is that, in general, there is a discontinuity in the received power level between the beginning and end of the turn.…”

Path Loss Model with Low Antenna Height for Microwave Bands in Residential Areas

“…It is therefore necessary to construct a path loss model to clarify the propagation characteristics and evaluate interference occurring between MTs in such cases. Path loss models with low antenna height have been studied for predicting path loss in microwave bands [5]- [7]. The model reported in [5] is constructed on street microcell environments and predicts path loss by using distance attenuation and corner loss.…”

“…Path loss models with low antenna height have been studied for predicting path loss in microwave bands [5]- [7]. The model reported in [5] is constructed on street microcell environments and predicts path loss by using distance attenuation and corner loss. The model reported in [6] expanded the applicability of the street microcell model reported in [5] to a residential area by using loss parameters derived in the area.…”

“…The model reported in [5] is constructed on street microcell environments and predicts path loss by using distance attenuation and corner loss. The model reported in [6] expanded the applicability of the street microcell model reported in [5] to a residential area by using loss parameters derived in the area. The model reported in [7] also predicts path loss by using distance attenuation and corner loss, parameters that are derived in residential areas for the 3.4, 5.3, and 6.4 GHz bands.…”

“…This is because if both transmitter (Tx) and receiver (Rx) have the same antenna height, if Tx and Rx are reversed, different calculation results will be obtained under the same conditions despite the reversibility of the propagation path. The models introduced above [5]- [7] cannot satisfy the requirement for invertible prediction formulas. Therefore, it is necessary to construct a path loss model that considers the above area characteristics, is applicable to areas where there are many gently curved corners, and satisfies the requirement for invertible prediction formulas.…”