Experimental evaluation of space/frequency/polarization diversity in the indoor wireless channel

Abstract

A series of experiments that were conducted to evaluate the relative merits of three types of diversities in the indoor portable radio channels at 900 MHz is described. Unmodulated tones were used to probe the channel in a typical university work environment. The statistics of the signal envelopes were analyzed to determine the correlation of the field strengths when the signals are separated in space, frequency or polarization. According to the results presented here, the perforOf a narrow-band system ( < 2oo kHz) at 900 MHz greatly benefit from a frequency diversity scheme provided that the separation between the two frequencies is greater than approximately 5 MHz. Similarly, the advantage of space diversity is found significant when the two antennas are spaced by 3/4 wavelength or more. It is also reported that co-polarized and cross-polarized signals are nearly uncorrelated and their relative field strengths differ by less than 2 dB in most locations.specifically at obtaining parameters pertaining to different diversity schemes. ~~f i~~~ and cox [71 and cox, M~~~~~, and Norris 181 used continuous wave (CW) signals to investigate the radio coverage inside a building when the transmitter was placed outside. Alexander [9], [IO] was one of the first to report on truly indoor propagation measurements. He used CW signals to probe the channel on one floor, where both the transmitter and receiver were placed in locations inside the buildi%. A h a n d e r and I1 l1 used a two-branch space diversity receiver with selection combining to see the possible improvements in the signal envelope. Patsiokas et al. 1121 performed indoor attenuation measurements at several frequencies using cw There have also been several reports on experimental data in papers devoted primarily to system studies. In all these studies, however, there has been little results that directly address the question of parameters from the impulse response measurements, but that the results and the In Section II a description of our experiment is given, followed by a presentation of the results in Section 111, and conclusions in Section Iv. THE EXPERIMENT

Smart-antenna operation for indoor wireless local-area networks using OFDM

“…Since the frequency correlation is relatively short ranged, interleaving the data to the whole frequency band is expected to provide a good protection against fading. The spatial correlation does not noticeably depend on distance above half a wavelength, which is in agreement with the results of [13] and [14] for 10 GHz and 900 MHz, respectively. The mean narrowband [12] polarization correlations (averaged over antennas and TX positions) are summarized in Table I.…”

“…For Heikkiläntie, Airport and Airport 2, on the other hand, even higher values of 4.9, 4.4, and 3.8 dB, respectively, were obtained. These values are of the same order as those reported for 900 MHz in [14]. For this reason, if the noise level is tuned according to the vertical polarization, the PER performance of 16 QAM in Ruoholahti with four vertically polarized antennas is about 2 dB better than in the case, where half of the diversity branches use horizontal polarization.…”

Network Experimentation for Cooperative Localization

“…All nodes can be treated as anchors or agents; nevertheless N b = 5 positions (labeled B1-B5) have been considered for anchors and N a = 20 for agents (numbered [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20] to compare noncooperative and cooperative networks. Range and waveform measurements for each pair of anchor and agent were made for a noncooperative setting (i.e., 5 × 20 links).…”

“…In particular, we consider sum-product algorithm over a wireless network (SPAWN), which aims to infer agents positions based on measurements among nodes. 10 Results are given for SPAWN with and without range error mitigation techniques. In the case of range error mitigation, both WED bias model with environmental information and WED bias model with channel state identification based on MAP decision are considered.…”

Polarization division multiple access with polarization modulation for LOS wireless communications

“…While polarization does not attract much attention in wireless communications until some new findings, such as six-polarization, polarization filtering (PF) and polarization diversity, have been researched and applied [12][13][14][15][16][17][18][19][20][21][22][23]. Considering the applications of PF in radar and wireless communications for example [17][18][19][20][21][22][23], the usage of polarization extends the available resource domains when dealing with interference suppressions and signal separations problems.…”