CN-122027058-A - Channel measurement method for resisting small-scale fading in complex mountain area environment

Abstract

The invention discloses a channel measurement method for resisting small-scale fading in a complex mountain area environment, and belongs to the technical field of communication. The method comprises the steps of constructing a mountain channel measurement system, wherein a transmitting end antenna adopts a VHF/UHF dual-band omni-directional antenna, a receiving end antenna adopts a 5-element antenna array, five antenna units in the 5-element antenna array are arranged in a radial mode and uniformly divide a circumference, a transmitting end uses a linear frequency modulation signal as a measurement signal, the symbol period is 10kHz, the signal bandwidth is 1MHz, the receiving end detects, direction-finding, acquisition and storage of the signal of the transmitting end, the receiving levels of the five antenna units are calculated according to stored IQ data, and the average value of the 5 paths of receiving levels is calculated by adopting a linear space average method to finish channel measurement. The invention adopts a multichannel channel measurement system, has multichannel incoming wave direction measurement capability, can greatly reduce the influence of small-scale fading on measurement, and can also verify the multipath propagation prediction result.

Inventors

• JIANG TAO
• ZHAO YONGLEI
• YU JINLEI
• LIU LIQIANG

Assignees

• 中国电子科技集团公司第五十四研究所

Dates

Publication Date

20260512

Application Date

20260127

Claims (2)

1. 1. The channel measurement method for resisting small-scale fading in the complex mountain area environment is characterized by comprising the following steps: Step1, building a mountain channel measurement system, wherein a transmitting end antenna adopts a VHF/UHF dual-band omni-directional antenna, a receiving end antenna adopts a 5-element antenna array, and five antenna units in the 5-element antenna array are arranged in a radial manner and uniformly divide a circumference; step 2, the transmitting end uses the linear frequency modulation signal as a measuring signal, the symbol period is 10kHz, the signal bandwidth is 1MHz, the receiving end detects, direction-finding, collects and stores the signal of the transmitting end, and the receiving levels of the five antenna units are calculated according to the stored IQ data; and step 3, calculating the average value of 5 paths of receiving levels by adopting a linear space average method, and finishing channel measurement.
2. 2. The method for measuring a channel in a complex mountain environment against small-scale fading according to claim 1, wherein step2 comprises the steps of: (201) The transmitting end transmits signals at a transmitting point T: Wherein, the In order to transmit the amplitude of the signal, For the initial frequency of the signal, For the rate of change of the frequency of the signal, i.e. the rate of change of the instantaneous frequency with time, Time is; The receiving end receives signals at a receiving point R, S1 and S2 are terrain shielding on a non-main line path, the signals of a transmitting point T respectively reach the receiving point R from a direct path, a diffraction path through S1 and a diffraction path through S2, For the length of the direct path, i.e. the distance between T and R, Is the distance between T and S1, For the distance between S1 and R, Is the distance between T and S2, Is the distance between S2 and R; the signal received at the S1 point is: The signal received at the S2 point is: The signal received by the R point through S1 is: the signal received by the R point through S2 is: In the formula, The amplitude of the signal is received for point S1, The amplitude of the signal is received for point S2, The amplitude of the received signal is forwarded via S1 for point R, The amplitude of the received signal is forwarded by the R point through the S2, and c is the light speed; (202) Forming multipath signals at the S point near the receiving point R, wherein the connection line length between the central points z1, z2, z3, z4 and z5 of five antenna units in the 5-element antenna array and the center z0 of the antenna array is R, and the included angle between two adjacent antenna units The method comprises the following steps: the distances from the S point to the five antenna units are calculated as follows: the delays from the multipath signal to the five antenna units are respectively as follows: Wherein, the As the distance from the S point to z0, For an azimuth angle from point S to z0, Azimuth angles z1 to z 0; (203) The receiving end transmits the signal amplitude according to the time delay The reception level of each antenna element is calculated.

Description

Channel measurement method for resisting small-scale fading in complex mountain area environment Technical Field The invention belongs to the technical field of communication, and particularly relates to a channel measurement method for resisting small-scale fading in a complex mountain area environment. Background The complex mountain communication wave propagation has various propagation mechanisms such as direct radiation, diffraction, reflection and the like, and is a multipath channel with various mechanism mixed propagation. Multipath propagation is a main phenomenon of electric wave propagation in mountains, and is also a key problem that electric wave propagation is complex and changeable and difficult to predict. Small scale fading caused by multipath superposition is an important factor affecting mountain channel measurement. The existing mountain area propagation loss prediction method is calculated according to the transmitting-receiving end linear section diagram, multipath propagation is not considered, and large modeling errors are caused in many cases. The conventional mountain channel measurement system does not have the capability of measuring the direction of incoming waves, only can prove the existence of multipath, and cannot carry out targeted verification on multipath propagation signals. Disclosure of Invention In view of this, the present invention proposes a channel measurement method for combating small-scale fading in a complex mountain area environment. The invention receives signals through the 5-element antenna array, has the capability of measuring the incoming wave directions of multiple channels, can greatly reduce the influence of small-scale fading on measurement by an average value method, and can also verify the multipath propagation prediction result. The invention is realized by the following technical scheme: A channel measurement method for resisting small-scale fading in a complex mountain area environment comprises the following steps: Step1, building a mountain channel measurement system, wherein a transmitting end antenna adopts a VHF/UHF dual-band omni-directional antenna, a receiving end antenna adopts a 5-element antenna array, and five antenna units in the 5-element antenna array are arranged in a radial manner and uniformly divide a circumference; step 2, the transmitting end uses the linear frequency modulation signal as a measuring signal, the symbol period is 10kHz, the signal bandwidth is 1MHz, the receiving end detects, direction-finding, collects and stores the signal of the transmitting end, and the receiving levels of the five antenna units are calculated according to the stored IQ data; and step 3, calculating the average value of 5 paths of receiving levels by adopting a linear space average method, and finishing channel measurement. Further, the step 2 specifically includes the following steps: (201) The transmitting end transmits signals at a transmitting point T: Wherein, the In order to transmit the amplitude of the signal,For the initial frequency of the signal,For the rate of change of the frequency of the signal, i.e. the rate of change of the instantaneous frequency with time,Time is; The receiving end receives signals at a receiving point R, S1 and S2 are terrain shielding on a non-main line path, the signals of a transmitting point T respectively reach the receiving point R from a direct path, a diffraction path through S1 and a diffraction path through S2, For the length of the direct path, i.e. the distance between T and R,Is the distance between T and S1,For the distance between S1 and R,Is the distance between T and S2,Is the distance between S2 and R; the signal received at the S1 point is: The signal received at the S2 point is: The signal received by the R point through S1 is: the signal received by the R point through S2 is: In the formula, The amplitude of the signal is received for point S1,The amplitude of the signal is received for point S2,The amplitude of the received signal is forwarded via S1 for point R,The amplitude of the received signal is forwarded by the R point through the S2, and c is the light speed; (202) Forming multipath signals at the S point near the receiving point R, wherein the connection line length between the central points z1, z2, z3, z4 and z5 of five antenna units in the 5-element antenna array and the center z0 of the antenna array is R, and the included angle between two adjacent antenna units The method comprises the following steps: the distances from the S point to the five antenna units are calculated as follows: the delays from the multipath signal to the five antenna units are respectively as follows: Wherein, the As the distance from the S point to z0,For an azimuth angle from point S to z0,Azimuth angles z1 to z 0; (203) The receiving end transmits the signal amplitude according to the time delay The reception level of each antenna element is calculated. Compared with the background tech