Millimeter wave indoor intelligent passive coverage method
Technical Field
The invention relates to mobile communication, in particular to an indoor intelligent passive millimeter wave coverage method.
Background
The rate of mobile communication is higher and higher, and in order to meet the requirement of high rate, the operating frequency of mobile communication is also higher and higher, and the millimeter wave frequency band is entered. The path loss of millimeter waves is relatively large with respect to electromagnetic waves having a relatively low frequency, and particularly, since the wavelength is relatively short, the shielding effect of obstacles is also relatively large. In a room, the partitions of each room form barriers for millimeter wave propagation, millimeter waves hardly penetrate through a wall body, and an open door or window is arranged, but because the millimeter wave diffraction capacity is weak, the linear propagation property is strong, and the beam direction is hardly aligned with a door or window just right, so that a plurality of shadow areas are covered by the millimeter waves in the room. Even in the direct light region, the number and intensity of scatterers are sometimes not ideal, and channel capacity is also affected.
In order to improve coverage effect of the shadow area, an active relay method, such as a repeater, is generally adopted. The base station is sometimes added directly to reduce the range of the shadow zone. These methods are high in power consumption and high in cost. And the relay parameters cannot be adjusted in real time according to the dynamic change of the service.
With the development of mobile communication technology, multiple Input Multiple Output (MIMO) technology is increasingly used. The MIMO technology requires strong independence between multiple channels, so that the millimeter wave coverage is required to solve the problem of large path loss and the problem of MIMO channel independence.
Disclosure of Invention
The invention aims to provide a millimeter wave indoor intelligent passive coverage method which can improve the path loss of a shadow area, improve the channel capacity, dynamically adjust the channel characteristics according to service requirements, has the characteristics of energy conservation, wide working frequency band and low cost, and is easy to be fused with the existing indoor environment.
The technical scheme is as follows: the millimeter wave indoor intelligent passive coverage method adopts a direct irradiation coverage method in a direct irradiation area and adopts a passive reflector irradiation coverage method in a shadow area, so that the signal intensity of the shadow area is improved, and the channel characteristic of the shadow area is improved; the passive reflector comprises a primary passive reflector and a multi-stage passive reflector; the signals from the base station are reflected by the passive reflector, pass through the parts, such as indoor doors and windows, and the like, which are easy to penetrate by millimeter waves, and reach the shadow area; the position of the passive reflector ensures that the total reflection times of the base station signal to the shadow area path through the passive reflector is as small as possible and the total distance is as short as possible so as to reduce the total path loss of the path; the beam direction, the beam quantity and the polarization direction of the reflected wave of the passive reflector can be adjusted and changed in real time;
the beam direction, the number of beams and the polarization direction of the wave reflected by the passive reflector can be changed in real time according to service requirements so as to adjust or improve the characteristics of path loss, arrival angle, channel correlation and the like of the base station to a shadow area channel thereof.
The base station can be outdoors or indoors; if the base station is located indoors, the base station is located at the intersection of the corridor without the shielding object in the room or located at the indoor opening without the shielding object nearby, so that the area occupied by the direct incidence area in the service area is large, and meanwhile, the base station signal can reach the shadow area through the paths with the minimum reflection times and the shortest possible path, so that the total path loss of the paths is reduced.
The first-stage passive reflector is positioned in a direct incidence area of the base station, and reflects direct incidence signals of the base station to a shadow area; the multi-stage passive reflector is positioned in a shadow area of the base station; the primary passive reflector and the multi-stage passive reflector can reflect relay for many times, and can send electromagnetic wave signals of the base station to a shadow area which can be reached through many times of reflection.
Multiple paths from the base station to the shadow zone can be formed in the same shadow zone by utilizing multiple groups of passive reflectors, so that the characteristics of path loss, channel correlation and the like of channels between the base station and the shadow zone are further improved.
The passive reflectors with different reflecting surface shapes can be used to obtain reflected waves with different beam directions and polarization directions, and then the beam width reaching a shadow area is adjusted by selecting and adjusting the reflecting surface shape of the passive reflector so as to improve the characteristics of path loss, arrival angle, channel correlation and the like of a channel.
The passive reflector can be a specially manufactured passive reflector, or can be a passive reflector by using naturally existing objects such as ground, ceilings, indoor wall partitions and the like; the indoor wall partition can also be subjected to surface treatment, the shape of the indoor wall partition is changed to form a passive reflector with a required shape, the surface material composition of the indoor wall partition is changed to improve the reflectivity, and the surface smoothness of the indoor wall partition is changed to improve the reflectivity; specially manufactured passive reflectors may be individually mounted on the walls or ceilings of the room.
In order to improve the channel characteristics in the direct zone, passive reflectors may be used in the direct zone to increase the number of propagation paths to reduce the correlation of the channels and provide channel capacity, according to the Multiple Input Multiple Output (MIMO) requirements.
The different shaped reflector surfaces produce reflected waves of different characteristics, in general, the convex surface will cause the beam of the reflected wave to widen and diverge, and the concave surface will cause the beam of the reflected wave to narrow and focus into the focal region. According to the spatial relationship between the base station and the shadow area and the range of the shadow area, a plurality of passive reflectors with various shapes can be used for converting the electromagnetic wave from the base station into the direction, the width, the focal area and the like of the wave beam through the passive reflectors with different shapes, so that the width range of the wave beam is consistent with the range of the shadow area as far as possible, and the attenuation of a channel from the base station to the shadow area is as small as possible.
The use of passive reflectors allows the formation of multiple propagation paths from the base station to the shadow region, which not only makes the best use of electromagnetic wave energy from the base station, but also improves diversity reception performance, improves the characteristics of the base station to the shadow region MIMO channel, for example, reduces correlation between channels.
The determination principle of the number and the positions of the passive reflectors is as follows: 1) Meeting the coverage area requirement; 2) The path loss from the base station to the shadow area is minimal.
And determining the size of the passive reflector according to the signal intensity requirement of the shadow region.
The reflection capability of a passive reflector for a signal can be characterized by a radar reflection section (RCS), which is related to its area, shape, surface material and signal frequency. In general, for a planar passive reflector, its radar reflection cross section is proportional to the square of the frequency. Because the millimeter wave frequency is high, the passive reflector with the same area has strong reflection capability on millimeter wave signals, and thus the coverage capability of the passive reflector on a shadow area is greatly improved.
MIMO requires strong independence between the individual channels, i.e. weak channel correlation, which is related to the number of scatterers in the propagation path and also to the intensity, direction, polarization form of the scattered waves. The passive reflector is also a diffuser, so that the beam direction, number of beams and polarization form of the reflected waves from one or more passive reflectors can be changed in real time according to the service requirements of different areas, so as to adjust or improve the characteristics of the channels from the base station to the areas, such as independence between channels, path loss, number of paths, etc.
The beneficial effects are that: the millimeter wave indoor intelligent passive coverage method has the advantages that the method can reduce the path loss of millimeter wave propagation, reduce loss factors, improve the path loss of a shadow area, improve the independence of MIMO channels and adjust the number and the characteristics of beams of the shadow area in real time according to service requirements; the method has the characteristics of energy conservation, wide working frequency band and low cost, and is easy to be fused with the existing indoor environment.
Drawings
Fig. 1 is a schematic diagram of an indoor intelligent passive coverage method for millimeter waves.
Fig. 2 is a schematic diagram of a passive reflector.
The drawings are as follows: base station 1, service area 2, direct area 21, shadow area 22, passive reflector 3, primary passive reflector 31, multi-stage passive reflector 32, path 4, reflected wave 6, beam direction 61, and polarization direction 62.
Detailed Description
The invention is further described below with reference to the drawings and examples.
The invention adopts the following embodiments: the millimeter wave indoor intelligent passive coverage method adopts a direct irradiation coverage method in a direct irradiation area 21 and adopts a passive reflector 3 irradiation coverage method in a shadow area 22, so that the signal intensity of the shadow area 22 is improved, and the channel characteristic of the shadow area 22 is improved; the passive reflector 3 includes a one-stage passive reflector 31 and a multi-stage passive reflector 32; the signal from the base station 1 is reflected by the passive reflector 3, passes through the parts, such as indoor doors and windows, which are easy to penetrate by millimeter waves, and reaches the shadow area 22; the passive reflector 3 is positioned such that the total number of reflections of the base station 1 signal through the passive reflector 3 to the shadow zone 22 path 4 is as small as possible and the total distance is as short as possible to reduce the total path loss of the path 4; the beam direction, the number of beams and the polarization direction of the reflected wave of the passive reflector 3 can be adjusted and changed in real time;
the beam direction 61, the number of beams and the polarization direction 62 of the reflected wave 6 of the passive reflector 3 can be changed in real time according to the service requirement, so as to adjust or improve the characteristics of the path loss, the arrival angle, the channel correlation and the like of the channel from the base station 1 to the shadow zone 22 thereof.
The base station 1 may be located outdoors or indoors; if the base station 1 is located indoors, the base station 1 is located at the intersection of hallways without shielding in the room or at the indoor opening without shielding nearby, so that the area occupied by the direct-incidence area 21 in the service area 2 is larger, and meanwhile, the signals of the base station 1 can reach the shadow area 22 through the shortest possible reflection times and the shortest possible path 4, so as to reduce the total path loss of the path 4.
The primary passive reflector 31 is located in the direct area 21 of the base station 1, and the primary passive reflector 31 reflects the direct signal of the base station 1 to the shadow area 22; the multi-stage passive reflector 32 is located in the shadow area 22 of the base station 1; the primary passive reflector and the multi-stage passive reflector reflect relay for many times, and can send the electromagnetic wave signal of the base station 1 to the shadow area 22 which can be reached only through many times of reflection.
With multiple sets of passive reflectors 3, the same shadow area 22 can form multiple paths 4 from the base station 1 to the shadow area 22 to further improve the characteristics of path loss, channel correlation, etc. of the channel between the base station 1 and the shadow area 22.
The passive reflectors 3 with different reflection surface shapes can be used to obtain reflected waves 6 with different beam directions 61 and polarization directions 62, and further, the beam width reaching the shadow zone 22 is adjusted by selecting and adjusting the reflection surface 3 shape of the passive reflector so as to improve the characteristics of path loss, angle of arrival, channel correlation and the like of the channel.
The passive reflector 3 may be a specially manufactured passive reflector 3, or a naturally occurring object such as a floor, a ceiling, or a wall partition in a room may be used as the passive reflector 3; the indoor wall partition can also be subjected to surface treatment, the shape of the wall partition is changed to form a passive reflector 3 with a required shape, the surface material composition of the wall partition is changed to improve the reflectivity, and the surface smoothness of the wall partition is changed to improve the reflectivity; the specially manufactured passive reflector 3 may be mounted separately on a wall or ceiling of the room.
In order to improve the channel characteristics in the direct zone, according to the requirement of MIMO, the passive reflectors 3 may be used in the direct zone to increase the number of propagation paths 4, so as to reduce the correlation of channels and provide channel capacity.
The differently shaped reflector surfaces produce reflected waves 6 of different characteristics, and in general, the convex surface will cause the beam of the reflected wave 6 to widen and diverge, and the concave surface will cause the beam of the reflected wave 6 to narrow and focus into the focal area. According to the spatial relationship between the base station 1 and the shadow area 22 and the range of the shadow area 22, a plurality of passive reflectors 3 with various shapes can be used to transform the electromagnetic wave from the base station 1 into the beam direction 61, width, focal area and the like of the reflected wave 6 through the passive reflectors 3 with different shapes, so that the width range of the beam is as consistent as possible with the range of the shadow area 22 when the reflected wave 6 reaches the shadow area 22, and the attenuation of the channel from the base station 1 to the shadow area 22 is as small as possible.
The use of the passive reflector 3 makes it possible to form a plurality of propagation paths 4 from the base station 1 to the shadow zone 22, which not only makes use of electromagnetic wave energy of the base station 1 as much as possible, but also improves diversity reception performance, improves characteristics of MIMO channels of the base station 1 to the shadow zone 22, for example, reduces correlation between channels.
The number and location of the passive reflectors 3 are determined by: 1) Meeting the coverage area requirement; 2) The path loss from the base station 1 to the shadow zone 22 is minimal.
The size of the passive reflector 3 is determined according to the signal strength requirement of the shadow region 22.
The reflection capability of the passive reflector 3 for signals can be characterized by a radar reflection section (RCS), the radar reflection section of the passive reflector 3 being related to its area, shape, surface material and signal frequency. In general, for a planar passive reflector 3, its radar reflection cross section is proportional to the square of the frequency. The passive reflector 3 with the same area has strong reflection capability on millimeter wave signals because of high millimeter wave frequency, so that the coverage capability of the passive reflector 3 on the shadow area 22 is greatly improved.
MIMO requires strong independence between the individual channels, i.e. weak channel correlation, which is related to the number of scatterers in the propagation path and also to the intensity, direction, polarization form of the scattered waves. The passive reflector 3 is also a kind of scatterer, so that the beam direction 61, the number of beams and the polarization direction 62 of the reflected wave 6 of one or more passive reflectors 3 can be changed in real time according to the traffic requirements of different areas to adjust or improve the characteristics of the base station to the channels of the areas, such as independence between channels, path loss, number of paths, etc.
The artificial electromagnetic structure, PIN switching tubes and varactors of sub-wavelength can be used to form the passive reflector 3 with reconfigurable beam directions, beam numbers and polarization types, so that the beam directions 61 and numbers of the reflected waves 6 of the reconfigurable passive reflector 3 and the polarization directions 62 of the reflected waves 6 can be remotely controlled.
The present invention can be achieved in accordance with the above.