The smart antenna is a kind of installed in the scene of the base station antennas, through a set of two-way with a programmable electronic phase relationship fixed antennae unit obtain directional, and can also obtain stations and mobile station every link between the direction of properties. The smart antenna is principle will the radio signal oriented specific Direction, produce dimensional directional antenna beam, make the main beam alignment user signal reaches Direction of Arrinal DOA (Direction), side-lobe or zero trapped on interference signals arrive Direction, achieve full efficient use of mobile user signal and delete or suppress jamming signal purpose.
type
Smart antenna can be divided into two types: exchange beam antenna and adapt to the array.
Exchange beam
Exchange beam use many narrow beam antennas, each point to a tiny have different direction, which covers the whole 120 degrees sector. When sector within the mobile user moves, the system of intelligent antenna array antenna transformation from one to another antenna.
Adaptive array
Adaptive array antenna array using a digital signal processing and mature come from one location to the next position conversion days harness.
Edit this paragraph development process
Since 1990s, the array processing technology into the field of mobile telecom, soon formed a new hotspot - smart antenna. Smart antenna, wide application in improving the system of quality, alleviate wireless communication increasingly development and spectrum resources insufficient contradiction, and reduce the cost and improve system as a whole system management etc, have a unique advantage.
Initial smart antenna technology is mainly used in radar, sonar, military anti-jamming communication, to complete spatial filtering and positioning, etc. In recent years, with the development of mobile communication and mobile radio waves propagation, network technology, antenna theory of research on gradually thorough, modern digital signal processing technology development is rapid, digital signal processing chip processing ability constantly improve, using a digital technology in baseband form antenna beam becomes possible, improves the antenna system reliability and flexibility. Smart antenna technology so used to have complex radio waves propagation environment of mobile communication. In addition, with the mobile communication subscribers rapid growth and people to call quality requirements unceasing enhancement, mobile communications network in large capacity requirements under still has high voice quality. The study found that, smart antenna can be the radio signal oriented specific direction, produce dimensional directional antenna beam, make the main beam alignment user signal reaches direction of arrinal DOA (direction), side-lobe or zero trapped on interference signals arrive direction, achieve full efficient use of mobile user signal and delete or suppress jamming signal purpose. At the same time, using different mobile between users signals space, through the different characteristics of antenna array technology in the same channel is received and transmitted multiple mobile user signal without produces mutual interference, make use of the radio spectrum and the signal transmission more effectively. Without any increase in system complexity case, use the smart antenna can meet the service quality and network expansion needs. In fact it makes communication resources are no longer limited to the time domain (TDMA), frequency domain (FDMA) or code domain (CDMA) and expand into space domain, belong to air multiple access (SDMA) system.
Technical classification
review
Smart antenna technology has two main branch. Beam conversion technology? Switched beam technology) and adaptive space digital processing technology (spatial adaptive digital proc
Essing technology), or simply as beam conversion antenna and adaptive antenna array. Antenna with multiple high-gain ones.the dynamic narrow beam respectively tracking multiple expectations from narrow beam, the signal outside the signal is restrained. But the smart antenna beam tracking doesn't mean it will narrow high-gain ones.the tow-dimensional desired user physical direction, in fact, in random multipath channel, mobile users of physical direction is hard to define, especially in the launch pad to receiver is point-blank path exists stumbling block, users of physical direction is not necessarily ideal beam direction. Smart antenna beam tracking the true meaning is in the best path direction and narrow beam form high-gain ones.the tracking the best path changes, make full use of signal effectively send power to minimize electromagnetic interference.
Convert antenna beam
Convert antenna beam with finite number, fixed, predefined direction diagram, through the antenna array technology in the same channel use multiple beam at the same time give multiple users send different signal, it from several predefined, fixed beam by selecting one of, detection signal strength, when the mobile station across sectors, from a beam switch to another beam. In a particular direction improve sensitivity, thereby improving communication capacity and quality.
To ensure the beam conversion antenna sharing the same channel each mobile users receive only to send their own signal but not occur string words, requirement base station antenna array into multiple beam irradiation, different users, respectively, in particular, in each beam to send information different and should not interfere with each other.
Each beam direction is fixed, and its width along with the antenna array yuan several changes. For mobile users, choose different corresponding base beam, and receive the signal strength to the largest. But user signal may not in fixed beam center, when the user is at the edge of a beam, jamming signal in a beam of central, reception is the worst. Therefore, compared with the adaptive array antenna beam conversion, can achieve the best receiving signal. Because of fan-shaped distortion, beam conversion antenna gain in azimuth on non-uniform distribution. But beam conversion antenna has simple structure and need not judge user signal direction (DOA) advantage. Mainly used for simulation of communication system.
Adaptive antenna array
Blend in adaptive digital processing technology of the smart antenna is using a digital signal processing algorithm to measure different beam of signal intensity, so we can dynamically change the antenna beam transmission power concentration. Application space processing technology (technology) spatial allow can enhance signal ability, make multiple users common use a channel. Adaptive antenna configuration diagram shown as shown in figure 1.
T0 is between adjacent tapped the delay, Wn. J m is n antenna first m a tap factor. Every day the smart antenna
Line after another delay tap weighted nets, adaptive adjustments weighting coefficients. So at the same time with the time and spatial processing ability. Adaptive antenna array is a antenna array and real-time adaptive receiving signal processor consisting of a close-loop feedback control systems with feedback control method, it automatically adjustable quasi antenna array of directed graph, make it formed zero interference in direction, will commit jamming signal offset, and makes a useful signal is enhanced, so as to achieve the purpose of anti-jamming.
By adaptive antenna array received signals were weighted and consolidated, obtaining the best SNR coefficient. Applying M a linear arrays adaptive antenna, theoretically, adaptive antenna array value can produce (M - 1) times the antenna amplifier, can bring the 10lgM improve SNR, eliminate the influence of fan-shaped distortion and its (M - 1) times the diversity gain correlation is low enough. For the same communications quality requirements, the mobile station of the transmitted power can reduce 10lgM. This not only shows that can extend the mobile station battery life or can use smaller battery, also mean stations can and weak signal users to build normal communication link. To launch stations concerned, total power was assigned to M a, and due to the array elements DBF? Digital Beam - Forming can make the required total power decrease, accordingly, each array elements channel transmission power, which can greatly reduce use low power devices.
Using adaptive tap delay line antenna array on receiving signal, equilibrium and testing is very helpful. For each receiving antenna plus some tap delay line, and then sent into intelligent processor, can to multipath signal receiver, the best reduction multipath interference effects, thus make the base station of received signal SNR get a great degree rise, decrease the system ber.
Usually USES 4-16 antenna array yuan structure, and the adjacent array elements spacing generally take for receiving signals center frequency wavelength of 1/2. Excessive spacing, reduce the array elements received signal correlation, Array elements spacing is too small, will be directed graph cause unnecessary wave disc, therefore array elements half wave spacing is usually preferred. The antenna array yuan allocation way straight line type, containing the annular peaceful type, adaptive antenna is the main type of smart antenna. Adaptive antenna complete user signal can be considered sending and receiving omnidirectional antenna. It USES digital signal processing technology to identify users signal DOA, or is the main beam direction. According to different space user signal propagation direction, provide different space channel, overcome effectively on system interference. Adaptive antenna is mainly used in digital communication system.
type
Smart antenna can be divided into two types: exchange beam antenna and adapt to the array.
Exchange beam
Exchange beam use many narrow beam antennas, each point to a tiny have different direction, which covers the whole 120 degrees sector. When sector within the mobile user moves, the system of intelligent antenna array antenna transformation from one to another antenna.
Adaptive array
Adaptive array antenna array using a digital signal processing and mature come from one location to the next position conversion days harness.
Edit this paragraph development process
Since 1990s, the array processing technology into the field of mobile telecom, soon formed a new hotspot - smart antenna. Smart antenna, wide application in improving the system of quality, alleviate wireless communication increasingly development and spectrum resources insufficient contradiction, and reduce the cost and improve system as a whole system management etc, have a unique advantage.
Initial smart antenna technology is mainly used in radar, sonar, military anti-jamming communication, to complete spatial filtering and positioning, etc. In recent years, with the development of mobile communication and mobile radio waves propagation, network technology, antenna theory of research on gradually thorough, modern digital signal processing technology development is rapid, digital signal processing chip processing ability constantly improve, using a digital technology in baseband form antenna beam becomes possible, improves the antenna system reliability and flexibility. Smart antenna technology so used to have complex radio waves propagation environment of mobile communication. In addition, with the mobile communication subscribers rapid growth and people to call quality requirements unceasing enhancement, mobile communications network in large capacity requirements under still has high voice quality. The study found that, smart antenna can be the radio signal oriented specific direction, produce dimensional directional antenna beam, make the main beam alignment user signal reaches direction of arrinal DOA (direction), side-lobe or zero trapped on interference signals arrive direction, achieve full efficient use of mobile user signal and delete or suppress jamming signal purpose. At the same time, using different mobile between users signals space, through the different characteristics of antenna array technology in the same channel is received and transmitted multiple mobile user signal without produces mutual interference, make use of the radio spectrum and the signal transmission more effectively. Without any increase in system complexity case, use the smart antenna can meet the service quality and network expansion needs. In fact it makes communication resources are no longer limited to the time domain (TDMA), frequency domain (FDMA) or code domain (CDMA) and expand into space domain, belong to air multiple access (SDMA) system.
Technical classification
review
Smart antenna technology has two main branch. Beam conversion technology? Switched beam technology) and adaptive space digital processing technology (spatial adaptive digital proc
Essing technology), or simply as beam conversion antenna and adaptive antenna array. Antenna with multiple high-gain ones.the dynamic narrow beam respectively tracking multiple expectations from narrow beam, the signal outside the signal is restrained. But the smart antenna beam tracking doesn't mean it will narrow high-gain ones.the tow-dimensional desired user physical direction, in fact, in random multipath channel, mobile users of physical direction is hard to define, especially in the launch pad to receiver is point-blank path exists stumbling block, users of physical direction is not necessarily ideal beam direction. Smart antenna beam tracking the true meaning is in the best path direction and narrow beam form high-gain ones.the tracking the best path changes, make full use of signal effectively send power to minimize electromagnetic interference.
Convert antenna beam
Convert antenna beam with finite number, fixed, predefined direction diagram, through the antenna array technology in the same channel use multiple beam at the same time give multiple users send different signal, it from several predefined, fixed beam by selecting one of, detection signal strength, when the mobile station across sectors, from a beam switch to another beam. In a particular direction improve sensitivity, thereby improving communication capacity and quality.
To ensure the beam conversion antenna sharing the same channel each mobile users receive only to send their own signal but not occur string words, requirement base station antenna array into multiple beam irradiation, different users, respectively, in particular, in each beam to send information different and should not interfere with each other.
Each beam direction is fixed, and its width along with the antenna array yuan several changes. For mobile users, choose different corresponding base beam, and receive the signal strength to the largest. But user signal may not in fixed beam center, when the user is at the edge of a beam, jamming signal in a beam of central, reception is the worst. Therefore, compared with the adaptive array antenna beam conversion, can achieve the best receiving signal. Because of fan-shaped distortion, beam conversion antenna gain in azimuth on non-uniform distribution. But beam conversion antenna has simple structure and need not judge user signal direction (DOA) advantage. Mainly used for simulation of communication system.
Adaptive antenna array
Blend in adaptive digital processing technology of the smart antenna is using a digital signal processing algorithm to measure different beam of signal intensity, so we can dynamically change the antenna beam transmission power concentration. Application space processing technology (technology) spatial allow can enhance signal ability, make multiple users common use a channel. Adaptive antenna configuration diagram shown as shown in figure 1.
T0 is between adjacent tapped the delay, Wn. J m is n antenna first m a tap factor. Every day the smart antenna
Line after another delay tap weighted nets, adaptive adjustments weighting coefficients. So at the same time with the time and spatial processing ability. Adaptive antenna array is a antenna array and real-time adaptive receiving signal processor consisting of a close-loop feedback control systems with feedback control method, it automatically adjustable quasi antenna array of directed graph, make it formed zero interference in direction, will commit jamming signal offset, and makes a useful signal is enhanced, so as to achieve the purpose of anti-jamming.
By adaptive antenna array received signals were weighted and consolidated, obtaining the best SNR coefficient. Applying M a linear arrays adaptive antenna, theoretically, adaptive antenna array value can produce (M - 1) times the antenna amplifier, can bring the 10lgM improve SNR, eliminate the influence of fan-shaped distortion and its (M - 1) times the diversity gain correlation is low enough. For the same communications quality requirements, the mobile station of the transmitted power can reduce 10lgM. This not only shows that can extend the mobile station battery life or can use smaller battery, also mean stations can and weak signal users to build normal communication link. To launch stations concerned, total power was assigned to M a, and due to the array elements DBF? Digital Beam - Forming can make the required total power decrease, accordingly, each array elements channel transmission power, which can greatly reduce use low power devices.
Using adaptive tap delay line antenna array on receiving signal, equilibrium and testing is very helpful. For each receiving antenna plus some tap delay line, and then sent into intelligent processor, can to multipath signal receiver, the best reduction multipath interference effects, thus make the base station of received signal SNR get a great degree rise, decrease the system ber.
Usually USES 4-16 antenna array yuan structure, and the adjacent array elements spacing generally take for receiving signals center frequency wavelength of 1/2. Excessive spacing, reduce the array elements received signal correlation, Array elements spacing is too small, will be directed graph cause unnecessary wave disc, therefore array elements half wave spacing is usually preferred. The antenna array yuan allocation way straight line type, containing the annular peaceful type, adaptive antenna is the main type of smart antenna. Adaptive antenna complete user signal can be considered sending and receiving omnidirectional antenna. It USES digital signal processing technology to identify users signal DOA, or is the main beam direction. According to different space user signal propagation direction, provide different space channel, overcome effectively on system interference. Adaptive antenna is mainly used in digital communication system.
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