The signal processing technique that the multipath weight forms a cluster is studied
0 foreword Propagate under the scene actually, form a cluster to each multipath weight inner different multipath weight punish, consume a large number of the intersection of array and degree of freedom and take a large number of resource respectively, the gain to noise temperature ratio of characteristic that and its result brings is extremely definite, for this reason, how multipath to form a cluster to the null field to carry on appropriate treatment, it is a kind of important problem of studying the relevant algorithm of adaptive signal processing of array antenna while realizing. It is generally acknowledged, the array signal processing technique in the mobile communication field proceeds from its technological complexity and can be divided into 3 realization aspects at least: First, take the form of array antenna and realize in the group platform the space diversity of the up-chain signal is dealt with, this has already got general application in present mobile communiation system. Second, it is group platform array antenna beam scanning, can carry on the pitch angle of beam and angle sweep of the position respectively - -The former can be used in the antenna radiation beam of base station and have a down dip the angular electricity is adjusted, the latter can realize the beam transmission of the group platform and wireless communication link of mobile station. Third, namely adaptation array antenna treatment technology. The adaptive antenna is that one kind can follow environmental change, through adjusting it to the weighted value of every array element in the antenna array in order to improve it to output one kind of characteristic important aerial technology by oneself. It is optimum on the basis of making the aerial array output the performance index in a certain respect, and realize the response to the signal environment of the performance of antenna. For the above-mentioned understanding, try to utilize different space signal processing techniques, investigate, form a cluster, go on incoming the intersection of characteristic and difference punish, one incident wave as single incident wave. A space diversity technique The space diversity technique is this separate characteristic and diversity technique formed of electric field of utilizing different aerials apart far enough to produce, usually, the interval between the receiving antenna should be enough large, in order to guarantee the fading characteristic of signal that each of receiving antenna receives is independent each other. If the signal that the space diversity aerial receives is a single incident wave, and every No. signal fading is p to the probability under threshold level, then it is pL that L way signal declines to the probability under threshold level at the same time, when L is bigger, obviously pL In order to further receive the precise relation, take two branched space diversity receiving antenna as examples here, calculate the space diversity gain under forming a cluster and single incident wave situation of the incident wave separately. The artificial parameter chosen is: Every aerial incident wave forms a cluster one counts N =2,The incident wave forms a cluster wave angle φ 1 comes on average =-φ 2, the value is spent for 30 degrees and 60, the incident wave forms a cluster the angle is expanded 1 = 2 =10 degrees, obey the uniform distribution while forming a cluster, the array element of every aerial counts n =10,Amalgamate the way to amalgamate as the maximal ratio, interrupt rate Pout =10-2. Relation of diversity gain and aerial interval that can get under 2 kinds of situations by emulation method in Monte Carlo, the diversity gain under the single incident wave situation is smooth with the increase of the diversity interval to increase, and the diversity gain that forms a cluster under the situation in incident wave demonstrates and shakes the increased characteristic with the increase of the diversity interval, and the one that form a cluster in incident wave comes equally the wave angle is the greater, the more obvious the oscillatory behavior is, but, the maximum that the incident wave forms a cluster under maximum diversity gain and single incident wave situation under the situation is basically the same in diversity gain, this and measured result is identical. 2 beam scanning On the basis of the above-mentioned analysis, try, use the intersection of beam and the intersection of scanning and symbol examine, form a cluster when inner signal punish one incident wave as single the intersection of incident wave and signal, estimate the result error in incoming incident wave direction. Knowing by the literature [3 ], this error is influenced by many kinds of factors. For example, multipath distribution of the weight of incident wave while forming a cluster, incident wave form a cluster enter, hit kernel and angle, incident wave form a cluster the intersection of angular domain and range, incident wave form a cluster inner the intersection of ray and associativity and array processing characteristic such as sampling snapping several grades. Take ternary even linear array model that the omnibearing array element forms as examples here, utilize numerical analysis, to investigate continuous sampling respectively and sample various factors under the situation dispersedly with influencing, estimate the consequential change in incident wave direction introduced by difference between 2 autocorrelation matrixes. Among them, array the intersection of output data and all weight of vector ask that has linear phase relation, in calculating, choose the array element interval d to be 0.5λ, λ is the operating wavelength. (1)Impact on error of inner ray associativity of the range that the incident wave is multipath to form a cluster in the angular domain The artificial parameter chosen is: Multipath to form a cluster the angle of incident wave centre is 30 degrees, the angular domain range is 10 degrees, confirm the ray number (n that every direction incidents within the range of angular domain equally probably at random =10,20,30,40,50,80,100,200),It is 0 that the amplitude of each ray obeys mean value, variance is replying gauss distribution of 1, and multipath to let correlation coefficient among the 2 ray it obeys the module value to be sequentially form a cluster, 0, 0.2, 0.3, the phase place is in the uniform distribution inside of section [0, 2π ]. Output continuous sampling to the array in order to get the array and outputs the autocorrelation matrix, decompose through the characteristic, can be based on numerical calculation to further analyze. In results provided of Fig. 1, in order to receive the statistic average result, has already calculated independently 500 times respectively. Result show in the picture, with incident wave being multipath to form a cluster inner the intersection of ray and increase of number, the direction evaluated error of the incident wave is reduced gradually, however, when the ray number is the same, until multipath incident wave form a cluster inner the intersection of ray and associativity strengthen, incident wave direction evaluated error loud, needing less rays can make the direction evaluated error of the incident wave disappear.
