CN1547333A - A broad beam forming method for intelligent antenna base station - Google Patents

Abstract

The invention discloses a method for forming broad beams applied to intelligent antenna base stations. The above mentioned base stations have several array-unit antennas. The method includes several steps as follows: Some fixed narrow beams with the same quantity to the above mentioned array-unit antennas will form, the narrow beams lie in a sector with a preset angle and are pair-wise orthogonal, which weight can be computed; the broad beams weight of public channels between above link and nether link can be acquired by fitting off-line of the above mentioned several narrow beams; the broad beams weight of public channels between above link and nether link is given to the public channel beams which form units, the above mentioned weight vectors and received or transmitted signals are multiplied in complex number field on basis of the corrected weight of array channels, the reception and transmission in public channels of the above mentioned sector. The inventive method reduces overlap field and pilot pollution in pie slices, the users in switchover field decrease at the same time so that the system spending due to switchover decrease, conducing to enhance system capacity and improve service quality.

Description

The method that a kind of broad beam that is used for intelligent antenna base station forms

Technical field

Broad beam formation method when the method that the present invention relates to use the broad beam in the mobile communication system of intelligent antenna technology to form is particularly useful for the reception of common channel in fixed beam and the adaptive beam antenna system and emission.

Background technology

Smart antenna is the technology of the supreme arrogance of a person with great power of the communications field in recent years, in three big standards of the 3G (Third Generation) Moblie technology of having been adopted, in the TD-SCDMA standard that China Datang Telecom submits to independent intellectual property right, smart antenna becomes one of essential technology that improves power system capacity and coverage, simultaneously in other two big mainstream standard WCDMA and CDMA2000, agreement makes smart antenna become one of optional technology for the application of supporting intelligent antenna technology provides convenience (as auxiliary pilot).Industry shows that for following the 4th third-generation mobile communication Study on Technology smart antenna becomes the essential content among the 4G probably.

Usually, smart antenna is divided into three types: fixed beam smart antenna (wave beam switching), flexible multi-beam intelligent antenna (dynamic section) and adaptive beam smart antenna.In mobile communication, channel is divided into two types, i.e. common channel (as the Common Pilot Channel in the WCDMA standard, synchronizing channel (SCH), Common Control Channel (CCPCH) and Random Access Channel etc.) and dedicated channel (as special used for physical control channel DPCCH and Dedicated Physical Data Channel DPDCH etc.).In the base station of adopting smart antenna, dedicated channel at the user is carried out figuration according to user's physical location and space channel characteristic, carry out directional reception and emission to a group (fixed beam) or unique user (self adaptation), common channel then in the sector all users receive and launch.For common channel, the method that transmits and receives commonly used has: method 1: reception and the emission of using additional fan antenna and passage to carry out common channel when using array antenna to carry out dedicated channel reception and emission; Method 2: use one of them passage in the array channel to carry out the reception and the emission of common channel when using array antenna to carry out the directional reception of dedicated channel and emission; Method 3: by to the suitable array weight vector of common channel, make common channel when using array antenna to carry out the emission of dedicated channel directional reception to full sector transmission and reception.Preceding two kinds of methods use single passage to carry out the reception and the emission of common channel, will cause the covering radius of common channel and dedicated channel not wait, and the passage that method 1 need be special, and this has increased the cost of base station and has made troubles to installation.

The Chinese patent publication number is to disclose a kind of quadrature narrow beam and broad beam of forming based on said method 3 time in the patent of 1261989 radio antenna system by name to carry out the technology that dedicated channel and common channel receive emission, it forms the narrow beam of quadrature in order to receive and the emission dedicated channel at radio frequency by the Butler matrix, pass through to the suitable weight vector of common channel information at Butler matrix beam port simultaneously, make common channel signaling converge in one of them array element of array antenna, and the global semaphore on other array element is zero, thereby forms broad beam.This based on the broad beam formation method that signal gathering is arrived a certain bay, the problem of its existence is: 1) form in base band if be used for the narrow beam of dedicated channel emission, then the broad beam signal certainly will be focused on a certain passage, cause the imbalance of power amplifier transmitting power, limited its use in digital beam formation intelligent antenna base station; 2) since the broad beam signal gathering in a certain bay, so it is similar with the conventional fan antenna in said method 1 and the method 2, as shown in Figure 5, overlapping region between the broad beam sector that forms is bigger, pilot pollution between the sector is serious, it is more to be in Zone switched number of users, in the interference-limited like this system of CDMA, is unfavorable for further improving the covering radius and the capacity of base station; 3) form the quadrature narrow beam by radio frequency, limited some realizations based on the adaptive algorithm of array element.

Summary of the invention

The method that the object of the present invention is to provide a kind of broad beam for intelligent antenna base station to form; By using a plurality of passages to carry out reception and the emission of common channel; The design philosophy that forms broad beam is not to allow signal gathering in a certain bay; But allow adjacent quadrature narrow beam at the main lobe intersection with superimposed (relevant merge); All passages of array all participate in the formation of broad beam; So that special-purpose channel and common channel covering-ties uniformity problem in the method 1 of solution prior art and the method 2; Need not special additional channel

Technical scheme of the present invention is as follows:

The method that a kind of broad beam that is used for intelligent antenna base station forms, described base station has a plurality of array-element antenna, and this each array-element antenna is connected with one and is used for the front end that transmission duplex, low noise amplify; This each front end is connected with a receiving branch and a transmitting branch respectively; Described receiving branch carries out operations such as down-conversion, filtering, amplification, A/D conversion, shaping filter and channel correcting; Described transmitting branch carries out operations such as channel correcting, shaping filter, D/A conversion, up-conversion, filtering amplification, power amplification; Described base station also comprises a common channel processing unit and a dedicated channel processing unit, is used for the signal that receives or launch is handled; Described processing may further comprise the steps:

1) form the fixing narrow beam of counting equal number with described array-element antenna, these narrow beams are positioned at the sector and the pairwise orthogonal of a predetermined angular, and calculate its weights;

2) by described a plurality of narrow beam fitting off-line being obtained the weights of uplink downlink common channel broad beam;

3) the common channel broad beam weights with this uplink downlink dispose to common channel wave beam formation unit, on the basis of considering the array channel calibration weights, the signal of described weight vector and reception/emission is carried out complex multiplication, finish the reception/emission of common channel in described sector.

Described method, wherein, described step 2) further comprising the steps of:

A) draw the narrow beam directional diagram according to described a plurality of narrow beam weights, and the sensing angle of calculating adjacent two narrow beam point of interfaces;

B), calculate of the response of each narrow beam to its contiguous described sensing of point of interface angular direction incoming signal according to the steering vector at described a plurality of narrow beam weights and wave beam point of interface place;

C) construct a weight vector matrix according to these a plurality of narrow beams in the response of corresponding point of interface direction, the adjacent narrow wave beam is merged at the homophase at point of interface place, then the broad beam weights equal the matrix product of this weight vector matrix and described narrow beam weights;

D) in the aforementioned calculation process, consider the wavelength value difference of uplink and downlink frequency range, can obtain the common channel broad beam weights of uplink and downlink link.

Described method, wherein, when described method formed scheme when the radio frequency beam of the fixed beam antenna system that uses unit B utler matrix, described uplink and downlink link common channel broad beam weights all equaled described weight vector matrix, and get the wavelength value of frequency range separately respectively.

Described method, wherein, described sector area is 120 °, but is not limited to 120 ° of sectors.

The method that a kind of broad beam that is used for intelligent antenna base station provided by the invention forms, thereby, it utilize existing a plurality of narrow beam to carry out the broad beam that match forms a certain sector of covering because adopting, thereby all passages of array all participate in the formation of broad beam, and it has produced following beneficial effect:

1) use a plurality of passages to carry out the reception and the emission of common channel, dedicated channel and common channel be basically identical aspect up receiving sensitivity and down transmitting power, thereby covering radius is basic identical.

2) compare with 120 ° of traditional fan antennas, overlapping region between the sector reduces greatly, has reduced the pilot pollution between the sector, is in Zone switched number of users simultaneously and reduces, reduced owing to switch the overhead that causes, helped to improve power system capacity and improve service quality.

3) both can be used for fixing the antenna system of multi-beam, also can be used for the antenna system of adaptive beam.

4) both can be used for the intelligent antenna base station system that pure base-band digital wave beam forms, and also can be applied to have in the base station system of radio frequency beam formation unit such as Butler matrix.

5) be not limited to the reception and the emission of common channel,, also can be used for the reception and the emission of dedicated channel according to the needs of system.

Description of drawings

Fig. 1 is a kind of realization block diagram of broad beam formation method of the present invention;

Fig. 2 is the General Principle schematic diagram of the line array of the inventive method;

The schematic diagram of the narrow beam point of interface of mentioning in the broad beam directional diagram of the applied quadrature narrow beam of Fig. 3 algorithm of the present invention, match thus and the algorithm;

The covering schematic diagram of cellular basestation when Fig. 4 is to use the formed broad beam of the present invention;

The covering schematic diagram of sub-district when Fig. 5 is to use conventional fan antenna;

Fig. 6 is when radio frequency forms the quadrature narrow beam, the realization block diagram of broad beam formation method of the present invention.

Embodiment

Below preferred embodiment of the present invention is described in detail.

As shown in Figure 1, it is a specific implementation block diagram of the broad beam formation of the inventive method, the signal of line direction array antenna 1-1～1-N reception carries out transmission duplex, low noise amplification through its front end 2-1～2-N respectively thereon, enters receiving branch 3-1～3-N then and carries out sending into common channel processing unit 5 and dedicated channel processing unit 6 after the operations such as down-conversion, filtering, amplification, A/D conversion, shaping filter and channel correcting; The upstream data that enters this common channel processing unit 5 in up common channel Beam-former 5-1 with the uplink common channel broad beam weights W of configuration _OUBe weighted processing, form the broad beam of pointing to whole sector, enter the normal signal that carries out other among the up common channel processing unit 5-3 again and handle; The down direction common channel data of sending here among the descending common channel processing unit 5-4 in descending common channel Beam-former 5-2 with descending common channel broad beam weights W _ODBe weighted processing, after being sent to operations such as carrying out channel correcting, shaping filter, D/A conversion, up-conversion, filtering amplification, power amplification among transmitting branch 4-1～4-N again, after described front end 2-1～the 2-N duplex is multiplexing, be radiated in the air, form the descending broad beam that covers full sector by described array antenna unit 1-1～1-N; Common channel telecommunications processor 5-5 be used to finish common channel broad beam weights configuration, this unit monitoring and with functions such as communicating by letter of system.Signal processing flow in the dedicated channel processing unit 6 with fixed beam with adaptive beam and different, not at the row of narration of the present invention.

As shown in Figure 6, be the application example of broad beam implementation method of the present invention in the fixed beam antenna system that uses 4 unit B utler matrixes, it is in full accord that its common channel handling process and base band wave beam shown in Figure 1 form handling process, difference is that the uplink downlink common channel broad beam weights that dispose to up-downgoing Beam-former 5-1 and 5-2 are all provided by the weight vector matrix W ｀ of narrow beam at the response structure of corresponding point of interface direction, below explain detailedly.

Particularly, the implementation method that is used for intelligent antenna base station common channel broad beam of the present invention may further comprise the steps (present embodiment is an example with 4 array-element antenna, but the inventive method is not limited to the array antenna of 4 array elements):

1) at first form 4, promptly count equivalent number with bay, fixing narrow beam B1～B4, these 4 fixing narrow beam pairwise orthogonals, its weights are designated as W _B(W _BBe 4 * 4 matrixes).In the intelligent antenna base station of fixed beam, W _BBe exactly to form the weights that the dedicated channel narrow beam is used in fact; In the adaptive beam smart antenna, W _BOnly be used for calculated off-line broad beam weights.

2) by 4 narrow beam fitting off-line being obtained the weights of uplink and downlink link common channel broad beam, be designated as down link common channel broad beam weights W respectively _ODWith uplink common channel broad beam weights W _OU

E) according to the described weights W of step 1) _BDraw the narrow beam directional diagram, and calculate the sensing angle of B1 and two wave beam point of interfaces of B2

The sensing angle of B2 and two wave beam point of interfaces of B3

The sensing angle of B3 and two wave beam point of interfaces of B4

F) according to described weights W _BAnd the steering vector at wave beam point of interface place, it is right to calculate the B1 wave beam

The response y of direction incoming signal ₁₂, the B2 wave beam is right The response y of direction incoming signal ₂₁, y ₂₂, the B3 wave beam is right The response y of direction incoming signal ₃₁, y ₃₃, the B4 wave beam is right The corresponding y of direction incoming signal ₄₃

G) according to the weight vector W ' of these 4 narrow beams, adjacent beams is merged, then broad beam weights W at the homophase at point of interface place at the response structure 1 * 4 of corresponding point of interface direction _O=W ' W _BIn the aforementioned calculation process, consider the wavelength value of up-downgoing frequency range, can obtain the common channel broad beam weights W of uplink downlink _ODAnd W _OUWhen the radio frequency beam of the fixed beam antenna system that uses 4 unit B utler matrixes forms scheme, as shown in Figure 6, described uplink downlink common channel broad beam weights W _ODAnd W _OUEqual described weight vector matrix W ', and get the wavelength value of frequency range separately respectively;

3) with step 2) the common channel broad beam weights W of described uplink downlink _ODAnd W _OUConfiguration forms the unit for the common channel wave beam, and on the basis of considering the array channel calibration weights, the signal of weight vector and reception and emission carries out complex multiplication, thereby finishes reception and the emission of common channel in the sector.

The basic principle figure of the line array of the inventive method as shown in Figure 2, the one dimension linear array antenna that it is made up of N array element, signal s (t) incides antenna array with the θ angle, and array output can be expressed as:

X(t)＝a(θ)s(t)+N(t) ①

Wherein:

X (t): antenna array output;

S (t): incoming signal;

N (t): additive noise vector;

A (θ): the steering vector of signal s (t) and

$a\left(\mathrm{\θ}\right)=\left[\begin{array}{c}1\\ \exp (-j2\mathrm{\π}*\frac{d}{\mathrm{\λ}}\sin \mathrm{\θ})\\ \exp (-j2\mathrm{\π}*2*\frac{d}{\mathrm{\λ}}\sin \mathrm{\θ})\\ \·\·\·\·\·\·\\ \exp (-j2\mathrm{\π}(N-1)\frac{d}{\mathrm{\λ}}\sin \mathrm{\θ})\end{array}\right]----\left(2\right)$

Here

D: the spacing between the adjacent array element;

λ: operation wavelength, general d=λ/2;

θ.: the angle of incident wave and front normal direction;

.: the beam position angle;

N: element number of array;

Point to angle θ with certain _kThe wave beam weight of coupling can be expressed as:

$w_{\mathrm{kn}}=\exp [j*(n-1)*\frac{d}{\mathrm{\λ}}*2\mathrm{\π}*\sin \left({\mathrm{\θ}}_k\right)]----\left(3\right)$

Wherein n=1,2 ... N is the array element sequence number, and k is the wave beam sequence number, and all the other parameters are the same.

With N=4 promptly the line array of 4 array elements be example, at first design 4 quadrature narrow beams that can cover 120 ° of sectors, these 4 narrow beams represent with B1, B2, B3, B4 that successively θ is used at its sensing angle respectively ₁, θ ₂, θ ₃, θ ₄If expression is with the θ of formula in 3. _kPointing to angle value, N value by it respectively is 4 can obtain the weights of these 4 narrow beam correspondences:

$W_B=\left[\begin{array}{c}{W}_{B1}\\ W_{B2}\\ W_{B3}\\ W_{B4}\end{array}\right]=\left[\begin{array}{cccc}1& w_{12}& w_{13}& w_{14}\\ 1& w_{22}& w_{23}& w_{24}\\ 1& w_{32}& w_{33}& w_{34}\\ 1& w_{42}& w_{43}& w_{44}\end{array}\right]----\left(4\right)$

Wave beam territory signal after the weighted sum can be expressed as:

Y _B＝W _BX ⑤

Make θ change between-180 °～180 °, and ignore The noise, the directional diagram of 4 the corresponding narrow beams that then can draw respectively as shown in Figure 3 and Figure 4, has been ignored back lobe among the figure, and the sensing angle of note B1 and two wave beam point of interfaces of B2 is

The sensing angle of B2 and two wave beam point of interfaces of B3 is

The sensing angle of B3 and two wave beam point of interfaces of B4 is

Design philosophy of the present invention is: form a broad beam that covers 120 ° of sectors thereby utilize existing 4 narrow beams to carry out match, the principle of wave beam match is: the main lobe that makes 4 wave beams is that B1 and two wave beams of B2 exist at the point of interface place with superimposed (the relevant merging) simultaneously The place exists with superimposed, B2 and two wave beams of B3

The place exists with superimposed, B3 and two wave beams of B4 The place is with superimposed, and this comes down to one and waits the relevant process that merges of gain.As shown in Figure 4, utilize the broad beam of 3 120 ° of sectors can cover whole honeycombs, its coverage effect covers than 3 single antenna wave beams of routine as shown in Figure 5, reduced the overlapping region between the sector, reduced the pilot pollution between the sector, be in Zone switched number of users simultaneously and reduce, reduced, help to improve power system capacity and improve service quality owing to switch the overhead that causes.

If n wave beam is designated as y in the response of k intersection _Nk, then:

The B1 wave beam is right The response of direction incoming signal is:

The B2 wave beam is right The response of direction incoming signal is respectively:

The B3 wave beam is right

The response of direction incoming signal is respectively:

The B4 wave beam is right The response of direction incoming signal is:

With in 4 narrow beams wherein 1 wave beam be benchmark, might as well be benchmark with the B3 wave beam here, structure weight vector W ', W ' W _BMake 4 narrow beams at the wave beam intersection all with superimposed, this weight vector then:

W′＝[exp(j( ₃₁- ₂₁+ ₂₂- ₁₂))，exp(j( ₃₁- ₂₁))，1，exp(j( ₃₃- ₄₃))]

Note broad beam weights are W ₀=[w _O1, w _O2, w _O3, w _O4], and:

W _O＝W′W _B ⑥

6. formula is among the present invention the broad beam weights computing formula of using wave beam match mode to obtain, but is not unique expression-form, chooses different beams as benchmark, and the value of W ' is difference to some extent, but based on broad beam of the present invention all with unanimity.In actual use, need consider respectively that the wavelength value of uplink and downlink works frequency can try to achieve the common channel broad beam weights W of described uplink downlink _OUAnd W _ODBelow do not consider the amplitude phase error of array channel, if the correction weights of note array channel are W _C=diag (W _C1, W _C2, W _C3, W _C4) (being the inverse of array channel amplitude phase error), the broad beam weights W that then only needs 6. formula to obtain when carrying out beam weighting _OWith correction weights W _OMultiply each other and get final product:

W _OC＝W _OW _C ⑦

For the antenna system that radio frequency beams such as using the Butler matrix forms, the broad beam weights are determined by following formula:

W _O＝W′＝[exp(j( ₃₁- ₂₁+ ₂₂- ₁₂))，exp(j( ₃₁- ₂₁))，1，exp(j( ₃₃- ₄₃))] ⑧

Claims (3)

1, the method that forms of a kind of broad beam that is used for intelligent antenna base station, described base station has a plurality of array-element antenna, and this each array-element antenna is connected with one and is used for the front end that transmission duplex, low noise amplify; This each front end is connected with a receiving branch and a transmitting branch respectively; Described receiving branch carries out down-conversion, filtering, amplification, A/D conversion, shaping filter and channel correcting operation; Described transmitting branch carries out channel correcting, shaping filter, D/A conversion, up-conversion, filtering amplification, power amplification operation; Described base station also comprises a common channel processing unit and a dedicated channel processing unit, is used for the signal that receives or receive is handled; Described processing may further comprise the steps:

1) form the fixing narrow beam of counting equal number with described array-element antenna, these narrow beams are positioned at the sector and the pairwise orthogonal of a predetermined angular, and calculate its weights;

2) by described a plurality of narrow beam fitting off-line being obtained the weights of uplink downlink common channel broad beam;

3) the common channel broad beam weights with this uplink downlink dispose to common channel wave beam formation unit, on the basis of considering the array channel calibration weights, the signal of described weight vector and reception/emission is carried out complex multiplication, finish the reception/emission of common channel in described sector.

2, method according to claim 1 is characterized in that, described step 2) further comprising the steps of:

A) draw the narrow beam directional diagram according to described a plurality of narrow beam weights, and the sensing angle of calculating adjacent two narrow beam point of interfaces;

B), calculate of the response of each narrow beam to its contiguous described sensing of point of interface angular direction incoming signal according to the steering vector at described a plurality of narrow beam weights and wave beam point of interface place;

C) construct a weight vector matrix according to these a plurality of narrow beams in the response of corresponding point of interface direction, the adjacent narrow wave beam is merged at the homophase at point of interface place, then the broad beam weights equal the matrix product of this weight vector matrix and described narrow beam weights;

D) in the aforementioned calculation process, consider the wavelength value difference of uplink and downlink frequency range, can obtain the common channel broad beam weights of uplink and downlink link.

3, method according to claim 2, it is characterized in that, when described method forms scheme when the radio frequency beam of the fixed beam antenna system that uses unit B utler matrix, described uplink and downlink link common channel broad beam weights all equal described weight vector matrix, and get the wavelength value of frequency range separately respectively.

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