CN101227214A - A Networking Method of Code Division Multiple Access System - Google Patents

Abstract

The invention discloses a network organizing method of a CDMA system, wherein the CDMA system comprises an intelligent antenna system, wherein the method comprises: firstly, arranging two or more than two intelligent antenna subsystems, and the summation of the antenna array element number in the intelligent antenna system is the antenna array element number which is predetermined, secondly, arranging all the intelligent antenna baseband processing modules in the intelligent antenna system to connect with a diversity combining module, carrying out corresponding intelligent antenna baseband processing module which receives input signals when the intelligent antenna system receives signals, and then outputting signals to the diversity combining module to do a combining process, and thirdly, independently forming descending shaped beam by the baseband intelligent antenna processing module in each intelligent antenna subsystem when the intelligent antenna system transmits signals. The method which is provided by the invention is utilized to prevent the problem of dropping call and incomplete coverage of a single antenna array, which also reduces the size of the antenna array and is convenient for installing.

Description

A Networking Method of Code Division Multiple Access System

technical field

The present invention relates to a method for networking of a Code Division Multiple Access (CDMA) system, in particular to a method for networking of a CDMA system using smart antennas.

Background technique

The mobile communication system, especially the interference among multiple users in the CDMA system limits the number of users that the system can accommodate, making the system exhibit interference-limited characteristics. When the CDMA system is networked, the introduction of the smart antenna system can reduce the interference among multiple users in the system through spatial filtering. The smart antenna is based on the principle of adaptive antenna array, using the beamforming of the antenna array to generate multiple independent beams, and adaptively adjusts the beam direction to track each user, so as to improve the signal-to-interference-noise ratio SINR and increase the system capacity. .

As shown in FIG. 1 , the composition of a smart antenna system in the prior art may basically include: an antenna array, a radio frequency channel group, and a smart antenna baseband processing module. The antenna array itself is composed of N spatially distributed antenna elements, and each antenna element sends the received signal to the smart antenna baseband processing module for processing after passing through its own radio frequency channel, or sends the signal sent by the smart antenna baseband processing module The baseband signal is modulated onto the RF channel.

According to the arrangement of the antenna elements, the antenna array can usually be divided into: linear array, circular array, planar array and other forms. There will be interference such as coupling and reflection between adjacent antenna elements. In the current CDMA system , in order to obtain higher shaping gain and reduce the interference among multiple users, the sectoral smart antenna system with 8-antenna element linear array structure is mostly used. However, in dense urban areas or mobile communication scenarios with many tall buildings, the multipath environment is complex and changes rapidly, and it becomes relatively difficult for the narrow beam smart antenna to track the signal direction, which may cause the receiving end to fail to receive the signal . This phenomenon is called "call drop" phenomenon in wireless communication, and this phenomenon is unacceptable. In this scenario, the good directivity of the smart antenna increases the possibility of "call drop" in the system, which is what the system hopes to avoid during design.

Still taking the smart antenna system with a linear array structure as an example, in order to reduce the antenna coupling interference, the minimum distance d between array elements is generally taken as λ/2, where λ is the wavelength of the carrier signal. However, in different applications, when the array element spacing d is λ/2, the coupling interference may not meet the requirements. At this time, the antenna array element spacing can be set to d=kλ/2, and k∈N and k≥ 2. Thus, the coupling interference between antennas can be further reduced to meet the requirements. Therefore, in order to eliminate interference as much as possible and to meet the minimum receiving antenna distance for space diversity, the spacing between antenna elements in the antenna array usually takes a value between λ/2 and 10λ according to the actual situation.

In practice, the antenna array is set with the above array element spacing, even if the antenna array element spacing of λ/2 is used, taking the CDMA system operating at 2010MHz as an example, if a smart antenna system with a linear array structure of 8 antenna elements is used, the antenna The width will not be less than 53cm. Therefore, the size of the smart antenna is usually very large, which will bring more problems to the site selection, engineering construction and maintenance.

Contents of the invention

The technical problem to be solved by the present invention is to provide a CDMA system networking method to solve the problems of high call drop rate and difficult base station construction existing in the prior art.

The present invention is achieved through the following technical solutions:

A method for networking a code division multiple access system, wherein the code division multiple access system includes a smart antenna system, and the number of antenna elements in the smart antenna system is determined according to the capacity requirements and coverage of the code division multiple access system, the method include:

(a) Set up two or more smart antenna subsystems, the smart antenna subsystems include: one or more antenna arrays, radio frequency channels respectively connected to the set number of antenna array elements in the antenna arrays, and all A smart antenna baseband processing module connected to a radio frequency channel; the sum of all antenna array elements in the smart antenna system is a predetermined number of antenna array elements;

(b) all smart antenna baseband processing modules are set to be connected with the diversity combining module; when the smart antenna system receives a signal, each antenna array element in the system will receive the signal through the respective radio frequency channel input corresponding smart antenna baseband processing module Processing; the output signals of all smart antenna baseband processing modules are output to the diversity combining module for combining processing;

(c) When the smart antenna system transmits signals, the baseband smart antenna processing modules of each smart antenna subsystem independently form downlink shaped beams.

Further, the one antenna array includes N antenna elements, and the distance between the N antenna elements is greater than 10λ, where λ is the carrier wavelength of the incident signal or the transmitted signal.

Further, the method further includes: setting the normals of any one of the antenna arrays according to a predetermined angle.

Furthermore, any number of antenna arrays described above are set at different locations.

Furthermore, any number of antenna arrays described above are set at the same location.

Further, the method also includes: arranging two or more antenna arrays at intervals in the vertical direction, and the vertical distance between two antenna array elements in different antenna arrays is greater than λ/2, where λ is the incident signal or The carrier wavelength of the transmitted signal.

Further, the antenna array is any one of a sectoral antenna array, an omnidirectional antenna array, and a multi-element antenna array with beam-shaping algorithm turned off.

Using the smart antenna system proposed by the present invention to carry out the CDMA system networking method can effectively prevent the problems of call drop and incomplete coverage of a single antenna array, and can also prevent the size of the antenna array from being too large, which is convenient for installation; At the same time, by using the above method, the existing CDMA system network can be conveniently transformed.

Description of drawings

FIG. 1 is a schematic diagram of a basic structure of a smart antenna system in the prior art;

FIG. 2 is a schematic diagram of a basic structure of a smart antenna system in an embodiment of the present invention.

Detailed ways

The present invention will be further introduced below in conjunction with the accompanying drawings and specific embodiments, but not as a limitation of the present invention.

The design concept of the present invention is: when the CDMA system is networked, the total number of antenna array elements of the smart antenna system in the CDMA system can be determined according to the capacity and coverage of the CDMA system, and the smart antenna system with a small number of array elements has a relatively small number of array elements. A smart antenna system with a large number of elements has the characteristic of a wide beam. In the same cell, several smart antenna subsystems with a small number of array elements are set up. The received signal of each smart antenna subsystem passes through its own smart antenna baseband. After processing by the processing module, the processing results are combined and processed before being output.

In the CDMA system networking process, taking 8 array elements as an example, the basic structural diagram of the smart antenna system used in the same cell is shown in Figure 2. It can be seen from the figure that the smart antenna system includes a diversity Merge module and 2 smart antenna subsystems A and B with 4 antenna array elements; smart antenna subsystem A and B have the same structure as the smart antenna system in the prior art, only the smart antenna subsystem in each smart antenna subsystem The antenna baseband processing modules are all connected to a shared diversity combining module.

When the above-mentioned smart antenna system receives signals, each array element in each smart antenna subsystem will receive the signal through its own radio frequency channel and enter the corresponding smart antenna baseband processing module. After processing in it, the signal will be output to the diversity Merging processing is performed in the merging module to further obtain diversity gain.

When the above-mentioned smart antenna system transmits signals, the information transmitted by each smart antenna subsystem is the same, and the corresponding baseband smart antenna processing modules independently form downlink shaped beams in the existing method.

In order to make the antenna coupling interference in adjacent smart antenna subsystems smaller, the distance between four consecutive smart antenna arrays should be greater than 10λ.

In the above description, the smart antenna subsystems in the same smart antenna system are used in the same cell, which can be realized by setting the smart antenna baseband processing module and diversity combining module in the same cell equipment.

Note: in the above-mentioned embodiment, the radio frequency channel and the smart antenna baseband processing module are the same as the prior art, so they will not be described in detail; and in the diversity combining module, the output signals of a plurality of smart antenna baseband processing modules are combined. Various methods in the prior art can also be selected according to the actual situation, and will not be repeated here.

In this embodiment, since the number of antenna elements in the smart antenna subsystem is relatively small, its antenna element beam is compared with the antenna element beam of the smart antenna system when only one smart antenna system is used in the cell in the prior art. Wider, so its ability to track the direction of wireless signals is stronger, which can effectively prevent the occurrence of dropped calls.

One point to explain: the above-mentioned embodiment is explained by taking a smart antenna system including two smart antenna subsystems as an example, and the above method can also be simply extended to the case where a smart antenna system includes N smart antenna subsystems, specifically The implementation method is the same as above, and will not be repeated here.

Furthermore, when it is difficult to select a smart antenna array site and it is difficult to cover the same area with one smart antenna system in the prior art, the N smart antenna subsystems used in the same cell in the above method can be used to The slices cover different places in the area. At this time, the normal direction of each smart antenna subsystem can be set to be different, and can be set at any angle between 0° and 180° as required. At this time, when the smart antenna system When transmitting signals, the broadcast information transmitted by each smart antenna subsystem is the same, and because different smart antenna subsystems are used to cover different areas, the data information transmitted by different smart antenna subsystems is different.

Furthermore, if any two smart antenna arrays are set to be placed at vertical intervals, they can complement each other to form continuous and good coverage, which can solve the problem of under-tower problems caused by imperfect technologies such as smart antenna zero filling in the prior art. black problem. At this time, the vertical distance between the smart antenna arrays in the two vertically placed smart antenna subsystems should be greater than λ/2, so that the coupling interference of the antenna arrays in the adjacent smart antenna subsystems is small.

It should also be explained that the smart antenna arrays mentioned in the embodiments of the present invention include sector antenna arrays, omnidirectional antenna arrays, and multi-element antenna arrays with the beam-shaping algorithm turned off. Different antenna arrays in the same cell Different forms of antenna arrays can be selected in the smart antenna subsystem.

As can be seen from the above embodiments, when the CDMA system is networked, the use of the above-mentioned smart antenna system can effectively prevent the problems of call drop and incomplete coverage of a single smart antenna array, and also make the size of the antenna array less than It is too large and easy to install; at the same time, using the above method, the existing CDMA system network can be conveniently transformed. At this time, it is only necessary to replace the smart antenna system with more array elements in the existing network with one with fewer N array elements. Smart antenna sub-system, and N is an integer greater than 1 but less than the number of array elements in the original smart antenna system. At this time, there is no need to make major or even no modifications to the hardware of the existing base station equipment.

Claims (7)

1. A networking method of a code division multiple access system, the code division multiple access system comprises a smart antenna system, determines the number of antenna array elements in the smart antenna system according to the capacity requirements and coverage of the code division multiple access system, It is characterized in that the method includes: (a) Set up two or more smart antenna subsystems, the smart antenna subsystems include: one or more antenna arrays, radio frequency channels respectively connected to the set number of antenna array elements in the antenna arrays, and all A smart antenna baseband processing module connected to a radio frequency channel; the sum of all antenna array elements in the smart antenna system is a predetermined number of antenna array elements; (b) all smart antenna baseband processing modules are set to be connected with the diversity combining module; when the smart antenna system receives a signal, each antenna array element in the system will receive the signal through the respective radio frequency channel input corresponding smart antenna baseband processing module Processing; the output signals of all smart antenna baseband processing modules are output to the diversity combining module for combining processing; (c) When the smart antenna system transmits signals, the baseband smart antenna processing modules in each smart antenna subsystem independently form downlink shaped beams. 2. The method according to claim 1, wherein said one antenna array includes N antenna elements, and the distance between said N antenna elements is greater than 10λ, where λ is an incident signal or a transmitted signal The carrier wavelength of the signal. 3. The method according to claim 1, further comprising: setting the normals of any of the antenna arrays according to a predetermined angle. 4. The method according to claim 3, characterized in that said arbitrary antenna arrays are arranged at different locations. 5. The method according to claim 3, wherein said arbitrary antenna arrays are arranged at the same location. 6. The method according to claim 1, further comprising: setting two or more antenna arrays at intervals in the vertical direction, and the vertical distance between two antenna array elements in different antenna arrays Greater than λ/2, where λ is the carrier wavelength of the incident signal or the transmitted signal. 7. The method according to claim 1, wherein the antenna array is any one of a sector antenna array, an omnidirectional antenna array, and a multi-element antenna array with beam-shaping algorithm turned off.

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