WO2006005236A1

WO2006005236A1 - Method for pilot offset number multiplex planning in cdma network

Info

Publication number: WO2006005236A1
Application number: PCT/CN2004/001486
Authority: WO
Inventors: Weishi Yang; Yi Hu; Yun Wu; Dongchuan Li; Yue Ma; Yongpan Zhao; Qingtao Meng; Hui Wang; Yaping Wang
Original assignee: Zte Corporation
Priority date: 2004-07-13
Filing date: 2004-12-21
Publication date: 2006-01-19
Also published as: CN1722624A; CN100375400C

Abstract

The present invention relates to a method for pilot offset number multiplex planning in CDMA networks, at least includes the following steps: determining the cover radius of the smallest subzone in dense areas and/or denseness areas according to network size and requirement of increasing capacity; determining a pilot increment value and the pilot difference between many subzones of one station, and then dividing the available pilot into some pilot groups; counting the multiplexing distance of the pilot offset number according to the cover radius of the smallest subzone and the pilot increment value; setting the grids and the grid line yardstick of the said pilot offset number multiplex areas, and then distributing each grid orderly to the said pilot groups, thereby implement the pilot offset number multiplexing between the areas. The present invention is clear on the steps and has widely applicability, it can efficiently and conveniently design the pilot for oversize network in one time, and it has thought over the question of increasing capacity for the future at design days. As a result, it doesn’t need to redesign the used pilot for increasing capacity in future, and it couldn't take impact to the existing network.

Description

Planning method for pilot offset number multiplexing in CDMA networks

The invention relates to a planning method for pilot offset number multiplexing in a C-A network, in particular to a method for orderly allocating pilots for pilot offset number multiplexing in a planning phase of a CDMA cellular mobile communication network. The planning method belongs to the field of communication technology. Background technique

With the rapid development of mobile communication technology, users have higher and higher requirements for network quality. How to effectively improve the communication quality of wireless networks is an important issue in the network construction process.

In the process of network construction, it involves many stages such as network planning, engineering construction, and network optimization. The network planning stage determines the architecture of the entire network and plays a decisive role in whether the final network meets the coverage and capacity requirements. In the network planning process, an important task in wireless parameter planning is the pilot offset number reuse planning, or PN (Pseudo random Number) multiplexing planning. Unsuitable multiplexing planning can cause serious consequences, resulting in networks. Quality is degraded.

The complexity of PN reuse planning increases sharply with the increase of network scale. Due to the unpredictable potential network scale and investment budget constraints, the construction of wireless networks must be carried out in batches, if there is no more forward-looking. The PN reuse planning method is bound to re-plan the PN every time it is built. This is not only time-consuming and laborious, but also likely to have a great impact on the existing network.

At present, there are only some guidelines for the reuse distance constraint and pilot pi lot -INC (pi lot increment) selection. How to plan for PN multiplexing of a network, especially a very large network? There is no more general practice.

There are two main patents:

US Patent No.: 6618432, invented by Ganesh et al., entitled: System and method for minimizing interference and PN planning schemes in CDMA networks (System and method for minimizing interference and opt imizing PN planning in CDMA The idea of networks is: to implement PN planning by simulation, first to each sub-division With PN, according to the performance of the allocated PN analog system, the cells with poor performance are marked, and then the PNs of these cells are adjusted to simulate the system performance again until the performance requirements are finally met.

US Patent No. 6490313, inventor: Ganesh et al., entitled: System and Method for PN Offset Indexing in a Digital CDMA Cellular System (System and method for PN off set index lanning in a di gi The idea of tal CDMA cel lular network ) is: Implement PN planning by simulation method, first assign PN to each cell, then use tool to simulate the interference between each cell, set reasonable threshold for interference, adjust for the situation beyond the threshold The PN of the relevant base station until the requirements are met.

The main idea of the existing patents is to use simulation tools to find possible problems based on the preliminary PN plan, and then adjust the PN to solve the problem in the problem area. The main disadvantages of this are:

1. The initial PN planning is too random, the initial planning results of different planners are different, and the complexity of subsequent adjustments is also different.

2. Due to the different initial planning, the final adjustment results will be different, which is actually not conducive to engineering application and archiving.

3. There is no or little consideration for the impact of adding stations. In fact, due to the overall relevance of the adjustment algorithm, the new stations often cause most base stations in the whole network or network to need to re-establish PN allocation; The cost is huge, and the overall adjustment means a large number of parameters such as neighborhood settings and changes in engineering files.

4. Use the simulation tool to perform interference calculation and guide adjustment. This is not allowed in some actual projects. It is hoped that there will be a way to ensure the reuse distance and make the PN plan more convenient.

In addition, the Chinese patent application, named "A PN Planning Method for C-A Cellular System", phased the human operation, using base stations in dense and non-dense area groups - mapping To some extent, the PN packet ensures that the multiplexing distance is not too close, but since this mapping relationship is based on the base station, it is impossible to give a general mapping rule, and the PN multiplexing distance is still guaranteed by the planner. The theoretical minimum multiplexing distance cannot be predicted by itself. In addition, the method guarantees the addition of the station by reserving the PN, and how many PNs are reserved to ensure that both the station requirement and the coverage of the reuse group are not too small, and still have to be answered. Summary of the invention

The object of the present invention is to solve the technical problems of the latent instability caused by the disorder of the PN reuse plan in the current C-A network planning, and the planning bottleneck for the network expansion and construction. A planning method for pilot offset number multiplexing in a CDMA network is provided, which can effectively perform pilot planning and meet the requirements of smooth expansion.

To achieve the above objective, the technical solution adopted by the present invention is a planning method for pilot offset number multiplexing in a CDMA network, which includes at least the following steps:

Step 1. Determine the coverage radius of the smallest cell in the dense area and the non-dense area according to the network scale and capacity expansion requirements;

Step 2: Determine the value of the pilot increment and the pilot difference of multiple cells in one base station, and divide all available pilots into several pilot groups;

Step 3: Calculate a pilot offset number multiplexing distance according to the coverage radius of the minimum cell and the value of the pilot increment.

Step 4: Setting a grid of the pilot offset number multiplexing area and a grid line scale _{7 respectively} assign each grid to the pilot group in order to implement inter-area pilot offset number multiplexing. .

Based on the foregoing technical solution, the following steps may also be included:

Step 5: multiplexing the pilot offset number of the base station in the non-dense area of the entire network for further amplification;

Step 6. Check the overall network planning result, and eliminate the result that the pilot offset number reuse distance is small. In step 1 above, by analyzing the potential network size and capacity expansion requirements, the coverage half of the minimum cell is determined for the network size of the same frequency band or a similar frequency band.

Considering that when the pilot interval of two sectors of the base station device is a pilot increment and the direction of the main lobe is positive, the pilot demodulation capability of the base station may be used to calculate the pilot increment in the second step based on mutual interference. Value.

In the fourth step, the length of the minimum cell coverage radius is twice the grid line scale, the pilot offset number multiplexing area is square, and the side length is the pilot offset number multiplexing distance, and the multiplexing area is within the multiplexing area. The grids are numbered sequentially, and the pilot groups are sequentially assigned to the grids in the multiplex area.

If there is a special case where two grids exist in one grid, you can borrow according to the specific situation. Use the pilot and follow these steps:

For a base station located on the boundary of a grid division, the squares on the horizontal line belong to the upper square, and the squares on the vertical line belong to the right side.

If the pilot group in a small grid is not enough, the pilot group remaining after the primary allocation is used preferentially. If the remaining pilot groups are used up, the first small squares are borrowed first, starting from the right. Clockwise or counterclockwise to 8 neighbors to borrow.

If the number of rasters is greater than the number of pilot groups, assign them from the beginning until all are assigned.

If the number of pilot groups is a multiple of the number of rasters, multiple pilots are assigned to each raster. If there is any remaining after the assignment is completed, it will be reserved for use. Some of the base stations that can be assigned this time can be used for a larger number of grids, and can be reserved for future expansion adjustment.

Compared with the prior art, the main technical features of the present invention are:

1, the disordered allocation is ordered filling, the method specification is fast '

2. The minimum PN multiplexing distance that can be predicted by the PN resource can be expected;

3. Using geochemical fill-in-the-blank method, it can be guaranteed that the minimum PN multiplexing distance will not be significantly reduced due to human factors and a small number of stationing factors;

4. Guarantee the planning of the new station for a long time. The PN has been pre-determined, and the PN will not be re-planned due to the addition of the station;

By using the method of the invention, the method has the advantages of clear process and wide adaptability, and can efficiently and succinctly plan the pilot of the extra large network, and considers the future expansion problem in the initial stage of construction, so the future network expansion is not It is necessary to re-plan the used pilots and will not cause an impact on the in-use network. DRAWINGS

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a flow chart of the present invention for orderly allocating PN multiplexing in a CDMA wireless network; Figure 2 is a schematic diagram of a specific embodiment of the PN multiplexing processing flow of the present invention. detailed description

The invention is further described below in conjunction with the drawings. The planning method for pilot offset number multiplexing in the CDMA network proposed by the present invention sets the pilot offset by setting the minimum coverage radius and the pilot increment (Pilot-INC) of the planned cell. The grid size of the number multiplexing area, each pilot is assigned a pilot group in order, and then the pilot offset number multiplexing between the areas is performed.

The invention can be used in the initial pilot planning process of the CDMA wireless network, and can also be used in the pilot planning of the network expansion assumption in the later stage, and has the characteristics of smooth expansion and small impact on the existing network.

A flow chart of the method of the present invention is shown in FIG.

The key processes implemented by this method are described below:

1. Analyze the potential network scale and capacity expansion requirements, and then determine the minimum cell coverage radius in dense urban areas, general urban areas, suburbs, and rural areas. For the analysis of the potential network scale, the method of comparison can be used to refer to the network scale of the carrier or the competitor in the same frequency band or similar frequency band.

2. It is assumed that the base station is in the pilot increment of two sectors (Pilot INC) and the direction of the main lobe is opposite, and the inverse demodulation capability of the base station can be calculated based on the scrambling to calculate the dense urban area and the non-dense urban area. The coverage radius of the cell, combined with the actual network complexity, determines the pilot value of the network (Pi lot INC). In addition, it is necessary to determine the pilot difference values of multiple cells in one base station, so that all available pilots are divided into several pilot groups (PN groups) in combination with the determined pilot increment (Pilot-INC) value.

3. The multiplexing distance of PN is in principle the larger the better, but the theoretical derivation indicates that the multiplexing distance of the pilot group is ultimately limited by the pilot increment (Pilot-INC). First consider the case where the base station is evenly distributed: Assuming that the cell radius is r and the coverage shape is a standard regular hexagonal wireless cell, the coverage area of one base station is: 6 X 1/2 X sin(60) X r ² = 2.6 X r ² The area covered by the base station in an ideal multiplexing area of η χ η cells is approximately: 2.6r ² xn ² , and the side length of the square multiplex block covered by the station group is (2.6 r ² xn ² ) ^ι =1.61η Xr, assuming that the multiplexing distance is kx r, then 1.61η χ r=kr, k= 1.61n, which is: η= 0.62k ₀

The total number of base stations: η χ η = ( 0.62k) ² = 0.3844k ² .

The total number of PN code resources is 512. Assuming that the base station has 3 sectors, the number of available pilot groups is 512/pilot_INC/3 according to the determined pilot increment (pilot-INC). To match the number of base stations to the available pilot groups, the following equation is available: 0.3844k ² = 512/pilot— INC/3, k = ( 443.98196/pilot_INC) ¹² 4. Obtain the minimum coverage radius of the planned cell, and use twice the length of the radius as the grid line scale. A pilot offset number multiplexing area is square, and the side length is the pilot offset number multiplexing distance, that is, kxr, so there are a total of k ² /4 grids, and the grids in the area are sequentially numbered sequentially.

5. The pilot groups are sequentially assigned to small grids in the multiplex area. If there is a special case of two base stations in a grid, pilots will be borrowed according to certain principles; these principles are summarized as follows:

(1) The belonging of the base station located on the boundary of the grid division: the square belonging to the upper line on the horizontal line and the square belonging to the right on the vertical line.

(2) The pilot group in a small grid is not enough: The pilot group remaining after one allocation is used preferentially. If the remaining pilot group is used up, it is preferentially borrowed from the small squares around, for the unique borrowing. The order starts from the right and is borrowed from 8 neighbors clockwise or counterclockwise.

(3) If the number of grids is greater than the number of pilot groups, assign them from the beginning until all are assigned.

(4) If the number of pilot groups is a multiple of the number of rasters, multiple pilots are assigned to each of the cells.

(5) If there is any remaining after the assignment is completed, it will be reserved for use. The number of base stations that can be loaned to this assignment can be used for a larger number of grids, or it can be reserved for future expansion adjustment.

6. According to different regions and different topography of the whole network, the above PN plan can be appropriately adjusted. For some rural and rural pilot offset numbers, the reuse distance can be further expanded.

7. Use the computer or manual to manually check the results of the whole network planning, and eliminate the result that the pilot offset number has a small reuse distance to ensure the entire network is qualified.

8. Archive the final pilot planning related output documents for future review and expansion planning.

The implementation process of the present invention will be described below by taking the pilot planning in the initial stage of CDMA network construction as an example.

The network is concentrated in an urban-rural and surrounding urban-rural integration department. The number of base stations is nearly 200. The method of using the case is shown in Figure 2. The total study period is 80 (Γ hours).

The main processing stages are as follows.

1. Network scale analysis: There are 186 base stations in the urban planning. Referring to the operator's 1800GSM system (the base station is close to 700), there is a potential demand for future station expansion. Comprehensive consideration, not only to solve the current network needs, but also to leave sufficient room for future expansion, in the future to add stations, expansion will not need to re-plan the entire network PN. Otherwise the planning behind will be very difficult.

1. Selection of PIL0T_INC and determination of PN group: Considering factors such as the density of base stations in the future, using PIL0T-INC as 3 and all base stations being 3 sectors, all available pilots can be used at one time and can be allocated to 512 / 3/ 3-56 base stations, the PN of each base station is called a PN group, even if there is a two-sector, omni-directional base station, we still allocate a PN group. The PN is set in 168 increments between sectors.

3. Determination of PN multiplexing distance: The minimum cell coverage radius according to the comparison analysis will reach 0. 5km, so the multiplexing distance is 6km. In order to ensure the multiplexing distance of 6km, increase lkm, select the 7km X 7km multiplex block.

4. Determination and ordering of small grid size: The multiplex block is divided into 49 small grids of lkm x lkm, and the spiral type is assigned 1 to 49 according to the upper right corner.

5, grid PN group assignment: the 1 ~ 49 PN group is assigned to the small grid in turn, the remaining spare.

6. Adjustment of the whole network: According to the actual topography, the western, eastern and southern parts of the city belong to the suburbs with small base station density, and the rural reuse distance can be increased to increase the coverage radius of each base station.

7. Full network check: The minimum reuse distance of this plan is 7. lkm by manually checking the electronic map and using the optimization tool for multiplex distance check.

8. Planning document archiving: Produce a document such as “a city PN planning template layer” (map info layer), which will serve as a blueprint for future review and station planning; at the same time, the document is easy to use for archiving; The "Public City PN Plan List" will be added to the base station information table for use as an open station.

It should be noted that the above embodiments are only intended to illustrate the technical solutions of the present invention and are not intended to be limiting, and the present invention will be described in detail with reference to the preferred embodiments. The modifications and equivalents of the present invention are intended to be included within the scope of the appended claims.

Claims

Rights request

A method for planning pilot offset number multiplexing in a CDMA network, comprising at least the following steps:

Step 2: Determine the value of the pilot increment and the pilot difference of multiple cells in one base station All available pilots are divided into several pilot groups;

Step 3: Calculate, according to the coverage radius of the minimum cell and the value of the pilot increment, a pilot offset number multiplexing distance.

Step 4: setting a grid and a grid line scale of the pilot offset number multiplexing area, and assigning each grid to the pilot group in order to implement inter-area pilot offset number multiplexing. .

2. The method for planning a pilot offset number reuse in a C-A network according to claim 1, wherein the step 4 further comprises the following steps:

Step 6. Check the overall network planning result, and eliminate the result that the pilot offset number reuse distance is small.

The method for planning pilot offset number multiplexing in a CDMA network according to claim 1 or 2, wherein the specific process of step 1 is to analyze potential network size and capacity expansion; compare the same frequency band or be similar The network size of the frequency band; determine the coverage radius of the smallest cell.

The method for planning the pilot offset number multiplexing in the CDMA network according to claim 1 or 2, wherein the value of the pilot increment in the second step is:

Consider that the pilot interval of the base station in two sectors is the pilot increment and the direction of the main lobe is positive. Next, according to the base station reverse demodulation capability, the coverage radius of the dense area and the non-dense area is calculated based on the mutual interference; and the actual network complexity is obtained.

The method for planning the pilot offset number multiplexing in the CDMA network according to claim 1 or 1, wherein the step 4 is specifically:

First, the grid line scale is twice the length of the minimum cell coverage radius; then, the grids located in the pilot offset number multiplexing area are sequentially numbered sequentially; the pilot The offset number multiplexing area is a square, and the side length is a pilot offset number multiplexing distance;

Finally, the pilot groups are sequentially assigned to all of the grids within the pilot offset number multiplexed region.

6. The method for planning pilot offset number multiplexing in a CDMA network according to claim 5, wherein in the process of sequentially assigning the pilot group, if there is one base station in the grid The step of borrowing the pilot is performed, and the borrowing pilot process is performed as follows: For the base station located at the boundary of the grid division, the grid belonging to the upper side above the horizontal line and the grid belonging to the right side on the vertical line.

7. The method for planning pilot offset number multiplexing in a CDMA network according to claim 5, wherein in the process of sequentially assigning the pilot group, if there is one base station in the grid And when a pilot group in a certain grid is not enough, performing a step of borrowing a pilot, the borrowing pilot process is to preferentially use a pilot group remaining after one allocation, when the remaining pilot group is used up When it is borrowed from the surrounding grids in priority, the order starts from the right and is borrowed clockwise or counterclockwise to 8 adjacent grids.

8. The method for planning pilot offset number multiplexing in a CDMA network according to claim 5, wherein in the process of sequentially assigning the pilot group, if one of the grids is present In the case of two base stations, and the number of the grids is greater than the number of pilot groups, the step of borrowing pilots is performed, the borrowing pilot process is assigned from the beginning until all are assigned.

9. The method for planning pilot offset number multiplexing in a CDMA network according to claim 5, wherein in the process of sequentially assigning the pilot group, if there is one of the two base stations in the grid And when the number of the pilot groups is a multiple of the number of the grids, the step of borrowing pilots is performed, and the process of borrowing the pilots is to assign a plurality of pilots in each grid.

10. The method for planning pilot offset number multiplexing in a CDMA network according to claim 5, wherein in the process of sequentially assigning the pilot group, if there is one base station in the grid The step of performing the borrowing of the pilot, if there is any remaining after the assignment is completed, is reserved or borrowed for the grid with a larger number of base stations in the assignment process for the expansion adjustment.