KR100262524B1 - A method for measurment and improvement of a pn pollution in code division multiple access system - Google Patents

Abstract

A method of measuring and improving pseudo noise pollution in a code division multiple access system is disclosed. The improvement method collects pilot signal strengths of PN offsets of base stations that can be detected in an arbitrary test area, and analyzes the collected data to determine the test area as PN pollution when an unnecessary PN offset is found. The total number of handoff attempts in the total handoff area of the base station transmitting unnecessary PN offsets and the number of handoff attempts by the base station in the test area determined as PN contamination are calculated. The performance of the base station is improved so that the ratio of handoff attempts is reduced.

Description

Measuring and Improving Pseudo Noise Contamination in Code Division Multiple Access Systems

The present invention relates to a method for measuring and improving pseudo noise pollution in a code division multiple access system, and more particularly, in a forward / reverse link of a system using a code division multiple access (CDMA) scheme. Pseudorandom Noise (PN) Containing a method for locating and improving PN Pollution areas.

1 shows a configuration of a known CDMA mobile communication system. As shown, a base station transceiver subsystem (BTS) 30, 31 that provides a mobile communication service to a mobile station (MS) 40, and a plurality of base stations 30, 31 are provided. A base station controller (BSC) 20 for controlling and a mobile switching center (MSC) for connecting a plurality of base station controllers 20 to a public switched telephone network (PSTN) 11. It comprises a (10).

The forward link of the CDMA system configured as described above refers to a channel directed from the base station to the mobile terminal, and the reverse link refers to a channel directed from the mobile terminal to the base station. According to the CDMA standard IS-95, a forward channel includes a pilot channel, a synchronous channel, a paging channel, and a traffic channel, and an access channel is an access channel. ) And traffic channels.

The channels exist together in one frequency. The division of the channels is called a Walsh code in the forward direction and a long PN code in the reverse direction. All forward channels in one base station have the same PN sequence offset. Therefore, the PN offset becomes an identification signal for distinguishing several base stations, and the mobile terminal detects a new PN offset signal and recognizes that it has entered the service area of the new base station.

The CDMA system has several PN offset and pilot strength search set data for each system. The pilot strength set includes an active set, a neighbor set, a candidate set, and a reserve set.

In an urban area having a complicated propagation environment, the PN offset signal of each base station may be irregularly detected. In this case, an unexpected handoff may occur because an unnecessary PN offset signal is detected in a certain region. This phenomenon is called PN pollution. Unexpected handoffs are a major factor in increasing the load on the system. This is because handoff is one of the main factors in generating load in call-related systems. Therefore, determining PN contamination is very important for optimizing the wireless environment and reducing system load.

The measurement equipment according to the prior art measures only the intensity of the pure PN offset and outputs the distribution of the PN offset. Therefore, the environment of the idle state and the traffic state of the mobile terminal could not be compared. That is, since the conventional measurement method only measures the PN contamination environment, it is difficult to improve the PN pollution environment because the PN pollution degree is not known in a call state, and there is a problem that the load improvement rate of the system cannot be known.

The present invention was devised to solve the problems of the prior art operating as described above, in consideration of the environment by region characteristics to derive a region with high PN pollution, and to analyze the PN offset distribution of the PN offset in the region PN It is an object to provide a method for measuring contamination.

It is another object of the present invention to provide a method for improving PN contamination by calculating the frequency of handoff occurrence in the measured PN contamination area.

Other objects and advantages of the present invention will become more apparent from the following detailed description of the invention and the accompanying drawings.

1 shows a configuration of a known CDMA mobile communication system.

2 is a flowchart illustrating a method for deriving PN pollution improvement rate according to the present invention.

3 is a block diagram of a log data collection apparatus used in the present invention.

<Explanation of symbols for main parts of drawing>

10: mobile switching center (MSC)

11: Public Switched Telephone Network (PSTN)

20: base station controller (BSC)

30,31: base station (BTS)

40,41: mobile terminal

200: data acquisition device

210: call collection device

220: idle collection device

230: analysis device

In the code division multiple access system according to the present invention devised to achieve the above object, a preferred embodiment of the method for measuring PN pollution is that each has a unique PN offset pilot signal. A mobile communication system comprising a base station providing a mobile communication service to a mobile terminal in a certain service area, a base station classifying a base station through a PN offset, and managing a base station and a base station high-level system for managing the base station.

Collecting pilot signal strengths of PN offsets of base stations that can be detected in any test area; And

Analyzing the collected data includes determining the test area as PN contamination if unnecessary PN offsets are found.

In an embodiment of the present invention, the collecting process,

Collecting pilot strength of a PN offset from an idle mobile terminal;

And collecting pilot strength and handoff related information of the PN offset from the mobile terminal in a call state,

The determining may be performed by comparing and analyzing data collected from an idle mobile terminal with data collected from a mobile terminal in a call state.

In the collecting process, it is preferable to collect the pilot strength of the PN offset for each search set of the PN offset.

In the determining, the mobile terminal may determine whether the collected PN offset data is unnecessary PN offset based on information received from the base station higher system.

In addition, a preferred embodiment of the method for improving pseudo noise pollution in a code division multiple access system according to the present invention,

Each base station has a pilot signal with a unique PN offset and provides a mobile communication service to a mobile terminal in a certain service area, and a mobile terminal and a base station which provide a mobile communication service by dividing the base station through a PN offset. A mobile communication system comprising a base station host system for managing,

Collecting pilot signal strengths of PN offsets of base stations that can be detected in any test area;

Analyzing the collected data and determining that the test area is PN contamination when an unnecessary PN offset is found;

Calculating total handoff attempts in all handoff regions of the base station transmitting the unnecessary PN offset and handoff attempts by the base station in a test region determined to be PN pollution; And

And improving the performance of the base station such that the ratio of the number of handoff attempts in the PN contaminated area to the total number of handoff attempts is reduced.

In an embodiment of the present invention, the collecting process,

Collecting pilot strength of a PN offset from an idle mobile terminal;

And collecting information on the pilot strength and the handoff of the PN offset from the mobile terminal in a call state,

The determining may be performed by comparing and analyzing data collected from an idle mobile terminal with data collected from a mobile terminal in a call state.

In the collecting process, it is preferable to collect PN offset and pilot strength for each search set of PN offset.

In the determining, it is preferable that the mobile terminal determines whether the collected PN offset data is unnecessary PN offset based on information received from the base station higher system.

The total handoff attempts P _b (s) Is the frequency of handoff ad occurrence in the entire handoff region of any base station b. F _b ^a (S _h ) The frequency of handoff drop occurrence in the entire handoff region of any base station b F ^d _b (S _h) The number of subscribers that cause a handoff among the total subscribers serving at base station b in any time interval T N _b ^h (T) The frequency of occurrence of the ad of base station b is α (t) The frequency of drop occurrence of BS b is β (t) When we say Is preferably,

remind F _b ^a (S _h ) Wow, F _b ^d (S _h ) , N _b ^h (T) , α (t) , β (t) It is preferable to obtain from the operation data stored in the base station host system,

Handoff attempts at the PN contaminated area P _b (s) Is the frequency of handoff ad occurrence by any base station b in the test area. F _b ^a (S _h ) And the frequency of handoff drop occurrence by any base station b in the test area. F _b ^d (S _h ) The number of subscribers that cause a handoff among the total subscribers serving at base station b in any time interval T N _b ^h (T) The frequency of occurrence of the ad of base station b is α (t) The frequency of drop occurrence of BS b is β (t) When we say Is preferably,

remind F _b ^a (S _h ) Wow F _b ^d (S _h ) It is preferable to obtain from the data collected in the collecting process.

The present invention provides a PN offset in all systems using CDMA, such as CDMA cellular and Personal Communications Services (PCS), Wireless Local Loop (WLL), and IMT-2000 (International Mobile Telecommunications-2000). We propose a method to find the PN contaminated area and calculate the improvement rate in the field environment by the pilot strength of.

In the following description of the present invention, if it is determined that a detailed description of a related known function or configuration may unnecessarily obscure the subject matter of the present invention, the detailed description thereof will be omitted. Terms to be described later are terms defined in consideration of functions in the present invention, and may be changed according to intentions or customs of users or operators. Therefore, the definition should be made based on the contents throughout the specification.

2 is a flowchart illustrating a method for deriving PN pollution improvement rate according to the present invention. As shown, a process of selecting an arbitrary section and collecting PN offset and pilot strength data in the section 110, and analyzing the collected data to determine PN contamination (120), the hand of the PN contamination region A process 130 of calculating the number of off attempts and a process 140 of improving a base station generating PN pollution are included.

Hereinafter, with reference to the accompanying drawings will be described in detail the operating principle of the preferred embodiment of the present invention.

The base station always transmits the information of the neighboring base station to the mobile terminal so that the mobile terminal can know the PN offset of the neighboring base station. The mobile terminal always manages the received relevant information, and measures the pilot strength with respect to the PN offset of that information and the previous information. Therefore, the PN offset pilot strength data is collected for each PN offset set by accessing the mobile terminal.

Figure 3 shows the structure of the log data collection device used in the present invention. As shown, the data collection device 200 is connected to the mobile terminal 40 in a call and the mobile terminal 41 in an idle state. The data collection device 200 is a personal computer (PC), and is connected to the mobile terminals 40 and 41 through RS-232C. The data collection device 200 includes a call collection device 210 that collects data from a mobile terminal in a call, and an idle collection device 220 that collects data from a mobile terminal in an idle state, and the collection devices 210 and 220. It consists of an analysis device 230 for analyzing the collected log data (Log Data).

The call collecting device 210 collects PN offset and pilot strength data for each PN offset set (active, neighbor, candidate location, reserve, etc.) and collects handoff related contents among messages between the mobile terminal and the base station. The idle collection device 220 collects PN offset and pilot strength data for each PN offset set.

The log data collected in the idle state and the call state is analyzed to determine whether there is PN contamination in the test area. (120) Output data related to PN offset and pilot strength of the analyzed log data as a time profile, Analyze the propagation environment in the defined area. If unnecessary PN offsets are found in the data collected in the defined area, the area is considered to be PN contamination. That is, the PN offset and pilot strength related data are displayed for each terrain, and the location and service conditions of the base station are compared with the profile to find an area with PN pollution. Also look for PN offsets that cause contamination in the area.

Then, the handoff incidence of the test area is derived from the analyzed data through handoff-related data. (130) In this case, the PN pollution and the handoff area and the handoff incidence of the idle state and the call state are extracted. Comparative analysis of the propagation environment of call state. The collected data can be output as a profile and displayed as a histogram to indicate the handoff rate of the test area.

The percentage of handoffs caused by a base station causing PN contamination in the test area is compared with the rate of handoffs in the entire handoff area of the base station to determine what percentage. The handoff occurrence rate in the entire handoff region of the base station can be known from the operating data stored in the base station higher system.

That is, the Busy Hour Handoff Attempt based on the total handoff occurrence rate of the base station is compared with the Busy Hour Handoff Attempt based on the handoff occurrence rate in the test area. At this time, a method of estimating handoff related system load for handoff processing is as follows.

Adding event frequency occurring in the entire handoff region of any base station b F _b ^a (S _h ) And dropping frequency (Dropping Event frequency) F _b ^d (S _h ) In this case, the total handoff incidence rate generated by the base station b. P _b (s) Is expressed as in Equation 1.

here N _b ^h (T) Is any subscriber serving base station b at any time interval T. N _b ^s (T) The number of subscribers causing a handoff. N _b ^h (T) = γ N _b ^s (T) Satisfy the relationship of, where γ Is the handoff fraction.

Also above α (t) Is a coefficient of the frequency of occurrence of the ad of base station b, β (t) Is the coefficient of the drop occurrence frequency of the base station b. α (t) Wow β (t) Is a variable due to propagation environment and system load.

Then, the total handoff attempt frequency introduced by the N base stations into the handoff related system (Handoff Attempt Frequency) P _c (T) Is the same as Equation 2.

remind F _b ^a (S _h ) Wow, F _b ^d (S _h ) , N _b ^h (T) , α (t) , β (t) Can be obtained from the base station host system.

Through the above process, the total number of handoff attempts generated in the entire handoff region of the base station b can be known. In addition, the frequency of ad occurrences and drop occurrences collected in the test area can be used to determine the number of handoff attempts generated in the test area determined to be a PN contaminated area. Therefore, it can be seen how much the number of handoff attempts generated in the PN polluted area is compared to the total number of handoff attempts in the entire base station area.

Adjust the transmit power or antenna main-lobe direction / down tilt and the handoff related parameters of the base station transmitting the PN offset causing the PN contamination. then F _b ^a (S _h ) Wow F _b ^d (S _h ) Can be appropriately reduced the load of the handoff-related system, and can improve the PN pollution phenomenon in the region (140) PN pollution for the total number of handoff attempts in the base station handoff area The base station is adjusted to have a small value so that the ratio of the number of handoff attempts in the region is small.

Through the above process, it is possible to find the PN contaminated area and improve the degree of contamination of the found PN contaminated area. In addition, the improvement rate of the system can be known from the ratio of the handoff attempts in the PN polluted area to the total handoff attempts in the base station total handoff area.

The present invention can be variously modified and can take various forms and only the specific embodiments thereof are described in the detailed description of the invention. It is to be understood, however, that the present invention is not limited to the specific forms mentioned in the detailed description of the invention, but rather includes all modifications, equivalents, and substitutions within the spirit and scope of the invention as defined by the appended claims. It should be understood to do.

The present invention operating as described above can measure PN contamination as described above, and analyze call capacity, sectorization, handoff area, and the like. It also improves PN contamination, reducing the load on the system that can be caused by unnecessary handoffs.

In addition, by calculating the ratio of the number of handoff attempts in the PN polluted area to the total number of handoff attempts in the base station total handoff area, the improvement rate of the handoff related system can be derived, and the load of the system can be appropriately reduced.

Claims (14)

A base station for providing a mobile communication service to a mobile terminal in a specific service area having a pilot signal having a unique pseudo noise offset (PN offset), a mobile terminal for distinguishing the base station through the PN offset, and receiving a mobile communication service; In the mobile communication system comprising a base station host system for managing the base station, Collecting pilot signal strengths of PN offsets of base stations that can be detected in any test area; And And analyzing the collected data and determining that the test area is a PN contamination area when unnecessary PN offset is found, pseudo noise pollution measurement method of a code division multiple access system. The method of claim 1, wherein the collecting of the signal strength comprises: Collecting pilot strength of PN offset from an idle mobile terminal; And And collecting pilot strength and handoff related information of the PN offset from the mobile terminal in a call state. The code division multiple access according to claim 1 or 2, wherein in the determining of the PN contaminated area, data collected from an idle mobile terminal and data collected from a mobile terminal in a call state are analyzed and determined. How to measure pseudo noise contamination in a system. The method of any one of claims 1 to 3, wherein in collecting the signal strength, the pilot strength of the PN offset for each search set of the PN offset is collected. The method of any one of claims 1 to 4, wherein the determining of the PN pollution area comprises: determining whether the collected PN offset data is an unnecessary PN offset based on information received by the mobile terminal from the base station higher level system. , Pseudo-noise Pollution Measurement in Code Division Multiple Access Systems. A base station providing a mobile communication service to a mobile terminal in a certain service area, each having a pilot signal having a unique pseudo noise offset (PN offset), and the mobile terminal distinguishing the base station through the PN offset and receiving a mobile communication service; And a base station higher system for managing the base station. Collecting pilot signal strengths of PN offsets of base stations that can be detected in any test area; Analyzing the collected data and determining that the test area is a PN contaminated area when an unnecessary PN offset is found; Calculating total handoff attempts in all handoff regions of the base station transmitting the unnecessary PN offset and handoff attempts by the base station in a test region determined to be PN pollution; And Improving the performance of the base station so that the ratio of the number of handoff attempts in the PN pollution area to the total number of handoff attempts is small. The method of claim 6, wherein the collecting of the pilot signal strength comprises: Collecting pilot strength of PN offset from an idle mobile terminal; And And collecting the pilot strength and handoff related information of the PN offset from the mobile terminal in a call state. 8. The code division multiple access of claim 6, wherein the determining of the PN polluted area comprises comparing and analyzing data collected from an idle mobile terminal with data collected from a mobile terminal in a call state. How to improve pseudo noise contamination in your system. 9. The method of claim 6, wherein the collecting of the signal strength collects PN offset and pilot strength for each search set of PN offsets. 10. 10. The method of any one of claims 6 to 9, wherein the determining of the PN pollution area comprises: determining whether the collected PN offset data is an unnecessary PN offset based on information received from the base station higher level system. To improve pseudo noise pollution in code division multiple access systems. 11. The method according to any one of claims 6 to 10, wherein the total number of handoff attempts P _b (s) Is, The frequency of handoff ad occurrences in the entire handoff region of any base station b F _b ^a (S _h ) , Frequency of handoff drop in the entire handoff region of any base station b F _b ^d (S _h ) , The number of subscribers that cause a handoff among the total subscribers served by base station b at any time interval T N _b ^h (T) , The frequency of occurrence of Ads in BSb α (t) , Drop frequency count of base station b β (t) When we say A method for improving pseudo noise pollution in phosphor-coded multiple access systems. The method of claim 11, wherein F _b ^a (S _h ) Wow, F _b ^d (S _h ) , N _b ^h (T) , α (t) , β (t) Is a method for improving pseudo noise pollution in a code division multiple access system, which is obtained from operational data stored in a base station host system. 7. The number of handoff attempts in the PN contaminated area according to claim 6 P _b (s) Is, The frequency of handoff ad occurrences by any base station b in the test area F _b ^a (S _h ) , The frequency of handoff drop occurrence by any base station b in the test area F _b ^d (S _h ) , The number of subscribers that cause a handoff among the total subscribers served by base station b at any time interval T N _b ^h (T) , The frequency of occurrence of Ads in BSb α (t) , Drop frequency count of base station b β (t) When we say A method for improving pseudo noise pollution in phosphor-coded multiple access systems. The method of claim 13, wherein F _b ^a (S _h ) Wow F _b ^d (S _h ) Is, obtained from the data collected in the process of collecting, the method for improving pseudo noise pollution in a code division multiple access system.