KR100665073B1 - A method of modeling a neighbor list for a mobile unit in a cdma cellular telephone system - Google Patents

Abstract

The computer-implemented process of determining which base stations are most likely to communicate with the mobile device determines the base station's probability of communicating with the mobile device at one location based on the actual received signal level that compares the interference level of the signal received at that location. For each set of base stations, calculate the probability that the set of base stations can communicate.

Description

A METHOD OF MODELING A NEIGHBOR LIST FOR A MOBILE UNIT IN A CDMA CELLULAR TELEPHONE SYSTEM}

1 is a partial view of a CDMA cellular telephone system.

2 is another partial diagram illustrating a portion of a CDMA cellular telephone system.

3 is a diagram useful in explaining the handoff category of a CDMA cellular telephone system.

4 is a curve diagram used to evaluate the probability that a base station providing a strength level to interference level ratio in a received signal can serve a particular location in a CDMA cellular telephone system.

5 is a two table diagram illustrating the probability of receiving a signal from a group of likely base stations at a location within a CDMA cellular telephone system.

6 is a process diagram in accordance with the present invention.

7 is a detailed view of some of the processes of FIG.

8 is a mobile device for collecting data to be used to perform the process of the present invention.

FIELD OF THE INVENTION The present invention relates to cellular telephone systems, and more particularly to a method for determining a base station with which a mobile device should communicate in a code division multiple access (CDMA) cellular telephone system.

Commercial mobile communication systems currently in use include a plurality of fixed base stations (cells) that transmit and receive signals differentially to / from within a communication area. In a CDMA system, each base station communicates with a mobile device by making digital transmissions over the same frequency spectrum. In most cellular systems, especially cellular systems with cells in urban areas carrying heavy traffic, each support station is divided into two or three sectors, each with its own transmission equipment with 180 or 120 degrees of antenna coverage. Here, when using a base station, the sector and the cell have the same indication.

CDMA systems send messages digitally. Since CDMA systems all transmit on the same frequency spectrum, the digital signals that make up each message must somehow be recognized from all available transmissions. To carry out this function, the digital message is decoded by a series of redundant digital codes. One of these codes, called a pseudo random noise code, applies to all transmissions throughout the CDMA system. The PN code is applied to encode each bit of the original message at the transmitter and to decode the encoded message at the receiver. In order to recognize the message provided by a particular base station, each base station begins to encode the transmission using that PN code using a number of repetitive initial times and a separate time offset (PN offset). Thus, one base station can initiate encoding transmission at its initial time, the second base station can initiate encoding transmission at one offset from its initial time, and the third base station can at two offsets from said initial time Encoding transmission can be initiated and the encoding transmission can be initiated up to a total of 512 offsets.

In addition, each transmission between the mobile device and the base station encodes the transmission with one of a plurality of Walsh codes so that each channel is efficiently located. Messages encoded by Walsh codes, such as PN codes, can be decoded by the same Walsh codes at the receiver. Thus, encoding transmission on multiple channels is decoded by applying a mask comprising a Walsh code and a PN code to a reception pattern of information bits starting at a PN offset specified for a particular base station.

The base station typically has a 64 Walsh code that can be used to form a channel to establish transmissions with the mobile device. Several such channels are pre-assigned to act as control channels. For example, to inform a particular offset used in a mobile device, each base station continuously transmits a PN code using the PN offset assigned to one of the channels (pilot channels) formed by the Walsh code. The mobile device monitors this preset pilot channel. When the mobile device finds an offset that the pilot can decode, another control channel (synchronization channel) determines the initial time and then identifies the PN offset of the base station. In addition, each system maintains a paging channel that sends an indication that a new message arrives. A total of nine channels are provided for this and other control functions.

In order for a mobile device to transmit and receive telephone communications as it travels over a large area, each base station is typically physically located such that its coverage area is adjacent and overlaps with the coverage areas of a plurality of other base stations. When a mobile device moves from an area covered by one base station to an area covered by another base station, communication with that mobile device is transmitted (hand off) from one base station to another base station in an area where coverage overlaps with another base station.

In most other kinds of cellular communication systems, a mobile device communicates with only one base station at a time. However, because CDMA systems all transfer on the same frequency spectrum, the mobile device can use all the information within that range. However, it only decodes the PN offset and the information on the Walsh code channel directed to it. A CDMA mobile device utilizes a receiver capable of simultaneously applying a plurality of decoding masks at different offsets of the entire information spectrum it receives. Currently, a vehicle receiver can decode up to six PN offsets at a time. However, in general, only three PN offsets are used to decode the message, while other offsets decode the control information. In a CDMA system, since the mobile device can receive the same information from multiple different base stations at the same instant, it decodes the information of a single message sent to the mobile device from multiple different base stations using different PN offsets and Walsh codes simultaneously, Combine the information to produce a single output message. Thus, while a signal transmitted at one base station can be faded, the same message can be received at an appropriate strength at another base station. The situation in which multiple base stations and mobile devices can communicate at one time is called "soft handoff."

 In order to take advantage of the advantages provided by CDMA technology, the mobile device must be able to accurately select the base station with which it is communicating. However, the mobile device is too slow to query the base station to determine which base station to communicate with at each 512 PN offset. As a result, the mobile device reduces the time required to search for such transmissions using a "neighbors list" that specifies the PN offsets that are most likely to be transmitted. The neighbor list is provided by the base station to which the mobile device is in contact.

It is very complicated how the mobile device determines whether contact is made with a particular base station. The mobile device constantly monitors the strength of signal propagation on a pilot channel and attempts to use the highest quality signal possible. The pilot signal for the base station to which the mobile device is currently contacting is rarely monitored following the pilot signal for the base station on the neighbor list, ie, the pilot signal for all base stations in a group. When the strength of a pilot signal provided at a particular base station rises above a certain threshold Tadd for all signal levels received by the mobile device (interference received despite encoding), the mobile device makes a request to the system, According to the indication, one of the receiving components is assigned to the base station. This is said to put the base station on its active list. When the strength of the pilot signal provided at the base station falls below another threshold level Tdrop for all signal levels received by the mobile device for one set of periods, the mobile device makes a request to the system and in accordance with the instruction The base station can then be removed from the active list and assigned to another strong base station. Furthermore, if the pilot signal is stronger than the weakest pilot signal of the base station in its active set, the mobile device will request the system and, upon indication, replace the more powerful base station and its weak base station.

In order for a system operator to intelligently allocate resources to a CDMA system, the operator typically models the system to determine where changes occur. One of the important categories in determining resource allocation is the determination of the base station that the mobile device contacts at any particular location. Most of the characteristics of the efficiency with which the system operates are made according to this determination because the active list base station determines the signal level compared to the interference at any location.

Although the practical way of determining the base station with which the mobile device is in contact is very complex, all conventional models require that the mobile station be provided with a pilot signal that provides a pilot signal that is greater than the blocking of the sum of all signals received by the mobile device before decoding. Simply assume that it will actually communicate with the device. This leads to incorrect modeling of the system and incorrect assignment of information providers.

As a result, it is desirable to provide a novel process in which the handoff characteristics of a CDMA cellular system can be modeled to improve the system in stages.

The present invention determines the base stations with which the mobile device can best communicate with the mobile device at a particular location, and the probability that each base station can communicate with the mobile device based on the actual received signal level compared to the interference level of the signal received at that location. , Calculate the probability that the base station can communicate with the mobile device at the location for each set of base stations, and add the base station and any other base station that serves together to other base stations throughout the system, the most likely It is executed by a computer running process that selects a list of neighboring base stations for each base station at each location from a high sum.

These and other features of the present invention will be more readily understood by reference to the detailed description taken in conjunction with the drawings in which like elements are referred to by the same numerals.

Referring now to FIG. 1, a portion of a CDMA cellular telephone system 10 including a plurality of individual base stations 12 arranged to provide coverage of a service area is shown. Each base station 12 of FIG. 1 is shown with an external boundary 13 indicating the limits of the effective communication range. The borders 13 of other adjacent base stations typically overlap.

Each base station 12 includes at least one cell that communicates with a mobile device 15 operating within its service area. In many cases, instead of one cell, the base station is divided into two or three sectors each with communication equipment communicating with a plurality of mobile devices in some region defined by an antenna pattern angle of 180 degrees or 120 degrees. . In a CDMA system, both base stations and mobile devices are transmitted digitally and are performed on the same "spread spectrum" frequency of 1.25 MHz. The digital information bits of each message are extended using various levels of encoding information. One such level is called a pseudo random noise (PN) code. Each base station throughout the system encodes the transmission information using the same PN code. Each base station identifies itself by using individual time offsets (generally referred to as PN offsets) from several iterative initial times that apply the PN encoding to any transmission. The initial time interval is divided into a total of 512. Thus, one base station begins encoding transmission at its initial time, the second base station initiates encoding transmission at one offset from its initial time, and the third base station initiates encoding transmission at two offsets. Typically, base stations that are physically near each other use PN offsets that are far from each other. Its initial time and various offsets are typically set accurately using circuitry such as global positioning system (GPS) circuitry.

Since each base station transmits all messages using the same PN code at the same PN offset, there must be a way for the mobile device to detect the messages. To accomplish this, each transmission with the base station is efficiently located with each channel by further encoding the transmission with one of a plurality of Walsh codes. Messages encoded with Walsh codes, such as PN codes, are sent and received using masks of the same pattern, so that messages sent using different Walsh codes are orthogonal to the encoding. The transmission on a particular channel is decoded by applying a mask containing the Walsh code and the PN code to the reception pattern of information bits starting at the PN offset indicating the particular channel.

The transmission CDMA system offers many advantages. One of these advantages is that the mobile device can receive the same message delayed through a plurality of different base stations at the same time. Since all transmissions occur on the same frequency band, the mobile device not only receives all the information available within that range but also decodes the information on the channel directed to the mobile device. A CDMA mobile device uses a receiver that can apply a plurality of different Walsh and PN decoding masks to the entire spectrum of information it receives at the same instant. By knowing the desired channel to receive, the mobile device simultaneously decodes information from one message sent to the mobile device by a plurality of different base stations and combines the information to generate one output message. Thus, while a message provided at one base station fades, the same message can be received from the other base station at an appropriate strength. This allows CDMA systems to provide significantly better transmission probabilities than other systems.

Despite these advantages, CDMA systems have several problems. One of these problems is caused by the fact that all transmissions occur on the same frequency spectrum. Since all transmissions occur on the same frequency band, the mobile device actually receives all the transmissions available within that range. Transmissions that are not directed to a particular receiver act like interference that obscures that given transmission. When the transmission level (preferred and undesirable) at the receiver reaches a level about 14 dB above the desired signal level, it becomes difficult to decode the desired transmission. Prior to decoding, the level of this signal is converted to a level approximately 7 dB above the level of interference after decoding the message directed to the receiver.

In order to provide high quality transmission, the CDMA system maintains its message strength after decoding at a typical level of approximately 7 dB or more on all interference levels on the channel, including the feature of automatically increasing or decreasing the strength levels at base stations and mobile devices. do.

The mobile device determines whether the strength of the received signal is strong enough by measuring the rate at which an error occurs in the received decoded signal (frame error rate), i.e., a factor directly related to the signal to interference ratio. When an error occurs above the limits described above, the mobile device signals the base station to increase the strength of the signal. The base station does this, but again increases the strength by gradually decreasing the signal strength from the high transmission level until the mobile device signals. Thus, when a signal becomes too high, indicating an intensity approximately 7 dB below the interference level after decoding, the base station automatically increases the strength of the transmitted signal to raise the received signal level for interference and improve the quality of the signal. Let's do it.

In a similar manner, the base station measures the strength of the signal received at the mobile device by monitoring the frame error rate and instructs the mobile device whether the transmission strength goes up and down. When the mobile device contacts a plurality of base stations, the mobile device receives a signal from each base station indicating whether the transmission strength is rising or falling for the base station. As long as there is one base station transmitting a signal to the mobile device to reduce its transmission strength, the mobile device ignores any signal and increases the transmission strength in response instead of the signal to increase the transmission strength. The reason is that one strong signal can sufficiently provide the interference free service for the mobile device.

In the CDMA service area, it is very useful to evaluate the quality of service and improve the operation of the system. In order to do this correctly, it is necessary to know the base station that provides the best service to any particular location throughout the system. Without knowing such a base station, it is impossible to understand the operation of the system. For example, by not knowing the base station to which a mobile device should be contacted at any location, it is impossible to know the transmission power level, interference level and similar characteristics of the system.

All conventional methods of evaluating a CDMA system to determine a base station to be provided at a particular location within the system use one of a plurality of different blocking levels to evaluate the signal strength. If the signal received by the mobile device from the base station is stronger than this blocking level before decoding, the base station is assumed to serve that location. As can be appreciated, one blocking level of any kind evaluated prior to decoding does not accurately represent the actual evaluation made by the mobile device when determining whether to add or drop a particular base station to its active server list. First, the signals evaluated before decoding provide only an unambiguous approximation of the actual signal to interference ratio after decoding. Second, the single threshold is described in detail and does not exhibit the complex handoff characteristics of the CDMA system shown in FIG. As a result, none of these conventional decisions can accurately characterize a system.

The present invention provides a process for accurately evaluating a base station that provides the best service at any location in a CDMA system so that an operator can step up the quality of service.

To evaluate any system, data about that system is first collected. This may be the same data as data collected using an AMPS or TDMA system in the same area as the CDMA system. The data may be accumulated to determine the quality of the CDMA service in the service area. In any case, the specific data used is data indicating a transmission signal strength transmitted from a base station, a reception signal strength transmitted from one location, and a reception location that records the location of the entire system.

In a CDMA system, data is collected by running a test using a specific receiver called a PN scanning receiver capable of receiving signals at levels greater than 21 dB and less than the overall received signal strength. PN scanning receivers are associated with global area position system (GPS) receivers and computers in test vehicles. The test vehicle drives the roads of the system 10 as the scanning receiver automatically measures at regular intervals (typically every 1 to 5 seconds). In each measurement interval, the receiver measures the total signal strength of all received signals and the strength of each pilot signal received at any base station. These values are generally stored in the computer of the test vehicle in accordance with the time and position values provided by the GPS receiver. 8 illustrates a mobile device for collecting the data.

When describing the system and collecting data, this data is used to provide the assessment. In contrast to conventional system evaluation methods, the present invention eliminates the need to infer the values provided by the terrain model using data obtained through actual measurements of the system.

Pilot signals generated by the base station on the pilot channel are transmitted with constant force through the system. Since the transmission powers are the same, the mobile device can compare the strengths of the pilot signals received at different base stations with each other. The known transmission level also determines the path loss transmitted from the base station received by the mobile device at that location. This path loss value, the pilot strength received from each base station of interest and the total received strength of all signals at the location are recorded at each location in the system. For this purpose, received pilot signal strength below some blocking level is considered indistinguishable by the mobile device.

Probability tests to determine which base stations serve one location (which is on the active list) are applied according to the invention of the method shown in FIG. Using a probability curve (derived from the data for the system), such as the curve shown in Figure 4, to evaluate the probability that there is a base station providing a received signal that serves a particular location at a specific signal to interference level (Ec / Io) ratio. In this case, the probability of an individual base station serving the location can be determined. For any location, the Ec / Io ratio can be determined for each base station by dividing the strength of the received pilot signal before decoding by the total received signal strength (total interference) at that location. It is found that two base stations are received at each location on the average pilot signal. For locations where one or more base stations provide a discernible pilot signal at a location, the probability for each individual base station is determined. Next, the probability for a possible group of base stations from which a discernible signal is received is multiplied by the probability for each individual base station received in the group by the probability of all other base stations, and the probability that all base stations not in the group cannot be received. Can be obtained by multiplication. This is illustrated for a group of four base stations providing pilot signals discernable by the table of FIG. This table shows the probability for a particular group of base stations to service the location at each intersection.

For example, the other pilot signal of FIG. 5 is assigned an example of the strongest pilot A with all interference ratios Ec / Io of 8 dB or less while each other pilot is progressively weakened and has a low rate. In the example graph of FIG. 4, the probability P (X) for the individual base station generating the pilot signals A-D is determined and placed in the P (X) column of FIG. 5 for the row specifying the particular pilot. This value is inferred at column level pn (X) for one embodiment of the present invention to provide a state in which a voice signal carrying only three channels can be received at one time. Next, in the second part of the figure, the value of the intersection of the row and column is the final probability for the pilot indicated at the beginning of each row and column. In that figure, the accent indicates that the particular pilot is absent.

In this, a list of possible base stations whose ranks of approximate probabilities are ranked is obtained at each location in consideration of one of the base stations that can serve that location. In order to determine the probability that any individual base station will provide the coverage area defined by the outer limit 13 of FIG. 1 of the primary base station, the probabilities for each group that the primary base station and other base stations are included are summed. . For example, in FIG. 5, the probability for each group including the base stations A and B can be determined. This sum provides a plurality of said locations. When adding up all locations of this coverage area, the total number of probabilities for each particular base station is executed. Thus, when determining the neighbor list for base station A, the probability that each of the other possible base stations (e.g., A and B, A and C, A and D) will serve the location is determined by the base station ( Together with A) provides a list of neighboring base stations based on the net probability of each other possible base station serving a location.

When identifying the base station serving a location, its transmitted signal strength needed to provide a quality signal is calculated for each base station. Each base station may adjust its transmitted signal strength to maintain a quality signal at the mobile device. The quality signal level is determined by an Eb / No value that measures the energy received at that location from its intended signal measured after decoding versus the total interference received. In determining the transmission power required to generate a quality signal, the average transmission power may be calculated by weighting the probability of receiving a signal from the base station at the location at that received signal strength. If the transmission power determined for each location throughout the system is added to the base station, the total transmission power will be determined.

The process of calculating the base stations (shown in FIG. 6), the probability of servicing one location and the required transmission power for each base station are each location in a system (some of the above systems) where modeling is performed until values for all locations are determined. Persists against. At the end of one calculation, each received signal strength needed to provide a quality signal at a location and each transmission strength required at a base station providing the quality signal at that location is used for the two calculations. That is, the increase in the value of the received signal at the location and the value of the signal transmitted at the base station is used to determine the new total received signal value at each location. The increase in the received signal value can be determined for each position by adding the incremental increase in the individual received signal value to a previously calculated total.

The new total received signal strength at each location is used for the received signal strength of the individual pilot signal to calculate Ec / Io and to determine a new probability of serving the location in the discussed manner. The probabilities for each possible group of base stations are calculated in the manner described above. Finally, the signal strength newly transmitted at the individual base station is calculated by the determination of the received signal strength to provide the movement (Eb / No) necessary for the location. For many locations, the transmission strength for any base station can be increased again, because an increase in the transmission strength required for the first calculation raises the total received signal strength at the primary location, resulting in signals received from many base stations. This is because the intensity needs to be increased to maintain Eb / No necessary for quality service.

At some point in the modeling process, the increase in the level of signal strength transmitted by all base stations and the increase in the interference level at each location in the system will be the same so that an additional number of calculations will have a minor impact on the interference of the system. . When the number of calculations for all positions has been completed, it is tested at the beginning of the calculation to determine the change in transmission signal strength. If the level is less than the predetermined level selected for a particular system to determine when the change is too small to be a problem, then the modeling ends. This is sometimes called convergence in this specification. The value determined for the required transmission power, the base station defined by the transmission power, and the group of base stations or base stations most likely to serve any position in the system are the base stations determined by the last calculation before the same test is met.                     

With each location value modeled through the CDMA system, a neighbor list can be prepared for each sector. Using the data accumulated at each location to determine the probability of another base station serving the location, the probability of any base station with a particular coverage area and another particular base station serving a location within the coverage area is determined for each of the entire system. Can be found in position.

This is done by determining the probability for each group of possible base stations among all the base stations whose groups can provide a location in the coverage area, including base stations with coverage areas and other base stations of interest. The probability for each group is generated by multiplying the probability of each base station in the group serving the location by the probability that a base station not in the group will not serve the location. This is the probability shown in the right part of the table in the example of FIG. The probability of each group containing two base stations is added to provide a probability that two base stations serve the location. Next, the probability of the base station serving another location within the coverage area of the primary base station and other specific base stations is added to all locations of the coverage area. Similarly, the probability of any base station and each other base station serving any particular location is determined and added through the system to provide a list of probabilities that the base station in each coverage area and other base stations can service the coverage area. Generated by the base station. The result is the sum of the probabilities of the base station and other base stations serving any location that the base station serves.

Until a sufficient number of neighboring base stations are selected for the capacity of the system, using a cumulatively low probability sum and selecting a list starting with the highest probability does not actually provide service to each service location. In order to provide a neighbor list including only other base stations in each base station. It should be noted that any particular base station weights the final value by the number of locations within the coverage area that can communicate with the vehicle. This effectively provides for the base station covering the wide sector area served by the primary base station. Such weighting is particularly useful for occasionally used new systems where the loading effect is not determined and is not critical.

On the other hand, in many situations, various areas of one system steer much more traffic than others. In such a case, it is desirable to consider the system. The present invention allows this. Use may be considered by assigning a useful factor to each location to further increase the area experiencing heavy traffic. Thus, for example, one location may have an average 1 / 10th of the user's traffic at all times while another location may have slightly less traffic. By weighting the probabilities for each individual base station by the usage factor for the location (eg, by multiplying the probability that 1/10 of the users are present), the sum of the probabilities obtained will be similarly weighted by the user factor. In addition, these usage factors may be used to determine the effect of different usage levels at different times.

It should be noted that this same use weighting is used to calculate the transmission force required to generate a quality signal at a location. For example, the transmission power may be determined in the process by multiplying the received signal power by the probability that the location is serviced by a particular base station, and then adding transmission loss. In addition, the transmission force for the location can be determined based on the usage factor. By weighting the received signal power by the probability and usage factor of each location, and then adding the transmission power to each sector, the transmission power can be determined more accurately for the base station.

The probability may be determined when determining the probability and including in the neighbor list any base stations whose number allocated in the above-described manner is greater than some preselected level. This tends to include base stations in a list based on coverage area and removes from the group most similarly capable of serving base stations that are less likely to actually serve by having a certain level of confidence in the signal. The level may be used depending on the probability and use factor of calculating the other category used in the determination of the neighbor list.

In addition, the probability determined for the group of base stations serving one location may be used to determine the interference level at one location. For example, instead of simply adding up all the signals received at one location, the signal values received from each location in a group may be added and weighted by the probability that the group of base stations provides the location. The results for all groups received at the station can then be combined to provide the level of interference.

Although the invention has been described in the preferred embodiments, those skilled in the art will recognize that various modifications and changes can be made without departing from the scope and spirit of the invention. Accordingly, the invention should be measured in the following claims.

Claims (18)

In a method of selecting a neighbor list in a CDMA system: Determining a set of base stations consisting of all base stations capable of communicating with a mobile device at a location based on the signal strength levels received from the base stations compared to the power levels of all signals received at the location; Determining a probability of communication at said location for each base station in said set of base stations capable of communicating with a mobile device at a location; Each indicating a combination of one or more base stations possible from the set of base stations; Calculating a communication probability at the location for each possible base station combination based on the communication probability of each of the base stations in the combination determined relative to the communication probability of the remaining base stations in the set; And Creating a neighbor list from the calculated probabilities of the combinations, the neighbor list indicating a relative probability of each base station servicing the location for each of the neighbor base stations on the list. Steps to create The method of selecting a neighbor list in a CDMA system comprising a. 2. The method of claim 1, wherein determining the probability that each base station capable of communicating with a mobile device at the location may communicate with the mobile device at that location is based on the signal strength level received at the base station versus the total at that location. Determining a list of neighbors in a CDMA system, comprising determining an interference ratio. 2. The method of claim 1, wherein determining the probability that each base station capable of communicating with a mobile device at the location may communicate with the mobile device at that location is based on the signal strength level received at the base station versus the total at that location. Comparing the interference level ratio with a curve that compares the level ratio with a probability that a signal will be received. The method of claim 1, wherein determining the probability that each base station capable of communicating with the mobile device at the location may communicate with the mobile device at the location comprises: neighboring to each base station from the most probable base station and combination; And selecting a list of neighbors in the CDMA system. 2. The method of claim 1, wherein calculating a probability that a possible combination of base stations in the set of all base stations can communicate with the mobile device at a location in communication with the mobile device comprises: the interference level of a signal received at a location and the set of base stations. The method of selecting a neighbor list in a CDMA system, characterized in that for comparing the actual power level of each base station in. The method of claim 1, wherein calculating the probability that each possible combination in the set of all base stations can communicate with the mobile device at a location in communication with the mobile device comprises one service base station with any other service base station throughout the system. Adding a probability for a neighbor list in a CDMA system. 7. The method of claim 6, wherein the sum of the probabilities depends on a plurality of locations serviced by one base station and any other base station throughout the system. 7. The method of claim 6, wherein the sum of the probabilities depends on the average number of users at each location serviced by one base station and any other base station throughout the system. . 8. The method of claim 7, wherein selecting a neighbor list for each base station from a combination of base stations and base stations capable of serving one location includes selecting a base station having a number greater than a threshold of mutually provided locations. A method of selecting a neighbor list in a CDMA system characterized by the above-mentioned.  8. The method of claim 7, comprising selecting a combination of base stations that can serve at one location and the number of predetermined base stations having the largest mutual service location from the base stations. Way. 8. The method of claim 7, wherein the step of selecting a combination of base stations that can serve at one location and a neighbor list for each base station from the base station comprises selecting a predetermined number of base stations with the largest mutual service user. A method of selecting a neighbor list in a CDMA system characterized by the above-mentioned. 8. The method of claim 7, wherein the step of selecting a combination of base stations to service at one location and a neighbor list for each base station from the base station comprises selecting a base station having a larger number of users than a threshold of mutually serviced users. The method of selecting a neighbor list in a CDMA system, characterized in that. 2. The method of claim 1, wherein determining each base station capable of communicating with a mobile device at the one location based on the signal strength level received at the base station compared to the strength levels of all signals received at that location. Calculating interference at each location from the measurement signal level received at the location, Determining a required signal level at each position for the quality signal; A base station calculating a transmission power capable of generating a required received signal level; Repeating said steps until a change in interference is less than a predetermined amount. 15. The method of claim 13, wherein the step of calculating the transmission power capable of generating the required received signal level by the base station uses the probability of the base station serving the location weighted by the average number of users at one location. How to select neighbor list in CDMA system. 15. The method of claim 13, wherein the calculating of the transmission power capable of generating the required received signal level by the base station adds an average transmission level at which the base station can service a plurality of locations to determine a total average transmission level for the base station. And selecting a neighbor list in a CDMA system, comprising: 14. The method of claim 13, wherein calculating the interference at each location from the measurement signal levels received at the location comprises adding signal levels received by each combination of base stations servicing one location; Weighting the sum sum by the probability of the base station combination serving the location; And generating a mean interference level at one location by adding a result for each combination of base stations serving one location. The method of claim 13, wherein the base station calculates a transmission power capable of generating a required received signal level Determining a transmission level for the base station at each location of the system using the probability of the base station servicing the one location weighted by the average number of users at one location; Comparing the difference in sector power between two successive iterations to determine convergence when the difference falls below a certain threshold. The method of claim 1, wherein determining each base station capable of communicating with a mobile device at the one location based on the signal strength level received from the base station compared to the strength levels of all signals received at the location. Calculating interference at each location from signal levels received at that location, Determining a required signal level received at each location for a quality signal; A base station calculating a transmission power capable of generating a required received signal level; Repeating said steps until the change in interference is less than a predetermined amount.

Images