JPH11122654A - Code division multiplex cellular mobile radio communication system, base station selection method and mobile station system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To attain communication with base stations of a proper number depending on a propagation environment and a mobile speed of the mobile stations by selecting many more number of connected base stations when a propagation loss level is fluctuated at a high speed and selecting a fewer numbers of connected base stations when fluctuation in the propagation loss is slow. SOLUTION: A transmission signal sent from a base station is received by a reception multicoupler 21 and given to a mobile speed detector 23 and a propagation loss measurement device 24 via an RF section 22. A mobile speed Vms and a propagation loss L1 (t) calculated by the mobile speed detector 23 and the propagation loss measurement device 24 are given to a soft hand-off base station selection device BSS, where a base station being a new soft hand- off object or a measurement whose connection is released is decided. The selection of the base station is attained efficiently with high reliability by changing a base station selection level and a hysteresis margin based on the fluctuation speed of the propagation loss.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a code division multiplexing cellular mobile radio communication system for implementing simultaneous connection with a plurality of base stations, and a base for realizing efficient base station selection in a mobile station of the system. The present invention relates to a station selection method and a mobile station device.

[0002]

2. Description of the Related Art A method of selecting a base station in a mobile station of a conventional code division multiplex cellular mobile radio communication system will be described below with reference to the drawings. A mobile station of a code division multiplexed cellular mobile radio communication system in which a plurality of radio base stations are unevenly distributed and these base stations simultaneously use the same frequency is always connected to a base station having a minimum propagation loss, and transmission power control is performed. , The interference to other wireless lines must be minimized. Since a certain period of time is required for the connection process with the new base station, the base station having the minimum propagation loss may change depending on the fluctuation of the propagation loss during that period, and may cause interference to the base station of the switching destination. .

[0003] Interference with a switching destination base station that occurs during the above-described connection processing with a new base station will be described in detail with reference to FIGS. Here, T _c is the connection threshold level, P _p is the time required for the base station switching process, C _r is the time indicating the time on the interference, T ₀ is a conventional method in the soft handoff embodiment , And T ₁ is the threshold for disconnecting the base station by the conventional method when performing soft handoff.

[0004] Consider a case where a mobile station connected to base station BS # A moves to the zone of base station BS # B. Base station B
When the difference in propagation loss between S # A and base station BS # B becomes smaller than threshold level T, base station switching processing is started, and the time required until switching processing ends _c is P _p
And During the P _p time, the mobile station performs transmission power control on base station BS # A.

[0005] performing the propagation loss of the base station BS # B during the connection processing time P _p as shown in FIG. 9 is smaller than that of the base station BS # A, a transmission power control to the base station BS # A The mobile station in question interferes with the base station BS # B having a smaller propagation loss than the base station BS # A. That is, the interference reaches the base station BS # B during the time Cr shown in FIG.

[0006] As a method of overcoming the interference problem caused by the connection processing, in May 1991, the Proceeding in IEE Vehicle Technology Conference, pp. 57-62, U.S.A. (Proc.
eating in IEEE Vehicular
Technology Conference, pp. 146-64.
57-62, May, 1991). The technique called soft handoff described in the above-mentioned literature uses a technique for simultaneously connecting to a plurality of base station candidates including the base station having the minimum propagation loss to prepare for fluctuations in the propagation loss. FIG. 10 shows this state.

Similar to FIG. 9, it is assumed that a mobile station connected to base station BS # A moves to the zone of base station BS # B. When the difference in propagation loss between base stations BS # A and BS # B becomes smaller than threshold level T ₀ , base station BS #
While maintaining the connection with A, the connection with the base station BS # B is started. When the connection processing with the base station BS # B through the connection processing time P _p is completed, the connection between both of the base station is started. Since transmission power control is always performed on the other base station with the lowest propagation loss during the simultaneous connection, the interference to the base station BS # B, which has been a problem in FIG. 9, does not matter. Thereafter, when the difference in propagation loss between the base stations BS # A and BS # B exceeds the threshold level T1, the connection with the base station BS # A is released. In this way, by performing simultaneous connection with a plurality of base stations whose propagation loss levels are tight, it is possible to cope with replacement of the minimum propagation loss base station and suppress interference.

[0008] A threshold level T ₀ for starting connection with a new base station and a threshold level T for releasing connection.
₁ sets the latter large. The difference between T ₀ and T ₁ , called the hysteresis margin, is provided to prevent frequent occurrence of base station disconnection switching when the difference in propagation loss between base stations changes drastically near a threshold level. Have been. The threshold level T ₀ when starting the connection with the base station and the threshold level T ₁ when releasing the connection are:
The larger the number, the greater the number of base stations connected simultaneously.

[0009]

However, the speed and magnitude of the propagation loss fluctuation from the mobile station to each base station vary depending on the moving speed of the mobile station and the surrounding propagation environment. For example, in an urban area where buildings and the like are densely populated, there are many objects that block the radio wave propagation path, so that the propagation loss changes greatly even if the vehicle travels a short distance. That is, in urban areas, the propagation loss fluctuates quickly and is large. On the other hand, in the suburbs, since there are few objects blocking the propagation path, the propagation loss changes slowly and the size is small.

[0010] The propagation loss threshold level in the above-described conventional base station selection method is always constant regardless of the propagation environment. However, in an area where the propagation loss fluctuates rapidly, such as in a city, it is necessary to set a relatively large propagation loss threshold level for disconnection to prepare for a sudden change in the propagation loss. Otherwise, the connection with the base station that causes the minimum propagation loss will be delayed, causing interference to this base station. on the other hand,
In a suburb where the propagation loss fluctuation is slow, it is only necessary to connect to a small number of base stations, and the propagation loss threshold level can be set low. That is, at a fixed pilot threshold level, the number of simultaneously connected base stations becomes excessive or insufficient, and efficient system operation cannot be realized.

When the fluctuation of the propagation loss is slow, the disconnection switching does not occur frequently, and the hysteresis margin may be set small. If an unnecessarily large hysteresis margin is set, useless connection with the base station is maintained, which hinders efficient operation of the system.

An object of the present invention is to eliminate the excess and deficiency of simultaneously connected base stations when implementing soft handoff and to realize efficient system operation.

[0013]

The base station selection method according to the present invention is characterized in that the base station selection threshold level and the hysteresis margin are changed according to the fluctuation speed of the propagation loss.

When the propagation member fluctuates at a high speed, the base station selection threshold level is increased to perform simultaneous connection with a large number of base stations to realize highly reliable base station selection. In addition, the hysteresis margin is set large to prevent frequent switching of base station connection release. On the other hand, when the fluctuation of the propagation loss is slow, the base station selection threshold level is reduced to simultaneously connect with a small number of base stations to improve efficiency. At the same time, the hysteresis margin is set small, and unnecessary connection with the base station is released early.

According to the present invention, the base station to which the mobile station is connected is selected by comparing the level of the propagation loss level from the mobile station that can be connected to a plurality of base stations to the base station group, The mobile station is capable of communicating with a plurality of base stations at the same time, and in the base station selection method of the code division multiplexing cellular mobile communication system for changing the base station to be connected with the movement of the mobile station, Grasping each relative path loss with respect to the plurality of base stations based on the path loss of the base station which becomes the minimum path loss among the path losses to the stations; and obtaining the variation speed of the relative path loss. A step of determining whether or not a station and the mobile station are connected; and, as a result of the determination, the relative propagation loss with respect to the unconnected and the corresponding unconnected base station, If the number is less than a threshold function given as a number, a method of selecting a base station in a code division multiplexed cellular mobile radio communication system, characterized by having a step of starting connection with a corresponding unconnected base station. can get.

Further, according to the present invention, when the result of the determination indicates that the relative propagation loss with respect to the unconnected and corresponding unconnected base station exceeds the threshold function, the corresponding unconnected state is determined. And a method for selecting a base station in a code division multiplexed cellular mobile radio communication system.

Further, according to the present invention, as a result of the determination, the relative propagation loss with respect to the connected and corresponding connected base station is determined by adding a hysteresis margin to the threshold function given as a function of the fluctuation speed. If the added level is exceeded, a base station selection method in a code division multiplexed cellular mobile radio communication system, characterized in that the connection with the corresponding connected base station is released.

Further, according to the present invention, as a result of the determination, the relative propagation loss with respect to the connected and corresponding connected base station is determined by adding a hysteresis margin to the threshold function given as a function of the fluctuation speed. If the level does not exceed the added level, a method of selecting a base station in a code division multiplexed cellular mobile radio communication system characterized by having a step of maintaining a connection state with a corresponding connected base station is obtained.

Further, according to the present invention, the threshold function is given by a function having the fluctuation speed of the relative propagation loss as an argument, and is set so as to become larger as the fluctuation speed becomes faster. A base station selection method in a code division multiplexed cellular mobile radio communication system.

Further, according to the present invention, the hysteresis margin is given by a function having the variation speed of the relative propagation loss as an argument, and is set so as to increase as the variation speed increases. A method for selecting a base station in a code division multiplexed cellular mobile radio communication system is provided.

According to the present invention, the base station to which the mobile station is connected is selected by comparing the level of the propagation loss level from the mobile station capable of connecting to a plurality of base stations to the base station group. The mobile station is capable of communicating with a plurality of base stations at the same time, and the base station selecting method of a code division multiplex cellular cellular mobile communication system that changes a base station to be connected with the movement of the mobile station. The step of grasping the relative path loss of each of the plurality of base stations based on the path loss of the base station that is the minimum path loss among the path loss of the base station, and the step of determining the variation speed of the relative path loss, Determining whether or not each base station and the mobile station are connected; and, as a result of the determination, the relative propagation loss with respect to the unconnected and corresponding unconnected base station is determined by the mobile station. A base station in a code division multiplexed cellular mobile radio communication system, characterized in that it has a step of starting connection with a corresponding unconnected base station when a threshold function given as a function of a moving speed is lower than the threshold function. A selection method is obtained.

Further, according to the present invention, if the result of the determination indicates that the relative propagation loss with respect to the unconnected and corresponding unconnected base station exceeds the threshold function, the corresponding unconnected state is determined. And a method for selecting a base station in a code division multiplexed cellular mobile radio communication system.

Further, according to the present invention, as a result of the determination, the relative propagation loss with respect to the connected and corresponding connected base station is calculated by adding a hysteresis margin to the threshold function given as a function of the fluctuation speed. If the added level is exceeded, a base station selection method in a code division multiplexed cellular mobile radio communication system, characterized in that the connection with the corresponding connected base station is released.

Further, according to the present invention, as a result of the determination, the relative propagation loss with respect to the connected and corresponding connected base station is calculated by adding a hysteresis margin to the threshold function given as a function of the fluctuation speed. If the level does not exceed the added level, a method of selecting a base station in a code division multiplexed cellular mobile radio communication system characterized by having a step of maintaining a connection state with a corresponding connected base station is obtained.

Further, according to the present invention, the threshold function is given by a function having the moving speed of the mobile station as an argument, and is set so as to increase as the moving speed increases. A method for selecting a base station in a code division multiplexed cellular mobile radio communication system is provided.

Further, according to the present invention, the hysteresis margin is given by a function using the moving speed of the mobile station as an argument, and is set so as to increase as the moving speed increases. A method for selecting a base station in a division multiplexed cellular mobile radio communication system is provided.

Further, according to the present invention, a propagation loss measuring device including a plurality of base stations and at least one mobile station, and measuring a propagation loss from the mobile station to each of the base stations, When the path loss level fluctuates at a high speed, the hysteresis margin for determining the start and release of connection with the base station is set large, and when the path loss changes slowly, the hysteresis margin is reduced. Equipped with a soft handoff base station selecting device to set,
The soft handoff base station selecting device grasps each relative path loss to the plurality of base stations based on the path loss of the base station which becomes the minimum path loss among the path losses to the plurality of base stations, and Find the rate of change of loss,
It is determined whether or not each of the base stations and the mobile station are connected, and as a result of the determination, the relative propagation loss with respect to the unconnected and the corresponding unconnected base station is a function of the fluctuation speed. When the threshold value is less than the threshold function given by the following formula, a connection with the corresponding unconnected base station is started, whereby a code division multiplexed cellular mobile radio communication system is obtained.

Further, according to the present invention, the threshold function is given as a function having the variation speed of the relative propagation loss as an argument, and the threshold function is set so as to increase as the variation speed increases. And a code division multiplexed cellular mobile radio communication system.

Further, according to the present invention, the soft handoff base station selecting device, as a result of the determination, the relative propagation loss with respect to the non-connected and corresponding non-connected base station exceeds the threshold function. In this case, a code-division multiplexed cellular mobile radio communication system characterized by maintaining a non-connection state with the corresponding non-connected base station is obtained.

Further, according to the present invention, the soft handoff base station selecting apparatus, as a result of the determination, determines that the relative propagation loss with respect to the connected and corresponding connected base station is:
A code division multiplexing cellular mobile radio communication system characterized by releasing the connection with the connected base station when the level exceeds a level obtained by adding a hysteresis margin to the threshold function given as a function of the fluctuation speed. can get.

Further, according to the present invention, the soft handoff base station selecting apparatus, as a result of the determination, determines that the relative propagation loss with respect to the connected and corresponding connected base station is:
Code division multiplexing cellular movement characterized by maintaining a connection state with a corresponding connected base station when the level does not exceed a level obtained by adding a hysteresis margin to the threshold function given as a function of the fluctuation speed. A wireless communication system is obtained.

Further, according to the present invention, a propagation loss measuring device including a plurality of base stations and at least one mobile station, and measuring a propagation loss from the mobile station to each of the base stations; A moving speed detecting device for detecting a speed, connected to the propagation loss measuring device and the moving speed detecting device,
If the moving speed is fast, start the connection with the base station, set a large hysteresis margin to determine the release,
A soft handoff base station selecting device for setting the hysteresis margin to be small when the moving speed is low, wherein the soft handoff base station selecting device is a base station having a minimum propagation loss among the propagation losses for the plurality of base stations. The relative path loss for each of the plurality of base stations is grasped based on the path loss of the base station, the variation speed of the relative path loss is obtained, and it is determined whether or not each of the base stations and the mobile station are connected. As a result of the determination, when the relative propagation loss for the unconnected and the corresponding unconnected base station is less than a threshold function given as a function of the moving speed,
A code division multiplexed cellular mobile radio communication system is obtained, in which a connection with a corresponding unconnected base station is started.

Further, according to the present invention, the threshold function is given by a function having the moving speed as an argument, and the threshold function is set so as to increase as the moving speed increases. A cellular mobile radio communication system is obtained.

Further, according to the present invention, the soft handoff base station selecting apparatus, as a result of the determination, the relative propagation loss with respect to the unconnected and corresponding unconnected base station exceeds the threshold function. In this case, a code-division multiplexed cellular mobile radio communication system characterized by maintaining a non-connection state with the corresponding non-connected base station is obtained.

Further, according to the present invention, the soft handoff base station selecting apparatus, as a result of the determination, determines that the relative propagation loss with respect to the connected and corresponding connected base station is:
A code division multiplexing cellular mobile radio communication system characterized by releasing the connection with the connected base station when the level exceeds a level obtained by adding a hysteresis margin to the threshold function given as a function of the fluctuation speed. can get.

Further, according to the present invention, the soft handoff base station selecting apparatus, as a result of the determination, determines that the relative propagation loss with respect to the connected and corresponding connected base station is:
Code division multiplexing cellular movement characterized by maintaining a connection state with a corresponding connected base station when the level does not exceed a level obtained by adding a hysteresis margin to the threshold function given as a function of the fluctuation speed. A wireless communication system is obtained.

Further, according to the present invention, when a path loss measuring apparatus for measuring a path loss from a mobile station to each base station is connected to the path loss measuring apparatus and the path loss level fluctuates at a high speed, A soft hand-off base station selecting device for setting a large hysteresis margin for determining the start and release of connection with the base station and for setting the hysteresis margin small when the fluctuation of the propagation loss is slow; The base station selection device grasps each relative path loss with respect to the plurality of base stations with reference to the path loss of the base station which becomes the minimum path loss among the path losses with respect to the plurality of base stations, and changes the relative path loss. A speed is determined, and it is determined whether or not each of the base stations and the mobile station are being connected. As a result of the determination, the prior to the unconnected and the corresponding unconnected base station is determined. Relative propagation loss is, if less than the threshold function given as a function of the variation rate, the mobile station device is obtained, characterized in that to initiate a connection with a base station in the relevant disconnected.

Further, according to the present invention, the threshold function is given by a function having the variation speed of the relative propagation loss as an argument, and is set so as to become larger as the variation speed becomes faster. A mobile station device that performs

Further, according to the present invention, the soft handoff base station selecting device, as a result of the determination, the relative propagation loss with respect to the non-connected and corresponding non-connected base station exceeds the threshold function. In such a case, a mobile station device characterized by maintaining a non-connection state with the corresponding non-connected base station is obtained.

Further, according to the present invention, the soft handoff base station selecting apparatus, as a result of the determination, determines that the relative propagation loss with respect to the connected and corresponding connected base station is:
When the level exceeds a level obtained by adding a hysteresis margin to the threshold function given as a function of the fluctuating speed, a connection with the corresponding connected base station is released.

Further, according to the present invention, the soft handoff base station selecting apparatus, as a result of the determination, determines that the relative propagation loss with respect to the connected and corresponding connected base station is:
When the threshold value does not exceed a level obtained by adding a hysteresis margin to the threshold function given as a function of the fluctuation speed, the mobile station apparatus maintains the connection state with the corresponding connected base station. Can be

Further, according to the present invention, a propagation loss measuring device for measuring a propagation loss from a mobile station to each base station, a moving speed detecting device for detecting a moving speed of the mobile station, and the propagation loss measuring device When the moving speed is fast, the hysteresis margin for determining the start and release of the connection with the base station is set large when the moving speed is high, and the hysteresis margin is set small when the moving speed is low. Soft handoff base station selecting device, the soft handoff base station selecting device, for each of the plurality of base stations on the basis of the propagation loss of the base station that becomes the minimum propagation loss among the propagation loss to the plurality of base stations Of the relative propagation loss, determine the variation speed of the relative propagation loss, determine whether or not each of the base station and the mobile station is connected, the determination of the Result, when the relative propagation loss for non-connection are and the appropriate base station in the non-connection is below a threshold function given as a function of the moving speed,
A mobile station apparatus characterized by starting connection with the corresponding unconnected base station is obtained.

Further, according to the present invention, the threshold function is given by a function having the moving speed as an argument, and the threshold function is set to a larger value as the moving speed is higher. Is obtained.

Further, according to the present invention, the soft handoff base station selecting device, as a result of the determination, the relative propagation loss with respect to the non-connected and corresponding non-connected base station exceeds the threshold function. In such a case, a mobile station device characterized by maintaining a non-connection state with the corresponding non-connected base station is obtained.

Further, according to the present invention, the soft handoff base station selecting apparatus, as a result of the determination, determines that the relative propagation loss with respect to the connected and corresponding connected base station is:
When the level exceeds a level obtained by adding a hysteresis margin to the threshold function given as a function of the fluctuating speed, a connection with the corresponding connected base station is released.

Further, according to the present invention, the soft handoff base station selecting apparatus, as a result of the determination, determines that the relative propagation loss with respect to the connected and corresponding connected base station is:
When the threshold value does not exceed a level obtained by adding a hysteresis margin to the threshold function given as a function of the fluctuation speed, the mobile station apparatus maintains the connection state with the corresponding connected base station. Can be

[0047]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a diagram showing a connection state in soft handoff of a code division multiplexing cellular mobile radio communication system. FIG. 2 and FIG. 3 show the mobile station device constituting the mobile station 13 and the base station devices constituting the base stations 12-1 and 12-2, respectively, according to the embodiment of the present invention.

First, the operation of the mobile station shown in FIG. 2 will be described. The transmission signal emitted from the base station is received by the transmission / reception sharing device 21, passes through the RF unit 22, and is input to the moving speed detection device 23 and the propagation loss measurement device 24. The moving speed detecting device 23 outputs the moving speed Vms of the mobile station itself, while the propagation loss measuring device 24 outputs a plurality of base stations located in the vicinity of the mobile station, and the propagation loss L _{i (t )} [DB] is estimated. Here, i represents a base station index given by an integer from 0 to N, and t represents a measurement time. In addition, the propagation loss to the plurality of base stations is roughly estimated based on, for example, the reception strength of the pilot signal emitted from each base station and the transmission output of the pilot signal. The moving speed Vms and the propagation loss Li _(t) are input to the soft handoff base station selection device BSS to determine a new soft handoff target base station or a base station whose connection is to be released. The determination result of the new soft handoff target base station or the base station whose connection is to be released is given as a connection release variable BS _{info, i} . BS _{info, i} =
1 means a connection request with the corresponding base station i, and BS
_{info, i} = -1 means release of connection with the corresponding base station i, and BS _{info, i} = 0 means that the current connection state is maintained. The disconnection variable BS _{info, i} determined by the soft handoff base station selecting device BSS is input to the control signal generating device 31, and generates a control signal to that effect to a base station group requested to connect or release. The output of the control signal generation device 31 and the transmission information 26 are combined in the combining device 25, and various additional information is inserted in the overhead insertion unit 30. The output signal of the overhead insertion unit 30 passes through the spreader 29, the modulator 28, and the amplifying device 27, and is then emitted toward the base station by the transmission / reception sharing device 21.

Next, the operation of the base station apparatus shown in FIG. 3 will be described. After the transmission signal emitted from the mobile station 13 passes through the transmission / reception sharing device 41, the RF unit 42 and the demodulator 43
Is demodulated through The control signal included in the output of the demodulator 43 is detected by the control signal detection device 44. The detected control signal is transmitted to the exchange 11, and the exchange 11 performs connection and release processing of the corresponding base station based on a base station connection command or a base station connection release command included in the control signal.

Next, one embodiment of the operation of the soft handoff base station selecting apparatus BSS shown in FIG. 2 is shown in FIG.
In the embodiment of FIG. 4, the propagation loss fluctuation speed is obtained from the propagation loss L _{i (t)} [dB] between the mobile station and the base station i, and the disconnection threshold level is determined thereby.

First, in step 100, the minimum value of the propagation loss L _{i (t)} [dB] with the base station i is set to L _{min (t)} [d
B]. Next, in step 101, 0 is set to a loop variable k representing a base station number. Step 10
2, L _{min (t)} [dB] is subtracted from the propagation loss L _{k (t)} [dB] with the base station k to obtain a relative propagation loss level L
_{n, k} [dB] is obtained. In step 103, L
_n, the absolute value of the differential value of _{k (t) [L n,} k (t)] is calculated. In step 104, it is determined whether the base station k and the mobile station are talking or not.
If not, the process proceeds to step 106.

In step 104, the value of the release threshold level T _r defined as a function of the speed is calculated, and T _r is calculated.
If (| L _{n, k (t)} |) is smaller than L _{n, k (t)} , the process proceeds to step 107; On the other hand, in step 106, it calculates the value of the connection threshold level T _a, which is defined as a function of speed, T _a (| L
_{If n, k (t)} |) is greater than Ln _{, k (t)} , step 109
Go to step 108, otherwise go to step 108. In step 107, a disconnection variable BS _{info, k} = -1 is set _, which means disconnection from the base station k.
In step 9, a connection release variable BS _{info, k} = 1 _, which means connection with the base station k, is set. In step 108, a disconnection variable BS _{info, k} = 0 is set so as to maintain the connection state with the base station k. Steps 107 to 109
Thereafter, the routine proceeds to step 110, where it is determined whether or not the loop variable k exceeds the number N of base stations. If k <N, after adding 1 to k in step 111, the process returns to step 102. If k is N or more, disconnection variable B
S _{info, i} is output to the control signal generator 31 shown in FIG.

The moving speed Vms of the mobile station itself detected by the moving speed detecting device 23 is not used in the present embodiment, and terminates in step 102.

[0054] Figure 5 is a diagram showing an example of the connection threshold level function T _a and release threshold level function Tr. T _a, with T _r, L n, represents the magnitude of the variation rate of the _{I (t) | L n,} i (t) | is set such that the larger increase. Also, the release threshold level Tr is set to be higher than Ta by the hysteresis margin, and the hysteresis margin is increased as | L _{n, i (t)} | The connection processing and release processing of the base station i according to the flowchart shown in FIG. 4 can be described as follows with reference to FIG.

If the base station i is not connected, the point (| L
Selection, L n, _i a _(t)) stippling on Figure 5, as the base station is the serving base station when this point is located in the lower portion than the connection threshold level _{T a | n, i (t} ) Is done. On the other hand, if the base station i is already connected, the point (| L _{n, i (t)} |, L
_{n, i (t)} ) is stippled on FIG. 2, and when this point is located above the release threshold level _Tr , the connection with this base station is released. In other cases, the current connection state is maintained.

Next, we describe an example of up to release from the base station selection in the case of applying the T _a, T _r shown in FIG.
6, the longitudinal axis L _{n, i (t),} the horizontal axis _{| L n, i (t)} | and that it is stippled on graph _{(| L n, i (t} ) | versus L _{n, i (t)} )
Is indicated by a curve. Point (| L _{n, i (t)} of | L _{n, i (t)}
|) Changes in the direction of the arrow shown in FIG. 6 over time.

[0057] point _{(| L n, i (t} ) |, L n, i (t)) is the time a, i.e. starts the connection process with the base station i at the time below the base station selection threshold level T _a I do. After the connection process, the connection with the base station i is started from the time point b. Thereafter, at time point c, that is, when the level exceeds the release threshold level _Tr , the connection with the base station i is immediately released. After all, the communication with the base station i is performed during the period from the time point b to the time point c.

Hereinafter, another embodiment of the present invention will be described with reference to the drawings.

FIG. 8 shows another embodiment of the soft handoff base station selecting apparatus BSS shown in FIG. According to the fact that the fluctuation speed of the propagation loss is proportional to the moving speed of the terminal, in the embodiment of FIG. 8, the disconnection threshold level is determined based on the moving speed Vms of the mobile station itself detected by the moving speed detecting device 23. I have.

First, at step 200, the minimum value of the propagation loss L _{i (t)} [dB] between the base station i and the mobile station is calculated as L
_{min (t)} is defined as [dB]. Next, in step 201, 0 is set to a loop variable k representing a base station number. In step 202, the propagation loss L with the base station k
_The relative path loss level L _{n, k} [dB] is obtained by subtracting L _{min (t)} [dB] from _{k (t)} [dB]. In step 203, it is determined whether or not the base station k and the mobile station are in a call. If the call is in a call, the process proceeds to step 204; otherwise, the process proceeds to a step 205.

At step 204, the moving speed detecting device 23
The moving speed Vms of the mobile station itself detected at is input,
The value of the release threshold level T _r defined as a function of speed is calculated. If T _r (Vms) is smaller than L _{n, k (t)} , go to step 206; On the other hand, in step 205, it calculates the value of the connection threshold level T _a, which is defined as a function of speed, T
_{If a} (Vms) is larger than Ln _{, k (t)} , step 208
Otherwise, to step 207. In step 206, a disconnection variable BS _{info, k} = −1 _, which means disconnection from the base station k, is set.
In step 8, a connection release variable BS _{info, k} = 1 _, which means connection with the base station k, is set. In step 207, a disconnection variable BS _{info, k} = 0 is set so as to maintain the connection state with the base station k. Steps 206 to 208
Thereafter, the process proceeds to step 209, where it is determined whether the loop variable k exceeds the number N of base stations. If k <N, 1 is added to k in step 210, and the process returns to step 202. If k> is equal to or greater than N, the disconnection variable BS _{info, i} is output to the control signal purification device 31 shown in FIG.

The fluctuation speed of the propagation loss is proportional to the moving speed of the terminal. The embodiment shown in FIG. 8 is a method for indirectly estimating the fluctuation speed of the propagation loss from the moving speed of the terminal. FIG.
In the embodiment shown in (1), the fluctuation speed of the propagation loss is directly detected by differentiating the estimation result of the propagation loss. In the case of FIG. 4, when the error component is included in the estimation result of the propagation loss,
There is a problem that the propagation loss estimation error propagates to the fluctuating speed estimation value, and an error occurs in the fluctuating speed estimation value. On the other hand, according to the embodiment shown in FIG. 8, since the propagation loss estimation error and the propagation loss fluctuation speed error are separated, propagation of the error can be avoided.

[0063]

As described above, according to the present invention,
By changing the base station selection threshold level and the hysteresis margin according to the fluctuation speed of the propagation loss,
Communication with an appropriate number of base stations according to the propagation environment and the moving speed of the mobile station becomes possible, and efficient and highly reliable base station selection can be realized.

[Brief description of the drawings]

FIG. 1 is a diagram showing a connection state in soft handoff of a code division multiplexing cellular mobile radio communication system.

FIG. 2 is a diagram showing a configuration of a mobile station device of the present invention.

FIG. 3 is a diagram illustrating a configuration of a base station device according to the present invention.

FIG. 4 is a flowchart showing each step of the base station selection method of the present invention.

FIG. 5 is a diagram showing an example of a threshold level for connection and release of a base station.

FIG. 6 is a diagram illustrating an example from connection to release of a base station.

FIG. 7 is a diagram illustrating an average simultaneous connection base station near a cell boundary with respect to a moving speed of a mobile station.

FIG. 8 is a flowchart showing steps of another base station selection method according to the present invention.

FIG. 9 is a diagram illustrating a base station switching process for a propagation loss variation when soft handoff is not performed in the related art.

FIG. 10 is a diagram showing a base station switching process in which a propagation loss varies when soft handoff is performed in the related art.

[Explanation of symbols]

L _{min (t)} minimum propagation loss measured level L _{n, i (t)} minimum propagation loss relative propagation loss measured level obtained by subtracting the measured level T _a connection threshold level function T _r release threshold level functions a base station connection process starts Time point b base station connection start time c base station connection release time BS # A connection source base station BS # B connection destination base station BSS soft handoff base station selection device 11 switching station 12-1,12-2 base station 13 mobile station 16 -1 Connection area with base station 12-1 16-2 Connection area with base station 12-2 21 Transmission / reception shared device 22 RF unit 23 Moving speed detection device 24 Propagation loss measurement device 25 Coupling device 26 Transmission information 27 Amplification device 28 Modulator 29 Spreader 30 Overhead insertion unit 31 Control signal generation device 41 Transmission / reception shared device 42 RF unit 43 Demodulator 44 Control signal detection device

Claims (40)

[Claims] 1. Selecting a base station to which the mobile station connects by comparing the magnitude of the path loss level from a mobile station capable of connecting to a plurality of base stations to the plurality of base stations;
The mobile station is capable of communicating with a plurality of base stations at the same time, and in the base station selecting method of the code division multiplexing cellular mobile communication system in which a base station to be connected is changed according to the movement of the mobile station, Is selected so as to increase the number of base stations to be connected when the speed fluctuates at high speed, and is selected so as to reduce the number of base stations to be connected when the fluctuation of the propagation loss is slow. A method for selecting a base station in a cellular mobile radio communication system. 2. A base station connected to the mobile station is selected by comparing the levels of propagation loss levels from a mobile station capable of connecting to a plurality of base stations to the plurality of base stations;
The mobile station is capable of communicating with a plurality of base stations at the same time, and in the base station selecting method of the code division multiplexing cellular mobile communication system in which a base station to be connected is changed according to the movement of the mobile station, When the speed fluctuates at a high speed, a hysteresis margin for determining the start and release of connection with the base station is set large, and when the fluctuation of the propagation loss is slow, the hysteresis margin is set small. A base station selection method in a division multiplexing cellular mobile radio communication system. 3. The base station to which the mobile station is connected is selected by comparing the level of the propagation loss level from the mobile station capable of connecting to a plurality of base stations to the base station group, In the base station selecting method of the code division multiplexing cellular mobile communication system capable of communicating with a plurality of base stations at the same time and changing a base station to be connected with the movement of the mobile station, the path loss to the plurality of base stations Grasping the relative path loss of each of the plurality of base stations based on the path loss of the base station having the minimum path loss, obtaining the variation speed of the relative path loss, Determining whether or not the station is connected; and, as a result of the determination, the relative propagation loss with respect to the unconnected and corresponding unconnected base station is given as a function of the fluctuation speed. A base station selection method for a code division multiplexed cellular mobile radio communication system, comprising a step of initiating a connection with a corresponding unconnected base station when the threshold value is below a threshold function. 4. When the relative path loss with respect to a non-connected and corresponding non-connected base station exceeds the threshold function as a result of the determination, a non-connection with the corresponding non-connected base station is determined. 4. The method according to claim 3, further comprising the step of maintaining a connection state. 5. As a result of the determination, if the relative propagation loss for the connected and corresponding connected base station exceeds a level obtained by adding a hysteresis margin to the threshold function given as a function of the fluctuation speed. 4. The connection to the corresponding connected base station is released.
A base station selection method in the code division multiplex cellular mobile radio communication system according to the above. 6. As a result of the determination, the relative propagation loss for a connected and corresponding connected base station does not exceed a level obtained by adding a hysteresis margin to the threshold function given as a function of the fluctuation speed. 4. The method according to claim 3, further comprising the step of maintaining a connection state with the connected base station in the case. 7. The threshold function is given as a function having a variation speed of the relative propagation loss as an argument, and the threshold function is set so as to increase as the variation speed increases. A method for selecting a base station in a code division multiplexed cellular mobile radio communication system according to any one of the above. 8. The method according to claim 3, wherein the hysteresis margin is given as a function having a variation speed of the relative propagation loss as an argument, and is set so as to increase as the variation speed increases. A method for selecting a base station in a code division multiplexed cellular mobile radio communication system according to any one of the preceding claims. 9. A base station connected to the mobile station is selected by comparing the magnitude of a path loss level from a mobile station capable of connecting to a plurality of base stations to the plurality of base stations,
The mobile station is capable of communicating with a plurality of base stations at the same time, and in a base station selection method of a code division multiplexed cellular mobile communication system that changes a base station connected with the movement of the mobile station, A code division multiplexing cellular, wherein the number of connected base stations is selected to increase when the moving speed is high, and the number of connected base stations is selected when the moving speed of the mobile station is low. A method for selecting a base station in a mobile radio communication system. 10. A base station to which the mobile station is connected by comparing the levels of propagation loss levels from a mobile station capable of connecting to a plurality of base stations to the plurality of base stations, and Can communicate with a plurality of base stations at the same time, and in the base station selection method of the code division multiplex cellular mobile communication system that changes the base station to be connected with the movement of the mobile station, the moving speed of the mobile station is Code division multiplexing cellular, characterized in that when fast, the hysteresis margin for determining the start and release of connection with the base station is set large, and when the moving speed of the mobile station is slow, the hysteresis margin is set small. A method for selecting a base station in a mobile radio communication system. 11. A base station connected to the mobile station is selected by comparing the level of a propagation loss level from a mobile station capable of connecting to a plurality of base stations to the base station group, and the mobile station is connected to the base station. It can communicate with multiple base stations at the same time,
In the base station selection method of the code division multiplexing cellular mobile communication system that changes the base station connected with the movement of the mobile station, the propagation loss of the base station that becomes the minimum propagation loss among the propagation losses for the plurality of base stations is determined. Grasping each relative propagation loss with respect to the plurality of base stations as a reference; obtaining a variation speed of the relative propagation loss; and determining whether each base station and the mobile station are connected. As a result of the determination, if the relative propagation loss with respect to the unconnected and the corresponding unconnected base station is less than a threshold function given as a function of the moving speed of the mobile station, A method for selecting a base station in a code division multiplexed cellular mobile radio communication system, comprising the step of initiating a connection with a connected base station. 12. As a result of the determination, when the relative propagation loss with respect to a non-connected and corresponding non-connected base station exceeds the threshold function, a non-connection with the corresponding non-connected base station is determined. The method for selecting a base station in a code division multiplexed cellular mobile radio communication system according to claim 11, further comprising a step of maintaining a connection state. 13. As a result of the determination, if the relative path loss for a connected and corresponding connected base station exceeds a level obtained by adding a hysteresis margin to the threshold function given as a function of the fluctuation speed. The method according to claim 11, wherein the connection with the corresponding connected base station is released. 14. As a result of the determination, the relative propagation loss for a connected and corresponding connected base station does not exceed a level obtained by adding a hysteresis margin to the threshold function given as a function of the fluctuation speed. 12. The method according to claim 11, further comprising the step of maintaining a connection state with the connected base station in the case. 15. The method according to claim 11, wherein the threshold function is given as a function having a moving speed of the mobile station as an argument, and is set so as to increase as the moving speed increases. A method for selecting a base station in a code division multiplexed cellular mobile radio communication system according to any one of the preceding claims. 16. The method according to claim 11, wherein the hysteresis margin is given by a function using the moving speed of the mobile station as an argument, and is set so as to increase as the moving speed increases. A method for selecting a base station in a code division multiplexed cellular mobile radio communication system according to any one of the preceding claims. 17. A propagation loss measuring device including a plurality of base stations and at least one mobile station, wherein the propagation loss measuring device measures a propagation loss from the mobile station to each of the base stations; A soft handoff base station that sets a large hysteresis margin for determining the start and release of connection with the base station when the loss level fluctuates at high speed, and sets a small hysteresis margin when the propagation loss fluctuates slowly. A code division multiplexing cellular mobile radio communication system comprising a selection device. 18. A propagation loss measuring device including a plurality of base stations and at least one mobile station, for measuring a propagation loss from the mobile station to each of the base stations, and connected to the propagation loss measuring device, A soft handoff base station that sets a large hysteresis margin for determining the start and release of connection with the base station when the loss level fluctuates at a high speed, and sets a small hysteresis margin when the propagation loss fluctuates slowly. Comprising a selection device, the soft handoff base station selection device, relative to the plurality of base stations relative to the plurality of base stations based on the propagation loss of the base station becomes the minimum propagation loss among the plurality of base stations. Grasp, determine the variation speed of the relative propagation loss, determine whether each of the base station and the mobile station is connected, as a result of the determination, not connected and When the relative path loss for the corresponding unconnected base station is lower than a threshold function given as a function of the fluctuation speed, the connection with the corresponding unconnected base station is started. Code division multiplexing cellular mobile radio communication system. 19. The threshold function according to claim 18, wherein the threshold function is given as a function having a variation speed of the relative propagation loss as an argument, and is set so as to increase as the variation speed increases. Code division multiplex cellular mobile radio communication system. 20. The soft handoff base station selecting apparatus, if the result of the determination indicates that the relative propagation loss to the unconnected and corresponding unconnected base station exceeds the threshold function, 20. The code division multiplexing cellular mobile radio communication system according to claim 18, wherein a non-connection state with a non-connected base station is maintained. 21. The soft handoff base station selecting apparatus, wherein as a result of the determination, the relative propagation loss with respect to the connected and corresponding connected base station is determined by the threshold function given as a function of the fluctuation speed. 20. The connection to the corresponding currently connected base station is released when the level exceeds a level obtained by adding the hysteresis margin.
2. A code division multiplexed cellular mobile radio communication system according to claim 1. 22. The soft handoff base station selecting apparatus, wherein as a result of the determination, the relative propagation loss with respect to a connected and corresponding connected base station is determined by the threshold function given as a function of the fluctuation speed. 20. The code division multiplexing cellular mobile radio communication system according to claim 18, wherein a connection state with a corresponding connected base station is maintained when the level does not exceed a level obtained by adding a hysteresis margin. 23. A propagation loss measuring device including a plurality of base stations and at least one mobile station, for measuring a propagation loss from the mobile station to each of the base stations, and a moving speed for detecting a moving speed of the mobile station. Detecting device, connected to the propagation loss measuring device and the moving speed detecting device, if the moving speed is fast, start connection with the base station, set a large hysteresis margin to determine the release, the moving speed is A code division multiplexed cellular mobile radio communication system, comprising: a soft handoff base station selecting device for setting the hysteresis margin to be small when the speed is slow. 24. A propagation loss measuring device including a plurality of base stations and at least one mobile station, for measuring a propagation loss from the mobile station to each of the base stations, and a moving speed for detecting a moving speed of the mobile station. Detecting device, connected to the propagation loss measuring device and the moving speed detecting device, if the moving speed is fast, start connection with the base station, set a large hysteresis margin to determine the release, the moving speed is If the delay is slow, the apparatus further includes a soft handoff base station selecting device that sets the hysteresis margin to be small, and the soft handoff base station selecting device reduces a propagation loss of a base station that is a minimum propagation loss among the propagation losses for the plurality of base stations. As a criterion, the relative propagation loss for each of the plurality of base stations is grasped, the variation speed of the relative propagation loss is determined, and the base station and the mobile station are connected. It is determined whether or not during the, as a result of the determination, the relative propagation loss for the non-connected and the corresponding non-connected base station is less than a threshold function given as a function of the moving speed, Starts a connection with a corresponding unconnected base station. 25. The code division multiplexing cellular according to claim 24, wherein the threshold function is given by a function having the moving speed as an argument, and is set so as to increase as the moving speed increases. Mobile radio communication system. 26. The soft handoff base station selecting apparatus, if the result of the determination indicates that the relative propagation loss with respect to the unconnected and corresponding unconnected base station exceeds the threshold function, 26. The code division multiplexing cellular mobile radio communication system according to claim 24, wherein a non-connection state with a non-connected base station is maintained. 27. The soft handoff base station selecting apparatus, wherein as a result of the determination, the relative propagation loss with respect to the connected and corresponding connected base station is determined by the threshold function given as a function of the fluctuation speed. 26. A connection to a corresponding currently connected base station is released when the level exceeds a level obtained by adding a hysteresis margin.
2. A code division multiplexed cellular mobile radio communication system according to claim 1. 28. The soft handoff base station selecting apparatus, wherein as a result of the determination, the relative propagation loss with respect to the connected and corresponding connected base station is determined by the threshold function given as a function of the fluctuation speed. 26. The code division multiplexing cellular mobile radio communication system according to claim 24, wherein a connection state with a corresponding connected base station is maintained when the level does not exceed a level obtained by adding a hysteresis margin. 29. A path loss measuring device for measuring a path loss from a mobile station to each base station, and a connection to the base station when the path loss level is changed at a high speed and connected to the path loss measuring apparatus. A mobile station characterized by comprising a soft handoff base station selecting device for setting a large hysteresis margin for determining start and release, and for setting a small hysteresis margin when the fluctuation of the propagation loss is slow. Station equipment. 30. A path loss measuring device for measuring a path loss from a mobile station to each base station, and a connection to the base station when the path loss level is changed at a high speed and connected to the path loss measuring apparatus. Start, set a large hysteresis margin to determine the release, if the variation of the propagation loss is slow, comprising a soft handoff base station selection device to set the hysteresis margin small, the soft handoff base station selection device, The relative path loss for each of the plurality of base stations is determined based on the path loss of the base station that is the minimum path loss among the path losses for the plurality of base stations, and the variation speed of the relative path loss is obtained. It is determined whether or not the base station and the mobile station are connected.As a result of the determination, the relative propagation loss with respect to the non-connected and corresponding non-connected base station is A mobile station apparatus characterized by starting connection with a corresponding non-connected base station when the threshold value is lower than a threshold function given as a function of the fluctuation speed. 31. The method according to claim 30, wherein the threshold function is given as a function having a variation speed of the relative propagation loss as an argument, and is set so as to increase as the variation speed increases. Mobile station equipment. 32. The soft handoff base station selecting apparatus, if the result of the determination indicates that the relative propagation loss for the non-connected and corresponding non-connected base station exceeds the threshold function, 32. The mobile station apparatus according to claim 30, wherein the mobile station apparatus maintains a non-connection state with a non-connected base station. 33. The soft handoff base station selecting apparatus, wherein as a result of the determination, the relative propagation loss for a connected and corresponding connected base station is determined by the threshold function given as a function of the fluctuation speed. 32. The connection to the corresponding currently connected base station is released when the level exceeds a level obtained by adding a hysteresis margin.
A mobile station device according to claim 1. 34. The soft handoff base station selecting apparatus, wherein, as a result of the determination, the relative propagation loss with respect to the connected and corresponding connected base station is determined by the threshold function given as a function of the fluctuation speed. 32. The mobile station apparatus according to claim 30, wherein a connection state with a corresponding connected base station is maintained when the level does not exceed a level obtained by adding a hysteresis margin. 35. A propagation loss measuring device for measuring a propagation loss from a mobile station to each base station, a moving speed detecting device for detecting a moving speed of the mobile station, the propagation loss measuring device and the moving speed detecting device When the moving speed is high, a hysteresis margin for determining the start and release of connection with the base station is set to be large, and when the moving speed is low, the hysteresis margin is set to be small. A mobile station device comprising the device. 36. A propagation loss measuring device for measuring a propagation loss from a mobile station to each base station, a moving speed detecting device for detecting a moving speed of the mobile station, the propagation loss measuring device and the moving speed detecting device When the moving speed is high, a hysteresis margin for determining the start and release of connection with the base station is set to be large, and when the moving speed is low, the hysteresis margin is set to be small. Device, and the soft handoff base station selecting device grasps respective relative propagation losses with respect to the plurality of base stations with reference to a propagation loss of a base station having a minimum propagation loss among the propagation losses with respect to the plurality of base stations. Then, determine the fluctuation speed of the relative propagation loss, determine whether each of the base station and the mobile station is connected, as a result of the determination, whether the connection is not If the relative path loss to the corresponding non-connected base station is less than a threshold function given as a function of the moving speed, a connection with the corresponding non-connected base station is started. Mobile station device. 37. The mobile station apparatus according to claim 36, wherein the threshold function is given by a function having the moving speed as an argument, and is set so as to become larger as the moving speed is higher. 38. The soft handoff base station selecting device, if the result of the determination indicates that the relative propagation loss for the non-connected and corresponding non-connected base station exceeds the threshold function, 38. The mobile station device according to claim 36, wherein the mobile station device maintains a non-connection state with a non-connected base station. 39. The soft handoff base station selecting apparatus, wherein, as a result of the determination, the relative propagation loss with respect to the connected and corresponding connected base station is determined by the threshold function given as a function of the fluctuation speed. 38. The connection with the corresponding currently connected base station is released when the level exceeds the level obtained by adding the hysteresis margin.
A mobile station device according to claim 1. 40. The soft handoff base station selecting apparatus, wherein as a result of the determination, the relative propagation loss with respect to the connected and corresponding connected base station is determined by the threshold function given as a function of the fluctuation speed. 38. The mobile station apparatus according to claim 36, wherein a connection state with a corresponding connected base station is maintained when the level does not exceed a level obtained by adding a hysteresis margin.