JP3682844B2 - Connected base station sector control method and mobile station apparatus in mobile communication system - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
TECHNICAL FIELD The present invention relates to a connected base station sector control method and a mobile station apparatus, and in particular, in a mobile communication system including a plurality of base stations and a mobile station that communicates with the base station, The present invention relates to a connected base station sector control method when connecting to a base station and a sector obtained by searching for a mobile station apparatus to which the control method is applied.
[0002]
[Prior art]
In mobile communication systems such as mobile phones that are currently popular, services are performed by dividing the entire service area into relatively small wireless zones called cells. FIG. 1 schematically illustrates such a mobile communication system, in which a plurality of base stations (base stations 1 to 4) covering divided radio zones (cells a to d) and base stations 1 to 4 are provided. Are configured from a plurality of mobile stations 5 to 8 which perform communication by setting a radio channel between them.
[0003]
In general, a radio wave transmitted from a base station with a predetermined transmission power reaches a reception point while the power is attenuated as it propagates due to a propagation loss received during spatial propagation. The attenuation amount received by the radio wave has a property that it increases as the distance between the transmission point and the reception point increases. For this reason, the perch channel transmitted from a base station far away from the mobile station is received with low reception strength, and the perch channel transmitted from a nearby base station is received with strong reception strength. In reality, the magnitude of the propagation loss varies depending not only on the distance but also on the terrain and the building. Due to this propagation loss fluctuation, the received power of the perch channel from each base station may fluctuate greatly as the mobile station moves.
[0004]
In order to receive the transmission signal from the base station with higher quality, it is important that the mobile station constantly monitors the perch channel from each base station and selects the best base station according to the monitoring result. When monitoring the perch channel, it is not efficient to always search for and monitor all channels operated on the mobile communication system.
[0005]
Therefore, in the control used in the conventional mobile communication system, the neighboring base station sector information is reported from the located base station to the mobile station using the perch channel transmitted from each base station, and the mobile station is notified. Search and monitoring are performed only for the perch channel from the base station.
[0006]
[Problems to be solved by the invention]
In such a conventional mobile communication system, the base station sector information broadcast from the perch channel to the mobile station is optimized as described later, so that the mobile station can connect to the connected base more appropriately and smoothly. It is necessary to change the station.
[0007]
By the way, since the reception intensity is greatly affected by the terrain feature, the size and shape of the realistic area covered by each base station are not necessarily the size and shape intended by the system designer. That is, the area of each base station may be complicated, the area of other stations may be spot-formed within a certain base station area, or the area may be irregular.
[0008]
Therefore, it is conceivable that peripheral base station sector information is created in consideration of these intricately or spot-arranged stations and the information is broadcast. However, when a mobile station moves across such an irregularly shaped area, if the moving speed of the mobile station is somewhat high, the connected base station is frequently switched, and this causes a mobile communication system. The load increases.
[0009]
On the other hand, in order to reduce the switching frequency of the connected base stations and prevent an increase in load, it is conceivable to delete base stations in irregularly shaped areas from the peripheral base station sector information. When the information is deleted, if the mobile station moves at a somewhat slow speed, the time rate at which the mobile station is located in the area of the base station from which the information has been deleted increases. This increase in stay time results in an increase in communication quality deterioration time with the currently connected base station, and in the worst case, forced disconnection of communication.
[0010]
Thus, in order to optimize the peripheral base station sector information, it is necessary to consider the moving speed of the mobile station, which is generally a difficult task.
[0011]
Accordingly, the present invention has been made in view of such problems, and an object thereof is to provide a peripheral base station in a mobile communication system including a plurality of base stations and mobile stations that communicate with each other. To provide a connected base station sector control method and a mobile station apparatus that allow a mobile station to connect to the best base station and sector without difficulty in optimizing station sector information.
[0012]
[Means for Solving the Problems]
In order to achieve the above object, an invention according to claim 1 is directed to a connected base station sector control method in a mobile communication system comprising a mobile station and a plurality of base stations that communicate with each other. And a first step of transmitting a perch channel including peripheral base station sector information for classifying the plurality of base stations into a plurality of categories classified according to the priority order of connected sectors to the mobile station, and the peripheral base station sector information The second step of searching for the plurality of base stations according to the above and controlling connection switching of the mobile station so that the mobile station automatically determines a connection base station or a connection sector to be connected next, The second step is a search step for searching from the connected base station or connected sector having a high priority, and the mobile station is connectable in the searching step. When a local station sector is found, the mobile station monitors the reception quality of the base station sector within a predetermined time weighted for each priority, and determines the reception quality obtained by monitoring, And providing a connection base station sector control method characterized by comprising switching a connection to a base station sector to be connected next when the quality always satisfies a desired quality.
Further, the invention of claim 2 is a connected base station sector control method in a mobile communication system comprising a mobile station and a plurality of base stations that communicate with each other, and the priority order of the connected base station and the connected sector A first step of transmitting to the mobile station a perch channel including peripheral base station sector information for classifying the plurality of base stations into a plurality of categories classified in accordance with the plurality of base stations according to the peripheral base station sector information; A second step of searching for a station and controlling connection switching of the mobile station so that the mobile station automatically determines a connection base station or a connection sector to which the mobile station is next connected, A search step for searching from the connected base station or connected sector having a priority order, and following the searching step, A base station sector that is currently connected to the mobile station based on the set diversity handover threshold when the mobile station finds a base station sector that can be connected. There is provided a connection base station sector control method characterized by determining a connection switching timing to a base station sector to be connected to.
Further, the invention of claim 3 is a connection base station sector control method in a mobile communication system comprising a mobile station and a plurality of base stations that communicate with each other, and the priority order of the connection base station and the connection sector A first step of transmitting to the mobile station a perch channel including peripheral base station sector information for classifying the plurality of base stations into a plurality of categories classified in accordance with the plurality of base stations according to the peripheral base station sector information; A second step of searching for a station and controlling connection switching of the mobile station so that the mobile station automatically determines a connection base station or a connection sector to which the mobile station is next connected, A search step for searching from the connected base station or connected sector having a priority order, and following the searching step, A base station sector within a predetermined time weighted for each priority when the mobile station finds a connectable base station sector in the searching step. The reception quality obtained by monitoring by the mobile station is determined, and the connection switching from the currently connected base station sector to the next connected base station sector is performed based on the determination result and the set diversity handover threshold. Provided is a connection base station sector control method characterized in that connection switching is performed by determining timing.
According to a fourth aspect of the present invention, in a mobile station apparatus that communicates with a plurality of base stations in a mobile communication system and determines a connection base station or a connection sector according to the communication, the priority of the connection base station and the connection sector is determined. Receiving means for receiving, from the plurality of base stations, a perch channel including peripheral base station sector information for classifying the plurality of base stations into a plurality of categories classified according to the order; and the plurality according to the peripheral base station sector information Is a control means for controlling connection switching so as to automatically determine a connection base station or a connection sector to be connected next, and searches from the connection base station or connection sector having a high priority. Control means having search means, and when a base station sector that can be connected by the search means is found, it overlaps each priority. The reception quality of the base station sector within the predetermined time is monitored, the reception quality obtained by monitoring is determined, and when the reception quality always satisfies the desired quality, the base station sector to be connected next There is provided a mobile station apparatus characterized in that connection switching to is performed.
The invention of claim 5 is a mobile station apparatus that communicates with a plurality of base stations in a mobile communication system and determines a connection base station or a connection sector according to the communication. Receiving means for receiving, from the plurality of base stations, a perch channel including peripheral base station sector information for classifying the plurality of base stations into a plurality of categories classified according to the order; and the plurality according to the peripheral base station sector information Is a control means for controlling connection switching so as to automatically determine a connection base station or a connection sector to be connected next, and searches from the connection base station or connection sector having a high priority. Control means having search means; and setting means for setting a diversity handover threshold according to the priority order. When a searchable base station sector is found by the search means, the connection switching timing from the currently connected base station sector to the next connected base station sector based on the diversity handover threshold set by the setting means The mobile station apparatus is characterized by determining.
According to a sixth aspect of the present invention, in a mobile station apparatus that communicates with a plurality of base stations in a mobile communication system and determines a connection base station or a connection sector according to the communication, the priority of the connection base station and the connection sector is determined. Receiving means for receiving, from the plurality of base stations, a perch channel including peripheral base station sector information for classifying the plurality of base stations into a plurality of categories classified according to the order; and the plurality according to the peripheral base station sector information Is a control means for controlling connection switching so as to automatically determine a connection base station or a connection sector to be connected next, and searches from the connection base station or connection sector having a high priority. Control means having search means; and setting means for setting a diversity handover threshold according to the priority order. When a searchable base station sector is found by the search means, the reception quality of the base station sector within a predetermined time weighted for each priority is monitored, and the reception quality obtained by monitoring is determined, Based on the determination result and the diversity handover threshold set by the setting means, the connection switching is performed by determining the connection switching timing from the currently connected base station sector to the next connected base station sector. A mobile station apparatus is provided.
[0022]
DETAILED DESCRIPTION OF THE INVENTION
First, referring to FIG. 2, a conceptual description of the basic technical idea of the present invention will be given.
[0023]
2A is an explanatory diagram for explaining the positional relationship between each base station (sector) and the mobile station, and FIG. 2B is a distance (horizontal axis) from the base station 1 and reception intensity (vertical axis). ), And each base station and mobile station are applied to a mobile communication system similar to the conventional example shown in FIG.
[0024]
In FIG. 2A, it is assumed that the mobile station 20 is first connected to the base station 1 at the starting point and moves in the direction of the arrow. When the mobile station 20 receives from the base station 1, the mobile station 20 searches for the next connection destination based on the information broadcast on the perch channel and monitors the reception quality of the perch channel transmitted from each base station 1, 2, 3. .
[0025]
The reception intensity of radio waves arriving at the mobile station 20 from the base stations 1, 2, and 3 according to the movement is as shown in the characteristic diagram of FIG. In the characteristic diagram, region 1 is a region where the perch channel (transmission wave) received from the base station 1 has the highest reception strength, and region 3 is a region where the perch channel transmitted from the base station 3 has the highest reception strength. Region 2 is the region where the perch channel received intensity transmitted from the base station 2 is the highest. As the distance from the base station 1 increases, the strongest reception strength base station changes in the order of base station 1, base station 3, and base station 2.
[0026]
When the mobile station 20 moves from the position closest to the base station 1 toward the base station 2 in such a reception intensity distribution, in the conventional mobile communication system, first from the base station 1 to the base station 3, and then from the base station 3 The connecting station is switched to the base station 2. However, when the moving speed of the mobile station 20 is fast during such movement and the time rate for connecting to the base station 3 is short, the connection is directly switched from the base station 1 to the base station 2 without connecting to the base station 3 on the way. Less load on the system. On the other hand, when the moving speed of the mobile station 20 is slow and the time rate for connecting to the base station 3 is long, switching the connection in consideration of the base station 3 can achieve better reception without communication quality degradation or forced disconnection. It can be carried out.
[0027]
According to the present invention, the mobile station 20 switches the connection from the base station 1 to the base station 2 when the mobile station 20 has a high moving speed in accordance with each peripheral base station sector information in the plurality of perch channels received by the mobile station 20. When the moving speed of the base station 1 is slow, the connection switching judgment of the base station 1 → the base station 3 → the base station 2 can be automatically performed.
[0028]
For example, the peripheral base station sector information broadcast by the perch channel of the base station 1 is classified into two categories, where the base station 2 is described in category 1 and the base station 3 is described in category 2. Here, category 2 has a lower priority than category 1. That is, the base station 3 classified into the category 2 has a longer reception quality monitoring time and the diversity handover threshold is higher than the base station 2 classified into the category 1.
[0029]
When the moving speed of the mobile station 20 is high, the probability that the reception quality of the perch channel from the base station 3 is always good within the monitoring time decreases as the moving speed of the mobile station 20 increases. In addition, the diversity / handover threshold is set high. Therefore, the probability that the mobile station 20 is connected to the base station 3 during low-speed movement is low.
[0030]
On the other hand, when the moving speed of the mobile station 20 is slow, the probability that the reception quality of the perch channel from the base station 3 is always good within the monitoring time becomes higher as the moving speed of the mobile station 20 is slower. Along with an increase in the probability that the reception quality is good, there is a high probability that the reception quality always exceeds the diversity handover threshold within the monitoring time. Therefore, the probability that the mobile station 20 is connected to the base station 3 during high-speed movement increases.
Next, an embodiment according to the present invention will be described in detail with reference to FIGS.
[0031]
FIG. 3 is a block diagram showing a main part configuration of a mobile station apparatus according to an embodiment of the present invention, and conceptually shows only a main part related to the present invention in the configuration of the mobile station apparatus. The mobile station apparatus shown in FIG. 3 is used for the mobile station in the mobile communication system shown in FIG.
[0032]
The mobile station transmitting / receiving apparatus 30 receives and demodulates radio-modulated user information and control signals transmitted from each base station (sector) (not shown), and encodes / modulates and transmits user signals and control signals. . Frequency division multiple access (FDMA), time division multiple access (TDMA), code division multiple access schemes such as code division multiple access schemes and CDMA) The difference in modulation / demodulation method in the radio section of the station transmission / reception device 30 does not affect the effect of the present invention. The mobile station transmission / reception device 30 is connected to an antenna 31 and a user interface 32, and receives a perch channel from each base station.
[0033]
The common control circuit 33 manages the overall control of the mobile station apparatus. The common control circuit 33 is connected to the perch channel quality measurement control circuit 34, the cell search control circuit 35, the connected base station sector control circuit 36, and the memory 37 via the bus 38. The perch channel quality measurement control circuit 34 instructs the mobile station transmission / reception device 30 to measure the quality of the perch channel, and acquires the measurement result from the mobile station transmission / reception device 30.
[0034]
The cell search control circuit 35 instructs the mobile station transmission / reception device 30 to execute the cell search, and acquires the cell search execution result from the mobile station transmission / reception device 30. The connected base station sector control circuit 36 determines whether to start connection based on the perch channel quality measurement result acquired by the cell search control circuit 35. Various kinds of data can be stored in the memory 37, and peripheral base station sector information broadcast from the area base station is stored.
[0035]
FIG. 4 is an explanatory diagram conceptually showing neighboring base station sector information acquired by a mobile station in an embodiment according to the present invention.
[0036]
In FIG. 4, the mobile station 40 is configured to include the components shown in FIG. The mobile station 40 is located in the area of the base station A, and obtains peripheral base station sector information 44 from the perch channel broadcast information transmitted from the base station A. In this information, base stations belonging to category 1 and base stations belonging to category 2 are classified and described.
[0037]
In category 1, the most powerful base station (sector) as the next connection base station (sector), specifically, the base stations B, C, D, E, F, adjacent to the existing area (base station A), respectively. G is described. In category 2, a base station to which the mobile station 40 may be connected by a base station other than category 1 specifically includes areas belonging to category 1 (base stations B, C, D, E, F, G ), The base stations H, I, J, K, L, M, N, O, P, Q, R, and S adjacent to each other are described. Further, the base station having the lowest priority that does not belong to either category 1 or 2 is set as another category (not shown).
[0038]
Next, the flow of processing until the mobile station 40 performs a cell search and determines a connected base station will be described with reference to the flowchart of FIG. This process performs connection switching control using peripheral base station sector information.
[0039]
First, under the control of the common control circuit 33, the mobile station 40 starts a cell search by the mobile station transmission / reception device 30 and the cell search circuit 35, thereby searching for a perch channel that can be received (step S50). As a result of the search, when a perch channel other than the communication base station A in the located area is received (step S51), the base station (sector) transmitting the channel is determined as a determination target base station, and each base station Which category it belongs to is searched according to the peripheral base station sector information (information broadcast from the base station A) 44 stored in the memory 37 (step S52).
[0040]
Subsequently, the reception quality monitoring time T is determined from the category to which each base station belongs (step S53). Category 1 is T1, category 2 is T2, and other categories are T3. Further, a diversity handover threshold (DHO threshold) L is determined (step S54). It is assumed that category 1 is L1, category 2 is L2, and other categories are L3. In both the above steps, T1 <T2 <T3 and L1 <L2 <L3 are set in order of category priority.
[0041]
The mobile station 40 uses the parameters determined in the above steps to determine whether or not to connect to the base station transmitting the reception perch channel according to the procedure from step S55.
When the monitoring is started and the monitoring time t is reset (step S55), and the reception quality is measured by the mobile station transmitting / receiving device 30 and the perch channel quality measurement control circuit 34 for the determined reception quality monitoring time T (steps S56 and S57). The monitoring is terminated (step S58). The reception quality measured here includes SIR in addition to the reception intensity described above.
[0042]
Subsequently, it is determined whether the reception quality (reception strength or SIR) is good (step S59) and whether the connection switching can be determined based on the DHO threshold value (step S60).
[0043]
The connection base station sector control circuit 36 determines that connection is possible when the reception quality is always determined to be good within the monitoring time T in step S59, and it is determined that connection is possible in the subsequent determination based on the DHO threshold value in step S60. It is. If the reception quality is not good, the process returns to step S50, and the mobile station 40 performs a cell search again and repeats a search for a receivable perch channel. Also, even if the reception quality is good, if the determination based on the DHO threshold L is not possible, the mobile station 40 returns to step S50 and performs a cell search again to repeat the search for receivable perch channels.
[0044]
When it is determined that the connection is possible by the above processing, the connection switching timing from the currently connected base station sector to the next connected base station is determined based on the diversity handover threshold, and the connection to the base station is determined. Start (step S61).
[0045]
In the above processing, since T1 <T2 <T3 and L1 <L2 <L3 are set, if the received perch channel is a category 1 base station, the monitoring time T is short and the DHO threshold is low. There is a high probability that the connection with the base station is started by the determination in steps S59 and S60. On the other hand, when a perch channel transmitted from a base station other than category 1 or 2 is received, the monitoring time T is long and the DHO threshold is high. The probability of starting is low.
[0046]
These probabilities vary depending on the relationship between the moving speed of the mobile station and the monitoring time, but the same can be said for each category.
[0047]
Therefore, according to the connected base station sector control method and the mobile station apparatus in the mobile communication system according to the present embodiment, the connection switching is controlled by using the neighboring base station sector information broadcast from the perch channel as described above. Therefore, it is possible to realize the connection between the mobile station and the best base station and sector without optimizing the difficult peripheral base station sector information required conventionally.
[0048]
【The invention's effect】
As described above, according to the method and apparatus of the present invention, a plurality of base stations are classified into a plurality of categories in a mobile communication system including a mobile station and a plurality of base stations that communicate with each other. A perch channel including peripheral base station sector information is transmitted to the mobile station, a plurality of base stations are searched according to the peripheral base station sector information, and the connected base station or connected sector to which the mobile station is connected next is automatically By controlling the connection switching so as to determine and classifying the peripheral base station sector information into a plurality of categories according to the priority order, it is possible to optimize the base station to the mobile station without optimizing the peripheral base station sector information. There is an effect that the connection with the station and the sector can be easily realized.
[Brief description of the drawings]
FIG. 1 is an explanatory diagram showing a schematic configuration of a conventional mobile communication system to which the present invention is applicable.
FIG. 2 is an explanatory diagram and a characteristic diagram conceptually explaining the basic technical idea of the present invention.
FIG. 3 is a block diagram showing a main configuration of a mobile station apparatus according to an embodiment of the present invention.
FIG. 4 is an explanatory diagram conceptually showing neighboring base station sector information acquired by a mobile station in an embodiment according to the present invention.
FIG. 5 is a flowchart showing a procedure of connection switching control processing using neighboring base station sector information according to an embodiment of the present invention.
[Explanation of symbols]
30 mobile station transceiver 31 antenna 32 user interface 33 common control circuit 34 perch channel quality measurement control circuit 35 cell search control circuit 36 connected base station sector control circuit 37 memory 38 bus 40 mobile station 44 peripheral base station sector information A to S base station

Claims (6)

In a connected base station sector control method in a mobile communication system composed of a mobile station and a plurality of base stations that communicate with each other.
A first step of transmitting to the mobile station a perch channel including peripheral base station sector information for classifying the plurality of base stations into a plurality of categories classified according to a priority order of a connecting base station and a connecting sector; A second step of searching for the plurality of base stations according to the station sector information and controlling connection switching of the mobile station so that the mobile station automatically determines a connection base station or a connection sector to be connected next; And
The second step includes
A search step for searching from the connected base station or the connected sector of high priority;
When the mobile station finds a connectable base station sector in the search step, the mobile station monitors and monitors the reception quality of the base station sector within a predetermined time weighted for each priority. A connection base station sector control method comprising: determining the obtained reception quality and performing connection switching to a next connected base station sector when the reception quality always satisfies a desired quality. In a connected base station sector control method in a mobile communication system composed of a mobile station and a plurality of base stations that communicate with each other.
A first step of transmitting to the mobile station a perch channel including peripheral base station sector information for classifying the plurality of base stations into a plurality of categories classified according to a priority order of a connecting base station and a connecting sector; A second step of searching for the plurality of base stations according to the station sector information and controlling connection switching of the mobile station so that the mobile station automatically determines a connection base station or a connection sector to be connected next; And
The second step includes
A search step for searching from the connected base station or the connected sector of high priority;
Subsequent to the searching step, setting a diversity handover threshold according to the priority order,
When the mobile station finds a connectable base station sector in the searching step, the connection from the currently connected base station sector to the next connected base station sector is performed based on the set diversity handover threshold. A connected base station sector control method characterized by determining a switching timing. In a connected base station sector control method in a mobile communication system composed of a mobile station and a plurality of base stations that communicate with each other.
A first step of transmitting to the mobile station a perch channel including peripheral base station sector information for classifying the plurality of base stations into a plurality of categories classified according to a priority order of a connecting base station and a connecting sector; A second step of searching for the plurality of base stations according to the station sector information and controlling connection switching of the mobile station so that the mobile station automatically determines a connection base station or a connection sector to be connected next; And
The second step includes
A search step for searching from the connected base station or the connected sector of high priority;
Subsequent to the searching step, setting a diversity handover threshold according to the priority order,
When the mobile station found a connectable base station sector in the search step, the mobile station monitored the reception quality of the base station sector within a predetermined time weighted for each priority. The reception quality is determined, and the connection switching is performed by determining the connection switching timing from the currently connected base station sector to the next connected base station sector based on the determination result and the set diversity handover threshold. A connected base station sector control method. In a mobile station apparatus that performs mutual communication with a plurality of base stations in a mobile communication system and determines a connection base station or a connection sector according to the communication,
Receiving means for receiving, from the plurality of base stations, a perch channel including peripheral base station sector information for classifying the plurality of base stations into a plurality of categories classified according to the priority order of the connecting base station and the connecting sector;
A control means for searching for the plurality of base stations according to the peripheral base station sector information and controlling connection switching so as to automatically determine a connection base station or a connection sector to be connected next. Control means having search means for searching from the connected base station or connected sector,
When a searchable base station sector is found by the search means, the reception quality of the base station sector within a predetermined time weighted for each priority is monitored, and the reception quality obtained by monitoring is determined. A mobile station apparatus that performs connection switching to a base station sector to be connected next when the reception quality always satisfies a desired quality. In a mobile station apparatus that performs mutual communication with a plurality of base stations in a mobile communication system and determines a connection base station or a connection sector according to the communication,
Receiving means for receiving, from the plurality of base stations, a perch channel including peripheral base station sector information for classifying the plurality of base stations into a plurality of categories classified according to the priority order of the connecting base station and the connecting sector;
A control means for searching for the plurality of base stations according to the peripheral base station sector information and controlling connection switching so as to automatically determine a connection base station or a connection sector to be connected next. Control means having search means for searching from the connected base station or connected sector;
Setting means for setting a diversity handover threshold according to the priority,
Switching the connection from the currently connected base station sector to the next connected base station sector based on the diversity handover threshold set by the setting means when a connectable base station sector is found by the search means A mobile station apparatus that determines timing. In a mobile station apparatus that performs mutual communication with a plurality of base stations in a mobile communication system and determines a connection base station or a connection sector according to the communication,
Receiving means for receiving, from the plurality of base stations, a perch channel including peripheral base station sector information for classifying the plurality of base stations into a plurality of categories classified according to the priority order of the connecting base station and the connecting sector;
A control means for searching for the plurality of base stations according to the peripheral base station sector information and controlling connection switching so as to automatically determine a connection base station or a connection sector to be connected next. Control means having search means for searching from the connected base station or connected sector;
Setting means for setting a diversity handover threshold according to the priority,
When a searchable base station sector is found by the search means, the reception quality of the base station sector within a predetermined time weighted for each priority is monitored, and the reception quality obtained by monitoring is determined. Determining the connection switching timing from the currently connected base station sector to the next connected base station sector based on the determination result and the diversity handover threshold set by the setting means. A featured mobile station apparatus.

Images