Patent Application
20140219122
This application is based upon and claims the benefit of priority from prior Japanese Patent Application No. 2013-021379, filed Feb. 6, 2013, the entire contents of which are incorporated herein by reference.
Embodiments described herein relate generally to a control apparatus, representative base station and base station control method.
As cellphone traffic increases year by year, it is required to further enhance the speed of mobile communications, which is why communication companies have started a service called Long Term Evolution (LTE), intended to speed up radio communications. Further, indoor cellphone traffic increases year by year, necessitating the quality of radio communications to be enhanced to further expand cellphone data traffic.
In order to enhance the indoor traffic capacity, it is necessary to arrange a large number of base stations called femtocells, which have a near-field range of several ten meters. If the base stations with the same operation frequency are arrange adjacent to each other, interference occurs and the throughput is lowered. It is thus required to suppress the interference by eliminating the indoor dead zone (outside the phone service) by adjusting the transmission power of femtocells and assigning the operation frequencies so as not to overlap the same operation frequency, and enhance the throughput to enhance the quality of indoor radio communications traffic.
Conventionally, it is requested for a design contractor to make calculations of parameters assigned to the respective base stations and the thus obtained parameters are manually configured in the respective base stations. However, with such manual setting, the cost for initial setting, maintenance and the like increases. Further, since the radio wave environment varies according to the indoor environment, optimum traffic cannot be maintained in some cases since in the previous system the parameters were fixed at the initial setting time by previously grasping the radio wave environment by use of a measurement terminal, which then automatically configured optimum parameters. Under such conditions, if an attempt is made to dynamically adjust the parameters, it becomes necessary to measure the radio wave environment again by use of the measurement terminal during the operation.
In general, according to one embodiment, a control apparatus includes a terminal information collecting unit, an area determining unit, a parameter calculator, and a parameter setting unit. The terminal information collecting unit acquires reception powers and physical cell IDs from a plurality of base stations, calculates a Signal to Interference and Noise power Ratio (SINR) for each of a plurality of communication terminals that make radio communications with the plural base stations based on the acquired reception powers and physical cell IDs, and collects the acquired reception powers and physical cell IDs. The reception powers are transmitted to a base station from a communication terminal communicating each other which receives signals transmitted from the plural base stations. The physical cell IDs are transmitted to a base station from a communication terminal communicating each other. The physical cell IDs are specifying base stations transmitting the signal. The area determining unit determines a low-throughput area in which sufficient throughput is not obtained in reference to at least one of the SINRs and reception powers. The parameter calculator selects a base station that causes the low-throughput area and calculates an operation frequency and transmission power of the selected base station to enhance the throughput of the low-throughput area. The parameter setting unit sets the calculated operation frequency and transmission power with respect to the selected base station.
Next, embodiments are explained with reference to the drawings.
The radio communication unit 31 makes radio communication with, for example, the base station 20-1 having the highest reception power of a signal to be transmitted among the base stations 20-1 to 20-3 according to an LTE protocol.
The reception power information acquiring unit 32 acquires a reception power of a signal transmitted from the base stations 20-1 to 20-3 and a physical cell ID used for specifying the base station that has transmitted the signal on a preset cycle. The reception power and physical cell ID can be acquired according to an LTE standard specification.
The reception power information holding unit 33 forms a correspondence table of the acquired reception power and physical cell ID, and holds the correspondence table. The reception power information holding unit 33 updates the correspondence table each time the reception power information acquiring unit 32 acquires a new reception power and physical cell ID.
The reception power information notifying unit 34 transmits the correspondence table as terminal information to the base station 20-1 according to a request from the base station 20-1 connected thereto. At this time, the reception power information notifying unit 34 adds an identifier of its own terminal to terminal information and transmits terminal information added the identifier to the base station 20-1. The reception power information notifying unit 34 may actively transmit terminal information to the base station 20-1 at a preset timing.
The base station 20-1 shown in
The radio communication unit 21 makes radio communications with the communication terminals 30-1 to 30-3. Further, the radio communication unit 21 monitors a handover of switching a connection to another base station by means of the communication terminals 30-1 to 30-3. The radio communication unit 21 forms a handover history indicating whether the communication terminals 30-1 to 30-3 succeeded or failed in making the handover.
The terminal information collecting unit 22 receives terminal information transmitted from the communication terminals 30-1 to 30-3 and collects the received terminal information together with an identifier. The terminal information contains the reception power, physical cell ID and handover history. The terminal information collecting unit 22 may request terminal information items with respect to all of the communication terminals 30-1 to 30-3. Further the terminal information collecting unit 22 may request terminal information with respect to only to the communication terminal that is set in a connected state except the idle state. The idle state is a state in which the communication terminal interrupts the communication function when no communications are made for a preset period between the base station and the communication terminal.
The terminal information notifying unit 23 puts the handover history for the communication terminals 30-1 to 30-3 into the collected terminal information and transmits the resultant information to the control apparatus 10 in response to a request from the control apparatus 10. The terminal information notifying unit 23 may transmit the terminal information to the control apparatus 10 at the preset timing.
For example, the control apparatus 10 includes a Central Processing Unit (CPU), a storage area such as a Read Only Memory (ROM) and Random Access Memory (RAM) for programs and data used for permitting the CPU to perform processes and the like. The control apparatus 10 includes a base station controller 11, terminal information collecting unit 12, area determining unit 13, parameter calculator 14 and parameter setting unit 15 shown in
The base station controller 11 controls the operations of the base stations 20-1 to 20-3.
The terminal information collecting unit 12 receives terminal information transmitted from the base stations 20-1 to 20-3. The terminal information collecting unit 12 calculates a Signal to Interference and Noise power Ratio (SINR) for each communication terminal identified by the identifier contained in the received terminal information with reference to the reception power and physical cell ID contained in the received terminal information. The terminal information collecting unit 12 collects terminal information items transmitted from the base stations 20-1 to 20-3. The terminal information collecting unit 12 outputs the calculated SINR and collected terminal information to the area determining unit 13.
The area determining unit 13 determines whether or not an area in which the communication terminal is present is a low-throughput area in which a sufficiently high throughput cannot be ensured with reference to at least one of the SINR, reception power and handover history. The area determining unit 13 outputs the determination result to the parameter calculator 14.
As a system for determining the low-throughput area, for example, the following three systems are given. First, as the first system, if the SINR calculated by the terminal information collecting unit 12 is less than a preset first threshold value (for example, 4 dB), the area determining unit 13 determines that an area in which a communication terminal having the SINR is present is a low-throughput area. As a result, for example, the area determining unit 13 can determine an area in which interference occurs because signals of the same frequency are transmitted from the adjacent base stations. The parameter calculator 14 that will be described later can specify base stations that transmit the signals causing the interference to determine the frequencies and transmission powers of the signals transmitted from the base stations.
Next, as the second system, if the maximum value of the reception power is less than a preset second threshold value in the respective communication terminals 30-1 to 30-3, the area determining unit 13 determines that an area in which a communication terminal having the maximum value is present is a low-throughput area. As a result, for example, the area determining unit 13 can determine an area in which the reception power is weak. The parameter calculator 14 can specify a base station whose transmission power is weak to calculate transmission power optimum for the base station.
Next, as the third system, if a communication terminal that has failed in making a handover a preset number of times or more in the preset closest period is present with reference to the handover history, the area determining unit 13 determines that an area in which the communication terminal is present is a low-throughput area. Further, if a communication terminal that keeps failing to make a handover in the preset closest period is present with reference to the handover history, the area determining unit 13 determines that an area in which the communication terminal is present is a low-throughput area. As a result, for example, the area determining unit 13 can determine an area that is set as a dead zone (outside the phone service). The parameter calculator 14 can specify a base station that causes the dead zone to calculate the transmission power optimum for the base station.
The parameter calculator 14 determines the transmission power, operation frequency, physical cell ID, neighbor list, handover threshold value, base station ID, frequency bandwidth, IP address of a base station, adjacent cell information, cell size and the like with reference to the determination result output from the area determining unit 13 to enhance the throughput in the low-throughput area. The neighbor list, adjacent cell information and handover threshold value can be combined with the transmission power and operation frequency to create an optimum radio wave environment. That is, if a frequency resource with respect to the communication terminal in the operation is assigned again by intentionally changing the neighbor list and adjacent cell information during the operation, the handover can be controlled to create an optimum radio wave environment. Further, if a handover threshold value obtained after changing is used as the handover threshold value, the throughput in the low-throughput area can be enhanced by changing the connection destination of the terminal.
Specifically, for example, the parameter calculator 14 refers to the determination result to select at least one of the base stations 20-1 to 20-3 as a base station that causes a low-throughput area. The parameter calculator 14 calculates the transmission power and operation frequency with respect to the selected base station to enhance the throughput in the low-throughput area. The parameter calculator 14 outputs the physical cell ID of the selected base station and the calculated transmission power and operation frequency to the parameter setting unit 15.
The parameter setting unit 15 sets the determined parameter in the base station specified by the physical cell ID output from the parameter calculator 14.
Next, the operation of the radio communication system with the above configuration when parameters of the base stations 20-1 to 20-3 are set is explained in detail.
First, the communication terminals 30-1 to 30-3 each notify a correspondence table, which holds the reception power and physical cell ID therein as terminal information, and an identifier that can identify each terminal to the base station 20-1 (sequence S41).
The base station 20-1 receives terminal information notified from the communication terminals 30-1 to 30-3 and collects the received terminal information (sequence S42).
The terminal information collecting unit 12 of the control apparatus 10 requests terminal information containing handover histories of the communication terminals 30-1 to 30-3 with respect to the base stations 20-1 to 20-3 at a preset timing (sequence S43). The base stations 20-1 to 20-3 notify the terminal information to the control apparatus 10 in response to the request from the control apparatus 10 (sequence S44).
The terminal information collecting unit 12 of the control apparatus 10 receives terminal information notified from the base stations 20-1 to 20-3 and calculates an SINR for each of the communication terminals 30-1 to 30-3 based on the reception power and physical cell ID contained in the received terminal information (sequence S45).
The area determining unit 13 refers to the SINR, reception power and handover history to determine a low-throughput area (sequence S48). The area determining unit 13 notifies low-throughput area information to the parameter calculator 14 (sequence S49). The parameter calculator 14 refers to the notified low-throughput area information to calculate parameters in the base stations 20-1 to 20-3 to enhance the throughput in the low-throughput area (sequence S410). The parameter calculator 14 notifies the calculated parameters to the parameter setting unit 15 (sequence S411). The parameter setting unit 15 sets the parameters notified from the parameter calculator 14 in the base stations 20-1 to 20-3 (sequence S412).
In the case of
On the other hand, as shown in
As described above, in the first embodiment, the base stations 20-1 to 20-3 receive reception power and the physical cell ID from the communication terminal 30 with which they make radio communications and output the received reception power and physical cell ID to the control apparatus 10 via the local network. The control apparatus 10 refers to the received reception power and physical cell ID to determine a low-throughput area and set parameters of the base stations 20-1 to 20-3 to enhance the throughput in this area. As a result, the radio communication system can dynamically enhance the throughput in the low-throughput area with reference to the reception power and physical cell ID acquired by the communication terminal 30.
Therefore, with the radio communication system according to the first embodiment, parameters can dynamically be adjusted to optimum values according to the radio wave environment during the operation.
Further, in the first embodiment, the base stations 20-1 to 20-3 each put their handover history into the terminal information and transmit the resultant information to the control apparatus 10. The control apparatus 10 determines a dead zone by referring to the handover history by the area determining unit 13 and calculates parameters for the base stations that cause a dead zone by the parameter calculator 14. Then, the control apparatus 10 sets the calculated parameters in the respective base stations by the parameter setting unit 15. As a result, the radio communication system can dynamically eliminate the dead zone.
In the first embodiment, a case wherein the terminal information collecting unit 12 collects all of the terminal information items transmitted from the base stations 20-1 to 20-3 is explained as an example, but the embodiment is not limited to this case. It is also possible for the terminal information collecting unit 12 to eliminate terminal information that does not satisfy a preset condition among the received terminal information items and collect only terminal information that satisfies the preset condition.
For example, the terminal information collecting unit 12 eliminates terminal information supplied from a communication terminal in which the SINR is larger than or equal to a preset threshold value. Then, the terminal information collecting unit 12 deals with terminal information supplied from a communication terminal in which the SINR is smaller than the threshold value as a to-be-processed object used in the following process. Further, the terminal information collecting unit 12 may refer to the handover history and eliminate terminal information supplied from a communication terminal that has failed in making a handover by less than a preset number of times in a preset closest period. At this time, the terminal information collecting unit 12 deals with terminal information supplied from a communication terminal that has failed in making a handover a preset times or more in the preset closest period as a to-be-processed object used in the following process. As a result, the processing amount in the area determining unit 13 will be reduced.
The radio communication unit 31 makes radio communication with the representative base station 40 based on an LTE protocol.
The reception power information acquiring unit 32 acquires reception powers of signals transmitted from the representative base station 40 and base stations 20-1, 20-2 and physical cell IDs used for specifying the base stations that have transmitted the signals on a preset cycle.
The reception power information holding unit 33 forms a correspondence table of the acquired reception power and physical cell ID, and holds the correspondence table. The reception power information holding unit 33 updates the correspondence table each time the reception power information acquiring unit 32 acquires a new reception power and physical cell ID.
The reception power information notifying unit 34 transmits the correspondence table as terminal information to the representative base station 40 in response to a request from the representative base station 40 connected thereto. At this time, the reception power information notifying unit 34 adds an identifier of its own terminal to the terminal information and transmits the resultant information to the representative base station 40. The reception power information notifying unit 34 may actively transmit terminal information to the representative base station 40 at a preset timing.
For example, the representative base station 40 shown in
The radio communication unit 41 makes radio communications with the communication terminals 30-1 to 30-3. Further, the radio communication unit 41 monitors a handover of switching a connection to another base station by means of the communication terminals 30-1 to 30-3. The radio communication unit 41 forms a handover history that indicates whether the communication terminals 30-1 to 30-3 have succeeded or failed in making the handover.
The base station controller 42 controls the operations of the base stations 20-1 to 20-3.
The first terminal information collecting unit 43 receives terminal information transmitted from the communication terminals 30-1 to 30-3 and collects the received terminal information together with an identifier. In this case, the first terminal information collecting unit 43 may request terminal information items with respect to all of the communication terminals 30-1 to 30-3. Further, the first terminal information collecting unit 43 may request terminal information with respect to only to the communication terminal that is set in a connected state except the idle state. The first terminal information collecting unit 43 puts handover histories for the communication terminals 30-1 to 30-3 into the collected terminal information and outputs the resultant information to the second terminal information collecting unit 44.
The second terminal information collecting unit 44 receives terminal information output from the first terminal information collecting unit 43 and receives terminal information transmitted from the base stations 20-1, 20-2. The second terminal information collecting unit 44 refers to a correspondence table contained in the received terminal information to calculate the SINR for each communication terminal identified by the identifier. The second terminal information collecting unit 44 collects terminal information items supplied from the first terminal information collecting unit 43 and base stations 20-1, 20-2. The second terminal information collecting unit 44 outputs the calculated SINR and collected terminal information to the area determining unit 45.
The area determining unit 45 determines whether or not an area in which the communication terminal is present is a low-throughput area in which sufficient throughput cannot be ensured with reference to at least one of the SINR, reception power and handover history. The area determining unit 45 outputs the determination result to the parameter calculator 46. A system for determining the low-throughput area in the area determining unit 45 is the same as the system realized by use of the area determining unit 13 in the first embodiment.
The parameter calculator 46 determines parameters such as transmission power of its own station and/or base stations 20-1, 20-2, operation frequency, physical cell ID, neighbor list, handover threshold value, base station ID, frequency bandwidth, IP address of a base station, adjacent cell information, cell size and the like with reference to the determination result output from the area determining unit 45 to enhance the throughput in the low-throughput area. Specifically, for example, the parameter calculator 46 refers to the determination result to select at least one of its own station and base stations 20-1, 20-2 as a base station that causes a low-throughput area. The parameter calculator 46 calculates the transmission power and operation frequency for the selected base station to enhance the throughput in the low-throughput area. The parameter calculator 46 outputs the physical cell ID of the selected base station and the calculated transmission power and operation frequency to the parameter setting unit 47.
The parameter setting unit 47 sets parameters calculated by the parameter calculator 46 in its own station when the base station specified by the physical cell ID output from the parameter calculator 46 is its own station. Further, the parameter setting unit 47 sets parameters calculated by the parameter calculator 46 in the base station 20-1, 20-2 when the base station specified by the physical cell ID output from the parameter calculator 46 is the base station 20-1, 20-2, respectively.
Next, the operation when the radio communication system with the above configuration sets parameters of the representative base station 40 and base stations 20-1, 20-2 is explained in detail.
First, the communication terminals 30-1 to 30-3 each notify a correspondence table, which holds the reception power and physical cell ID therein as terminal information, and an identifier that can identify each terminal to the representative base station 40 (sequence S111).
The first terminal information collecting unit 43 of the representative base station 40 receives terminal information notified from the communication terminals 30-1 to 30-3 and collects the received terminal information (sequence S112).
The second terminal information collecting unit 44 requests terminal information containing the handover history for the base stations 20-1, 20-2 at a preset timing (sequence S113). The base stations 20-1, 20-2 each notify the terminal information to the representative base station 40 in response to the request from the second terminal information collecting unit 44 (sequence S114).
The second terminal information collecting unit 44 receives the terminal information notified from its own station and base stations 20-1, 20-2 and calculates SINRs for the respective communication terminals 30-1 to 30-3 based on the reception power and physical cell ID contained in the received terminal information (sequence S115).
The area determining unit 45 refers to the SINR, reception power and handover history to determine a low-throughput area (sequence S118). The area determining unit 45 notifies low-throughput area information to the parameter calculator 46 (sequence S119). The parameter calculator 46 refers to the notified low-throughput area information to calculate parameters in its own station and base stations 20-1, 20-2 to enhance the throughput in the low-throughput area (sequence S1110). The parameter calculator 46 notifies the calculated parameters to the parameter setting unit 47 (sequence S1111). The parameter setting unit 47 sets the parameters notified from the parameter calculator 46 in its own station or base stations 20-1, 20-2 (sequence S1112).
As described above, in the second embodiment, the representative base station 40 receives the reception power and physical cell ID from the communication terminal 30 with which it makes radio communications and receives the reception power and physical cell ID from the base stations 20-1, 20-2. The representative base station 40 refers to the received reception power and physical cell ID to determine a low-throughput area and sets parameters of its own station and base stations 20-1, 20-2 to enhance the throughput in the area. As a result, the radio communication system can dynamically enhance the throughput in the low-throughput area with reference to the reception power and physical cell ID.
Therefore, with the radio communication system according to the second embodiment, parameters can dynamically be adjusted to optimum values according to the radio wave environment during the operation.
Further, in the second embodiment, the representative base station 40 determines a dead zone based on a handover history of the communication terminal contained in its own station and handover histories transmitted from the base stations 20-1, 20-2. Then, the representative base station 40 calculates parameters for the base stations that may cause a dead zone and sets the calculated parameters for the respective base stations. As a result, the radio communication system can dynamically eliminate the outside-range state.
In the second embodiment, a case wherein the second terminal information collecting unit 44 collects all of the terminal information items notified from the communication terminals communicating with and the terminal information items transmitted from the base stations 20-1, 20-2 is explained as an example, but the embodiment is not limited to this case. The second terminal information collecting unit 44 can eliminate terminal information that does not satisfy a preset condition among the received terminal information items and collect only terminal information that satisfies the preset condition.
While certain embodiments have been described, these embodiments have been presented by way of example only, and are not intended to limit the scope of the inventions. Indeed, the novel embodiments described herein may be embodied in a variety of other forms; furthermore, various omissions, substitutions and changes in the form of the embodiments described herein may be made without departing from the spirit of the inventions. The accompanying claims and their equivalents are intended to cover such forms or modifications as would fall within the scope and spirit of the inventions.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2013-021379 | Feb 2013 | JP | national |
