Wireless communication system

Abstract

A wireless communication system includes a plurality of base stations and a plurality of M2M devices, and is provided with a plurality of tracking areas. Among the M2M devices, there are fixedly provided fixed M2M devices that are driven by a battery. The plurality of base stations are provided in such a manner that the tracking areas include areas formed with cell overlap regions, which are areas in which a plurality of cells overlap each other. When a fixed M2M device that is fixedly provided within a cell overlap region is provided as an overlap region-provided M2M device (for example, an overlap region-provided terminal), the overlap region-provided M2M device is fixed to a specific dedicated cell among the plurality of cells that overlap each other in the cell overlap region to communicate with the base station. Thus, even when an M2M device that is fixedly provided at a prescribed location and is driven by a battery is particularly provided in a tracking area in which base stations are dense, the shortening of the battery life of the M2M device can be favorably suppressed.

Description

Technical Field

[0001] This invention relates to a wireless communication system comprising multiple base stations and multiple M2M (Machine to Machine) devices, and particularly to a wireless communication system that enables good communication with base stations when the M2M devices include devices fixed in a predetermined location and powered by batteries. Background Technology

[0002] In a cell-based mobile communication system, multiple base stations are configured within the communication service area. The communication areas of each base station constitute multiple cells, and these cells form a network within the communication service area. When a user device (UE) such as a portable terminal moves within the communication service area, it selects a cell and communicates with the base station located in that cell.

[0003] Furthermore, when the UE moves within the communication service area, it reselects a suitable cell for communication. The UE performs cell search not only during such movement, but also during startup, standby, and intermittent reception during communication, to detect cells that provide good communication quality for the local station.

[0004] In addition, in recent years, not only has human-to-human communication using portable terminals been a focus, but also machine-to-machine (M2M) communication between devices via wired or wireless means without human intervention has also attracted attention. Such M2M devices, like portable terminals, can connect to cellular mobile communication systems in a communicative manner. Among M2M devices, there are those that can move within the communication service area, like portable terminals, and those that are fixed in designated locations. For ease of explanation, the former will be referred to as "mobile M2M devices," and the latter as "fixed M2M devices."

[0005] As an example of the configuration of a fixed M2M device, a setting in a tracking area with dense base stations can be considered. Dense base stations mean a large number of densely packed cells. Therefore, if the communication quality of any cell that previously provided good wireless communication quality deteriorates due to various conditions, the fixed M2M device can detect other cells with good communication quality through cell search and select or reselect that cell. As a result, the fixed M2M device can continue to provide good wireless communication. For ease of explanation, the cell selection or cell reselection performed by the UE, including the fixed M2M device, will be collectively referred to as cell selection processing.

[0006] As an example of such cell selection processing performed by a fixed M2M device, the wireless communication system disclosed in Patent Document 1 can be cited. In this wireless communication system, cells are ranked based on the relationship between the coverage levels that can be accessed. According to this ranking criterion, any first cell and second cell are ranked, and it is evaluated whether the wireless device should perform a cell change from the first cell to the second cell.

[0007] In Patent Document 1, a typical mobile user device (UE) is mainly exemplified as a wireless device, but an M2M device is also exemplified. The M2M devices exemplified in Patent Document 1 include "mobile M2M devices" such as those included in vehicles, and also include "fixed M2M devices" such as power meters, industrial machinery, or household or personal electrical products.

[0008] Existing technical documents

[0009] Patent documents

[0010] Patent Document 1: Japanese Patent Publication No. 2019-535159 Summary of the Invention

[0011] The problem the invention aims to solve

[0012] Here, when the fixed M2M device is a device powered by a built-in battery, when the fixed M2M device is set in a tracking area with dense base stations, there is a situation where the current consumption increases excessively, resulting in a shorter battery life, as has been determined by the researchers of the inventors.

[0013] In densely populated tracking areas, overlapping areas (cell duplication areas) can easily arise. When a fixed M2M device is deployed in such a cell duplication area, its transmission and reception characteristics remain good regardless of which cell it is connected to, leading to frequent cell search and cell selection processes. Consequently, the fixed M2M device consumes unnecessary power, resulting in shorter battery life.

[0014] The present invention was made to solve the problem of how to provide a wireless communication system that can effectively suppress the shortening of the battery life of an M2M device, even when the M2M device, which is fixed in a designated location and powered by a battery, is specifically located in a tracking area with dense base stations.

[0015] Solution for solving the problem

[0016] To address the aforementioned problem, the wireless communication system disclosed herein comprises the following structure: multiple base stations each having at least one cell configured, and multiple M2M (Machine-to-Machine) devices capable of wireless communication with the base stations, and multiple tracking areas are defined. Among the M2M devices, a fixed M2M device is included, which is fixedly installed and powered by a battery. The multiple base stations are configured such that the tracking areas include areas forming cell overlap regions, where the cell overlap regions are areas where multiple cells of each base station overlap with each other. The fixed M2M device includes a repeating area configured M2M device fixedly installed within the cell overlap regions. This repeating area configured M2M device is fixed to a dedicated cell to communicate with the base stations, where the dedicated cell is a specific cell among the multiple cells overlapping in the cell overlap regions.

[0017] According to the aforementioned structure, when multiple base stations are configured to form cell overlap areas within the tracking area, the overlap area configuration M2M device, fixedly located within these cell overlap areas, is configured to communicate only with specific dedicated cells among the multiple cells of the base stations. Therefore, even if communication conditions change, the overlap area configuration M2M device only communicates wirelessly via the dedicated cells of the specific base stations, thus preventing the overlap area configuration M2M device from randomly performing cell search and cell selection processing on the multiple cells constituting the cell overlap area.

[0018] As a result, the repeated area-based M2M device effectively suppresses current consumption, thus mitigating battery life shortening. Synchronization with the base station is also improved, suppressing communication speed degradation. Furthermore, because battery life is suppressed, the battery life of the repeated area-based M2M device easily meets design values, and battery replacement is virtually unnecessary, thereby ensuring product quality. Therefore, it maintains good wireless communication and effectively suppresses battery life shortening, even in densely populated tracking areas.

[0019] The above-mentioned objects, other objects, features, and advantages of the present invention will become clear from the following detailed description of preferred embodiments, with reference to the accompanying drawings.

[0020] The effects of the invention

[0021] In this invention, the above structure achieves the following effect in providing a wireless communication system: even when the M2M device, which is fixed in a specified location and powered by a battery, is specifically located in a tracking area with dense base stations, the shortening of the battery life of the M2M device can be effectively suppressed. Attached Figure Description

[0022] [ Figure 1 ] Figure 1 This is a schematic diagram illustrating an example of the structure of a wireless communication system according to a representative embodiment of the present disclosure.

[0023] [ Figure 2 ] Figure 2 A is a schematic diagram illustrating the frequent cell search and cell selection processes that occur in conventional wireless communication systems. Figure 2 B is shown in Figure 2 A schematic current waveform diagram showing the current consumption of an M2M device in a repeated area over time under the condition shown in Figure A.

[0024] [ Figure 3 ] Figure 3 A is shown in Figure 1 The diagram illustrates the suppression of cell search and cell selection processes in a wireless communication system. Figure 3 B is shown in Figure 3 A schematic current waveform diagram showing the current consumption over time of an M2M device (fixed terminal) repeatedly set up in the area under the condition shown in Figure A. Detailed Implementation

[0025] [Insights that form the basis of this disclosure, etc.]

[0026] In wireless communication systems, the ability of a User Equipment (UE) to communicate with a large number of cells is generally preferred for maintaining a stable communication environment. However, according to our research, in the case of a battery-powered fixed M2M device, the ability to communicate with a large number of cells can excessively induce cell search and cell selection processing, thereby shortening battery life.

[0027] Therefore, through further in-depth research, the inventors independently discovered the following structure: a specific cell (dedicated cell) is deliberately set up among a large number of cells, and wireless communication is fixed between this dedicated cell and the fixed M2M device. According to this structure, not only can the shortening of the battery life of the fixed M2M device be effectively suppressed, but the synchronization connection between the fixed M2M device and the base station is also improved, and the reduction in communication speed is also suppressed. Furthermore, according to this structure, it is easy to ensure that the battery life of the fixed M2M device meets the design value, and in addition, battery replacement is substantially unnecessary, thus achieving product assurance for the fixed M2M device. In this way, the inventors have completed the technology disclosed herein.

[0028] Hereinafter, representative embodiments of the present invention will be described with reference to the accompanying drawings. Furthermore, in all the drawings, the same or equivalent elements are labeled with the same reference numerals, and repeated descriptions are omitted.

[0029] [Example of a wireless communication system structure]

[0030] First, refer to Figure 1 To illustrate specifically, a representative example of the wireless communication system involved in this disclosure (the wireless communication system involved in this embodiment) will be given. For example, in Figure 1 As schematically shown, the wireless communication system 10 according to this embodiment has multiple base stations 20 and multiple fixed terminals 30 as M2M (Machine to Machine) devices. Multiple tracking zones 11 are set in this wireless communication system 10. However, in Figure 1 In the diagram, for ease of explanation, a tracking area 11 is schematically shown only by a dashed ellipse.

[0031] exist Figure 1 In the illustrative example shown, three base stations 20 are configured within a tracking area 11, and each base station 20 is assigned a cell 12. Furthermore, in Figure 1 In this document, for ease of explanation of the main parts of this disclosure, the three base stations 20 are designated as "Base Station 20A", "Base Station 20B", and "Base Station 20C", respectively, and the respective cells 12 set for each base station 20A~20C are designated as "Cell 12A", "Cell 12B", and "Cell 12C". Additionally, the fixed terminal 30 within the tracking area 11 is designated as "Fixed Terminal 30A". Furthermore, in... Figure 1 In the diagram, neighborhoods 12A to 12C are schematically represented using ellipses with thin lines.

[0032] At least one cell 12A can be configured for a base station 20A, but as will be described later, multiple cells 12A can also be configured for a base station 20A. In particular, this disclosure can be appropriately applied even in the case of configuring multiple cells 12A for a base station 20A. There are no particular limitations on the method of configuring multiple cells 12A for a base station 20A, and known methods can be used.

[0033] Taking 3GPP's (Third Generation Partnership Project) LTE (Long Term Evolution, base station OFDM modulation) as a representative example, the number of cells can be determined based on the bandwidth occupied by the base station. Specifically, for example, a base station supports various frequency bands such as band 8 (900MHz band) and band 1 (2GHz band). Bandwidths of 1.4MHz, 3MHz, 5MHz, 10MHz, 15MHz, and 20MHz are assigned to each base station. Within the bandwidth available for processing each base station's frequency band, the number of cells can be determined based on the desired number of resource blocks (RBs) that can be processed. Furthermore, the number of subcarriers (ch: number of users or data volume) can be increased within a resource block. Generally, band 8 radio waves have a longer propagation distance (larger cell area) and process less data (lower frequency, smaller bandwidth), while band 1 radio waves have a shorter propagation distance (smaller cell area) and process more data (higher frequency, larger bandwidth).

[0034] In addition, Figure 1 In addition to the three base stations 20 (base stations 20A-20C) used to illustrate the main parts of this disclosure, a base station 20 is also schematically illustrated outside a tracking area 11. This means that the wireless communication system 10 involved in this disclosure includes base station 20 in addition to base stations 20A-20C. Of course, more than one cell 12 is also configured in this schematically illustrated base station 20, and the base station 20 is also configured within other tracking areas 11. Figure 1 The illustrations of other tracking areas 11 are omitted. It goes without saying that a real wireless communication system 10 has a large number of base stations 20, a large number of cells 12, and a large number of tracking areas 11.

[0035] In the wireless communication system 10 disclosed herein, multiple base stations 20 (base stations 20A to 20C) are densely configured. Specifically, the multiple base stations 20 are densely configured, such as... Figure 1 As shown, a tracking area 11 can include an area forming a cell overlap region 13, which is an area where multiple cells 12A-12C of each base station 20A-20C overlap. Figure 1 In the middle, the overlapping area 13 of the cell is schematically shown with a thick dashed line.

[0036] In this disclosure, at least one fixed terminal 30A is provided in the cell overlap area 13. For ease of explanation, the fixed terminal 30A provided in the cell overlap area 13 is referred to as the overlap area setting terminal 30A. Furthermore, in the wireless communication system 10 involved in this disclosure, it is not necessary for base stations 20A~20C to be densely configured in all tracking areas 11 of the multiple tracking areas 11. For example, it may include areas where multiple base stations 20 are distributed, or it may include areas configured at a standard density that is neither dense nor dispersed.

[0037] Furthermore, this disclosure does not specifically limit the conditions under which multiple base stations 20 are densely configured. A representative example is a situation where the UE can transmit and receive with multiple base stations 20 in an area (where cell interference exists) and the communication quality (transmission and reception) is good regardless of whether it is on the same frequency or different frequency. Under such conditions, when setting up as a fixed terminal 30 for the UE, the receiving sensitivity of the base station 20 and the cell ID with the most accesses are measured, and the terminal information such as the UE's (fixed terminal 30) ICCID (Integrated Circuit Card ID) and MYSDN (telephone number) are registered in the base station 20. As a representative receiving sensitivity, as a reference indicator, examples include (1) above -115dBm (outside the service area), (2) below -115dBm to -110dBm (weak electric field), (3) below -110dBm to -90dBm (normal), and (4) below -90dBm (strong electric field). Basically, (4) is selected.

[0038] The fixed terminal 30 (including the repeatable area setting terminal 30A) is an M2M device that is fixedly installed in any location and is battery-powered. Its specific structure is not particularly limited, as long as it can transmit and receive data with other M2M devices via wireless communication. Specific examples of the fixed terminal 30 are not particularly limited, but in this disclosure, gas meters or water meters can be cited as examples. Generally, gas meters or water meters are battery-powered and fixedly installed in any location. Therefore, if the fixed terminal 30 is a gas meter or water meter, the wireless communication system 10 disclosed herein can be appropriately applied.

[0039] Furthermore, in the wireless communication system 10 disclosed herein, the M2M device capable of communicating with the base station 20 (the cell 12 configured for the base station 20) is not limited to the fixed terminal 30. Generally, "terminal (device)" mostly refers to a device directly used by a user in a device connected to a communication network. Gas meters or water meters are generally installed in buildings or facilities that are users of gas or tap water; therefore, in this disclosure, such meters are referred to as fixed terminals 30. However, the wireless communication system 10 disclosed herein may also be a fixed M2M device that is not a "terminal (device)," such as an instrument or measuring device installed in a factory, etc.

[0040] Furthermore, the wireless communication system 10 disclosed herein may also include "terminals (devices)" other than fixed terminals 30 or fixed M2M devices. For example, a portable terminal (mobile M2M device) capable of movement, such as a mobile phone, smartphone, or tablet computer, may be able to communicate with the base station 20 (cell 12). Such a portable terminal does not conform to the M2M device, but the wireless communication system 10 disclosed herein may also have a structure that includes wireless communication devices other than M2M devices. In addition, such a portable terminal may also be configured to communicate with fixed terminals 30 or fixed M2M devices.

[0041] Furthermore, the wireless communication system 10 disclosed herein may include not only fixed M2M devices or portable terminals, but also mobile M2M devices. Examples of such mobile M2M devices include M2M devices mounted on automobiles or light vehicles, but there is no particular limitation. Additionally, in this embodiment, for ease of explanation, the wireless communication between the fixed terminal 30 and the base station 20 via the cell 12 is sometimes abbreviated as "communication between the fixed terminal 30 and the cell 12."

[0042] [Example of repeated area settings for communication between M2M devices and cells]

[0043] Next, refer to Figure 2 A, Figure 2 B and Figure 3 A, Figure 3 B will specifically illustrate an example of wireless communication between a cell 12 set by a base station 20 within a tracking area 11 including a cell overlap area 13 and a overlap area setting terminal 30A, which is an overlap area setting M2M device, in the wireless communication system 10 disclosed herein.

[0044] exist Figure 2 A and Figure 3 In diagram A, a scenario is illustrated where multiple cells 12 are configured for a single base station 20. For example, in... Figure 2In diagram A, three cells, 12A-1 to 12A-3, are designated for base station 20A. Each cell, 12A-1 to 12A-3, is symbolically arranged in a row as a circle. These cells 12A-1 to 12A-3 are designated for a single base station 20A by connecting the row of circular symbols with the symbol representing base station 20A using thin lines. The same applies to base station 20B and its designated cells 12B-1 to 12B-3, and to base station 20C and its designated cells 12C-1 to 12C-3.

[0045] In addition, Figure 2 A and Figure 3 In A, the symbols representing base stations 20A~20C, the symbols representing cells 12A-1~12A-3, 12B-1~12B-3, 12C-1~12C-3, and the block arrows CmA, CmB, and CmC that schematically represent wireless communication described later all contain hollow and grid-filled shapes, which schematically represent the differences in the frequency of wireless communication.

[0046] For example, cells 12A-1 to 12A-3 set for base station 20A are all shown as hollow diagrams, indicating that they are at the same frequency. Similarly, cells 12B-1 to 12B-3 set for base station 20B are all shown as filled diagrams, indicating that they are at the same frequency. In addition, cells 12A-1 to 12A-3 and cells 12B-1 to 12B-3, which have different frequencies, are also illustrated by the difference between hollow and filled diagrams.

[0047] On the other hand, among the cells 12C-1 to 12C-3 configured for base station 20C, only cell 12C-2 is shown with a filled mesh pattern, while cells 12C-1 and 12C-3 are shown with a hollow pattern. This indicates that cells 12C-1 to 12C-3 of different frequencies can be mixed and configured within a single base station 20C. Furthermore, it goes without saying that for each actual base station 20A to 20C, more than three cells 12A to 12C can be configured, and more than three frequencies can be configured.

[0048] Figure 2 The illustrative communication example shown in A corresponds to... Figure 1 The diagram schematically illustrates the communication status between base stations 20A-20C and the repeating area setting terminal 30A within tracking area 11. If the repeating area setting terminal 30A is, for example, a gas meter or water meter as described above, it is generally operated intermittently. Figure 2 B is with Figure 2 A is a schematic current waveform diagram representing the current consumption of the terminal with a repeated area setting of 30A over time.

[0049] Should Figure 2B shows the signal (paging signal) when any of the base stations 20A to 20C obtains synchronization (paging) from the repeating area setting terminal 30A (as a UE) via downlink communication (DL) at any period. This method is the power-saving technology eDRX (extended discontinuous reception), which confirms that the repeating area setting terminal 30A is not outside the service area. Figure 2 In diagram B, the arrows on the horizontal axis represent time passing from left to right, and the vertical axis, orthogonal to the horizontal axis, represents the magnitude of the current consumed.

[0050] In typical mobile communication, the UE is in sleep mode when not paging. Communication is usually switched to another base station's cell based on the paging signal reception sensitivity. For example, if the UE's reception sensitivity is not good, a cell search and cell selection process (reselection) is performed, allowing handover to a cell of another base station with a different TAC (Tracking Area Code).

[0051] In this disclosure, the UE is a fixed terminal 30 (repeated area setting terminal 30A). As an example of a fixed terminal 30, a gas meter or water meter can be cited, as described above. For example, if it is a gas meter, communication occurs between the flow measurement unit that measures the gas flow and the wireless communication unit that performs wireless communication, regardless of paging or sleep state. If this communication is referred to as "internal terminal communication" for ease of explanation, after the intra-terminal communication ends, the fixed terminal 30 pages and synchronizes with base stations 20A to 20C, and then enters a sleep state. Therefore, such synchronization is performed periodically in the fixed terminal 30. Thus, as... Figure 2 As shown on the left side of B, if the repeating region setting terminal 30A performs normal synchronization operation, then the long, pulse-like synchronization operation current i1 corresponding to the short-time drive is generated at equal intervals.

[0052] Here, as Figure 2 As shown in Figure A, the repeating area setting terminal 30A is configured to wirelessly communicate with any one of the cells 12A-1 to 12C-3 set for base stations 20A to 20C. These cells 12A-1 to 12C-3 are all cells 12 forming the cell repeating area 13. Here, when communication conditions change in the tracking area 11, the repeating area setting terminal 30A performs a detection of the communicable cell 12 (in...). Figure 2 In the example shown in A, cell search is performed for cells 12A-1 to 12C-3, followed by cell selection processing (cell selection or cell reselection).

[0053] For example, such as Figure 2As indicated by block arrow CmA in section A, the repeating area setting terminal 30A initially established wireless communication with cell 12A-1 of base station 20A. Subsequently, when communication conditions change and the receive sensitivity between repeating area setting terminal 30A and cell 12A-1 becomes poor, cell search is initiated in repeating area setting terminal 30A to detect co-frequency and inter-frequency cells 12. For example, cell 12B-2 of base station 20B is detected through this cell search. Cell 12B-2 is inter-frequency with cell 12A-1. Therefore, repeating area setting terminal 30A performs cell selection processing (cell reselection) to initiate wireless communication with cell 12B-2. When cell 12B-2 is reselected, repeating area setting terminal 30A initiates wireless communication with cell 12B-2 as indicated by block arrow CmB.

[0054] The current consumption at this time is as follows: Figure 2 As shown in Figure B, the current consumption corresponding to cell search in the repeating area setting terminal 30A is the vertically shaded cell search current i2, and the current consumption corresponding to cell selection processing is the horizontally shaded cell selection current i3. It can be seen that the pulse shape of both the cell search current i2 and the cell selection current i3 is larger than the pulse shape of the synchronization operation current i1, meaning that the current consumption is greater.

[0055] exist Figure 2 In the example schematically shown in B, the current consumption during cell search is not only greater per unit time than during synchronization, but the duration of cell search is also longer. Furthermore, while the current consumption during cell selection is less per unit time than during synchronization, the duration of cell selection is significantly longer than the duration of cell search. In other words, the current consumption required for both cell search and cell selection is significantly increased compared to the flow measurement as a synchronization operation.

[0056] If such cell search and cell selection processes occur infrequently, they will not significantly deplete the battery capacity of the repeating area setting terminal 30A. However, if... Figure 2 As shown in Figure A, if the repeated area setting terminal 30A can wirelessly communicate with any of the cells 12A-1 to 12C-3, then cell search and cell selection processes will occur frequently. For example, if the repeated area setting terminal 30A is wirelessly communicating with cell 12B-2, and the communication conditions change again, causing the wireless communication with cell 12B-2 to become poor, then cell search and cell selection processes will be performed.

[0057] Subsequently, for example, even if cell 12C-3 of base station 20C is reselected for wireless communication as shown by the block arrow CmC, cell search and cell selection processing are performed whenever communication conditions change. As a result, the battery charge of the repeated area setting terminal 30A is significantly depleted, and battery life is shortened. For example, if the repeated area setting terminal 30A is a gas meter, and it is a structure where the flow measurement unit and the wireless communication unit are integrated and share a battery (integrated type), then according to the metering law, the gas meter needs to be replaced every ten years. Therefore, the battery life of the gas meter is required to be at least ten years. However, if cell search and cell selection processing occur frequently, the battery life is significantly shortened, and it may be difficult to maintain ten years.

[0058] For gas meters, generally speaking, once the battery reaches the end of its lifespan, the gas meter itself is replaced, not the battery. Therefore, a shortened battery life leads to a shortened lifespan for the gas meter itself. This shortened battery life also means that the battery life deviated from the design specifications during the gas meter's design phase. Consequently, a shortened battery life also significantly impacts the product warranty of the gas meter.

[0059] Even though the repeatable area setting terminal 30A is a gas meter, and its flow measurement unit and wireless communication unit are separate structures with the wireless communication unit powered by a dedicated battery (separate type), it still requires the wireless communication unit's battery life to be at least ten years, just like an integrated gas meter. Therefore, even in the separate type of repeatable area setting terminal 30A, as with integrated gas meters, a shortened wireless communication unit battery life will lead to a shortened lifespan of the gas meter itself, significantly impacting the gas meter's product warranty.

[0060] In this regard, in the wireless communication system 10 disclosed herein, a specific cell 12 among cells 12A-1 to 12C-3 capable of communicating with the repeating area terminal 30A is designated as a "dedicated cell," and the repeating area terminal 30A is fixed to communicate wirelessly only with this dedicated cell. Essentially, in the wireless communication system 10, the UE is generally a portable terminal capable of movement; therefore, in this case, it is advantageous to be able to communicate well with various cells 12. However, as in this disclosure, base stations 20 are densely packed, forming a cell repeating area 13. In this cell repeating area 13, when a fixed, battery-powered terminal is set up... Figure 1 In the example shown, when terminal 30A is set for a repeating area, terminal 30A can communicate with many cells 12. In this case, it is advantageous to fix terminal 30A to communicate wirelessly only with a specific cell 12, as has been clearly demonstrated through the in-depth research of the inventors.

[0061] As in Figure 3 As shown by the block arrow CmA in A, for example, the overlapping area setting terminal 30A is fixed to communicate only with cell 12A-1 of base station 20A, which is one of the cells 12A-1 to 12C-3 that overlap with cell overlapping area 13. That is, in this example, cell 12A-1 is determined to be a dedicated cell, and the wireless communication between this dedicated cell and the overlapping area setting terminal 30A is fixed. Thus, even if the communication conditions change, the overlapping area setting terminal 30A will only communicate with the specific base station 20 (in Figure 3 A is a dedicated cell for base station 20A (in which...). Figure 3 In cell A, wireless communication is performed on cell 12A-1. Therefore, to avoid redundant area settings, terminal 30A randomly performs cell search and cell selection processing on multiple cells 12A-1 to 12C-3 that are capable of wireless communication.

[0062] If neither cell search nor cell selection processing occurs, then in the terminal 30A with repeated area settings, such as... Figure 3 As shown in Figure B, the current i1 is consumed only by intermittently generating short, pulse-like synchronization actions at equal intervals. As a result, the repeating area setting terminal 30A can effectively suppress its current consumption, thus effectively preventing the shortening of battery life. Furthermore, the synchronization connection with the specific base station 20 is also improved, and the reduction in communication speed is also suppressed. In addition, since the shortening of battery life is suppressed, the battery life of the repeating area setting terminal 30A can easily meet the design value, and battery replacement can be virtually eliminated, thereby ensuring the product warranty of the repeating area setting terminal 30A.

[0063] In particular, if multiple cells 12 are configured for a base station 20 as illustrated in this embodiment, the number of cells 12 that can perform wireless communication for the duplicate area setting terminal 30A increases relatively. However, if the duplicate area setting terminal 30A is fixed to communicate only with a specific dedicated cell (e.g., cell 12A-1) among the multiple cells 12A-1 to 12C-3, even with the relatively increased number of cells 12, the duplicate area setting terminal 30A can effectively avoid randomly performing cell search and cell selection processing.

[0064] The setting of a dedicated cell can be preset at the time point when the repeating area setting terminal 30A is set in the cell repeating area 13. For example, in the wireless communication system 10 disclosed herein, the setting and use of the fixed terminal 30 are performed in the following steps.

[0065] First, construction begins with setting up the fixed terminal 30. The receiving sensitivity of candidate locations is measured, a location with suitable receiving sensitivity at that time is selected, and the fixed terminal 30 is set up at that location. Next, a wireless communication connection test is conducted between the fixed terminal 30 and any cell 12. If the connection test results are good, construction is completed, and the fixed terminal 30 is put into use.

[0066] At this time, if the location of the fixed terminal 30 is in the cell overlap area 13, then the fixed terminal 30 (i.e., the overlap area setting terminal 30A) is in a state where it can communicate with the multiple cells 12 that form the cell overlap area 13. Therefore, during the connection test, for example, the cell 12 with higher transmit / receive characteristics than other cells 12 that is connected to the overlap area setting terminal 30A can be determined and registered as a dedicated cell. This allows for better communication quality for the overlap area setting terminal 30A.

[0067] (Postscript)

[0068] Based on the description of the above embodiments, the following technology is disclosed in this specification.

[0069] (Technology 1) A wireless communication system comprising a plurality of base stations each having at least one cell configured, and a plurality of M2M (Machine to Machine) devices capable of wirelessly communicating with the base stations, and a plurality of tracking areas configured, wherein the M2M devices include fixed M2M devices that are fixedly configured and powered by batteries, the plurality of base stations being densely configured such that the tracking areas include areas forming cell overlap regions, the cell overlap regions being areas where the plurality of cells of each base station overlap with each other, the fixed M2M devices including overlap region configured M2M devices fixedly configured within the cell overlap regions, the overlap region configured M2M devices being fixed to a dedicated cell to communicate with the base stations, the dedicated cell being a specific cell among the plurality of cells that overlap with each other in the cell overlap regions.

[0070] According to the aforementioned structure, when multiple base stations are configured to form cell overlap areas within the tracking area, the overlap area configuration M2M device, fixedly located within these cell overlap areas, is configured to communicate only with specific dedicated cells among the multiple cells of the base stations. Therefore, even if communication conditions change, the overlap area configuration M2M device only communicates wirelessly via the dedicated cells of the specific base stations, thus preventing the overlap area configuration M2M device from randomly performing cell search and cell selection processing on the multiple cells constituting the cell overlap area.

[0071] As a result, the repeated area-based M2M device effectively suppresses current consumption, thus mitigating battery life shortening. Synchronization with the base station is also improved, suppressing communication speed degradation. Furthermore, because battery life is suppressed, the battery life of the repeated area-based M2M device easily meets design values, and battery replacement is virtually unnecessary, thereby ensuring product quality. Therefore, it maintains good wireless communication and effectively suppresses battery life shortening, even in densely populated tracking areas.

[0072] (Technology 2) The wireless communication system according to Technology 1, wherein,

[0073] The base station has multiple cells.

[0074] According to the aforementioned structure, multiple cells are configured for a single base station, thus relatively increasing the number of cells that can be used for wireless communication for a duplicate area configuration M2M device. In response, the duplicate area configuration M2M device is configured to communicate only with dedicated cells. Therefore, even with the relatively increased number of cells, the duplicate area configuration M2M device can effectively avoid randomly performing cell search and cell selection processes. Consequently, battery life shortening can be effectively suppressed, synchronization with the base station is improved, and communication speed reduction can also be prevented.

[0075] (Technology 3) The wireless communication system according to Technology 1 or Technology 2, wherein,

[0076] The transmit / receive characteristics between the dedicated cell and the M2M device in the duplicate area are higher than those between the other cells and the M2M device in the duplicate area.

[0077] According to the structure, a dedicated cell for communication between the registered and duplicate area M2M devices is set based on the transmission and reception characteristics, thereby improving the communication quality of the duplicate area M2M devices.

[0078] (Technology 4) The wireless communication system according to Technology 3, wherein,

[0079] The transmission and reception characteristics include at least the electric field strength measured at the location where the M2M device is set in the repeating region.

[0080] According to the structure, at least the electric field strength is measured in the cell overlap area, and the registration dedicated cell is set based on at least the electric field strength, so that the communication quality of the M2M device set in the overlap area can be better.

[0081] (Technology 5) A wireless communication system according to any one of Technologies 1 to 4, wherein,

[0082] The tracking area includes a tracking zone in which the base stations are densely arranged.

[0083] According to the structure, when base stations are densely packed, cell duplication areas are likely to occur, but even in such cases, good wireless communication can be maintained and the reduction in battery life can be effectively suppressed.

[0084] (Technology 6) A wireless communication system according to any one of technologies 1 to 5, wherein,

[0085] The fixed M2M device is a gas meter or a water meter.

[0086] According to the structure described, the fixed M2M device is a gas meter or a water meter, thus enabling the appropriate application of these battery-powered and fixedly installed meters to wireless communication systems.

[0087] Furthermore, the present invention is not limited to the embodiments described above, and various modifications can be made within the scope of the claims. Therefore, embodiments obtained by appropriately combining the technical means disclosed in different embodiments and multiple modifications are also included within the technical scope of the present invention.

[0088] Furthermore, based on the foregoing description, many improvements and other embodiments of the present invention will be apparent to those skilled in the art. Therefore, the foregoing description should be interpreted as illustrative only and is provided for the purpose of teaching those skilled in the art the best mode for carrying out the invention. Details may be made that allow for substantial changes to the construction and / or function of the invention without departing from its spirit.

[0089] Industrial availability

[0090] This invention can be widely and appropriately applied in the field of wireless communication, which includes multiple base stations and multiple M2M devices, particularly in the field of wireless communication, which includes fixed M2M devices that are fixedly installed in a specified location and are powered by batteries.

[0091] Explanation of reference numerals in the attached figures

[0092] 10: Wireless Communication System

[0093] 11: Tracking Area

[0094] 12A~12C: Residential Area

[0095] 12A-1~12A-3: Residential area

[0096] 12B-1~12B-3: Residential Area

[0097] 12C-1~12C-3: Community

[0098] 20: Base station

[0099] 20A~20C: Base Station

[0100] 30: Fixed terminal (fixed M2M device)

[0101] 30A: Repeated Area Setting Terminal (Repeated Area Setting M2M Device)

[0102] i1: Synchronous operation consumes current

[0103] i2: Cell search consumes current

[0104] i3: Cell selection consumes current

Claims

1. A wireless communication system, characterized in that, It includes multiple base stations, each with at least one cell configured, and multiple M2M devices (machine-to-machine devices) capable of wireless communication with these base stations, and multiple tracking zones are defined. The M2M devices include stationary M2M devices that are permanently installed and powered by batteries. Multiple base stations are configured such that the tracking area includes areas forming cell overlap regions, where multiple cells of each base station overlap. The fixed M2M device includes a repeating area M2M device that is fixedly installed within the repeating area of ​​the cell. The overlapping area configures an M2M device to be fixed in a dedicated cell to communicate with the base station. This dedicated cell is a specific cell among the multiple cells that overlap in the overlapping area.

2. The wireless communication system according to claim 1, wherein, The base station has multiple cells.

3. The wireless communication system according to claim 1, wherein, The transmit / receive characteristics between the dedicated cell and the M2M device in the duplicate area are higher than those between the other cells and the M2M device in the duplicate area.

4. The wireless communication system according to claim 3, wherein, The transmission and reception characteristics include at least the electric field strength measured at the location where the M2M device is set in the repeating region.

5. The wireless communication system according to claim 1, wherein, The tracking area includes a tracking zone in which the base stations are densely arranged.

6. The wireless communication system according to any one of claims 1 to 5, wherein, The fixed M2M device is a gas meter or a water meter.

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