CN101820632B - Spectrum sharing method, corresponding base station, mobile terminal and communication system thereof - Google Patents

Abstract

The invention discloses a frequency spectrum sharing method, a corresponding base station, a mobile terminal and a communication system. The method is used in a system including a base station and a plurality of mobile terminals, and the system uses working channels and standby channels for communication. The method includes: the base station determines the beacon channel from the working channel or the standby channel, and the beacon channel is used to send beacon information or monitor other beacon information in the medium; the base station sends the determined result to the mobile terminal; As a result of the determination, a beacon channel is set in the working channel or the standby channel; the mobile terminal sends the beacon information in the set channel or listens to the beacon information in the medium. Using the technical solution disclosed above can solve the problem of low frequency spectrum sharing efficiency in the prior art.

Description

Spectrum sharing method and its corresponding base station, mobile terminal and communication system

technical field

The invention relates to the field of wireless resource management, in particular to a frequency spectrum sharing method and a corresponding base station, mobile terminal and communication system.

Background technique

Spectrum sharing has been proven to be an effective means of spectrum utilization. The use of spectrum sharing among similar systems is a common spectrum sharing scenario. Usually in this case, there is no central entity for global management and coordination of the entire system, but through beacon exchange between systems: Spectrum sharing systems with the same PHY/MAC profile (PHY/MAC profile) pass through the air Interfaces exchange beacons for communication. Beacons carry system or coexistence-related information, such as resource allocation mapping, system traffic load, geographic location, resource competition information, etc. To enable beacon communication, it is common practice to embed a beacon channel/slot into a working channel for beacon transmission.

In the IEEE 802.22 WRAN protocol, a solution for inter-system communication over the air interface is proposed. WRAN works in the DTV licensed frequency band. The overlapping WRANs form a spectrum sharing group (Community). In order to provide proper protection for DTV services and share idle DTV spectrum, WRANs need to communicate with each other. The intersystem communication of WRAN depends on the interface in the air, without the participation of the backbone network (such as IP network).

FIG. 6 shows a structure diagram of a WRAN MAC frame with a dedicated time slot self-coexistence window (SCW) time slot in the prior art. As shown in FIG. 6 , the inter-system communication mechanism of the WRAN is implemented by exchanging Coexistence Beacon Protocol (CBP) packets. Coexistence Beacon Protocol (CBP) message exchange is performed on the SCW in the upstream subframe of the working channel. The upstream flow in the WRAN is an upstream channel (uplink) in the usual sense. The CBP message is beacon information that carries management messages (such as resource allocation, channel utilization, traffic load, and geographic location information) for spectrum allocation and coexistence between overlapping WRAN cells. The SCW time slot is located at the end of the MAC upstream subframe. This time slot in each MAC frame is optional based on whether inter-system information exchange is required. SCW slots can be scheduled in regular mode or random mode. In the periodic mode, the base station periodically schedules SCW time slots according to a preset mode. While in random mode, SCW time slots are temporarily scheduled to handle emergency situations.

Embedding the beacon channel into the working channel can provide a reliable signaling channel. However, in a spectrum sharing scenario, using a working channel to carry beacon information has the following disadvantages.

First, beacons for inter-system communication between spectrum sharing systems transmit system-related information and coexistence-related information. Such information may be system load, bandwidth/spectrum occupancy, spectrum preference, spectrum trading (trading) signaling, and the like. Beacon communication will consume part of spectrum resources, which is especially prominent in distributed spectrum sharing scenarios. In this case, in order to obtain the best spectrum utilization, each member system participating in spectrum sharing needs to know the complete information of other systems in the spectrum sharing group. In WRAN, CBP beacon communication needs to consume up to 12-15% of channel resources in a frame. The method of carrying beacon information through the working channel will occupy a considerable proportion of channel resources in the working channel, making the channel resources for data services less.

Second, CBP beacon communication between systems is more likely to be triggered by uncertain events. A typical uncertain event is a change in available spectrum. Once the spectrum utilization in the DTV primary system (or sometimes in the WRAN secondary system) changes, the systems in the spectrum sharing group should adapt to this situation by initiating an A standard communication session is used to complete this adaptive process. Since the spectrum variation has no definite behavioral characteristics, many inter-system beacon communication processes usually adopt random scheduling. Random SCW time slot scheduling will lead to "spectrum breathing" phenomenon in the working channel, making the available bandwidth between adjacent frames erratic and bringing great challenges to resource management and business quality of service (QoS) guarantee.

Contents of the invention

The purpose of the present invention is to provide a spectrum sharing method to solve the problems caused by the prior art.

A spectrum sharing method is provided, which is used in a system including a base station and multiple mobile terminals. The system uses working channels and standby channels to communicate with other spectrum sharing systems. The method includes the base station determining from the working channel or the standby channel Beacon channel, the beacon channel is used to send beacon information or monitor other beacon information in the medium; the base station sends the determination result to the mobile terminal; the mobile terminal sets the beacon in the working channel or standby channel according to the received determination result Channel: The mobile terminal sends beacon information in the set channel or listens to the beacon information in the medium.

The present invention also provides a base station that communicates with other spectrum sharing systems through a mobile terminal using a working channel and a standby channel. The base station includes a control device for determining a beacon channel from the working channel or the standby channel. It is used to send beacon information or monitor other beacon information in the medium; the transmission device is used to send the determination result to the mobile terminal.

The present invention also provides a mobile terminal, which communicates with other spectrum sharing systems through the base station using the working channel and the standby channel. A beacon channel is set in the channel, and the beacon channel is used to send beacon information or monitor other beacon information in the medium; the implementation device is used to send beacon information or monitor beacon information in the medium in the channel set by the control device letter information.

The present invention also provides a communication system, including the above-mentioned base station and a plurality of above-mentioned mobile terminals.

Compared with the existing technical solutions, the above technical solutions have the following advantages.

First, since beacons carry a large amount of system and coexistence information to achieve coexistence and resource sharing among spectrum sharing groups, transmitting beacons will consume considerable spectrum resources. In the prior art, if the working channel is selected as the bearer of the beacon, a part of the MAC frame has to be reserved for beacon transmission and detection. In this case, MAC frame resources for data traffic are reduced. However, the above schemes according to embodiments of the present invention use spare channels that are idle (at least temporarily idle) for beacon transmission. Compared with the prior art, the amount of spectrum used for data communication is increased, and the spectrum utilization rate is also increased.

Second, in a spectrum sharing environment, beacon communications can be regular or random. Unanticipated beacon communications will exacerbate changes in available spectrum resources. In the prior art, this change will cause different degrees of "spectrum breathing", resulting in a dynamic change in the available spectrum that can be used for data services. However, according to the solution of the embodiment of the present invention, carrying the beacon on the spare channel avoids the impact of "spectrum breathing" on data service communication.

Third, the beacon transmission in the beacon channel in the prior art is usually based on contention. Because the beacon channel in the standby channel according to the solution of the embodiment of the present invention is a regular channel compared with the optional channel in the working channel, transmitting the beacon in the standby channel can effectively avoid beacon transmission competition. As more beacon channels become available, beacon transmissions can be made free from contention and collisions. This further improves the reliability of beacon communications in the spectrum sharing group.

Description of drawings

From the following detailed description in conjunction with the accompanying drawings, the above-mentioned features and advantages of the present invention will be more apparent, wherein:

FIG. 1 shows a MAC frame structure diagram of a working channel and a standby channel in a system and a method according to an embodiment of the present invention;

Fig. 2 shows a schematic diagram of a system for spectrum sharing according to an embodiment of the present invention;

FIG. 3 shows a schematic block diagram of a base station for spectrum sharing according to an embodiment of the present invention;

FIG. 4 shows a schematic block diagram of a mobile terminal for spectrum sharing according to an embodiment of the present invention;

FIG. 5 shows a schematic diagram of a process of interaction between a BS and an MS in an application example according to an embodiment of the present invention;

FIG. 6 shows a WRAN MAC frame structure diagram with SCW time slots in the prior art.

Detailed ways

The present invention will be described in detail below with reference to the accompanying drawings.

In spectrum sharing, the available spectrum changes and the available channels also change. Channels are usually divided into different types based on job protection and business continuity situations. Generally divided into two categories: working channel and backup channel. The former is an active channel carrying data services, and the latter is an emergency channel as a candidate for a working channel.

In contrast to known solutions, according to the implementation of the present invention, efficient utilization of the spectrum is achieved and "spectrum breathing" problems are eliminated by using spare channels in inter-system beacon communication. Since the spare channel is idle for a period of time, by properly designing the MAC protocol, the spare channel can be used adaptively to carry the beacon information of resource requirements without weakening the spectrum detection and channel switching performance of the spare channel.

The backup channel MAC frames are designed to be synchronized with the working channel MAC frames for ease of beaconing and sounding/detection.

The structure and method of the embodiment of the present invention will be described below by taking the TDD system as an example. FIG. 1 shows a MAC frame structure diagram of a working channel and a standby channel in the system and method according to an embodiment of the present invention. An optional beacon channel/time slot is defined at the end of the uplink subframe of the MAC frame of the working channel. Such a MAC frame structure can realize the beacon communication function within the system and between systems. Only one beacon channel is included in the backup channel, which is synchronized with the possible beacon channel in the working channel. It should be noted that once the beacon channel is used in the standby channel, the optional beacon channel in the working channel can be canceled, and the resources of the optional beacon channel in the working channel can be used for data communication. Marked channels are official channels.

The base station of the system can schedule the beacon channel in active or passive mode. In active mode, a mobile station (MS) can send beacon information in a beacon channel. While in passive mode, the MS can detect the presence of beacons of other systems in the beacon channel. To facilitate beacon detection, the working and backup channels should be known to all spectrum sharing systems. In addition, in beacon transmission, if an alternate channel is available, the beacon information should be transmitted on the alternate channel with priority. In beacon detection, the alternate channels of adjacent systems should be detected first.

According to an embodiment of the present invention, in order to support a spectrum efficient beacon communication procedure, key management messages are defined in the UL-MAP Information Element (IE). UL-MAP is a downlink management message, which is transmitted at the beginning of each downlink subframe as shown in FIG. 1 . Table 1 shows the structure of this message. For the sake of brevity, Table 1 only shows the parts related to the present invention, but it does not mean that the message cannot contain other contents. As shown in Table 1, where:

A connection ID (CID) is used to identify the connection between the base station and the MS.

An Uplink Interval Usage Code (UIUC) is used to specify the uplink interval usage type.

The number of symbols (Number of symbols) is used to limit the duration of the beacon channel specified in the UL-MAP. In this example, when the number of symbols is set to 2 bits, the maximum duration of the beacon channel is 3 symbol periods. According to the specific In other cases, it is also possible to specify other desired beacon channel durations by changing the number of symbols.

The beacon channel number (Beacon channel number) is used to inform the MS identified by the CID on which channel it should operate. The number of the beacon channel is determined by the base station, and should be selected according to the rule that the standby channel always has a scheduling priority higher than that of the working channel. When the working frequency band changes, the base station updates the information, and also performs corresponding updates in the MS.

grammar size Remark UL-MAP_{ CID 12 bits Connection ID, which identifies the connection between the base station and the MS. UIUC 6 bits The uplink interval usage code is used to specify the uplink interval usage type. If UIUC=0, active mode, beacon transmission; if UIUC=1, passive mode, beacon detection. Number of symbols 2 bits Symbol number of the beacon channel/slot at the end of the frame. Beacon channel number 8 bits A channel number specifying the beacon channel on which the MS sends a beacon in case of active mode, or the beacon channel on which the MS listens to the medium for a beacon in case of passive mode. … }

Table 1 UL-MAP information elements for spectrum efficient beacon communication

Fig. 2 shows a communication system according to an embodiment of the present invention. For the sake of brevity, only one base station and multiple mobile terminals are shown in the system shown in FIG. 2 . But in actual scenarios, the communication system usually includes multiple base stations and more mobile terminals.

FIG. 3 shows a schematic block diagram of a base station in the system shown in FIG. 2 . FIG. 4 shows a schematic block diagram of a mobile terminal in the system shown in FIG. 2 . For the sake of brevity, only components related to the embodiment of the present invention are shown in FIG. 3 and FIG. 4 , but it does not mean that other components cannot be included.

As shown in Figure 3, the base station according to the embodiment of the present invention at least has: a control device 310, which is used to determine the beacon channel from the working channel or the standby channel, and the beacon channel is preferentially a standby channel for sending beacon information or monitoring Other beacon information in the medium; transmission means 320, configured to send the determination result to the mobile terminal.

In addition, the transmission device 320 is also used to receive the detection report of the mobile terminal; the base station shown in Figure 3 also includes a detection device 330, which is used to detect the available frequency spectrum and generate a detection result; The results and the detection report received by the transmission means 320 classify the available channels into working channels and standby channels; the transmission means 320 is also used to send the classification results of the classification means 340 to the relevant mobile terminals.

In addition, the control device 310 is also used for judging whether there is a spare channel, if yes, designate a beacon channel to be set in a spare channel; if not, set a beacon channel in each working channel.

The base station shown in Figure 3 also includes a storage device 350, which is used to store a standby channel list 350 formed by arranging standby channels according to preset rules. Select the first standby channel to set the beacon channel; if the standby channel list is empty, set the beacon channel in each working channel.

As shown in Figure 4, the mobile station according to the embodiment of the present invention at least has: a control device 410, which is used to set the beacon channel in the working channel or the standby channel according to the beacon channel determination result received from the base station, and the beacon channel has priority It is a spare channel for sending beacon information or listening to other beacon information in the medium; implementing means 420 is used for sending beacon information or listening to beacon information in the medium in the channel set by the control means 410 .

The control device 410 is also used to judge whether the beacon channel specified in the determination result is a working channel according to the received determination result and the received channel classification information, if yes, choose to set the beacon channel in the working channel, if not, Switch the current working channel to the standby channel specified in the determination result, and set a beacon channel in the specified standby channel.

The mobile terminal shown in FIG. 4 also includes a storage device 430 for storing channel classification information sent from the base station and sending the channel classification information to the control device 410 .

Although the base station and the mobile station of this embodiment have been described above in the form of separate functional modules, each component shown in Figure 3 and Figure 4 can be implemented with multiple devices in practical applications, and the multiple components shown In practical application, it can also be integrated in a chip or a device. The following is a detailed description of the above-mentioned technical process for implementing spectrum sharing through interaction between the base station and the terminal.

Fig. 5 shows a process of interaction between a base station (BS) and a mobile terminal (MS) in an application example of spectrum efficient beacon communication according to an embodiment of the present invention.

As shown in FIG. 5 , in step 501 , the detection means 330 of the MS and the BS detect the available frequency spectrum. After initialization, in step 502, the classification means 340 of the BS classifies all available channels into different groups based on the spectrum detection results from the detection means 330 and the spectrum detection report received by the transmission means 320 from the MS. In this example, the available channels are basically divided into groups of working channels and groups of backup channels. Then in step 503, the channel classification information Ch_Clss_info is broadcast to the relevant MSs through the transmission means 320 . When the used frequency band changes, the classification means 340 of the BS re-classifies and updates the classification result.

Once the beacon communication trigger event in step 504 occurs, the BS initiates communication with the MS to configure the beacon channel and use the configured beacon channel to communicate with other spectrum sharing systems. It should be noted that the triggering event mentioned here refers to both unexpected events, such as the unexpected arrival of the main system (incumbent system), and also refers to regular periodic beacon communication events, such as regular inter-system communication.

In step 505, the control device 310 determines whether there are available spare channels in the spare channel group, and if so, in step 506, selects to set a beacon channel in one of the spare channels, and uses its number as the UL channel in step 508. - Beacon channel number in MAP management message. The selection principle here may be that the sorting device 340 arranges all available spare channels according to preset rules (such as arranging according to indicators such as channel quality) to form a list of spare channels and stores them in the storage device 350, and the control device 310 selects from the spare channels Select the top alternate channel in the list as the beacon channel. Meanwhile, in step 508, the control device 310 also specifies the beacon channel duration in the UL-MAP, the length of which is limited by the number of symbols in the UL-MAP.

If the standby channel group is empty, in step 507, a beacon channel is set in each working channel. In this case, the control device 310 schedules the beacon channel at the end of the uplink subframe of the working channel, and similarly to selecting the standby channel as the beacon channel, correspondingly sets the message in the UL-MAP in step 508 .

After receiving the UL-MAP information, in step 509, the control device 410 in the MS identified by the CID fetches the beacon channel number and determines whether the designated beacon channel is a backup channel based on the received Ch_Clss_info. Ch_Clss_info may be stored in the storage device 420 of the MS for use by the control device 410 . If it is a backup channel, in step 510, the control device 410 will guide the fast switching process to switch to the backup channel MAC frame shown in Figure 1, and the implementation device 430 determines to send beacon information or detect other system's information in step 511 according to the UIUC value Beacon information. After the beacon communication time interval (the length of which is limited by the symbol number of UL-MAP), the control device 410 returns the MS to the working channel for normal data transmission operation. If the control device 410 determines that the designated beacon channel is a working channel, the MS does not need to perform channel switching processing. In step 511, the implementing device 430 directly uses the beacon channel in the working channel to send beacon information or detect beacons of other systems information.

In the above solution of the embodiment of the present invention, the spare channel is used for inter-system beacon communication where resources are scarce. The main benefit is increased spectral efficiency. A backup channel is an emergency channel that serves as a backup for the working channel. Alternate channels are set in the context of spectrum sharing to provide system protection and business continuity. Before becoming an active working channel, the standby channel will be idle for a period of time, resulting in a waste of spectrum resources. By utilizing the backup channel to carry beacon information, the working channel can be freed from heavy beacon signaling overhead. In this case, more spectrum can be used for data traffic in the working channel.

It should be noted that this scheme is also an adaptive inter-system communication solution. In this scheme, the beacon channel can be a backup channel or a working channel. However, standby channels have priority over working channels. The configuration of the beacon channel in the backup channel is exactly the same as that in the working channel, so as to facilitate channel switching and backup channel management. This means that the solution is easy to implement and enhances the existing spectrum sharing system without making obvious changes to the system MAC protocol or PHY layer signaling processing.

The technical solution of the present invention is also applicable to the FDD system.

The above description is only used to realize the embodiment of the present invention, and those skilled in the art should understand that any modification or partial replacement without departing from the scope of the present invention should belong to the scope limited by the claims of the present invention. Therefore, this The protection scope of the invention should be determined by the protection scope of the claims.

Claims (23)

1. a frequency spectrum sharing method, for comprising the system of a base station and a plurality of mobile terminals, described system is used working channel and alternate channel and other spectra sharing systems to communicate, and described method comprises:

Beacon channel is determined in described base station from described working channel or described alternate channel, and described beacon channel is for sending other beacon message of beacon message or monitoring medium;

Described base station will determine that result sends to mobile terminal;

Described mobile terminal arranges beacon channel according to the definite result receiving in described working channel or described alternate channel;

Described mobile terminal sends beacon message or monitors the beacon message in medium in set beacon channel.

2. method according to claim 1, also comprises:

Described base station is categorized as working channel and alternate channel according to the spectrum measurement of self and the spectrum detection report that receives from mobile terminal by available channel.

3. method according to claim 2, also comprises: available channel being categorized as after working channel and alternate channel, the result of classification is sent to mobile terminal.

4. method according to claim 3, wherein, the described result by classification sends to mobile terminal and comprises by channel classification information (Ch_Clss_Info) result of described classification is broadcast to relevant mobile terminal.

5. method according to claim 4, wherein, when used frequency range changes, upgrades the result of described classification.

6. method according to claim 2, wherein, describedly from working channel or alternate channel, determine that beacon channel comprises:

Judge whether to exist alternate channel;

If exist, specify in an alternate channel described beacon channel is set;

If there is no, described beacon channel is set in each working channel.

7. method according to claim 6, wherein, also comprises: by all available alternate channels according to default regularly arranged formation alternate channel list,

Describedly judge whether to exist alternate channel to comprise to judge whether described alternate channel list is empty;

If described, there is alternate channel, specify in and in an alternate channel, arrange that beacon channel comprises if described alternate channel list, for empty, selects the most forward alternate channel that beacon channel is set in described alternate channel list;

If there is no, in each working channel, arrange that beacon channel comprises if described alternate channel list, for empty, arranges beacon channel in each working channel.

8. method according to claim 7, wherein, describedly comprises all available alternate channels: all available alternate channels are arranged to the list of formation alternate channel according to cqi according to default regularly arranged formation alternate channel list.

9. method according to claim 2, wherein, described by determining that result sends to mobile terminal and comprises the beginning of using in each downlink subframe, utilizes downlink management message to send to described mobile terminal by result is set.

10. method according to claim 9, wherein, described downlink management message is UL-MAP message, described UL-MAP message comprises following field:

Connection identifier (CID), for identifying the connection between base station and mobile terminal;

Uplink interval is used code (UIUC), is used to specify between-line spacing type of service, when UIUC=0, and the pattern that has the initiative, beacon message transmission is carried out in indication, and when UIUC=1, in Passive Mode, beacon message detection is carried out in indication;

Symbolic number, is used to indicate the number of symbols of the beacon channel/time slot that is arranged in postamble;

Beacon channel numbering, is used to specify mobile terminal and when aggressive mode, sends beacon message or when Passive Mode, monitor medium to obtain the beacon channel of beacon message.

11. methods according to claim 10, wherein, described mobile terminal arranges beacon channel and comprises according to the result that arranges receiving in described working channel or described alternate channel:

Described mobile terminal determines according to the channel classification information judgement that result is set and receives receiving whether the beacon channel of appointment in result is working channel;

If so, be chosen in this working channel beacon channel is set;

If not, work at present channel is switched to and determines specified alternate channel in result, and in the alternate channel of described appointment, beacon channel is set.

12. methods according to claim 11, wherein, the described beacon channel that arranges comprises:

At the up channel subframe postamble scheduling beacon channel of the alternate channel of described working channel or appointment, the symbolic number field of the length of described beacon channel in described UL-MAP message determines.

13. methods according to claim 12, wherein, the beacon message sending in set channel in beacon message or monitoring medium comprises:

When the uplink interval in described UL-MAP message is used the value of code to be 0, on described beacon channel, send beacon message;

When the uplink interval in described UL-MAP message is used the value of code to be 1, on described beacon channel, monitor beacon channel to obtain beacon message.

14. methods according to claim 12, wherein, if beacon channel is set in described alternate channel, after beacon sign off, described mobile terminal returns to working channel and carries out normal data transfer operation.

15. 1 kinds of base stations, are used working channel and alternate channel to communicate by mobile terminal and other spectra sharing systems, and described base station comprises:

Control device, for determining beacon channel from described working channel or described alternate channel, described beacon channel is for sending the beacon message of beacon message or monitoring medium;

Transmitting device, for determining that result sends to mobile terminal.

16. base stations according to claim 15, wherein, described transmitting device is also reported for the detection of mobile terminal receive;

Described base station also comprises:

Checkout gear, for detection of available frequency spectrum and produce testing result;

Sorter, is categorized as working channel and alternate channel for the examining report receiving according to the testing result of described checkout gear and described transmitting device by available channel;

Described transmitting device is also for sending to relevant mobile terminal by the classification results of described sorter.

17. base stations according to claim 16, wherein, described control device, also for judging whether to exist alternate channel, if existed, specifies in an alternate channel described beacon channel is set; If there is no, described beacon channel is set in each working channel.

18. base stations according to claim 16, also comprise:

The memory cell of storage alternate channel list, described alternate channel list is for the regularly arranged alternate channel according to default;

If described control device is not also empty for the described alternate channel list of judgement, in described alternate channel list, select the most forward alternate channel that beacon channel is set; If described alternate channel list is empty, in each working channel, beacon channel is set.

19. 1 kinds of mobile terminals, are used working channel and alternate channel to communicate by base station and other spectra sharing systems, and described mobile terminal comprises:

Control device, for determining that according to the beacon channel receiving from base station result arranges beacon channel at described working channel or described alternate channel, described beacon channel is for sending other beacon message of beacon message or monitoring medium;

Device for carrying out said, for sending beacon message or monitoring the beacon message in medium at the set channel of described control device.

20. mobile terminals according to claim 19, wherein, described control device also determines for the definite result receiving described in basis and the channel classification information receiving judgement whether the beacon channel of result appointment is working channel, if, be chosen in this working channel beacon channel is set, if not, work at present channel is switched to and determines specified alternate channel in result, and in the alternate channel of described appointment, beacon channel is set.

21. mobile terminals according to claim 20, wherein, if described beacon channel is arranged in described alternate channel, described control device, also for after beacon sign off, switches back working channel by described mobile terminal and carries out normal data transfer operation.

22. mobile terminals according to claim 21, also comprise storage device, for storing the channel classification information sending from base station, for described control device, use.

23. 1 kinds of communication systems, comprise base station and a plurality of mobile terminal as described in any one in claim 19 to 22 as described in any one in claim 15 to 18.

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