WO2011049024A1 - Spatial multiplexing slot allocation method and base station - Google Patents

Abstract

A base station that conducts communication with a plurality of terminals using a spatial multiplexing slot allocation method, is provided with a receiving unit that receives connection requests transmitted by the terminals; and a control unit that allocates a slot to the aforementioned terminal using a sub-slot method, when the spatial multiplexing number within the base station has become the maximum, and when the aforementioned connection request indicates that the call by the aforementioned terminal is a narrow band call, or when a value indicating the wireless communication quality of the aforementioned connection request is not more than a prescribed value, and allocates a slot to the aforementioned terminal using a full-slot method, in all the other cases.

Description

Spatial multiplex slot allocation method and base station

The present invention relates to a spatial multiplexing slot allocation method and a base station.

In the conventional spatial multiplexing system of a base station equipped with an adaptive array antenna system (hereinafter referred to as “adaptive array base station”), a new request is rejected when the maximum number of spatial multiplexing is reached. . In addition, when all calls are spatially multiplexed, an appropriate service grade and spatial multiplexing may not be maintained for each call. Therefore, a conventional technique (see Patent Document 1) that classifies calls according to levels, determines calls that are not spatially multiplexed calls, and provides an appropriate service grade has been proposed.

JP 2002-58061 A

The proposed technology described above makes it possible to provide an appropriate service grade for calls. However, it still cannot accept new call connections when the spatial multiplexing number reaches the maximum. A particular problem here is that even calls from terminals requiring high immediacy such as VoIP (Voice Over IP = narrowband call) (hereinafter referred to as “narrowband call terminals”) are uniformly rejected. It is. In addition, a user terminal (hereinafter referred to as “far-field terminal”) located at a long distance as viewed from the base station and a user terminal (hereinafter referred to as “high-speed mobile terminal”) that moves at high speed are generally wireless. Communication quality is likely to change, and wireless quality is deteriorating. However, the above-described proposed technique does not solve the problem of how to assign a spatial multiplexing slot to the terminal.

Therefore, the present invention assigns communication calls to full slots or subslots according to characteristics such as narrowband call terminals such as VoIP and radio quality for each terminal, and improves spatial convenience multiplexing to improve user convenience and frequency utilization efficiency. It is an object to provide a slot allocation method and a base station.

In order to solve the above-mentioned problems, a spatial multiplexing slot allocation method according to a first invention is a reception step of receiving a connection request transmitted from a terminal in the spatial multiplexing slot allocation method of a base station communicating with a plurality of terminals. When the number of spatial multiplexing in the base station is the maximum, the connection request indicates that the terminal call is a narrowband call, or a value indicating the radio quality of the connection request is a predetermined value. In the determination step of determining whether or not, the determination step indicates that the terminal call is a narrowband call, or the value indicating the radio quality of the connection request is equal to or less than a predetermined value An allocation control step of allocating slots to the terminal in a sub-slot scheme when determined, and allocating slots to the terminal in a full slot scheme in other cases; Is Dressings.

The spatial multiplexing slot allocation method according to the second aspect of the invention relates to a part of the subslots obtained by dividing the full slot into a plurality of subslots in the spatial multiplexing slot of the local station when the slot is allocated to the terminal by the subslot method. A subslot management step of determining whether there is a free subslot that a subslot is in use and other subslots are unused, and the allocation control step includes a free subslot in the subslot management step; When it is determined that there is a slot, allocation control is performed to allocate the empty subslot to the terminal.

As described above, the solution of the present invention has been described as a method. However, the present invention can be realized as a device (base station), a program, and a storage medium that records the program, substantially equivalent to these. It should be understood that these are included within the scope of the present invention.

For example, a base station according to a third aspect of the present invention that realizes the present invention as an apparatus includes a receiving unit that receives a connection request transmitted from a terminal in a base station that communicates with a plurality of terminals by a spatial multiplexing slot assignment method, A spatial multiplexing number management unit for managing the spatial multiplexing number in the base station, and the spatial multiplexing number is maximum, and the connection request indicates that the terminal call is a narrowband call, or When the value indicating the radio quality of the connection request is equal to or less than a predetermined value, the slot is allocated to the terminal in the subslot mode, and in other cases, the slot is allocated to the terminal in the full slot mode. And a control unit.

Further, in the base station according to the fourth invention, when the control unit assigns a slot to the terminal by a subslot method, a part of the subslots obtained by dividing the full slot into a plurality of subslots in the spatial multiplexing slot of the own station When there is a vacant subslot in which another subslot is in use and other subslots are unused, allocation control for allocating the vacant subslot to the terminal is performed.

According to the present invention, when the number of spatial multiplexing in the base station is maximized, all communication calls from VoIP (narrowband call) terminals with low frequency utilization efficiency and communication calls from terminals with poor radio quality are sub- Allocating to slots and restricting other full data user terminals to full slots. Thereby, a great improvement can be expected from the viewpoint of the frequency utilization efficiency of the entire system.

FIG. 1 is a block diagram of an adaptive array base station according to an embodiment of the present invention. FIG. 2 is a flowchart showing processing of the spatial multiplexing slot allocation algorithm (method) according to the embodiment of the present invention. FIG. 3 is a timing chart for explaining an example of the subslot system according to the embodiment of the present invention. FIG. 4 is a flowchart showing processing of a spatial multiplexing slot allocation algorithm (method) according to another embodiment of the present invention.

100 Adaptive Array Base Station 110 Burst Receiver 120 Narrow Band Call Determination Unit 130 Slot Assignment Control Unit 140 Maximum Spatial Multiplex Number Determination Unit 150 Subslot Management Unit 160 Burst Transmission Unit 170 Subslot Switching Control Unit 180 Radio Quality Measurement Unit 190 Radio Quality Threshold decision unit ANT Adaptive array antenna SS11, SS12 Subslot SS21, SS22 Subslot SS31-SS34 Subslot SS41-SS44 Subslot

Hereinafter, the base station according to the embodiment of the present invention will be described in detail with reference to the drawings. FIG. 1 is a block diagram of an adaptive array base station according to an embodiment of the present invention. As shown in FIG. 1, the adaptive array base station 100 includes a burst reception unit 110, a narrowband call determination unit 120, a radio quality measurement unit 180, a radio quality threshold determination unit 190, a slot allocation control unit 130, a maximum spatial multiplexing number determination. Unit 140 (spatial multiplexing number management unit), subslot management unit 150, subslot switching control unit 190, and burst transmission unit 160. The burst receiving unit 110 receives the RA burst. The narrowband call determination unit 120 determines whether or not the VoIP is a narrowband call. The radio quality measurement unit 180 measures a value (eg, SINR: Signal-to-Interference and Noise power Ratio) indicating the radio quality of the RA burst (connection request). Radio quality threshold determination section 190 determines whether or not a value indicating the radio quality (SINR) of the RA burst is equal to or less than a predetermined threshold. The slot allocation control unit 130 controls slot allocation. The maximum spatial multiplexing number determination unit 140 manages the spatial multiplexing number and determines whether or not the maximum spatial multiplexing number has been reached. When the subslot switching control unit 190 receives the RA burst when the maximum spatial multiplexing number is reached, the subslot switching control unit 190 receives a value indicating a narrowband call terminal or a radio quality among predetermined terminals connected in the same spatial multiplexing. Terminals below the threshold are switched from full slots to subslots. The burst transmission unit 160 transmits an AA burst. The narrowband call determination unit 120 and the radio quality threshold determination unit 180 are collectively referred to as a “determination unit”. In addition, the narrowband call determination unit 120, the radio quality measurement unit 180, the radio quality threshold determination unit 190, the slot allocation control unit 130, the maximum spatial multiplexing number determination unit 140, the subslot management unit 150, and the subslot switching control unit 170 And a control unit configured around a processing device such as a CPU (Central Processing Unit). The adaptive array base station 100 further includes an adaptive array antenna ANT composed of a plurality of antennas.

Next, the data flow is shown. First, a terminal (not shown) transmits an RA burst (connection request) to the adaptive array base station 100 side. The burst receiving unit 110 of the adaptive array base station 100 receives the RA burst. Next, the maximum spatial multiplexing number determination unit 140 determines whether or not the adaptive array base station 100 has reached the maximum spatial multiplexing number. The narrowband call determination unit 120 reads VoIP (narrowband call) bits embedded in advance in the RA burst. Then, the narrowband call determination unit 120 determines whether the terminal is a narrowband call terminal such as a VoIP terminal (that is, indicates whether the terminal call is a narrowband call). Note that when a terminal is registered (registered), a terminal identification number ID is assigned to each terminal. For this reason, it is possible to determine whether the call is a broadband call or a narrowband call at the time of registration, or to specify from the terminal side. In that case, the terminal does not need to include a VoIP (narrowband call) bit in the RA burst transmitted to the base station. Then, if the terminal transmits the terminal identification number ID at the time of registration included in the RA burst, the narrowband call determination unit 120 determines whether the call is a wideband call or a narrowband call based on the terminal identification number ID. It becomes possible. Then, the narrowband call determination unit 120 outputs the determination result to the slot allocation control unit 130 and the radio quality measurement unit 180. Radio quality measuring section 180 measures a value (for example, SINR) indicating the radio quality of the RA burst when receiving the RA burst. Note that any radio value other than SINR can be used as the value indicating the radio quality. Further, the radio quality measurement unit 180 may measure (acquire) the radio quality by reading a radio quality value embedded in advance in the RA burst, for example. Radio quality measuring section 180 then outputs the measurement result to slot allocation control section 130. Further, when the determination result from the narrowband call determination unit 120 indicates that the terminal is not a narrowband call terminal, the radio quality measurement unit 180 displays a value indicating the radio quality as a measurement result as a radio quality threshold determination unit. To 190. The radio quality threshold determination unit 190 determines whether or not the value indicating the radio quality input from the radio quality measurement unit 180 is equal to or less than a predetermined threshold. Radio quality threshold determination section 190 then outputs the determination result to slot allocation control section 130. Next, the slot allocation control unit 130 refers to the determination result of the narrowband call determination unit 120, the determination result of the radio quality threshold determination unit 190, and the information of the subslot management unit 150 and the subslot switching control unit 170. However, slot allocation control is performed using a spatial multiplexing slot allocation algorithm (method) described in detail later.

Next, the burst transmission unit 160 notifies the terminal of the allocation result in the slot allocation control unit 130. Here, the “full slot” means a normal slot configuration. On the other hand, the “subslot” requires only a narrow band such as VoIP. For example, for one set (two) users, the “full slot” is divided into two by time share and used. That is. As the time sharing method, there are a method of alternately using even frames and odd frames of two users, and a method of dividing slots into the first half and the second half and using them by two users. Details of the full slot and the subslot will be described later.

FIG. 2 is a flowchart showing processing of a spatial multiplex slot allocation algorithm (method) according to the embodiment of the present invention. As shown in FIG. 2, first, in step S10, burst receiving section 110 of adaptive array base station 100 (a communication apparatus that controls slot allocation and spatial multiplexing) receives an RA burst (connection request) from a terminal. . Next, the maximum spatial multiplexing number determination unit 140 determines whether or not the current spatial multiplexing number has reached the maximum (step S11). When the determination result of the maximum spatial multiplexing number determination unit 140 indicates that the maximum spatial multiplexing number has not been reached, the slot allocation control unit 130 allocates a full slot to the terminal, and the burst transmission unit 160 transmits an AA burst ( Full slot allocation) is transmitted (step S12). Then, the allocation algorithm processing is finished. On the other hand, when the determination result of the maximum spatial multiplexing number determination unit 140 indicates that the maximum spatial multiplexing number has been reached, the narrowband call determination unit 120 determines that the VoIP (narrowband call) embedded in the RA burst in advance. It is determined whether the terminal is a narrowband call terminal by reading a bit or the like (step S13). When the determination result of the narrowband call determination unit 120 indicates that the terminal is not a narrowband call terminal, the wireless quality threshold determination unit 190 has a predetermined value (SINR) indicating the wireless quality measured by the wireless quality measurement unit 180. It is determined whether it is below the threshold value (step S14).

When it is determined in step S13 that the terminal is not a narrowband call terminal in the narrowband call determination unit 120, and further in S14, the wireless quality threshold determination unit 190 determines that the value indicating the wireless quality exceeds a predetermined value Then, the slot allocation control unit 130 rejects the connection of the terminal, and transmits an AA burst (connection rejection) from the burst transmission unit 160 to the terminal (step S15). Then, the allocation algorithm processing is finished.

When the narrowband call determination unit 120 determines that the terminal is a narrowband call terminal in step S13, or in S14, the wireless quality threshold determination unit 190 determines that the value indicating the radio quality is equal to or less than a predetermined value. If so, the slot allocation control unit 130 performs control to allocate subslots to the terminals. In this case, the subslot management unit 150 determines that some subslots out of the subslots obtained by dividing the full slot into a plurality of parts (for example, divided into two) are other narrowband calls or a value indicating the radio quality is a predetermined value. It is determined whether or not there is an empty subslot (an empty subslot with no pair) that is used by the following terminals and that no other subslot is used (step S16). As a result of the determination by the subslot management unit 150, if there is an empty subslot with no pair, the slot allocation control unit 130 allocates the empty subslot to the terminal, and the burst transmission unit 160 sends an AA burst (subslot (Assignment) is transmitted (step S17). Then, the allocation algorithm processing is finished.

In step S16, when there is no empty subslot with no pair, the subslot management unit 150 indicates the terminal of another narrowband call that can switch the slot to be used from the full slot to the subslot, or the radio quality. It is determined whether there is a call paired with a terminal whose value is equal to or less than a predetermined value and that has transmitted an RA burst (step S18). If there is no call that can be switched from the full slot to the subslot as a result of the determination by the subslot management unit 150, the slot allocation control unit 130 rejects the terminal connection, and the burst transmission unit 160 sends an AA burst to the terminal. (Connection refused) is transmitted (step S19). Then, the allocation algorithm processing is finished.
As a result of the determination by the subslot management unit 150 in step S18, if there is a call that can be switched from a full slot to a subslot and is paired with a terminal that has transmitted an RA burst, the slot allocation control unit 130 Then, an AA burst (Extend assignment) is transmitted from the burst transmission unit 160 to the terminal so as to retry after N frames (step S20). Next, from the determination result of the subslot management unit 150, the subslot switching control unit 170 uses a full slot, or another narrowband call terminal, or a terminal whose radio quality value is a predetermined value or less. Are switched to subslots (step S21).

Thus, according to this embodiment, first, a full call is assigned to a communication call from a VoIP (narrowband call) terminal having low frequency utilization efficiency and a terminal having deteriorated radio quality. Then, switching is performed so that subslots are allocated depending on the subsequent communication status, that is, whether or not the number of spatial multiplexing in adaptive array base station 100 reaches the maximum. Thereby, it can be expected that the frequency utilization efficiency of the entire system is greatly improved. Further, the influence of interference by a terminal whose radio quality is deteriorated is limited to the subslot. For this reason, the frequency utilization efficiency in the spatial multiplexing slot can be expected to improve slightly. Furthermore, when the number of spatial multiplexing has not reached the maximum, sub-slot switching processing becomes unnecessary, leading to a reduction in processing load.

FIG. 3 is a timing chart for explaining an example of the sub-slot method according to the embodiment of the present invention. (A) in FIG. 3 shows a time slot (full slot) of the full slot system. When viewed from the base station, the upper Tx is the time slots # 1 to # 3 on the transmission side, and the lower Rx is Time slots # 1 to # 3 on the receiving side are asymmetric time intervals.

(B) in FIG. 3 shows a state where a full slot is divided into subslots by dividing the allocation of full slots into frames of a certain fixed period such as even frames and odd frames. To user 1, slot # 1 of frame F1, which is an odd frame, is assigned as subslot SS11, and slot # 1 of frame F3 is assigned as subslot SS12. Similarly, for user 2, slot # 1 of frame F2, which is an even frame, is assigned as subslot SS21, and slot # 1 of frame F4 is assigned as subslot SS22.

(C) in FIG. 3 shows a system in which one time slot is divided into a first half and a second half to form subslots. User 1 is assigned the first half of slot # 1 of each frame F1 to F4 as subslots SS31 to SS34. On the other hand, the second half of slot # 1 of each frame F1 to F4 is assigned to user 2 as subslots SS41 to SS44. Note that the slot on the receiving side, which has half the transmittable data procedure compared to the slot on the transmitting side, remains a full slot, and if any user's slot is temporarily shared, subslotting Communication quality and communication area degradation can be kept to a minimum.

Next, processing of a spatial multiplexing slot allocation algorithm (method) according to another embodiment of the present invention will be described using the flowchart of FIG. In the flowchart of FIG. 4, only the points different from the flowchart of FIG. 2 are described.

In step S13, the narrowband call determination unit 120 determines that the terminal is not a narrowband call terminal, and in S14, if the wireless quality threshold determination unit 190 determines that the value indicating the wireless quality exceeds a predetermined value, The slot management unit 150 has a plurality of other narrowband call terminals or a plurality of terminals whose radio quality values are equal to or less than a predetermined value that can switch a slot to be used from a full slot to a subslot, It is determined whether or not one set (in this case, two terminals) that can be accommodated in a sub-slot obtained by dividing a full slot into a plurality of parts (for example, divided into two) can be configured (step S30). As a result of the determination by the subslot management unit 150, if one set that can be accommodated in the subslot cannot be configured, the slot allocation control unit 130 rejects the terminal connection, and the burst transmission unit 160 sends an AA burst (connection to the terminal). (Reject) is transmitted (step S15). Then, the allocation algorithm processing is finished. If it is determined in step S30 that the subslot management unit 150 can configure one set that can be accommodated in the subslot, the slot allocation control unit 130 causes the burst transmission unit 160 to retry the terminal after N frames. AA burst (Extend assignment) is transmitted from the terminal to the terminal (step S31). Then, the subslot switching control unit 170 switches each terminal that can be accommodated in the subslot from the full slot to the subslot (steps S32 and S33).

As described above, according to the present embodiment, when the number of spatial multiplexing in the adaptive array base station 100 reaches the maximum, a terminal that is not a VoIP (narrowband call) with low frequency utilization efficiency and radio quality is good. The communication call from the terminal is not rejected immediately, and the switching is performed so that the subslot is allocated in the situation of the terminal to which the full slot is allocated. Thereby, the adaptive array base station 100 may be able to allocate a full slot without refusal. Therefore, it can be expected that the frequency utilization efficiency of the entire system is greatly improved.

As described above, in the adaptive array base station and the control method thereof according to the present invention, for example, when all the connections of the spatial multiplexing slots are narrowband call terminals such as VoIP and terminals with poor radio quality, compared with the conventional case. Thus, it is possible to connect with twice as many users. In addition, since a wide slot call is assigned a full slot as in the past, the communication quality of the user of the broadband call is not affected.

Although the present invention has been described based on the drawings and examples, it should be noted that those skilled in the art can easily make various changes and modifications based on the present disclosure. Therefore, it should be noted that these variations and modifications are included in the scope of the present invention. In addition, the functions included in each part, each means, each step, etc. can be rearranged so that there is no logical contradiction, and it is possible to combine or divide a plurality of means, steps, etc. into one. It is. For example, in the embodiment, the sub-slot allocation has been described with reference to only the transmission slot in which the base station transmits data to the terminal. However, the sub-slot allocation is similarly allocated to the reception slot for receiving data from the terminal. Note that you can.

In addition, sub-slotting by dividing a full slot is divided into two frames, such as an odd frame and an even frame, and a format in which one full slot is divided into two parts, the first half and the second half. However, it may be a format that is divided into more subslots such as three divisions or four divisions.

Claims (4)

In a spatial multiplexing slot allocation method of a base station that communicates with a plurality of terminals,
A receiving step for receiving a connection request sent from the terminal;
When the number of spatial multiplexing in the base station is maximum, the connection request indicates that the terminal call is a narrowband call, or the value indicating the wireless quality of the connection request is less than a predetermined value. A determination step for determining whether there is,
In the determination step, when it is determined that the call of the terminal is a narrowband call, or when it is determined that the value indicating the wireless quality of the connection request is equal to or less than a predetermined value, for the terminal, A spatial multiplex slot assignment method, comprising: assigning slots in a subslot manner; and, in other cases, assigning a slot in a full slot manner to the terminal. The spatial multiplex slot allocation method according to claim 1,
When allocating slots to the terminal using the subslot method, some of the subslots obtained by dividing the full slot into a plurality of subslots in the spatial multiplexing slot of the local station are in use, and other subslots are not yet used. Further comprising a subslot management step of determining whether there is a free subslot that is in use;
The allocation control step performs allocation control for allocating the empty subslot to the terminal when it is determined in the subslot management step that there is an empty subslot. In a base station that communicates with a plurality of terminals using the spatial multiplexing slot allocation method,
A receiving unit for receiving a connection request transmitted from the terminal;
A spatial multiplexing number management unit for managing the spatial multiplexing number in the base station;
When the spatial multiplexing number is the maximum and the connection request indicates that the terminal call is a narrowband call, or the value indicating the wireless quality of the connection request is a predetermined value or less, A base station comprising: a control unit that allocates slots to the terminal in a sub-slot scheme, and in other cases, allocates slots to the terminal in a full slot scheme. In the base station according to claim 3,
When assigning a slot to the terminal by a subslot method, the control unit uses some of the subslots obtained by dividing the full slot into a plurality of subslots in the spatial multiplexing slot of the local station. When there is an empty subslot that a subslot is unused, the base station performs assignment control for assigning the empty subslot to the terminal.

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