JP2001177865A - Slot assignment method in mobile communication and base station and mobile station using the method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a slot assignment method adopting a TDD system with high efficiency and high flexibility that is suitable for accommodation of vertically asymmetrical traffic, attains slot assignment in response to the quality of service and improves the throughput. SOLUTION: A plurality of borders for changeover of incoming slots and outgoing slots in one frame is provided to assign slots, and TDD borders are dynamically changed according to prescribed conditions. A base station assigns slots and informs a mobile station about the assigned slots by using a control mini-slot in a frame. This method is characterized in that a slot number less than a requested slot number in a congestion state is assigned and a slot number more than the requested slot is assigned in a congestion-free state depending on the traffic congestion state on the basis of the QoS such as a service ranking.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a mobile communication TDD.
The present invention relates to a slot allocation method in a system, and a base station and a mobile station using the same.

[0002]

2. Description of the Related Art In the application of a TDD system (Time Division Duplex) for exchanging information by dividing a carrier into slots, a vertically symmetric slot arrangement has been used in the prior art. This is because in voice communication, uplink / downlink traffic is almost symmetric.

[0003] However, due to the recent development of multimedia services, the ratio of non-voice is rapidly increasing, and various information providing services, applications for exchanging e-mails, and transmitting information from users are increasingly used in the future. It is considered to be. When considering these applications and services from the viewpoint of traffic, the information providing service is mainly based on data distribution from a database, and it is considered that the traffic of downlink information increases in a network. In the upstream direction, information traffic for information transmission from the user increases. Thus, the data,
In non-speech communication such as images, the amount of upstream and downstream traffic is often asymmetric.

At this time, as in the case of the conventional voice communication, T
When vertically symmetrical slot allocation is used in the DD scheme, the other slot becomes excessive when the traffic volume is increased, and the other slot becomes insufficient when the traffic volume is decreased. As a result, highly efficient and efficient information transmission cannot be performed. For such a problem, reference 1: Lan Chen, Susumu Yoshida, Hideka
zu Murata and Shouichi Hirose, “A dynamic timeslot
assignment algorithm for asymmetric traffic in mu
ltimedia TDMA / TDD mobile radio ", IEICE Trans. Fund
amentals, vol.E81-A, pp.1358-1366, no.7, July 1
998 proposes an asymmetrical slot allocation method for accommodating asymmetric traffic.

[0005] In the conventional slot allocation method disclosed in the above-mentioned document 1, as shown in FIG. 1, the boundary (TDD boundary) for switching between uplink and downlink slots in one frame is one.
Only the location is determined, and the TDD boundary is moved within a movable range according to the up / down traffic. As shown in FIG. 1, although slots 4 and 5 are vacant, they cannot be used as an uplink, and the slots cannot be used effectively.

[0006] In the method described in the above document 1, the reception control of packet transmission is performed as follows. When the mobile station informs the base station of the required number of slots per frame, the number of slots that the mobile station intends to use for signal transmission, the base station attempts to allocate slots to the mobile station. At this time, even if the TDD boundary is moved, if the number of available empty slots is insufficient, signal transmission is rejected. Also, when there are more empty slots at the time of allocation than the number of slots requested by the mobile station, or when a new empty slot is generated during signal transmission and it becomes possible to allocate more slots than the requested slot,
The number of slots actually allocated is the same as the number of requested slots.

[0007]

In the above-mentioned conventional slot allocation method, the TDD boundary is moved in order to cope with the asymmetry of the up / down traffic. However, since there is only one uplink / downlink boundary in one frame, if a slot adjacent to the boundary is in use, even if other slots are released, a conventional downlink slot is allocated to an uplink slot area. Conversely, it is not possible to allocate an upstream slot to a downstream slot area. Therefore, the empty slot cannot be used, and the maximum use of slot resources cannot be achieved. For this reason, in data transmission, there are major drawbacks in that the frequency utilization efficiency does not increase, the transmission delay increases, and the transmission incomplete rate increases.

Further, when the number of slots required by the mobile station cannot be ensured due to traffic congestion or the like, the acceptance of data transmission is rejected, and data is discarded or enters a wait state for retransmission. There were drawbacks that the incomplete rate was high and the transmission delay was large.
If the number of empty slots is larger than the required number of slots during off-peak hours, or if a new empty slot occurs during communication, the number of slots required for mobile stations and base stations or the number of slots currently used for communication If a means capable of performing the above data transmission is provided, a higher speed signal transmission can be performed by using the empty slot. However, the conventional technology has a drawback that the empty slot is not actively used and the throughput is low.

[0009] The present invention has been made in view of the above,
It is an object of the present invention to provide a highly efficient and flexible slot allocation method capable of accommodating up / down asymmetric traffic and maximizing throughput while maximizing service quality.

[0010]

To achieve the above object, the present invention is configured as follows. The invention described in claim 1 is a slot allocation method in a TDD system applied to a mobile communication system, wherein a plurality of boundaries for switching between an uplink slot and a downlink slot in one frame (hereinafter, referred to as TDD boundaries) are provided. And slot allocation is performed.

In the invention described in claim 2, slot assignment for dynamically changing the TDD boundary is performed during standby or during communication. In the invention described in claim 3, the TDD boundary is variable according to a predetermined condition. According to the first to third aspects of the present invention, it is possible to allocate an upstream slot or a downstream slot regardless of the position of an empty slot, so that it is possible to reduce the occurrence of useless slots as in the related art. Therefore, the above object can be achieved. Here, the above-mentioned predetermined condition is, for example, a condition in which a slot is vacant after a certain communication is completed, a case of traffic congestion, a level of a QoS request from a user, or the like. For example,
When a user receives a high-level QoS request, a lot of slots are dynamically allocated for data transmission of the user. Details will be described in Examples.

According to a fourth aspect of the present invention, there is provided a slot allocation method in a TDD system applied to a mobile communication system, wherein a base station allocates a slot of a next frame in one frame and allocates a slot of a control mini-slot. To notify the mobile station of the information including the slot assignment information. According to the present invention, since the allocation information is indicated by the control mini-slot, the mobile station only needs to access the slot according to the information, and both the uplink and downlink slots can be freely allocated to empty slots in the frame.

[0013] According to a fifth aspect of the present invention, the base station includes:
Data including a desired number of slots is received in one frame, and slots corresponding to the desired number of slots are allocated from empty slots in the next frame. In the invention described in claim 6, the base station accepts data including a desired number of slots in one frame, and when the number of empty slots in the next frame is smaller than the desired number of slots, the base station receives the data within a predetermined range. The number of slots smaller than the number of slots is allocated to the next frame.

According to a seventh aspect of the present invention, when the base station receives data including a desired number of slots in one frame and the number of empty slots in the next frame is larger than the desired number of slots, the base station receives the data within a predetermined range. Assigns the number of slots larger than the desired number of slots to the next frame.
According to the invention described in claim 8, when a new empty slot is generated during data transmission, the base station allocates a larger number of slots than the number of slots used for the data transmission within a predetermined range.

According to a ninth aspect of the present invention, the base station comprises:
During data transmission, a smaller number of slots than the number of slots used for the data transmission is allocated within a predetermined range according to a system or traffic situation. Claims 6-9
According to the invention described in (1), the number of allocated slots can be dynamically changed according to a request or a communication situation, and the slots can be used efficiently. here,
The above-mentioned predetermined range is, for example, a range of the maximum number of slots available for a certain communication and the minimum number of necessary slots, which will be described in detail in the embodiments.

According to a tenth aspect of the present invention, the information on the control mini-slot includes information on the up / down / empty state of each slot, information for confirming the reception status of the up data, and which slot in the next frame. Is included in the allocation slot information. According to the present invention, a slot to be used in the next frame can be reserved, and the mobile station can confirm whether transmission data has been received by the base station.

According to the invention described in claim 11, the service quality is classified into service classes, and the base station performs slot assignment according to the class rank. Claim 12
In the invention described in (1), the first packet of data transmitted from the mobile station to the base station includes a QoS request, and the QoS
The request includes a maximum number of slots available for transmission of the data, a minimum number of slots, a class of service,
The base station allocates a maximum slot number or a minimum slot number to a frame according to the service class.

According to the eleventh and twelfth aspects of the present invention,
The quality of data transmission can be changed according to the service class. The invention as set forth in claim 13 is characterized in that TDD
Base station in a mobile communication system performing communication in a system, comprising means for allocating a slot of a next frame in one frame, and means for notifying the mobile station of information including the slot allocation information in a control mini-slot. .

According to a fourteenth aspect of the present invention, the base station receives data including a desired number of slots in one frame, and sets the number of slots corresponding to the desired number of slots out of empty slots in the next frame. It has means for assigning. The invention according to claim 15 is characterized in that the base station accepts data including a desired number of slots in one frame, and when the number of empty slots in the next frame is smaller than the desired number of slots, the base station receives the data within a predetermined range. Means are provided for allocating a smaller number of slots to the next frame than the number of slots.

[0020] In the invention described in claim 16, the base station receives data including a desired number of slots in one frame, and when the number of empty slots in the next frame is larger than the desired number of slots, the base station receives the data within a predetermined range. And means for allocating the number of slots larger than the desired number of slots to the next frame. In the invention described in claim 17, the base station allocates a larger number of slots than the number of slots used for data transmission within a predetermined range when a new empty slot is generated during data transmission. Having means.

[0021] In the invention described in claim 18, the base station, during data transmission, has a number of slots smaller than the number of slots used for the data transmission within a predetermined range according to a system or traffic situation. Means for assigning In the invention described in claim 19, the information of the control mini-slot includes information on the state of uplink / downlink / vacancy of each slot, information for confirming the reception status of uplink data, and which slot is used in the next frame. The slot information.

[0022] The invention described in claim 20 has means for the base station to allocate a slot to a frame according to a service class included in a QoS request transmitted from the mobile station. According to the inventions described in claims 13 to 20, it is possible to provide a base station suitable for using the above-described slot allocation method.

According to a twenty-first aspect of the present invention, there is provided a mobile station for communicating with the base station, wherein the means for transmitting information including a QoS request in a first packet of data to be transmitted to the base station, Means for transmitting in the assigned slot notified by the mini-slot. According to the present invention, a mobile station suitable for communication with the base station can be provided.

[0024]

BRIEF DESCRIPTION OF THE DRAWINGS FIG.
An embodiment of the present invention corresponding to D will be described. First, an outline of each embodiment will be described, and then each embodiment will be described in detail. In the first embodiment, the basic operation of the present invention will be described. In the second embodiment, a case will be described in which slots are allocated by a QoS request according to the traffic situation at the time of receiving packet transmission. Here, as a priority, it is assumed that a class 2 user, which will be described later, is preferentially reduced in quality during congestion. In the third embodiment, if the number of available slots increases or decreases during packet transmission, the service class and Q
A method for changing the number of slots according to the oS request will be described. Furthermore, when deleting the number of slots when the number of available slots decreases, it is assumed that the quality is preferentially reduced for class 2 users.

In the fourth embodiment, a case will be described in which slots are allocated by a QoS request according to the traffic situation at the time of receiving packet transmission. As a difference from the second embodiment, the second embodiment preferentially lowers the quality of class 2 users in the case of congestion at the time of reception, whereas the fourth embodiment reduces the minimum number of slots or the number of desired slots in the case of congestion at the time of reception. Slots assigned more are deleted with priority.

In the fifth embodiment, a case will be described where the number of available slots is increased or decreased during packet transmission, and the number of slots to be allocated is changed according to a service class and a QoS request. As a difference from the third embodiment, the third embodiment preferentially reduces the quality of class 2 users in the case of congestion during transmission, whereas the fifth embodiment has the minimum number of slots or the desired number of slots in the case of congestion during transmission. The priority is to delete slots assigned more frequently.

(Embodiment 1) TDMA / T
The basic operation of the present invention corresponding to DD will be described. FIG. 2 is a diagram showing a slot configuration according to the first embodiment of the present invention. As shown in the figure, a carrier 11 is composed of a frame 12 that repeats at predetermined time intervals, and the frame is composed of a plurality of information slots 1.
3. It is composed of the same number of control mini-slots 14 corresponding to the information slots. The information slot is used as either up or down.

In this embodiment, uplink / downlink is assigned without restriction. That is, it is allowed that one frame includes a plurality of boundaries between the upstream slot and the downstream slot.
In the example shown in FIG. 2, one frame includes ten information slots, and there are three boundaries between S1-S2, S3-S4, and S4-S5 for uplink / downlink. At the end of each frame,
Control mini-slots 14 corresponding to each slot are provided in the same number as the information slots. The control mini-slot indicates the slot allocation status in the next frame (up / down / empty: U
/ D / I) 16, the confirmation data of the mobile station that has been successfully transmitted in the current frame, and the slot number (AL) 18 in the next frame to be allocated to the data transmission when signal transmission is continued in the next frame. Is done. Regarding the confirmation data, in the case of TDD, any information can be used as long as the transmitting mobile station can confirm whether or not the data transmitted by the own station is correctly received. In this case, partial data (PE) of the data transmitted by the transmitting station is used. 17 is used.

With respect to the number of assigned slots, the base station determines the number of assigned slots according to the degree of traffic congestion, and indicates the number of the slot to be accessed by the mobile station in the next frame. In the example of FIG. 2, the maximum number of assigned slot numbers is 10. The head packet 31 in the uplink transmission has a packet length L, QoS expressed by a slot length.
It comprises a request unit 33 (including the maximum number of slots B, the desired number of slots E, the minimum number of slots W, and the service class C) and information bits 34.

Next, an example of a slot assignment method according to the first embodiment of the present invention will be described with reference to FIG. (A) of FIG.
Part (b) shows the operation on the base station (BS) side, that is, the operation in the slot assignment circuit of the base station, and part (b) shows the operation on the mobile station (MS) side. As shown in the figure, transmission 1 from the mobile station to the base station has already started, and its communication uses slots 1, 2, and 3.

First, transmission from the base station to the mobile station, that is, downlink signal transmission will be described. In frame 0, a downlink transmission request 2 with the desired number of slots of 2 is generated from the base station side, and the number of slots is allocated. Here, in the next frame, slots 0, 4, 5, 6, 8, and 9 are vacant, so that slots 8 and 9 correspond to empty slots in the control mini-slot immediately after slot 9 in frame 0. The use schedule is indicated. Then, transmission is started from frame 1 using slots 8 and 9.

Next, a case where transmission from a mobile station to a base station, that is, uplink signal transmission is performed will be described. When an uplink transmission request 3 occurs in frame 0, the slot allocation status in the next frame in the immediately following control mini-slot is checked, and slots 8 and 9 are assigned to downlink transmission request 2 as described above.
, The empty slots 0, 4, 5,
One slot is randomly selected from 6 and 7, and transmission is started.

In the example shown in FIG. 3, the mobile station starts transmission corresponding to uplink transmission request 3 using slot 4, and sets information packet length L = 5 and QoS request (maximum number of slots B =
4, the desired number of slots E = 3, the minimum number of slots W = 1, and the service class C = 1) are added to the head of the information bit and transmitted. How to use each of the maximum slot number B, the desired slot number E, the minimum slot number W, and the service class C will be described later. Since the desired number of slots for transmission 3 is 3, the base station allocates slots 0, 4, and 5, and notifies the mobile station of the allocated slot number using the control mini-slot (AL = 0, 4, 5). Notice).

Then, based on the contents of the control mini-slot 4, the mobile station receives the data transmitted by itself at slot 4 of frame 1 at the base station, and receives data at slots 0, 4,.
Check that 5 has been assigned. After the frame 2, the mobile station transmits a signal according to the instruction of the control mini-slot. In addition, by receiving the PE portions of the control mini-slots 0, 4, and 5 of the frame 2 and comparing them with the own-station transmission signal, reception and non-reception of the own-station transmission signal on the receiving side can be confirmed.

Since the data length of the uplink transmission 3 is 5, after the mobile station transmits data in slots 0, 4, and 5 of frame 2, the remaining data length becomes 1, and the base station immediately follows frame 2 In the control mini-slot, slot 0 is allocated for transmission in frame 3, and slots 4 and 5 are made empty. That is, when the base station confirms the reception of the last information packet, the use status of the corresponding information slot of the next frame is set to empty I, the allocation number is set to null, and the control minislot is notified to the mobile station.

Based on the contents of the control mini-slot of frame 2, the mobile station confirms that it has received its own data and that the remaining one packet has been allocated to slot 0 of the next frame (frame 3). When the mobile station sends the last packet to the base station in slot 0 of frame 3, the base station does not make the next assignment for transmission 3. Then, the mobile station looks at the control mini-slot 0 of frame 3 and confirms that the data of the own station has been received and that the slot assignment has been completed with the completion of the data transmission. Since the data length of the downlink transmission 2 is 10, the transmission is continued at the time of the frame 3.

FIG. 4 is a flowchart showing the operation of the mobile station. When a transmission request is issued from the mobile station (step 1),
The control minislot at the end of the frame is received (step 2), and it is checked whether or not there is an empty slot in the next frame (step 3). If there is no empty slot in the next frame, it is checked whether a time-out has occurred (step 4). If it is timed out, the transmission is not completed. If not, the process waits for reception of a minislot in the next frame (step 5).

On the other hand, if there is a vacant slot in the next frame in step 3, a vacant slot is selected at random, and the packet length L, the maximum number of slots B, the desired number of slots E, the minimum number of slots W, and the service class C are represented. The information bit is added to the head and transmitted to the base station (step 6). Next, the control mini-slot transmitted from the base station corresponding to the transmitted empty slot is received (step 7), and it is checked whether the transmission was successful (step 8). If transmission fails, retransmission is performed (steps 9 and 1).
0), if the number of retransmissions exceeds the limited number, the process ends with incomplete transmission.

If the transmission is successful in step 8, it is checked whether or not the transmission of the packet is completed (step 11). If not completed, the transmission is continued using the assigned information slot of the next frame (step 12 to). FIG. 5 is a flowchart of the operation of the base station according to the first embodiment. If there is a request to receive an uplink head packet from the mobile station or a downlink transmission request from the base station (step 21), if the number of available empty slots is equal to or greater than the desired slot, allocation is performed with the desired number of slots (steps 22 and 23). If the number of available empty slots is less than the desired number of slots, the process waits until the next frame (steps 22 and 24).

When the slots are allocated, the control mini-slot notifies the mobile station of the slot use status U / D / I of the next frame, the reception confirmation PE, and the slot number AL of the next frame allocated (step 25). When the available resources are changed during transmission, if the number of available slots is equal to or larger than the desired number of slots (step 26 and step 2).
If the number of available slots is smaller than the desired number of slots (NO in step 27), the system enters a waiting state until the number of desired slots is sufficient (steps 28 and 29). In the case of the last packet in the uplink (in the case of YES in step 30), the control mini-slot indicates that the slot use status of the next frame is empty I,
The mobile station is notified of the reception confirmation PE and the allocation number AL = Null (step 31).

The steps 22 to 24 are referred to as sequence 1 and the steps 26 to 29 are referred to as sequence 2. FIG. 6 is a diagram showing a configuration of a mobile station according to an embodiment of the present invention, in which 71 is an encoding circuit, 72 is a transmission control circuit, 73 is a modulation circuit, 74 is a logical operation circuit, and 7
6 denotes a decoding circuit, 77 denotes a signal separation circuit, and 78 denotes a demodulation circuit.

FIG. 7 is a diagram showing the configuration of a base station according to one embodiment of the present invention, wherein 81 is a demodulation circuit, 82 is a signal separation circuit, 83 is a decoding circuit, 85 is a broadcast control circuit, and 86 is a logical operation. Circuit, 87 is a modulation circuit, 88 is a signal multiplexing circuit, 89
Represents an encoding circuit, and 90 represents a slot assignment circuit. In this embodiment, operations of the mobile station and the base station will be described.

When it becomes necessary for the mobile station to transmit an uplink message, the encoding circuit 71 in FIG. 6 performs processing such as error correction encoding and the like, and is input to the transmission control circuit 72 to wait for transmission. In the logical operation circuit 74, partial data (PE in FIG. 2) on which a certain process such as extracting a part of the bit string of the uplink information of the transmission signal is input to the transmission control circuit 72 and stored.

The data from the base station demodulated by the demodulation circuit 78 is separated into control mini-slots (broadcast signal portion shown in FIG. 1 and the like) by a signal separation circuit 77 and input to a transmission control circuit 72, where U / D / An empty slot is selected from the left for a slot with I information, and transmission is started from the first burst at the timing of the selected slot. The base station receives this burst signal, passes through a demodulation circuit 81 and a signal separation circuit 82, and as shown in FIG. 7, the number of packets constituting the message included in the first burst (packet length L32 in FIG. 2). , The QoS request (QoS request section in FIG. 2) 33 is input to the slot allocating circuit 90, and according to the allocation result, the information slot usage status U / D / I
(U / D / I16 in FIG. 2) and the assigned slot number (AL18 in FIG. 2) are input to the notification control circuit 85. On the other hand, the uplink information from the mobile station is subjected to processing such as error correction in a decoding circuit 83. As a result, the reproduced uplink information is input to the logical operation circuit 86, and the partial data 1 as a result of performing the same processing as performed by the logical operation circuit 74 of the mobile station
7 is input to the notification control circuit 85.

The notification control circuit 85 sets the use status U / D / I of each information slot, the partial echo, and the assigned slot number. This notification signal is transmitted to the mobile station via the signal multiplexing circuit 88 and the modulation circuit 87. In the mobile station, the broadcast information is input to the transmission control circuit 72 via the demodulation circuit 78 and the signal separation circuit 77. The transmission control circuit 72 compares the partial echo input from the signal separation circuit 77 with the result stored in the logic operation circuit 74 before transmission, and if they match, determines that the transmission data has been correctly received. Then, in the next frame, the assigned slot is accessed according to the assigned slot number AL, and transmission is continued.

If the partial data do not match, the system enters a wait state for transmitting from the first burst again, and after a random time delay or immediately after, the U / D /
Transmission resumes when I is I. (Embodiment 2) In Embodiment 2, a case will be described where priorities are assigned to packet transmissions and slots are allocated using QoS requests according to the traffic situation at the time of receiving packet transmissions.

In this embodiment, the priority is assigned in two stages, that is, service class 1 and service class 2, respectively. However, service classes can be divided more finely and more flexible allocation according to multi-QoS is possible. In this embodiment, a channel (slot) is allocated to a user of service class 1 (high class) so as to guarantee the desired quality to the maximum, and a user of service class 2 (low class) is assigned best effort. Perform channel assignment.

Further, in the case of accepting packet transmission, the quality is preferentially reduced with respect to class 2 users during congestion. That is, as will be described later, when the available empty slots are not enough and the number of user slots is deleted and assigned to the new class 1 user packet transmission, the class 2
, The number of slots allocated more than the minimum number of slots of class 1, the minimum number of slots of class 2, and the number of slots allocated more than the desired number of slots of class 1 are used in order of allocation to a new user.

The slot configuration of the second embodiment is the same as that of the first embodiment and is shown in FIG. The flowchart of the operation of the mobile station is the same as that of the first embodiment, and is shown in FIG. FIG. 8 shows a flowchart of the operation of the base station in the second embodiment. When a packet transmission is accepted (step 4
1) Check the service class (step 42),
If the service class is 1, the process of 3-1 shown in FIG. 9 is performed (step 43). If the service class is not 1, the process of 3-2 shown in FIG. 10 is performed (step 44). The processing after the completion of step 43 or step 44 is the same as the processing from step 25 of the flowchart shown in FIG.

Next, a channel assignment method for class 1 users will be described with reference to FIG. When there is a transmission request from the mobile station, if the number of available empty slots is larger than the maximum number of slots (YES in step 51), allocation is performed with the maximum number of slots of the user (step 5).
2) If the number of available empty slots is smaller than the maximum number of slots but larger than the desired number of slots (step 53)
In the case of NO), allocation is performed using the number of available empty slots (step 54).

On the other hand, if the number of slots is insufficient to allocate the desired number of slots (YES in step 53).
), Slots allocated for transmission of class 2 users more than the minimum number of slots in that transmission;
That is, the sum of the margin with respect to the minimum number of slots
If the number of slots is smaller than the number of slots in step 3 (step 5
5), a slot is obtained in the descending order of the margin, and the class 1 is assigned together with available empty slots.
Of users. In the case of NO in step 55, the minimum slot number of the class 2 user is deleted and used (YES in step 57 and step 58).

If it is not sufficient to delete the number of slots from the users of class 2 (NO at step 57), the slots are deleted from the users assigned more than the desired number of slots of the same class (class 1). A new class 1 user is assigned (steps 59 and 60). Here, when there are a plurality of users with the same condition, they are selected at random. If that is not enough (NO in step 59), the number of slots having a margin with respect to the minimum number of slots is used (steps 61 and 62). If not, the process waits until the next frame (step 63).

In the above processing, the class 2 user whose number of slots is smaller than the minimum number of slots temporarily stops transmission and resumes transmission as soon as a slot becomes available (step 64). Next, a channel assignment method for class 2 users will be described using the flowchart of FIG. This corresponds to the process of step 44 in FIG.

When there is a class 2 transmission request, the number of available empty slots is checked (step 71). If the number of available empty slots is larger than the maximum number of slots (YES in step 71), Assignment is performed with the maximum number of slots (step 72). The number of available empty slots is smaller than the maximum number of slots (step 71).
If the number is larger than the minimum number of slots (NO in step 73), allocation is performed using the number of available empty slots (step 74). If the number of available empty slots is smaller than the minimum number of slots (step 73)
In the case of YES), slot allocation is attempted after one frame delay (step 75).

The configurations of the mobile station and the base station in the second embodiment are shown in FIGS. 6 and 7, respectively, as in the first embodiment. (Embodiment 3) This embodiment describes a method of changing the number of slots according to a service class and a QoS request when the number of available slots increases or decreases during packet transmission. Furthermore, in this embodiment, when the number of available slots is reduced and the number of slots is deleted, the quality is preferentially reduced for class 2 users. That is, as will be described later, when the number of slots is deleted, the slots allocated in the order of the minimum number of slots in the class 2, the minimum number of slots in the class 2, and the slots allocated in the number larger than the desired number of slots in the class 1 are arranged in this order. Delete the number and use it for a new assignment.

The slot configuration of the third embodiment is the same as that of the first embodiment, and is shown in FIG. FIG. 11 shows a flowchart of the base station operation in the third embodiment. A process when the available resources are changed during transmission (referred to as sequence 4) will be described. If there is a change in the available resources (YES in step 81), it is checked whether the available resources have increased (step 8).
2) If the number has increased, the process of 4-1 shown in FIG. 12 is performed (step 83). If the number has not increased, 4-2 shown in FIG.
(Step 84).

Next, the processing when there is a slot to be newly released or when the system resources increase, that is, the processing of the above step 83 will be described with reference to the flowchart of FIG. A check is made of users whose assigned slot number is less than or equal to the desired slot number among the class 1 users, and a user who has a shortage from the desired slot number (Y in step 91)
In the case of ES, priority is given to additional allocation of slots up to the desired number of slots (step 92). Further, it is also possible to randomly perform additional allocation from users who do not have the desired number of slots.

If there is a remaining slot available after the additional assignment of class 1 (YES in step 93),
In class 2, users whose number is equal to or less than the minimum number of slots are checked (step 94), and a user who has a large number of shortages from the minimum number of slots (YES in step 94) is preferentially allocated to the minimum number of slots (step 94). 9
5). It is also possible to randomly perform additional allocation for users less than the minimum number of slots.

Next, the processing when the number of slots available during transmission decreases, that is, the processing of the above step 84 will be described with reference to the flowchart of FIG. As shown in FIG. 13, slots are deleted in the following order. That is, when the number of usable slots decreases by S (step 10).
1), slots allocated more than the minimum number of slots of class 2 users (steps 102 to 104), minimum number of slots of class 2 (steps 105 to 107), slots allocated more than the desired number of slots of class 1 (Steps 108 to 110), slots that are assigned more than the minimum number of slots for class 1 users (steps 111 to 113), and slots are deleted in the order of the minimum number of slots for class 1 (step 114). Users whose slots have been cut below the minimum number of slots stop transmission,
The transmission is restarted when a vacancy is found (step 115).

The configurations of the mobile station and the base station in this embodiment are the same as in the first embodiment, and are shown in FIGS. 6 and 7, respectively. (Fourth Embodiment) In a fourth embodiment, a case will be described in which priorities are assigned to packet transmissions and slots are allocated according to a QoS request according to the traffic situation at the time of accepting packet transmissions. The difference from the second embodiment is that the second embodiment
In the case of congestion at the time of reception, class 2 users are preferentially degraded in quality. On the other hand, in the case of congestion at the time of reception, the number of slots allocated more than the minimum number of slots or the number of desired slots is given priority in the fourth embodiment. It is to delete.

The slot configuration of the fourth embodiment is the same as that of the first embodiment and is shown in FIG. The flowchart of the mobile station operation is the same as that of the first embodiment, and is shown in FIG. FIG. 14 shows a flowchart of the base station operation. The change in the number of slots when there is a change in available resources follows Sequence 2 or Sequence 4 described above. Here, the operation at the time of receiving a user (sequence 5) will be described.

When the service class is 1, FIG.
5-1 shown in FIG. 15 (step 122), and if the service class is not 1, the process 5-2 shown in FIG. 15 is performed (step 123). Next, the above step 12
2, that is, a slot allocation operation in the base station for a user of service class 1 will be described with reference to the flowchart in FIG. If the number of available empty slots is equal to or greater than the maximum number of slots (YES in step 131), allocation is performed using the maximum number of slots (step 13).
2). If the number of available slots is equal to or larger than the desired number of slots (NO in step 133), allocation is performed using the number of available empty slots (step 134).

If the number of available slots is smaller than the desired number of slots (NO in step 133), slots are deleted in the following order and assigned to a new user. That is, slots allocated to more than the minimum number of slots of class 2 (steps 135 and 136), slots allocated to more than the desired number of slots of class 1 (steps 137 and 138), and the minimum number of slots of class 2 (steps 137 and 138) 139, 140), slots allocated more than the minimum number of slots (steps 141, 1).
In the order of 42), slots of other users are deleted and assigned to new users.

The assignment operation for the service class 2 user is the same as in FIG. The configurations of the mobile station and the base station are shown in FIGS. 6 and 7, respectively, as in the first embodiment. (Fifth Embodiment) In a fifth embodiment, a case will be described where priorities are assigned to packet transmissions, and the number of slots to be allocated by a QoS request is changed according to the traffic situation during packet transmission. As a difference from the third embodiment,
In the third embodiment, class 2 users are preferentially reduced in quality in the case of congestion during transmission, and in the fifth embodiment, the number of slots allocated more than the minimum or desired number of slots in the case of congestion during transmission. Is preferentially deleted.

The slot configuration of the fifth embodiment is the same as that of the first embodiment and is shown in FIG. The flowchart of the mobile station operation is the same as that of the first embodiment, and is shown in FIG. The base station operation is shown in the flowchart of FIG. The operation when the available resources are changed is sequence 6 (step 15).
1 to 154). The processing in step 153, that is, the operation of the base station when the available resources increase, is the same as that shown in FIG. 12. The processing in step 154, that is, the operation of the base station when the available resources decrease. Figure 1
This will be described with reference to the flowchart of FIG.

As shown in FIG. 17, when the number of available slots decreases (step 161), the order of deleting slots is as follows. That is, the slots allocated to the class 2 more than the minimum number of slots (step 1)
62 to 164), slots that are assigned more than the desired number of slots of class 1 (steps 165 to 167),
Class 2 minimum slot number (steps 168-17)
0), the slots allocated more than the minimum number of slots of class 1 (steps 171 to 173), and the minimum number of slots (step 174). The user whose number of slots is smaller than the minimum number of slots stops transmission, and retransmits after a random time (step 175).

The configurations of the mobile station and the base station in this embodiment are shown in FIGS. 6 and 7, respectively, as in the first embodiment.
It should be noted that the present invention is not limited to the above-described embodiments, but can be variously modified and applied within the scope of the claims.

[0068]

As described above, according to the present invention, the slot is not divided into the uplink and the downlink as in the conventional TDD system, and a plurality of times of the up / down operation are required. Slots are allocated with inversion allowed. Therefore, a slot can be dynamically allocated according to the amount of up / down traffic, and a slot allocation method capable of efficiently accommodating asymmetric traffic can be realized.

Further, the service quality (QoS) is divided into classes, and as much as possible assurance is provided so that the desired quality of the high-class user is maximally satisfied. Provide best effort service. Therefore, the slot allocation is performed according to the service class and the allowance, the slot utilization efficiency and the throughput are improved, and the slot allocation method that provides the maximum service quality can be realized.

[Brief description of the drawings]

FIG. 1 is a diagram for explaining an up / down switching boundary (TDD boundary) of a TDD scheme in a conventional technique.

FIG. 2 is a diagram showing a slot configuration in an embodiment of the present invention.

FIG. 3 is a diagram for explaining operations of a base station and a mobile station for slot allocation in Embodiment 1 of the present invention.

FIG. 4 is a diagram for explaining an operation flowchart of a mobile station in Embodiments 1, 2, 3, 4, and 5 of the present invention.

FIG. 5 is a flowchart of an operation of the base station according to the first embodiment of the present invention.

FIG. 6 is a diagram illustrating a configuration of a mobile station.

FIG. 7 is a diagram illustrating a configuration of a base station.

FIG. 8 is a flowchart of a base station operation according to the second embodiment of the present invention.

FIG. 9 is a flowchart of slot assignment when a class 1 user is accepted in the second embodiment.

FIG. 10 is a flowchart of slot assignment at the time of accepting a class 2 user in the second and fourth embodiments.

FIG. 11 is a flowchart of a base station operation according to the third embodiment.

FIG. 12 is a flowchart of slot addition allocation of a class 1 user when resources available during transmission increase in the third and fifth embodiments.

FIG. 13 is a flowchart of changing the number of allocated slots when the resources available during transmission are reduced in the third embodiment.

FIG. 14 is a flowchart of a base station operation according to the fourth embodiment.

FIG. 15 is a flowchart of slot assignment when class 1 user packet transmission is accepted in the fourth embodiment.

FIG. 16 is a flowchart of an operation of a base station according to the fifth embodiment.

FIG. 17 is a flowchart of changing the number of allocated slots when the resources available during transmission are reduced in the fifth embodiment.

[Explanation of symbols]

 Reference Signs List 11 carrier 12 frame 13 information slot 14 control mini-slot 16 occupation state of information slot U / D / I 17 partial echo PE of information slot 18 assigned slot number AL 31 upstream first packet 32 packet length represented by slot length L 33 QoS request 34 Information bit 71 Encoding circuit 72 Transmission control circuit 73 Modulation circuit 74 Logical operation circuit 76 Decoding circuit 77 Signal separation circuit 78 Demodulation circuit 81 Demodulation circuit 82 Signal separation circuit 83 Decoding circuit 85 Notification control circuit 86 Logical operation circuit 87 Modulation circuit 88 Signal multiplex image path 89 Encoding circuit 90 Slot assignment circuit

Continuation of the front page (72) Inventor Yasushi Yao 2-10-1 Toranomon, Minato-ku, Tokyo NTT Mobile Communication Network Co., Ltd. F term (reference) 5K028 AA11 BB04 CC02 CC05 DD01 DD02 EE03 EE05 EE08 KK01 KK12 LL12 RR02 5K067 AA13 BB04 CC04 CC08 EE02 EE10 EE72 HH26

Claims (21)

[Claims] 1. A slot allocation method in a TDD system applied to a mobile communication system, wherein a plurality of boundaries (hereinafter referred to as TDD boundaries) for switching between an up slot and a down slot in one frame are provided and slot allocation is performed. Performing a slot allocation method. 2. The slot assignment method according to claim 1, wherein slot assignment for dynamically changing the TDD boundary is performed during standby or during communication. 3. The slot allocation method according to claim 2, wherein the TDD boundary is variable according to a predetermined condition. 4. A slot allocation method in a TDD system applied to a mobile communication system, wherein a base station allocates a slot of a next frame in one frame and information including the slot allocation information in a control mini-slot. Is notified to the mobile station. 5. The slot allocation method according to claim 4, wherein the base station receives data including a desired number of slots in one frame and allocates the desired number of slots from empty slots in the next frame. 6. The base station accepts data including the desired number of slots in one frame, and if the number of empty slots in the next frame is smaller than the desired number of slots, the base station receives less than the desired number of slots within a predetermined range. The method of claim 4, wherein the number is assigned to a next frame. 7. The base station accepts data including a desired number of slots in one frame, and if the number of empty slots in the next frame is larger than the desired number of slots, the base station receives more data than the desired number of slots within a predetermined range. The method of claim 4, wherein the number is assigned to a next frame. 8. When a new empty slot is generated during data transmission, the base station allocates a larger number of slots within a predetermined range than the number of slots used for the data transmission.
3. The slot allocation method according to 1. 9. The slot according to claim 4, wherein, during data transmission, the base station allocates a smaller number of slots than the number of slots used for the data transmission within a predetermined range according to a system or traffic situation. Assignment method. 10. The control mini-slot information includes uplink / downlink / empty status information of each slot, information for confirming the reception status of uplink data, and allocation of which slot may be used in the next frame. 10. The slot allocation method according to claim 4, further comprising slot information. 11. The slot allocation method according to claim 4, wherein service quality is classified into service classes, and said base station performs slot allocation according to a class rank. 12. The first packet of data transmitted by the mobile station to the base station includes a QoS request, the QoS request comprising a maximum number of slots available for transmission of the data, a minimum number of slots, The slot allocation method according to any one of claims 4 to 11, including a service class, wherein the base station allocates a maximum number of slots or a minimum number of slots to a frame according to the service class. 13. A base station in a mobile communication system for performing communication according to a TDD system, comprising: means for allocating a slot of a next frame in one frame; A base station comprising means for notifying the base station. 14. A system comprising: means for receiving data including a desired number of slots in one frame; and means for allocating slots corresponding to the desired number of slots from empty slots in the next frame.
A base station as described in. 15. When data including a desired number of slots is received in one frame, and the number of empty slots in the next frame is smaller than the desired number of slots, the number of slots smaller than the desired number of slots is reduced within a predetermined range to the next frame. 14. The base station according to claim 13, further comprising means for assigning to the base station. 16. When data including a desired number of slots is received in one frame and the number of empty slots in the next frame is larger than the desired number of slots, the number of slots larger than the desired number of slots within a predetermined range is changed to the next frame. 14. The base station according to claim 13, further comprising means for assigning to the base station. 17. The base according to claim 13, further comprising means for allocating a larger number of slots within a predetermined range than the number of slots used for data transmission when a new empty slot is generated during data transmission. Bureau. 18. The base station according to claim 13, further comprising means for allocating a smaller number of slots than the number of slots used for the data transmission within a predetermined range during data transmission according to a system or traffic situation. . 19. The control mini-slot information includes uplink / downlink / empty status information of each slot, information for confirming the reception status of uplink data, and allocation of which slot may be used in the next frame. The base station according to any one of claims 13 to 18, comprising slot information. 20. The base station according to claim 13, further comprising means for allocating a slot to a frame according to a service class included in a QoS request transmitted from the mobile station. 21. A mobile station that communicates with the base station according to claim 13, wherein the mobile station transmits information including a QoS request in a first packet of data to be transmitted to the base station. And a means for performing transmission in the assigned slot notified by the control mini-slot.