JPH10209956A - Radio packet communication method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a radio packet communication method with which the throughput of entire channel can be prevented from being lowered in a TDMA- TDD radio communication system. SOLUTION: At the slot of down channel 3-1, the number of slot transmissible due to random access namely, idle slot information 3-8 is periodically reported and at the time point when a transmission packet is generated, a radio packet terminal receives this idle slot information 3-8, selects any slot out of accessible up slots at random and performs random access through this slot. As a result, up access load is prevented from being concentrated to any specified slot by the configuration of TDD like the case of performing random access immediately at the time point of packet generation, and can be uniformly distributed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a TDMA-TDD.
(Time-division multiplexing / single-wave decoding system) This relates to an access system for performing packet communication in a wireless communication system.

[0002]

[Prior art]

§1. Prior art 1 (general random access) When wireless packet communication is performed between a wireless base station and a plurality of wireless packet terminals, the normal random access by the wireless packet terminals immediately follows when a transmission packet is generated. , Access to the channel is started.
FIG. 13 shows ICMA (Idle signal Casting Multiple Acc).
ess) shows an operation example of the method. In this method, in the downlink channel (12-1), the use status of the uplink channel (12-2) is indicated by a Busy / Idle signal (12-3), and when busy, Busy is used. Idle is announced.
When an uplink packet is generated, the wireless packet terminal immediately receives a control signal (Busy / Idle signal) on the downlink channel, and performs random access on the immediately subsequent uplink channel when the Idle signal is broadcast.

§2. Prior art 2 (TDD ALOHA reservation method) As shown in FIG. 14, a frame of this method includes a plurality of uplink control slots (13-2), downlink control slots (13-3), and It consists of a data transfer slot (13-4) used for packet transfer. In this scheme, a radio packet terminal that intends to transmit first transmits a reservation signal (13-7) in an uplink control slot, and the radio base station that has received the reservation signal (13-7) determines whether there is another uplink packet or downlink packet. In consideration of the above, a data transfer slot is allocated, and in the downlink control slot, data transfer slot allocation information (13
-8) is notified. The wireless packet terminal transmitting the reservation signal transmits the uplink packet (13-9) at the timing indicated by the slot allocation information. In this system, the distribution of uplink / downlink is dynamically controlled. Also, the wireless packet terminal is synchronized with the TDD frame, and performs random access (slotted ALO) on a slot randomly selected from a plurality of uplink control slots.
HA).

[0004]

By the way, in the above-described conventional wireless packet communication method, when upstream and downstream are mixed in one frame as in TDD, the conventional technology 1
As described above, there is a problem in that the reservation signal is concentrated in the uplink slot immediately after the downlink period.
As a result, there is a problem that the collision rate of the slot increases and the overall throughput decreases.

On the other hand, in the prior art 2, since a slot that can be randomly accessed is fixedly allocated in the frame as an uplink control slot, each wireless packet terminal synchronizes with the frame to set the slot to be accessed. Can be selected at random. However, since it is necessary to periodically secure control slots, the channel efficiency is reduced for randomly generated packets. Further, in a system in which a channel is shared with a circuit-switched call or another cell and an empty slot is dynamically allocated according to traffic, it is difficult to secure a sufficient number of control slots.

An object of the present invention is to provide a packet channel allocating method which solves the above points.

[0007]

Means for Solving the Problems In order to solve the problems described in the preceding section, in the present invention, in a downlink slot, the number of a transmittable slot by random access is periodically broadcast, and the radio packet terminal The most main feature is that, when a transmission packet is generated, the broadcast signal is received, a slot is randomly selected from accessible uplink slots, and random access is performed in this slot. ). As a result, it is possible to prevent the uplink access load caused by the TDD configuration from concentrating on a specific slot, as in the case where random access is immediately performed when a packet is generated, and to uniformly distribute the uplink access load. By the way, when the transmission slot is selected at random as in claim 1, the packet is delayed because the wireless packet terminal transmits in the selected slot. For this reason,
Within this delay time, a packet call or circuit-switched call with another slot assignment may be interrupted, and the slot may already be in use at the time of packet transmission. Therefore,
Immediately before transmitting in the selected slot, each wireless packet terminal needs to confirm again that the slot is usable. This complicates the access operation and requires that the downlink signal be confirmed twice, which may be a factor in lowering the success rate of access, particularly in wireless communication with low reliability. Therefore, when a new packet call or circuit-switched call occurs, the radio base station notifies each radio packet terminal of the vacant space in which the information content has been changed due to the slot allocation to the packet call or circuit-switched call. Until the slot information is broadcast, the assignment of the slot to the packet call or the circuit-switched call is suspended (claim 2), and the access of the wireless packet terminal to the once broadcasted empty slot is guaranteed. As a result, the confirmation of the empty slot information can be performed only once, so that there is an effect that the access operation is simplified and the access incomplete rate due to a transmission error is reduced.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS §1. First Embodiment Hereinafter, a first embodiment of the present invention will be described with reference to the drawings. FIG. 1 shows an example of a system configuration according to the present embodiment.
FIG. 2 shows an example of a channel configuration in the present embodiment.
As shown in FIG. 1, the system according to the present embodiment includes a wireless base station (1-1) and a plurality of wireless packet terminals (1--1) existing in a wireless zone (1-4) formed by the wireless base station.
2) and a circuit switching terminal (1-3).

As shown in FIG. 2, the radio channel of the present embodiment is a vertically symmetric four-channel TDMA-TDD.
One or a plurality of slots (2-3) not used for a circuit-switched call are bundled and used as a packet channel. In FIG. 2, slot (2-4) is a slot used for circuit-switched call 1. On the packet channel, the downlink channel (2-
1) is continuously transmitted from the wireless base station, but in the uplink channel (2-2), a signal is transmitted only when a packet occurs, and signals of a plurality of wireless packet terminals are packet-multiplexed.

In the present embodiment, when there is no empty slot at the time of occurrence of a circuit-switched call and a packet channel is set, one of the slots of the packet channel is set.
Release one and assign it to a circuit-switched call. In FIG. 2, slots 0, 1, and 3 are initially used as packet channels, but thereafter, slot 1 is assigned as a communication slot (2-7) of the interrupted circuit-switched call 2,
As a result, it is shown that the remaining slots 0 and 3 are packet channels. As described above, in the present embodiment, slots are preferentially allocated to circuit-switched calls, and slots not used for circuit switching are used as packet channels.

Next, FIG. 3 shows an example of transferring an upstream packet in the present embodiment. Here, slot 1 is used as a circuit-switched call 1 slot (3-4), and the remaining slots are set as packets (3-3). Empty slot information (3-8) is given to each downlink slot, and the number of a slot currently available for random access of a packet is broadcasted (here, slots 0, 2, and 3 are empty slots). is there).

The wireless packet terminal where the transmission data has occurred is
An arbitrary downlink slot is received, and a slot used by the own station is randomly selected from the empty slot information broadcast there. In FIG. 3, during the period of frame F = 1, the radio packet terminal in which uplink packet 1 has occurred receives slot 0 of the next frame (frame F = 2), selects uplink slot 2 as a slot to be accessed, You are doing random access. Similarly, in frame F = 4, the wireless packet terminal in which uplink packet 2 has occurred
Receives downlink slot 3 of frame F = 4, slot 2
Is selected as an access slot. Here, transmission cannot be performed in uplink slot 2 immediately after the access slot selection (that is, uplink slot 2 of frame F = 4) because sufficient control delay cannot be secured, and transmission is performed in slot 2 of the next frame (frame F = 5). I'm going to do it.

On the other hand, if a circuit-switched call 2 is generated during the period of frame F = 4, the radio base station sets the upper and lower slots 2 after frame F = 5 to the slot for circuit-switched call 2 (3-7). ) Is assigned to the circuit-switched call 2. As a result, the empty slot information of each downlink slot reports (0, 2, 3) up to slot 1 of frame F = 5, and (0, 3) after slot 2 of the same frame as empty slots. Therefore, immediately before transmission, during the period of frame F = 5, referring to the empty slot information of downlink slot 2,
The wireless packet terminal that has confirmed that slot 2 has been deleted from the vacant slot information suspends transmission of slot F of frame F = 5 in slot 2 and attempts access again after a random delay.

As described above, in order for the wireless packet terminal in which the uplink packet 2 has occurred to interrupt the transmission operation in the slot 2 of the frame F = 5, immediately before the transmission, the empty slot information of the corresponding downlink slot is re-examined. It is necessary to confirm. Therefore, the wireless packet terminal obtains an accessible slot number and checks immediately before transmission whether or not the selected slot is unusable halfway,
It is necessary to receive the empty slot information twice in total.

Next, an operation example of the radio base station and the radio packet terminal according to the present embodiment will be described. FIG. 4 shows an operation flow of the wireless packet terminal in the present embodiment. The wireless packet terminal having generated the transmission packet first receives the empty slot information broadcast in the downlink slot (step 6-2). If there is an accessible slot available here (step 6-3), an up slot to be used for access by the own station is randomly selected from the available slots (step 6-4). After that, it waits until the selected slot (step 6-5), confirms the empty slot information again immediately before transmission (step 6-6), and if the selected transmission slot is idle, packet transmission is continued. Perform (step 6-8), but if it is already occupied by another communication, return to step 6-3 again to select a slot again.

Next, an operation flow of the radio base station in the present embodiment is shown in FIG. The radio base station always broadcasts empty slot information in the downlink slot (step 7-).
2) If a circuit-switched call occurs (step 7-3)
Determines whether there is a slot allocated for a packet (step 7-6), and if there is no allocatable slot such as being all allocated to circuit switching, a call loss occurs. (Step 7-7). On the other hand, if there is a packet slot that can be assigned to circuit switching, one of them is diverted for circuit switching. After selecting a slot to be diverted (step 7-8), the slot for the packet is released (step 7-9), and the slot is allocated to a circuit-switched call (step 7-11).
At the same time, the empty slot information is changed (step 7).
-10). Conversely, when the circuit-switched call is completed (step 7-4), the slot used for the communication is diverted for packet communication (step 7-5), and the vacant slot information is changed. (Step 7-10).

§2. Second Embodiment Next, a second embodiment of the present invention will be described. Note that the system configuration example and the channel configuration example in the present embodiment are the same as those in the first embodiment (see FIGS. 1 and 2). FIG. 6 shows an example of transferring an upstream packet in the present embodiment. Here, as in FIG. 3, slot 1 is used as a slot (4-4) for circuit-switched call 1. The empty slot information (4-8) is broadcast only in the slot 0 of each frame, and each wireless packet terminal always receives this slot.

The radio packet terminal in which the upstream packet 1 has occurred during the period of the frame F = 1 obtains free slot information from the downstream slot 0 of the frame F = 2, and then selects the upstream slot 2 to obtain the frame F = 2, random access is performed. Similarly, the radio packet terminal in which the upstream packet 2 has occurred during the period of the frame F = 4 obtains the empty slot information from the downstream slot 0 of the next frame F = 5, and then obtains random information in the upstream slot 2 of the same frame F = 5. Have access.

In the frame F = 4, a circuit-switched call 2 is generated at the same time as the generation of the upstream packet 2.
In such a case, in the first embodiment, the slot is preferentially assigned to the circuit-switched call 2 in the frame immediately after the occurrence of the circuit-switched call 2 (frame F = 5). , The assignment in the frame immediately after the occurrence (frame F = 5) is suspended. This is because the slot F =
This is because it becomes 6 or later. Therefore, with frame F = 6,
At the same time as changing slot 0 to the slot for circuit-switched call 2 (4-7), the up slot 0 is deleted from the vacant slot information in the vacant slot information of the down slot 0. Accordingly, in the present embodiment, access to the slot specified by the empty slot information is guaranteed within the same frame, and the wireless packet terminal need only receive the downlink slot once before transmission. .

FIG. 7 shows an operation flow of the wireless packet terminal in the present embodiment. The difference from the first embodiment (FIG. 4) is that the determination (step 8-2) for selecting slot 0 for which the empty slot information is broadcast is added, and This means that the reconfirmation (steps 6-6 and 6-7 in FIG. 4) has been deleted.

FIG. 8 shows an operation flow of the radio base station in this embodiment. The main differences from the first embodiment (FIG. 5) are the notification of empty slot information (step 9-3), the release of a slot for a packet to be allocated to a circuit-switched call (step 9-5), and the Assignment to a switched call (step 9-6) is performed with slot 0 as an opportunity (step 9-2). As a result, slot assignment to a circuit-switched call received at a timing other than slot 0 is as follows:
The call is held until the empty slot information in which the information content is changed in accordance with the slot assignment to the call is notified.

The embodiment of the present invention has been described in detail with reference to the drawings. However, the specific configuration is not limited to this embodiment, and a design change or the like may be made without departing from the gist of the present invention. Even if there is, it is included in the present invention.

[0023]

Next, a specific example of the above embodiment will be described. In this embodiment, a system configuration in which the circuit switching terminal (1-3) is omitted from FIG. 1 is used. Also,
In the above-described embodiment, a circuit-switched call is assumed as the interrupting communication. However, in the present embodiment, a case where a packet signal itself interrupts is considered. In the present embodiment, it is assumed that the packet is transferred using a plurality of slots continuously. Furthermore, random access is performed only in the first slot, and for subsequent data, the radio base station allocates a slot to be used for transfer based on information of the first packet received in random access. It shall be.

FIG. 9 shows an example of transfer of an upstream packet in this embodiment. Here, slot 3 is used as a slot for circuit-switched call 1 (5-4). Frame F =
The upstream packet 1 generated in 1 transmits the first data in the upstream slot 2 of the frame F = 2 with reference to the empty slot information (5-5) of the slot 0 of the frame F = 2.

On the other hand, the radio base station transmits the frame F =
An allocation notification is made in slot 2 of No. 3. In this assignment notice,
The slot number (0, 1, 2) used for packet transmission is indicated, and the wireless packet terminal transmits a packet using this slot continuously. However, since the empty slot information (0, 1, 2) has already been broadcasted in slot 0 of the same frame (frame F = 3), the subsequent data of packet 1 Assigned.

At this time, as described above, the frame F =
In slot 0 of slot 3, empty slot information (0, 1,
2), the frame F = 3,
It is assumed that a new packet 2 has been generated and that the leading data has been transmitted in uplink slot 0. In this case, the wireless base station transmits the packet 1 for the subsequent data transfer of the packet 2.
The subsequent data is allocated from the slot immediately after the end of the transfer (slot 1 of frame F = 5). At the same time, the vacant slot information is updated according to the slot allocation status after frame F = 4. Here, (-) indicates that there is no usable slot. Note that the present embodiment is a case in which the second embodiment is considered, but can be realized using only the first embodiment.

FIG. 10 shows an operation flow of the wireless packet terminal in the present embodiment. The difference from the second embodiment (FIG. 7) is that the packet transmission is divided into the first data and the subsequent data, and the wireless packet terminal transmits the first data (step 10-7) and then transmits the first data from the wireless base station. The point is that the assignment signal is received (step 10-8), and the subsequent data is transmitted (step 10-11) using one or a plurality of slots designated there continuously. here,
If the head data is not correctly received by the radio base station due to a collision or the like, after the random delay (step 10-9), the processing is restarted from the reception of the empty slot information (step 10-3).

FIG. 11 shows an operation flow of the radio base station in this embodiment. Here, the flow relating to the assignment of circuit switching is omitted. The wireless base station reports empty slot information in slot 0 (step 11-3), and when receiving the first data in the packet uplink slot (step 11-4), sets the uplink slot to be used for transmitting the subsequent packet. Assign one or more. Here, if an uplink slot has already been assigned to another packet, it is necessary to cause the subsequent packet to be transmitted immediately after the transmission of this packet ends. In order to do this, for example, it is necessary to specify the length of the succeeding packet in the head data and perform scheduling such as calculating the timing for transmitting each packet based on this information in the radio base station. It is effective. In the present embodiment, the radio base station performs this scheduling (step 11-5), and transmits an assignment signal designating transmission timing (step 11-6). Thereafter, the free slot information is changed based on the scheduled result (step 11-7). Also, when the transmission of all the packets being transmitted has been completed (step 11-
8) also changes the empty slot information (step 11-7)
After that, the process returns to step 11-2.

FIG. 12 shows theoretical calculation results when the packet throughput according to the present invention is applied to a 4-channel TDMA-TDD. As shown in this figure, when the present invention is used, the throughput is improved over almost the entire region except for the overload state. In addition, there is no need to periodically secure a slot for random access, and the radio base station dynamically designates an access slot according to the use state of the slot. It is easy to realize even when shared with other cells.

[0030]

According to the present invention, it is possible to prevent random access from being concentrated on a specific slot depending on the configuration of the TDD. Furthermore, in the present invention, even when using the multi-slot access method of the present invention, the wireless packet terminal need only receive a specific slot at the time of access,
Since it is only necessary to confirm the empty slot information once, there is an effect that the access operation is simplified and the access incomplete rate due to a transmission error is reduced.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram illustrating a system configuration example according to a first embodiment and a second embodiment.

FIG. 2 is an explanatory diagram showing a channel configuration example in the first embodiment and the second embodiment.

FIG. 3 is an explanatory diagram illustrating an example of packet transfer according to the first embodiment.

FIG. 4 is a flowchart illustrating an operation example of the wireless packet terminal according to the first embodiment.

FIG. 5 is a flowchart illustrating an operation example of the wireless base station according to the first embodiment.

FIG. 6 is an explanatory diagram illustrating a packet transfer example according to the second embodiment.

FIG. 7 is a flowchart illustrating an operation example of a wireless packet terminal according to the second embodiment.

FIG. 8 is a flowchart illustrating an operation example of a wireless base station according to the second embodiment.

FIG. 9 is an explanatory diagram illustrating an example of packet transfer according to the embodiment;

FIG. 10 is a flowchart illustrating an operation example of the wireless packet terminal according to the embodiment.

FIG. 11 is a flowchart illustrating an operation example of the wireless base station in the embodiment.

FIG. 12 is a graph showing the effect of improving the throughput according to the present invention.

FIG. 13 is an explanatory diagram showing an operation example of the ICMA method.

FIG. 14 is an explanatory diagram showing an operation example of the TDD ALOHA reservation method.

[Explanation of symbols]

1-1: wireless base station 1-2: wireless packet terminal 1-3: circuit-switched terminal 1-4: wireless zone, 2-1, 3-1, 4-1 and 5-1 ..., downlink channel, 2-2, 3-2, 4-2, 5-2 ... uplink channel, 2-3, 3-3, 4-3, 5-3 ... packet slot, 2-4 3-4, 4-4, 5-4 ... slots for circuit-switched call 1, 2-7, 3-7, 4-7 ... slots for circuit-switched call 2, 3-8, 4-8, 5- 5 ... Free slot information

──────────────────────────────────────────────────の Continued on front page (51) Int.Cl. ⁶ Identification code FI H04Q 7/26 7/30 11/04 301

Claims (2)

[Claims] 1. A wireless packet communication is performed between a wireless base station and a plurality of wireless packet terminals under the wireless base station by using a common packet channel. It takes a frame configuration in which slots are combined into one frame, and further includes a downlink slot for transferring a packet from the radio base station to the radio packet terminal, and an uplink slot for transferring a packet from the radio packet terminal to the radio base station. A wireless packet communication method that applies a one-wave duplex method that is multiplexed in a time-division manner within the frame and the wireless packet terminal performs random access in the uplink slot and transmits a packet; In the downlink slot, empty slot information indicating an uplink slot usable for packet communication is provided. Broadcast every slot or at regular intervals, prior to performing random access, the radio packet terminal receives the broadcasted empty slot information, and from among the uplink slots indicated by the empty slot information. , Randomly selecting an uplink slot to be used for the random access, and then immediately before performing transmission in the selected uplink slot, receiving the empty slot information again, and the uplink slot is still usable. And transmitting the packet after confirming the above. 2. A wireless packet communication is performed between a wireless base station and a plurality of wireless packet terminals under the wireless base station by using a common packet channel. It takes a frame configuration in which slots are combined into one frame, and further includes a downlink slot for transferring a packet from the radio base station to the radio packet terminal, and an uplink slot for transferring a packet from the radio packet terminal to the radio base station. A wireless packet communication method that applies a one-wave duplex method that is multiplexed in a time-division manner within the frame and the wireless packet terminal performs random access in the uplink slot and transmits a packet; In the downlink slot, the free slot information is reported at regular intervals, Prior to performing random access, receive the broadcasted empty slot information, from among the uplink slots indicated by the empty slot information, randomly select an uplink slot to be used for the random access, Transmitting the packet in the selected uplink slot, and, when a packet call or a circuit-switched call accompanied by a new slot allocation occurs, the radio base station assigns a slot to the packet call or the circuit-switched call. A wireless packet communication method, wherein the allocation of slots for the packet call or the circuit-switched call is suspended until the vacant slot information having the accompanying change is notified.