JPH09107580A - Radio channel allocation method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To set a time slot interval in response to a frequency switching capability by providing a time slot interval between adjacent radio channels in a TDMA(time division multiplex access) frame. SOLUTION: Let a length of an i-th time slot in a TDMA frame be Tts(i), and a time required to frequency switching by a radio terminal equipment be Tcg, then at least a k (k is an integer being 1 or over) time slot interval is provided between radio channels with different frequency. In this case the number (k) satisfies equation I.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a radio channel allocation method for deciding a method of allocating a plurality of radio channels between a radio base station and a radio terminal which communicate by a TDMA (Time Division Multiple Access) communication system.

[0002]

2. Description of the Related Art FIG. 9 shows an arrangement example of radio channels.
In the figure, n times are allocated to m timeslots (TS) 1 to m of 1 TDMA frame, and m × n wireless channels (1,1) to (m, n) are arranged as a whole. . For example, the combination of the time slot (TS) 3 and the frequency 2 forms the wireless channel (3, 2).

FIG. 10 shows an example of conventional radio channel allocation. In the conventional radio channel allocation method, a method of allocating one radio channel such as radio channel (3, 2) between a radio base station and a radio terminal is generally used. Even when assigning multiple wireless channels, wireless channels with the same frequency are selected, such as wireless channels (1,4), (2,4), (3,4), (4,4). It was

Further, when the already assigned radio channel cannot be used continuously due to the influence of an interference wave or the like, and when switching to another radio channel, a radio channel of another time slot of the same frequency is selected. It was FIG.
In the example shown in 0, wireless channels (1,4), (2,4), (3,4), (4,
4) is assigned, the radio channel (5,4) ~
It was switched to either (m, 4).

[0005]

By the way, a method of allocating different frequencies between radio channels when allocating a plurality of radio channels in a TDMA frame or switching radio channels is being studied. In order to realize this, it is necessary for the radio base station and the radio terminal to switch the frequency of the oscillator within the guard time between each time slot, or to switch by providing a plurality of oscillators having different oscillation frequencies. However, in the former case, high-speed frequency switching is required, and in the latter case, an increase in power consumption and a decrease in portability due to the provision of a plurality of oscillators cannot be avoided.

From the above, a method has been considered in which, when a plurality of radio channels are allocated, a time slot is separated by at least one time slot to allow a margin for frequency switching between the radio channels and one oscillator is used. However, the method of determining the number of time slots to be actually separated is not considered. The present invention sets the time slot interval of each radio channel according to the frequency switching ability of the radio terminal when allocating a plurality of radio channels having different frequencies in a TDMA frame or when switching to a radio channel having a different frequency. It is an object of the present invention to provide a wireless channel allocation method that enables the

[0007]

According to the wireless channel allocation method of the present invention, the time slot lengths are not uniform.
When allocating a plurality of radio channels having different frequencies in a DMA frame, an interval of at least k time slots is provided between adjacent radio channels. This k is (1)
The minimum value obtained by the formula.

Further, the radio channel allocating method of the present invention, when allocating a plurality of radio channels having different frequencies in a TDMA frame having a uniform time slot length, at least [Tcg /
Tts] +1 time slot interval is provided.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION

(Embodiment of claim 1) FIG. 1 is a flowchart showing a wireless channel allocation method according to claim 1. TDMA
Let Tts (i) be the length of the i-th time slot in the frame
, Tcg is the time required to switch the frequency of the wireless terminal. Here, it is assumed that Tcg is longer than the guard time between time slots, and the frequency cannot be switched between adjacent time slots. Therefore, at least k (k is an integer of 1 or more) between wireless channels with different frequencies.
Provide time slot intervals. k is calculated as follows.

For the radio channel assigned to the j-th time slot in the TDMA frame, the length T from the j + 1-th to the j + k-th time slots is calculated.
T is

[0011]

(Equation 2)

## EQU1 ## First, T (=
It is determined whether Tts (j + 1)) is larger than Tcg. When T is smaller than Tcg, T (= Tts (j
+1) + Tts (j + 2)) is greater than Tcg. Similarly, the minimum k when T ≧ Tcg is obtained. As a result, the time slot to be assigned next to the radio channel assigned to the j-th time slot is j
It is the + k + 1th and subsequent ones.

(Embodiment of Claim 2) FIG.
3 is a flowchart showing a wireless channel allocation method of FIG. Tts in which the length of the time slot in the TDMA frame is uniform, and the time required for frequency switching of the wireless terminal is Tcg.
And Here, it is assumed that Tcg is longer than the guard time between time slots, and the frequency cannot be switched between adjacent time slots. Therefore, the minimum number of time slots required between radio channels having different frequencies is k =
[Tcg / Tts] +1 is calculated. Where [Tcg / Tts]
Is the maximum integer that does not exceed Tcg / Tts. As a result, the time slot to be assigned next to the radio channel assigned to the j-th time slot will be the j + k + 1-th time and thereafter.

(Embodiment of Claim 3) FIG.
3 is a flowchart showing a wireless channel allocation method of FIG. Here, it is assumed that the time Tcg required for frequency switching of the wireless terminal is defined as the performance at the time of system construction. Radio channels are assigned based on this regulation. That is, it is determined whether or not the lengths of the time slots in the TDMA frame are uniform, and if they are not uniform, the process proceeds to the flowchart shown in FIG. 1, and if they are uniform, the process proceeds to the flowchart shown in FIG.

(Embodiment of Claim 4) FIG.
3 is a flowchart showing a wireless channel allocation method of FIG. Here, it is assumed that the time Tcg required for frequency switching of the wireless terminal is stored in a database provided in the wireless base station or a database accessible from the wireless base station. Radio channels are assigned based on this data. That is, it is determined whether or not the lengths of the time slots in the TDMA frame are uniform, and if they are not uniform, the process proceeds to the flowchart shown in FIG. 1, and if they are uniform, the process proceeds to the flowchart shown in FIG.

(Embodiment of Claim 5) FIG.
3 is a flowchart showing a wireless channel allocation method of FIG. Here, it is assumed that the wireless terminal notifies the wireless base station of the time Tcg required for frequency switching of the wireless terminal when the wireless channel is allocated. Radio channels are assigned based on this notification. That is, TDMA
It is determined whether or not the lengths of the time slots in the frame are uniform, and if they are not uniform, the process proceeds to the flowchart shown in FIG. 1, and if they are uniform, the process proceeds to the flowchart shown in FIG.

[0017]

【Example】

(Embodiment of claim 1) FIG. 6 shows an example of wireless channel allocation in the wireless channel allocation method of claim 1.
First, it is assumed that the wireless channel (1, 2) is set by the combination of the time slot (TS) 1 and the frequency 2. Next, when allocating the radio channel of the same frequency, the radio channel (2,2) is selected. On the other hand, when allocating a radio channel of a different frequency next, k is determined according to the flowchart shown in FIG. Here, an example in which the wireless channel (3,3) is selected while k = 1 for j = 1 and the wireless channels after the time slot (TS) 3 can be selected is shown.

Next, when allocating the radio channel of the same frequency, the radio channel (4, 3) is selected. on the other hand,
Next, when assigning radio channels of different frequencies, k is similarly determined. Here, since the length of the time slots (TS) 4 and 5 is short, k = for j = 3.
2, the wireless channel (6,1) is selected while the wireless channels after the time slot (TS) 6 can be selected.

The time slot to which the last radio channel of the TDMA frame is assigned is the next TDMA.
At least k with the first radio channel of the frame
Allow time slot spacing. FIG.
Shows an example of wireless channel switching in the wireless channel allocation method of claim 1.

In the figure, radio channels (1,2), (3,3),
It is assumed that (6,1), ... Has already been assigned. Here, when it becomes impossible to continue using the wireless channel (3, 3) due to an interference wave or the like, the candidates for the switching destination of the wireless channel are as follows. If the frequency switching is not performed for the immediately preceding wireless channel (1, 2), the wireless channel
(2,2) and (3,2) are candidates, and one time slot interval is required for frequency switching.
(3,1), (3,4), ..., (3, n) are candidates. On the other hand, if frequency switching is not performed for the radio channel (6,1) immediately after that, radio channels (3,1), (4,1), (5,1) become candidates,
When frequency switching is performed, since an interval of two time slots is required, wireless channels (3,2), (3,4), ..., (3, n) are candidates. The wireless channels that are candidates for channel switching have been hatched in the figure.

(Embodiment of claim 2) FIG. 8 shows an example of radio channel allocation in the radio channel allocation method of claim 2. First, it is assumed that the wireless channel (1,2) is set by the combination of the time slot 1 and the frequency 2. Next, when allocating the radio channel of the same frequency, the radio channel (2,2) is selected. On the other hand, when allocating a radio channel of a different frequency next, k = 1 is determined according to the flowchart shown in FIG. here,
An example in which the wireless channel (3,3) is selected while the wireless channels after time slot 3 can be selected is shown.

Next, when allocating the radio channels of the same frequency, the radio channel (4, 3) is selected. on the other hand,
Next, when allocating radio channels of different frequencies, an example in which the radio channel (6, 1) is selected while the radio channels after the time slot 5 can be selected is shown.
The time slot to which the last radio channel of the TDMA frame is assigned is arranged so that at least one time slot is provided between the time slot and the first radio channel of the next TDMA frame.

(Other Embodiments) The radio channel allocation method of the present invention can also be applied to the allocation of control channels and data transfer channels used in TDMA frames. Here, the control channel is a channel for performing communication control such as allocation of data transfer channels.

For example, in the radio channel allocation example shown in FIG. 8, the radio channels (1,2) are used as control channels, and the radio channels (3,3), (6,1), ... Are used as data transfer channels. You can The number of data transfer channels may be single.

[0025]

As described above, according to the wireless channel allocation method of the present invention, when the required number of wireless channels cannot be secured in one frequency, it is possible to allocate in another frequency. The degree of freedom of allocation can be increased. Further, when it becomes necessary to switch the already assigned wireless channels, it is possible to perform assignment using another frequency, so that the degree of freedom in channel switching can be increased.

[Brief description of the drawings]

FIG. 1 is a flowchart showing a wireless channel allocation method according to claim 1.

FIG. 2 is a flowchart showing a wireless channel allocation method according to claim 2.

FIG. 3 is a flowchart showing a wireless channel allocation method according to claim 3.

FIG. 4 is a flowchart showing a wireless channel allocation method according to claim 4.

FIG. 5 is a flowchart showing a wireless channel allocation method according to claim 5.

FIG. 6 is a diagram showing an example of wireless channel allocation in the wireless channel allocation method of claim 1;

FIG. 7 is a diagram showing an example of wireless channel switching in the wireless channel allocation method of claim 1;

FIG. 8 is a diagram showing an example of wireless channel allocation in the wireless channel allocation method of claim 2;

FIG. 9 is a diagram showing an arrangement example of wireless channels.

FIG. 10 is a diagram showing an example of conventional radio channel allocation.

Claims (5)

[Claims] 1. A wireless communication system in which a wireless base station and a wireless terminal, which communicate by a TDMA communication method, communicate using a plurality of wireless channels in a TDMA frame, wherein a plurality of wireless devices having different frequencies in the TDMA frame are used. When allocating channels, if the length of the i-th time slot in the TDMA frame is Tts (i) and the time required for frequency switching of the wireless terminal is Tcg, the wireless channel allocated to the j-th time slot is When assigning the next wireless channel to The method for allocating a radio channel is characterized in that the minimum k that satisfies the above relationship is obtained, and at least k time slot intervals are provided between adjacent radio channels. 2. A wireless communication system in which a wireless base station and a wireless terminal, which communicate in a TDMA communication system, communicate using a plurality of wireless channels in a TDMA frame, wherein a plurality of wireless devices having different frequencies in the TDMA frame are used. When allocating a channel, the length of the time slot in the TDMA frame is Tts, and when the time required for frequency switching of the wireless terminal is Tcg, Tcg / Tts
A wireless channel allocation method, wherein a maximum integer not exceeding Tcg / Tts is represented as [Tcg / Tts] by providing at least [Tcg / Tts] +1 time slot interval between adjacent wireless channels. 3. The radio channel allocation method according to claim 1, wherein a time Tcg required for switching the frequency of the radio terminal is defined as a performance at the time of system construction. 4. The time Tcg required for frequency switching of the wireless terminal is stored in a database provided in the wireless base station or a database accessible from the wireless base station. The radio channel allocation method described. 5. The wireless channel allocation method according to claim 1, wherein the wireless terminal notifies the wireless base station of the time Tcg required for frequency switching of the wireless terminal when the wireless channel is allocated. .