JP2595166B2 - Channel assignment method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a channel allocation method in a multicarrier hopping TDMA system in a radio communication field such as a satellite communication and a mobile communication. The present invention relates to a channel allocation method that can reduce a call loss rate for a transmission / reception call relating to a station.

[0002]

2. Description of the Related Art FIG. 4 shows a multicarrier hopping TDM.
Shows an example of a typical system configuration of a satellite communication system according to A method, which according to the case, the slave station 2 ₁ to 2 _L each channel allocation request based on random call arising from a transmission station number and the receiving station numbers and call When the control station 1 is at the control station 1 via the communication satellite 3 together with the speed type, the control station 1 determines the channel positions to be allocated to the call for the required number of channels, and transmits the channel position to the slave station that has issued the channel allocation request. The channel and the receiving channel are notified to the slave station of the communication destination in advance.
Here, the concept of the channel is referred to as multicarrier hopping T
To explain the DMA system, this is because, as shown in FIG. 5, the number of channels per carrier is N (N: 2
The number of carriers is M (M: an integer of 2 or more),
Therefore, the number of time slots is N and the number of all channels is M
× N. When the data burst 4 is of the basic rate, one of the available channels is allocated to a predetermined one. However, as the data rate increases, two or more empty channels need to be allocated. I have.

Now, multicarrier hopping TDMA
The following describes the channel allocation method according to the prior art in the system. However, in the following description, for the sake of simplicity, each slave station can transmit and receive only one carrier within one time slot. Therefore, the maximum number of channels that can be transmitted and received at each slave station is the number of channels per carrier. (= N). That is, FIG.
1 shows a main configuration of a control station according to a channel allocation method described in Japanese Patent Application Laid-Open No. 44829/44. In this case, the channel management table 7 indicates whether or not each channel is currently idle, and for each non-empty channel, the transmitting station (unique identification) number for each slave station that is currently using it. The receiving station (unique identification) number can be updated at any time, and is managed under the control of the call control management unit 5. The vacant channel searching unit 8 based on a command from the call control managing unit 5 searches the vacant channel position in the time slot designated by the call control managing unit 5 from the channel management table 7, The total number of transmission channels of the designated transmitting station and the total number of receiving channels of the designated receiving station in the time slot designated by the call control management unit 5 are obtained from the channel management table 7 (as described above, the child station Since each of the allowable number of transmission / reception channels within one time slot is one, it is sufficient to actually check the presence / absence of a transmission channel at the designated transmission station and the presence / absence of a reception channel at the designated reception station. ).

More specifically, FIG. 7 shows a channel allocation control flow in the control station shown in FIG. In this case, assuming that a call from the transmitting station 2 _i to the receiving station 2 _j newly occurs, the call control management unit 5 first specifies the time slot t ₁ to the empty channel search unit 8. It has become. Based on this, the free channel in time slot search section 8 searches for a free channel in the time slot t ₁ from the channel management table 7. As a result, when an empty channel exists in the time slot t ₁ , the call control management unit 5 specifies the time slot t ₁ , the transmission station number i, and the reception station number j to the used channel number measurement unit 6. Thereafter, the used channel number measuring unit 6 calculates the total number of transmission channels of the transmitting station 2 _i (presence or absence of transmission channels) and the total number of reception channels of the receiving station 2 _j (presence or absence of reception channels) in the time slot t ₁ from the channel management table 7. It is something that can be done. As a result, if the transmitting station 2 _i is not currently used for transmission and the receiving station 2 _j is not currently used for receiving, one empty channel in the time slot t ₁ is selected, and The newly generated call (hereinafter, referred to as a new call) is allocated as a used channel. Thereafter, the call control management unit 5 sets the transmitting station number i and the receiving station number j to the newly allocated channel position on the channel management table 7, thereby completing the process of selecting an empty channel. .
At this time, if there is no free channel in the time slot t ₁ , or if there is a free channel,
If the transmitting station 2 _i has already been used for transmission or the receiving station 2 j has already been used for receiving, it is not possible to select an empty channel in the time slot t ₁ , Is selected until the other time slots t ₂ , t ₃ ,... T _N
The same process is repeated each time the data is sequentially updated, so that an empty channel is selected. If the new call is a high-speed call and the required number of channels for the new call is k (k: an integer of 2 or more) channels, k channels are selected by the same processing, and Although it is assigned, if k channels cannot be selected, it is treated as a call loss.

Here, the above-mentioned channel allocation method will be described in detail with reference to FIGS. 8 (a) to 8 (c) which show a specific example of the channel management table 7.
After being a matrix structure of M, the element (n, m) in each channel (t _n, f _m) calls using the (A → B)
The transmission station number A and the reception station number B are stored as updatable. However, in FIGS. 8A to 8C,
(O → O) indicates an empty channel, and all channels in each of the elements not shown represent non-empty channels. Now, first, the channel allocation state in FIG. 8 (a), the assuming a case where the number of the required channel has occurred is one channel of the call (2 → 3) to the receiving station 2 ₃ from the transmitting station 2 _2, the call control The time slot t ₁ is specified from the management unit 5 to the free channel search unit 8, and based on this, the free channel search unit 8 searches the channel management table 7 to find a free channel at the channel (t ₁ , f _M ) position. Will be found. Based on this, the time slot t ₁ , the transmitting station number 2 and the receiving station number 3 are designated from the call control management section 5 to the number-of-used-channels measuring section 6, and the number-of-used-channels measuring section 6 stores the number in the channel management table 7. in time slot t _1, but it will be examined and the presence or absence of reception of the presence or absence and the receiving station 2 ₃ transmission on the transmission station 2 _2, as a result, that the transmitting station 2 ₂ has already been used for transmission It is something to find. Accordingly, it is intended to determined that idle channel time slots t ₁ the call control management unit 5 is not selectable. afterwards,
Subsequently, when the same processing for the time slot t _2, time slot t ₂ in channel (t _2, f
₁₎ free channel is present at the position, moreover since the transmission in the transmission station 2 ₂ not performed, also received the receiving station 2 ₃ is not performed, after all, the unused channel (t
₂ , f ₁ ) is assigned to a new call (2 → 3). The required number of channels for the new call (2 → 3) is 1
Since the channel is a channel, the selection of an empty channel is completed by this, and the channel (t ₂ , f ₁ ) becomes as shown in FIG.
It is updated from (0 → 0) to (1 → 2).

[0006]

As described above, according to the channel assignment method according to the prior art, a new call (2 → 3) generated in the channel assignment state shown in FIG. (b), the has to those assigned to the time slot the time slot t _2. Here, consider a case where communication traffic is concentrated on a specific slave station. Figure 9 is an example, the traffic volume of bias in the case where traffic in the slave station 2 ₁ is concentrated, the slave station 2 ₁ to 2 _L
This is indicated by the thickness of an arrow connecting between them. The thicker the arrow, the greater the traffic volume, but such a bias in traffic volume can be caused by, for example, one large-scale head office and small branches scattered around. Among them, it has been found that various business communications are performed via a satellite communication system. In such a case, station child traffic is concentrated (hereinafter, referred to as toll) calls going from 2 ₁ to another slave station 2 _x (1 → X)
(X ≠ 1), or directed from the other slave stations 2 _x to the central station 2 ₁ call (X → 1) frequency ratio (X ≠ 1) occurs, receiving a call toll 2 ₁ no matter (X → Y) (X ≠ 1, Y
The frequency ratio of occurrence of (1) is considerably larger.

Accordingly, the channel allocation state shown in FIG. 8 (b), for example, new toll 2 ₁ slave station 2 ₂
Even if a call (1 → 2) occurs to the central station 2 ₁ , the two time slots t ₁ and t _N in which an empty channel exists are already used for transmission. It can be seen that a channel cannot be assigned to 1 → 2), resulting in a call loss. However, if the previous call (2 →
In assigning 3), previously detected in advance that traffic to the central station 2 ₁ is concentrated, as shown in FIG. 8 (c), the call (2 → 3) to the in the time slot t _N vacant channel (t _N, f ₂₎ by assigning a time slot t ₂ the frequency ratio is greater call, i.e., if so set aside for allocation of transmission and reception call according to the central station 2 _1, a new call (1 → 2) means that a channel can be allocated without causing a call loss.

[0008] As described above, the easy reception call according to the central station 2 ₁ is a call loss, in the channel assignment method according to the prior art, as the time slot t ₂ in FIG. 8 (b), the central station 2 The cause is required because a time slot in which there is no transmitted / received call related to _{1 or in} which an empty channel cannot be selected is likely to appear.

An object of the present invention is to provide a channel allocation system capable of suppressing a call loss rate for a transmission / reception call relating to a specific slave station when traffic is concentrated in a specific slave station.

[0010]

The above object is achieved by the means described in the appended claims. That is, prior to each of the plurality of slave stations transmitting and receiving a burst including information data to and from each other, the control station transmits an arbitrary carrier within one time slot based on a channel assignment request from each of the slave stations. What is claimed is: 1. A multicarrier hopping TDMA system for allocating as a channel to be used, comprising: first means for managing a transmission station number and a reception station number for each channel; Second means for measuring the total number of transmission channels of the designated transmitting station and the total number of receiving channels of the designated receiving station, and a third means for searching for an allocatable vacant channel in an arbitrary time slot or carrier.
Means, and when a new call is generated, the third
Means for allocating a call newly generated to a vacant channel searched by the means for detecting a station to which traffic is concentrated, comprising: The number of used channels of the station where the traffic detected by the fourth means is concentrated is measured with respect to the time slot in which the vacant channel exists, and the number of used channels of the station where the traffic is concentrated is measured. This is a channel allocation method in which the number of available channels equal to the number of required channels of a newly generated call is selected and assigned to a newly generated call.

[0011]

When selecting a free channel by the channel allocation method according to the prior art, the selection of a time slot in which a free channel can be selected is performed based on the station number of a slave station related to traffic concentration detected separately in advance. The priority order is controlled. That is,
Based on the station number of the slave station related to the traffic concentration that has been separately detected in advance, the total number of transmitted / received calls related to the slave station in each of the time slots in which a vacant channel can be selected from the management table is determined, and the number is determined according to the call speed type. Only one vacant channel is selected from each of the vacant channel selectable time slots. In the case of allocation for burst transmission / reception, a time slot in which no transmission / reception call relating to the slave station does not exist and in which a vacant channel cannot be selected is less likely to appear, so that the call loss rate for transmission / reception call relating to the slave station is suppressed to a small value.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to FIGS. First, the control station according to the present invention will be described with reference to FIG.
Shows the configuration of the main part in one example. As shown in the figure, the control station includes a call control management unit 5, a used channel number measurement unit 6, a channel management table 7, and a free channel search unit 8, and the functions of these components are based on the above-described conventional technology. It is the same as that at the control station. The difference from the control station according to the prior art is that a centralized station detection unit 9 is newly added. In general, the central station detecting section 9 constantly monitors the traffic that fluctuates every moment, and as a result of the monitoring, detects that the slave station where the traffic is currently concentrated is updatable.

FIG. 1 also shows the flow of channel allocation control at the control station according to the present invention. In this case, assuming that a new call from the transmitting station 2 _i to the receiving station 2 _j occurs, the call control management unit 5 first specifies the time slot t ₁ to the empty channel search unit 8. was over, it has become a vacant channel is searched in the time slots t ₁ on the channel management table 7 by idle channel search unit 8. As a result of the search, if there is an empty channel in the time slot t ₁ , the call control management unit 5 sends the used channel number measurement unit 6
Time slot t ₁ and the transmission station number i and the reception station number j is specified, the number of used channels measuring unit 6, the presence or absence and the reception of the transmission at the transmission station 2 _i in time slot t ₁ on the channel management table 7 with respect to The presence or absence of reception at the station 2 _j can be checked. As a result, the transmitting station 2 _i is not used for transmission and the receiving station 2 _j
There when not used for reception, the call control management unit 5 is adapted to select the time slot t ₁ as prima facie assignable time slots. Thereafter, the call control management unit 5 sends the station number of the centralized station detected by the centralized station detecting unit 9 to the used channel number measuring unit 6,
It has become a thing of the time slot t ₁ is specified. Depending on the used channel number measuring unit 6 based on this designation,
The total number of used channels related to the designated central station in the time slot t ₁ on the channel management table 7 is checked, and is notified to the call control management unit 5. With this, the call control manager 5 can know the presence or absence of an empty channel in the time slot t ₁ and the total number of used channels related to the designated central station. Such a process is sequentially repeated for each of the remaining time slots.

[0014] That is, either does not exist free channel on a time slot t _1, used in its time slot t _1, on whether the transmitting station 2 _i have already been used for transmission or reception station 2 _j is already received If it is, or if the total number of the number of channels used in accordance with the designated central station in the time slots t ₁ was examined, on the processing target time slot that have been updated in the time slot t _2, the same processing time slot it is intended to be performed for t _2.
Each of the time slots 2 _{3 to} 2 _N is sequentially performed. As a result of such processing, at the time when the processing for the last time slot t _N is completed, the call control management unit 5 sets the time at which an available channel can be selected. The total number of slots and the number of channels used by the central station in each of the time slots is known. Based on this processing result, the call control management unit 5 selects the number of available channels equal to the required number of channels of the new call (i → j) in order from the time slot having the largest total number of channels used by the central station, and This is to be assigned to the new call (i → j). If, at this time, the number of time slots from which an empty channel can be selected is small and the number of empty channels equal to the required number of channels for a new call (i → j) cannot be selected, it is determined as a call loss. As a result of such an idle channel selection process, a time slot in which a transmitted / received call related to the centralized station does not exist is less likely to appear, and as a result, a call loss rate for a transmitted / received call related to the centralized station is suppressed to a small value.

Here, the channel allocation method according to the present invention will be described more specifically with reference to FIGS. 8A to 8C described above. That is, when the traffic to the slave station 2 ₁ is concentrated currently, from the notification of the traffic condition monitoring result from the central station detection unit 9, that effect is made to that become known in advance by the call control manager 5 . Now, as the channel allocation state under such traffic conditions is as shown in FIG. 8 (a), similarly required number of channels to a receiving station 2 ₃ from the transmitting station 2 ₂ the previous example is one channel call Assuming that (2 → 3) occurs, first, a time slot t ₁ is specified from the call control management unit 5 to the free channel search unit 8, and based on this, the free channel search unit 8 By searching the time slot t ₁ on the management table 7, an empty channel is found at the position of the channel (t ₁ , f _M ). Next, the time slot t ₁ , the transmitting station number 2 and the receiving station number 3 are designated from the call control managing section 5 to the used channel number measuring section 6, and based on the time slot t ₁ , the used channel number measuring section 6 specifies the channel management table 7. The above time slot t ₁ is referred to.
_Since it is found that ₂ is already used for transmission in the time slot t ₁ , the call control manager 5 determines that it is impossible to select an empty channel from the time slot t ₁ .

Next, the time slot t_Two Similar for
If processing is performed, time slot t_TwoThen transmitting station 2_Two Sent
Not receiving and receiving station 2_Three Have not received
From the available channel (t_Two , F₁ ) Thailand exists
Muslot t_Two Is an allocatable time slot
It is to be selected. Thereafter, the call control manager 5
From the central station number 1 and
And time slot t _Two Is specified and the number of channels used
In the measuring unit 6, the time slot on the channel management table 7
t_Two By referring to the time slot t_Two At the inner
Is the central station 2₁ Not used by
Bureau 2₁ Number of channels used by
Is notified to the call control management unit 5 that the total number is 0.
Swelling. Thereafter, the same processing is performed for the time slot t.
_Three ~ T_N-1 It is performed sequentially for each, but these times
Slot t_Three ~ T_N-1 Has no free channels
It has become the original. Eventually, the call control manager 5
End time slot t_N To the empty channel search section 8
However, by performing the same processing, call control management
In part 5, the time slot t_N Time slot that can be assigned
Time slot t_N Concentration within
Station 2₁ That the total number of channels used by the
It is something to be done. Therefore, the above series of processing
From the result, the call control management unit 5 has two time slots t
_Two , T_N Is an allocatable time slot,
Lot t_Two , T_N Central Bureau 2₁ Number of channels used by
Are known to be 0 and 2, respectively.
You. From this, the call control management section 5 sets the central station 2₁ Use by
Time slot with the largest total number of
Time slot t_N Is selected and shown in FIG.
Time slot t_N Free channels within (t
_N , F_Two) Is assigned to a new call (2 → 3)
Things. The required number of channels for the new call (2 → 3) is
Since there is only one channel, select a free channel at this point
Is to be completed. As you can see,
In the case of the channel assignment method based on
Space that could not be selected by the channel assignment method
Channel (t_N , F_Two8) as a result, FIG.
Time slot t shown in_Two Central office 2 like₁ Pertain to
Time slots with no incoming or outgoing calls are less likely to appear
Things. Therefore, the channel shown in FIG.
In the assignment state, the central station 2₁ Outgoing and incoming calls (1 →
Even if 2) newly occurs, the time slot t_Two Or
It is possible to select a free channel from
Minutes, Central Bureau 2₁ Call loss rate for transmitted and received calls related to
It is something that can be suppressed.

Finally, considering the effect of the present invention, FIG. 3 shows a traffic volume-blocking rate characteristic (in a centralized station) of the channel allocation system according to the present invention by traffic simulation under the conditions shown in the figure. FIG. 9 shows the results of the call loss rate characteristics for the transmitted and received calls, together with those of the channel assignment method according to the related art. As shown,
The horizontal axis of the calls are likely to occur, call toll 2 ₁ transmits and receives (1 → X), or call (X → 1) (X ≠
Shows the rate of occurrence of 1), the traffic to the extent this value is large and is obtained by means that are concentrated in the central station 2 _1. According to the traffic simulation results shown in the figure, in the channel allocation method according to the prior art, as traffic concentrates on a specific slave station, the call loss rate for transmission / reception calls related to the slave station increases. In the case of the channel allocation method according to the above, it is understood that the increase in the call blocking rate can be reduced to a smaller extent than in the conventional method.

In the above-described embodiment, the time slot numbers are sequentially designated in the empty channel search section 8 and the empty channel is sequentially assigned from the smallest time slot (ie, in the order of t ₁ , t ₂ ,..., T _N ). Is described, but the empty channel search unit 8 specifies carrier numbers in order, and sequentially starts with the lowest carrier (ie, f ₁ , f ₂ ,
.., F _{M (even in} the order of f _M ), it is difficult to create a time slot in which there is no call transmitted and received by the centralized station, only in the direction of searching for a free channel. As before, a small call blocking rate can be similarly realized for calls transmitted and received by the central station.

[0019]

As described above, according to the present invention,
When traffic is concentrated on a specific slave station, the call loss rate for transmitted / received calls related to the slave station can be reduced.

[Brief description of the drawings]

FIG. 1 is a diagram showing a channel allocation control flow in a control station according to the present invention.

FIG. 2 is a diagram showing an example of a main configuration of a control station according to the present invention.

FIG. 3 shows a traffic simulation.
FIG. 3 is a diagram showing an example of a call traffic-loss rate characteristic in the channel assignment method according to the present invention, together with that in the channel assignment method according to the related art.

FIG. 4 is a diagram illustrating an example of a general system configuration of a satellite communication system based on a multicarrier hopping TDMA scheme;

FIG. 5 shows the multicarrier hopping TDM.
Diagram for explaining method A

FIG. 6 is a diagram showing an example of a main configuration of a control station according to the related art.

FIG. 7 is a diagram showing a channel allocation control flow in the control station.

FIGS. 8A to 8C are diagrams showing specific examples of a channel management table for explaining the channel allocation control flow;

FIG. 9 is a diagram for explaining a traffic volume bias in a case where traffic is concentrated on a specific slave station;

[Explanation of symbols]

1 ... control _{station, 2 (2 1 ~2 L)} ... slave station, 3 ... communication satellite, 4
... Data burst, 5 ... Call control management unit, 6 ... Used channel number measurement unit, 7 ... Channel management table, 8 ... Unused channel search unit, 9 ... Concentrated station detection unit

 ────────────────────────────────────────────────── ─── Continuation of front page (56) References JP-A-1-128632 (JP, A) JP-A-3-80716 (JP, A) 1992 IEICE Spring Conference Lecture Volume 2, B- 162, (1992-3-15) P. 162 Transactions of the Institute of Electronics, Information and Communication Engineers Communication 1-Information Communication System / Theory VOL. 76-B-1, NO. 2 (1993-2-25) p. 191 -194

Claims (1)

(57) [Claims] 1. Prior to each of a plurality of slave stations transmitting and receiving a burst including information data to and from each other, the control station assigns an arbitrary carrier within one time slot based on a channel allocation request from each of the slave stations. A multicarrier hopping TDMA system for allocating as a channel to be used by each station, comprising: first means for managing a transmitting station number and a receiving station number for each channel; and a time specified by using the first means. Second means for measuring the total number of transmission channels of the designated transmitting station and the total number of receiving channels of the designated receiving station within the slot, and searching for an allocatable vacant channel within any time slot or carrier A third means is provided, and when a new call is generated, an empty channel searched by the third means is newly generated. In the channel allocation method for call allocation, a fourth method for detecting a station where traffic is concentrated
Means, and for a time slot in which there is an allocatable vacant channel searched by the third means, the total number of used channels of a station where the traffic detected by the fourth means is concentrated. It is characterized in that, by measuring, in the order of the time slot having the largest total number of used channels from the time slot having the largest number, the number of available channels equal to the number of required channels of the newly generated call is selected and allocated to the newly generated call. Channel assignment method to be used.