1. A wireless transmission device for t r ansmi t t ing traffic to another wireless transmission device via a selected one of a plural i ty of connected wireless transmission paths, the wi reless transmission device comprising5 : a swi tching control uni t which judges, when a faul t has occur red in the wi reless t ransmission path for t ransmi t t ing the t raf fic, whether the traf fic is transmi t table wi th use of the wi reless t ransmission path in which the faul t has occur red, namely, a faul ty transmission path, and which 10 selects the faul ty t ransmission path, as th e wireless t ransmission path for transmi t t ing the t raf f ic, when judging that the t raf fic is transmi t table.

2. The wi reless transmission device according to Claim 1, wherein when there are a plural i ty of faul ty transmission paths capable of 15 transmi t t ing the t raf f ic, the swi tching control uni t selects the faul ty transmission path whose transmission capaci ty is the largest , as the wireless transmission path for transmi t t ing the traffic.

3. The wi reless transmission device according to any one of Claims 1 20 to 2, wherein the swi tching cont rol uni t receives a modulat ion method and an SNR (Signal to noise rat io) value relat ing to the faul ty t ransmission path from the another wireless transmission device direct ly connected via the faul ty transmission path, and judges that the traffic is t ransmi t table by the 25 faul ty transmission path, when the modulat ion method is the modulat ion method whose mul t i -value number is not larger than a predetermined number , and when the SNR value is not lower than a predetermined value.

4. The wi reless transmission device according to any one of Claims 1 46 to 3, wherein the swi tching cont rol uni t judges whether the traffic is transmi t table wi th use of the faul ty transmission path, when t ransmission of the t raf fic by the wireless transmiss ion path other than the faul ty transmission path is disabled5 .

5. The wi reless transmission device according to any one of Claims 1 to 4, wherein the traffic is low pr iori ty informat ion, namely, extra t raf fic. 10

6. A wireless transmission system compr ising two or more wi reless transmission devices connected via a plural i ty of wireless t ransmission paths, wherein each of the wi reless transmission device s is the wi reless 15 transmission device according to any one of Claims 1 to 5.

7. The wi reless transmission system according to Claim 6, wherein the two or more wi reless transmission devices are connected in the form of a ring. 20

8. A communicat ion l ine select ion method for select ing a wireless transmission path f rom a plural i ty of wireless transmission paths s o as to transmi t t raf fic to a communicat ion dest inat ion, comprising: judging, when a faul t has occur red in the wireless t ransmission path 25 for t ransmi t t ing the t raf fic, whether the traf fic is t ransmi t table wi th use of the wi reless t ransmission path in whic h the faul t has occurred, namely, a faul ty transmission path, and select ing the faul ty transmission path as the wireless transmission path for transmi t t ing the traffic, when judging that the traffic is t ransmi t table. 47

9. The communicat ion l ine select ion me thod according to Claim 8, wherein when there are a plural i ty of faul ty transmission paths capable of transmi t t ing the t raf f ic, select ing the faul ty t ransmission path whos5 e transmission capaci ty is the largest as the wireless t ransmission path for transmi t t ing the t raf f ic.

10. The communicat ion l ine select ion method according to Claims 8 to 10 9, wherein receiving a modulat ion method and an SNR value relat ing to the faul ty t ransmission path, and judging that the t raf fic is transmi t table by the faul ty transmission path, when the modulat ion method is the modulat ion method whose mul t i -value number is not larger than a predetermined 15 number , and when the SNR value is not lower than a predetermined value .

11. The wi reless transmission device according to any o ne of Claims 3 to 5, wherein the faul ty t ransmission path whose transmission capaci ty is the 20 largest is the faul ty t ransmission path of the modulat ion method whose mul t i -value number is the largest .

12. The wi reless transmission device according to any o ne of Claims 1 to 5, or 11, wherein 25 the swi tching cont rol uni t measures a t raf fic amount of t raf fic to be received f rom the wi reless t ransmission path for each of the wireless transmission paths, and in response to input of a traffic amount of traffic to be received by a wireless transmission system const i tuted of the wireless transmission 48 devices, namely a transmission traffic amount , the swi tching control uni t judges that the faul t has occur red in the wireless transmission path for transmi t t ing the t raf f ic, when there is the wireless transmission path whose rat io of the received traf fic amount wi th respect to the transmission traff ic amount is not larger than a predetermined value for a predetermine5 d period.

13. The wi reless transmission system according to any one of Claims 6 to 7, wherein 10 the wi reless t ransmission path is a duplex wi reless t ransmission path const i tuted of an act ive system wireless transmission path and a standby system wireless transmission path.

14. The communicat ion l ine select ion method according to Claim 10, 15 wherein the faul ty t ransmission path whose transmission capaci ty is the largest is the faul ty t ransmission path of the modulat ion method whose mul t i -value number is the largest . 20 15. The communicat ion l ine select ion method ac cording to any one of Claims 8 to 10, or 14, wherein judging whether the traf fic is transmi t table wi th use of the faul ty transmission path, when transmission of the traffic by the wireless transmission path other than the faul ty t ransmission path is disab led. 25 16. The communicat ion l ine select ion method according to any one of Claims 8 to 10, or 14 to 15, wherein the traffic is low pr iori ty informat ion, namely, extra t raf fic.

[Technical Field5 ]
[0001]
The present invent ion relates to a wireless transmission device, a
wireless transmiss ion system, and a communicat ion l ine select ion method,
and more part icularly, to a wireless transmission device, a wi reless
10 transmission system, and a communicat ion l ine select ion method for
cont inuing transmission of low priori ty informat ion, wi thout affe ct ing
transmission of high priori ty informat ion.
[Background Art ]
[0002]
15 In recent years, as the Internet has developed and global izat ion has
progressed, both domest ic and internat ional large -capaci ty t runk
transmission networks have progressed. A genera l trunk transmission
network is used for t ransmi t t ing informat ion of a variety of users.
Therefore, the t runk transmission network is required to be a transmission
20 network which is less l ikely to cause l ine disconnect ion. In view of the
above, the general trunk t ransmission network is const i tuted of a duplex
transmission path having an act ive system and a standby system. When a
l ine faul t has occur red in the act ive system transmission path, a
transmission device on the trunk transmission network swi tches the
25 transmission path to the standby system transmission path for saving a
transmission signal . Further, in the general t runk t ransmission network,
a technique of connect ing a duplex transmission path in the form of a ring,
and bypassing a t ransmission s ignal to a t ransmission path in the opposi te
direct ion, even when a l ine faul t has occurred in a part ial sect ion, in other
3
words, in both of the act ive system and standby system transmission paths
has come into pract ical use in order to enhance the rel iabi l i ty of the
transmission network.
[0003]
Incidental ly, in the t ransmission system in which the duple5 x
transmission path is connected in the form of a r ing (hereinaf ter , cal led as
a “r ing-type transmission system” ) as described above, the standby system
transmission path is in an idl ing state when there is no l ine faul t in the
act ive system t ransmission path. General ly, a standby system
10 transmission path has the same t ransmission capaci ty as an act ive system
transmission path. Therefore, taking into consi derat ion the overal l
system, only hal f of the maximum transmi t table capaci ty is used. Thus,
the transmission eff iciency is poor. In view of the above, Patent
Li terature 1 and Patent Li terature 2 disclose a technique of t ransmi t t ing
15 low prior i ty t ransmiss ion informat ion (hereinafter, cal led as “extra
traf fic” ) via a standby system t ransmission path in order to enhance the
transmission ef ficiency of the ring-type t ransmission system.
[0004]
However, in the technique disclosed in Patent Li terature 1 and the
20 l ike, high prior i ty informat ion (hereinafter , cal led as “service traf fic”) that
has been t ransmi t ted via an act ive system transmission path is bypassed to
a standby system t ransmission path, when a l ine faul t has occur red in the
act ive system t ransmission path. This resul ts in disconnect ion of extra
traf fic. In view of the above, Patent Li terature 3 discloses a technique of
25 bypassing extra t raf f ic to an unused standby system t ransmission path or
act ive system t ransmission path so that the extra t raf fic is not cut of f, even
when a l ine faul t has occur red in the transmission path along which the
service t raf fic has been transmi t ted. The above-described “unused
standby system t ransmission path or act ive system t ransmission path ” is
4
hereinafter simply cal led as an “unused transmission path” .
[Ci tat ion List ]
[Patent Li terature]
[0005]
[PTL 1] Japanese Patent Appl icat ion Publ icat ion No. 2000-78175 6
[PTL 2] Japanese Patent Appl icat ion Publ icat ion No. 2000-83042
[PTL 3] Japanese Patent Appl icat ion Publ icat ion No. 2003-143171
[Summary of Invent ion]
[Technical Problem]
10 [0006]
However, the ring-type transmission system disclosed in Patent
Li terature 3 has a problem such that when an unused transmission path is
not avai lable in bypassing the extra t raf fic at the t ime of l ine faul t ,
transmission of the extra t raf fic cannot be cont inued.
15 [0007]
The reason for the above is that the ring- type t ransmission system
disclosed in Patent Li terature 3 (hereinafter , cal led as the “ transmission
system of Patent Li terature 3”) const i tutes transmission paths wi th a wi red
l ine configured such that the l ine is completely disconnected at the t ime of
20 l ine faul t . As a resul t , in the transmission system of Patent Li terature 3,
when an unused t ransmission path is not avai lable, there is no transmission
path for bypassing the extra t raf fic, and i t is not possible to cont inue
transmission of the extra t raf fic.
[0008]
25 An object of the present invent ion is to provide a wi reless
transmission device, a wireless t ransmission system, and a communicat ion
l ine select ion method which solves the above-described problem.
[Solut ion to Problem]
[0009]
5
To achieve the above-described object , a wireless transmission
device of the present invent ion is a wi reless t ransmission device for
transmi t t ing traff ic to another wi reless t ransmission device via a selected
one of a plural i ty of connected wireless transmission paths. The wireless
transmission device comprises a swi tching control uni t which judges, whe5 n
a faul t has occurred in the wi reless t ransmission path for transmi t t ing the
traf fic, whether the t raf fic is transmi t table wi th use of the wireless
transmission path in which the faul t has occur red, namely, a faul ty
transmission path, and which selects the faul ty t ransmission path, as the
10 wireless transmis sion path for transmi t t ing the traffic, when judging that
the traffic is t ransmi t table.
[0010]
To achieve the above-described object , a wireless transmission
system of the present invent ion is a wi reless t ransmission system
15 comprising two or more wireless t ransmission devices connected via a
plural i ty of wi reless transmission paths. The wi reless t ransmission
device is a wireless t ransmission device for t ransmi t t ing t raf fic to another
wireless t ransmission device via a wireless transmission path selected f rom
a plural i ty of connected wi reless t ransmission paths. The wi reless
20 transmission device comprises a swi tching control uni t which judges , when
a faul t has occurred in the wi reless t ransmission path for transmi t t ing the
traf fic, whether the t raf fic is tr ansmi t table wi th use of the wireless
transmission path in which the faul t has occur red, namely, a faul ty
transmission path, and which selects the faul ty t ransmission path, as the
25 wireless transmission path for transmi t t ing the traffic, when judging that
the traffic is t ransmi t table.
[0011]
To achieve the above-described object , a communicat ion l ine
select ion method of the present invent ion is a communicat ion l ine select ion
6
method for select ing a wireless t ransmission path from a plural i ty of
wireless transmission paths so as to t ransmi t traff ic to a communicat ion
dest inat ion. the communicat ion l ine select ion method compr ises, when a
faul t has occurred in the wireless transmission path for transmi t t ing the
traf fic, judging whether the t raf fic is t ransmi t tabl e wi th use of the wi reles5 s
transmission path in which the faul t has occur red, namely, a faul ty
transmission path, and select ing the faul ty transmission path as the
wireless transmission path for transmi t t ing the traffic, when judging that
the traffic is transmi t table.
10 [Advantageous Ef fects of Invent ion]
[0012]
According to the present invent ion, the transmission system is
capable of cont inuing transmission of extra traff ic wi thout af fect ing
transmission of service t raf fic, even when an unused transmission path is
15 not avai lable at the t ime of l ine faul t .
[Brief Descript ion of Drawings ]
[0013]
Fig. 1 is a diagram i l lustrat ing a configurat ion example of a
wireless transmission system in a fi rst exemplary embodiment of the
20 present invent ion.
Fig. 2A is a diagram i l lust rat ing a configurat ion example of a
wireless transmission device const i tut ing the wireless transmission system
in the fi rst exemplary embodiment of the present invent ion.
Fig. 2B is a diagram i l lust rat ing a configurat ion example of the
25 wireless transmission device const i tut ing the wireless transmission system
in the fi rst exemplary embodiment of the present invent ion.
Fig. 2C is a diagram i l lust rat ing a configurat ion example of the
wireless transmission device const i tut ing the wireless transmis sion system
in the fi rst exemplary embodiment of the present invent ion.
7
Fig. 3A is a diagram for represent ing adapt ive modulat ion to be
performed by the wi reless transmission device in the fi rst exemplary
embodiment of the present invent ion.
Fig. 3B is a diagram for represent ing adapt ive modulat ion to be
performed by the wi reless transmission device in the fi rst exemplar5 y
embodiment of the present invent ion.
Fig. 4 is a diagram i l lustrat ing an example of a communicat ion
path set in the wi reless t ransmi ssion system in the f irst exemplary
embodiment of the present invent ion.
10 Fig. 5 is a diagram i l lustrat ing a set t ing example of a
communicat ion path, when a faul t has occur red in an act ive system
transmission path of the wi reless t ransmission system in the f irst
exemplary embodiment of the present invent ion.
Fig. 6 is a diagram i l lustrat ing a set t ing example of a
15 communicat ion path, when a faul t has occur red in act ive system and
standby system t ransmission paths of the wireless transmission system in
the fi rst exemplary embodiment of the present invent ion.
Fig. 7 is a flowchart i l lust rat ing a traff ic bypass operat ion to be
performed by the wi reless transmission device in the fi rst exemplary
20 embodiment of the present invent ion.
Fig. 8 is a diagram i l lustrat ing a set t ing example of a
communicat ion path, when a faul t has occur red in the standby system
transmission path of the wi reless t ransmission system in the f irst
exemplary embodiment of the present invent ion.
25 Fig. 9 is a diagram i l lustrat ing a set t ing ex ample of a
communicat ion path, when a path for bypassing extra t raf fic is not
avai lable in the wi reless transmission system in the fi rst exemplary
embodiment of the present invent ion.
Fig. 10 is a diagram i l lust rat ing a configurat ion example of a
8
wireless transmission system in a second exemplary embodiment of the
present invent ion.
[Descript ion of Embodiments ]
[0014]
In the fol lowing, exemplary embodiments of the present invent io5 n
are described in detai l refer ring to the drawings.
[0015]
[First Exemplary Embodiment]
[Descript ion of Conf igurat ion]
10 Fig. 1 is a diagram i l lustrat ing a configurat ion example of a
wireless transmission system in a fi rst exemplary embodiment of the
present invent ion. Further, Fig. 2A, Fig. 2B, and Fig. 2C are diagrams
i l lust rat ing a configurat ion example of a wireless transmission device
const i tut ing the wireless transmission system in the fi rst exemplary
15 embodiment of the present invent ion.
[0016]
(1) Configurat ion of wireless transmission system
As i l lust rated in Fig. 1, the wi reless transmission system in the fi rst
exemplary embodiment is const i tuted of a plural i ty of wireless
20 transmission devices 1 to 5. Further, the wireless t ransmission devices 1
to 5 are connected in the form of a ring by act ive system wireless
transmission paths P2 and P4, and standby system wi reless transmission
paths P1 and P3 having a clockwise or counterclockwise l ine. Al though
not i l lust rated, each of the wireless transmission devices 1 to 5 is
25 connected to a supervisory cont rol device via a wir ed l ine such as an LAN
(Local Area Network).
[0017]
Whi le five wi reless t ransmission devices are i l lust rated in Fig. 1,
the number of wi reless t ransmission devices is not l imi ted to five. The
9
number of wi reless transmission devices may be four or less, o r may be six
or more. Further, whi le four wi reless t ransmission paths are i l lust rated
in Fig. 1, the number of wi reless t ransmission paths is not l imi ted to four .
The number of wireless transmission paths may be three or less, or may be
five or more5 .
[0018]
(2) Basic operat ion of wireless t ransmission system
The wi reless transmission system in the f irst exemplary
embodiment sets a communicat ion path for use in t ransmi t t ing informat ion
10 (hereinafter , cal led as a “communicat ion path”) by a wel l -known funct ion,
as wel l as the t ransmission system disclosed in Patent Li terature 3. For
instance, when informat ion is t ransmi t ted f rom the wireless transmission
device 1 to the wi reless transmission device 3 in Fig. 1, the wireless
transmission system in the present exemplary embodiment sets a
15 communicat ion path on the wi reless t ransmission path P2 between the
wireless transmission devices 1 to 3, and per forms informat ion
transmission on the communicat ion path.
[0019]
(3) Configurat ion and funct ion of wi reless t ran smission devices
20 1 to 5
(3-1) Configurat ion of wireless transmission devices 1 to 5
As i l lust rated in Fig. 2A, the wi reless t ransmission devices 1 to 5
are const i tuted of IF circui t uni ts 201 and 202, a swi tching circui t uni t 203,
a swi tching control uni t 204, a ring map storage uni t 205, and a radio l ink
25 control uni t 206. Further, as i l lustrated in Fig. 2B and Fig. 2C, the
wireless transmission devices 1 to 5 are const i tuted of receiving antennas
211, 221, 231, and 241, radio receiving uni ts 212, 222, 2 32, and 242, and
radio ci rcui t extract ion uni ts 213, 223, 233, and 243. Further , as
i l lust rated in Fig. 2B and Fig. 2C, the wi reless transmission devices 1 to 5
10
are const i tuted of radio ci rcui t mul t iplexer uni ts 214, 224, 234, and 244,
radio t ransmission uni ts 215, 225, 235, and 245, and t ransmission antennas
216, 226, 236, and 246.
[0020]
(3-2) Connect ion of components of wi reless transmission device5 s
1 to 5
Fi rst of al l , the receiving antennas 211, 221, 231, and 241 are
connected to the wireless transmission paths P1 to P4. Speci fical ly, the
receiving antenna 211 is connected to the act ive system wi reless
10 transmission path P1, and the receiving antenna 221 is connected to the
standby system wireless transmission path P2. Further , the receiving
antenna 231 is connected to the act ive system wi reless t ransmission path
P4, and the receiving antenna 241 is connected to the standby system
wireless transmission path P3. Fur thermore, the receiving antennas 211,
15 221, 231, and 241 are respect ively connected to the radio receiving uni ts
212, 222, 232, and 242, and the radio receiving uni ts 212, 222, 232, and
242 are respect ively connected to the radio circui t extract ion uni ts 213,
223, 233, and 243. The radio circui t extract ion uni ts 213, 223, 233, and
243 are connected to the swi tching ci rcui t uni t 203.
20 [0021]
The swi tching ci rcui t uni t 203 is connected to the radio ci rcui t
mul t iplexer uni ts 214, 224, 234, and 244. The radio ci rcui t mul t iplexer
uni ts 214, 224, 234, and 244 are respect ively connected to the radio
transmission uni ts 215, 225, 235, and 245. Further, the radio
25 transmission uni ts 215, 225, 235, and 245 are respect ively connected to the
transmission antennas 216, 226, 236, and 246, and the t ransmission
antennas 216, 226, 236, and 246 are connect ed to the wireless transmission
paths P1 to P4. Specifical ly, the transmission antenna 216 is connected
to the act ive system wireless transmission path P1, and the transmission
11
antenna 226 is connected to the standby system wireless transmission path
P2. Further, the t ransmission antenna 236 is connected to the act ive
system wireless t ransmission path P4, and the t ransmission antenna 246 is
connected to the standby system wi reless transmission path P3.
[00225 ]
Al though not i l lust rated, the IF ci rcui t uni t s 201 and 202 are
connected to a user terminal , for instance, to a PC (Personal Computer) via
a wired l ine such as an LAN. Further , the IF ci rcui t unis 201 and 202 are
connected to the swi tching ci rcui t uni t 203, and the swi tching circui t uni t
10 203 is connected to the swi tching cont rol uni t 204. Furthermore, the
swi tching control uni t 204 is connected to the ring map storage uni t 205.
In addi t ion, the radio l ink cont rol uni t 206 is connected to the ring map
storage uni t 205, the radio receiving uni ts 212, 222, 232, and 242, the radio
circui t extract ion uni ts 213, 223, 233, and 243, and the radio circui t
15 mul t iplexer uni ts 214, 224, 234, and 244. Al though not i l lustrated, the
swi tching control uni t 204 and the ring map storage uni t 205 are connected
to the supervisory control device via a wi red l ine such as an LAN.
[0023]
(3-3) Funct ion of components of wi reless t ransmission devices 1
20 to 5
The IF circui t uni t 201 and the IF ci rcui t uni t 202 convert input
service t raf fic or extra traff ic into data in the da ta format of a wired l ine,
and output the converted data as transmi t table data by the wired l ine.
Further, the IF circui t uni t 201 and the IF circui t uni t 202 convert data
25 input f rom a wi red l ine into service traffic or extra t raf fic in accordance
wi th the data format , and output the service t raf fic or extra t raffic.
[0024]
The swi tching ci rcui t uni t 203 outputs the input service traffic or
extra t raf fic to an output dest inat ion t ransmission path represented by
12
swi tching control informat ion. The above-described swi tching control
informat ion is cont rol informat ion represent ing an input source
transmission path and an output dest inat ion transmission path, and is input
to the swi tching ci rcui t uni t 203. For instance, when swi tching control
informat ion represent ing that the input source t ransmission path=P1 an5 d
the output dest inat ion transmission path=P4 is input , the swi tching ci rcui t
uni t 203 outputs, to the wi reless t ransmission path P4, service traf fic or
extra t raf fic received f rom the wireless transmiss ion path P1. When
swi tching control informat ion represent ing that the input source
10 transmission path=P1 and the output dest inat ion transmission path=IF
circui t uni t 201 is input , the swi tching ci rcui t uni t 203 outputs, to the IF
circui t uni t 201, service t raf fic or extra t raf fic input f rom the wireless
transmission path P1.
[0025]
15 The swi tching control uni t 204 moni tors the presence or absence of
a faul t in each of the wi reless t ransmission paths. Speci fical ly, the
swi tching control uni t 204 measures a t raffic amount of service t raf fic or
extra t raf fic to be received by the swi tching control uni t 204 (hereinafter,
cal led as a “ received traf fic amount ” ) for each of the wi reless t ransmission
20 paths. Further , when a transmission traffic amount of each of the
wireless transmission paths ( the detai ls thereof are described later in the
sect ion “(4) Supervisory Cont rol Device ”) is input to the swi tching cont rol
uni t 204, the swi tching control uni t 204 checks whether there is a wi reless
transmission path whose rat io of the received traff ic amount wi th respect
25 to the t ransmission t raf fic amount is not larger than a predetermined value
for a predetermined period. As a resul t of the checking, when there is
such a wireless transmission path as descr ibed above, the swi tching cont rol
uni t 204 detects that the wi reless t ransmission path is a wireless
transmission path having a l ine faul t . The predetermined per iod and the
13
predetermined value are set in the swi tching cont rol uni t 204 by the user of
the wi reless t ransmission system in the present exemplary embodiment .
The predetermined value may be variable in accordance wi th the
transmission t raf fic amount .
[00265 ]
When a wi reless t ransmission path having a l ine faul t is detected,
the swi tching cont rol uni t 204 outputs inf ormat ion represent ing the
wireless transmission path in which the l ine faul t has occur red (hereinafter,
cal led as a “ faul ty l ine”) , and a faul t status of the faul ty l ine. The faul t
10 status includes an SNR (Signal to noise rat io) value of an input faul ty l i ne.
[0027]
Further, when a faul t informat ion not i ficat ion is input , the
swi tching control uni t 204 judges whether i t is necessary to bypass the
service t raf fic or extra traff ic being t ransmi t ted, based on the faul t
15 informat ion not i ficat ion or an input ring map. A concrete method for
judging whether i t is necessary to bypass the traffic is described later in
detai l in the sect ion “(6-2) Operat ion of swi tching circui t uni t
203/swi tching cont rol uni t 204” . Further, the above-described faul t
informat ion not i ficat ion is a not if icat ion represent ing that a faul t has
20 occurred somewhere in a wireless transmission path on the wireless
transmission system. The detai ls of the faul t informat ion not ificat ion are
described later in the sect ion “ (4) Supervisory cont rol device” . The
above-described ring map is informat ion represent ing how a
communicat ion path is set on a wi reless t ransmission path of the wi reless
25 transmission system in the present exemplary embodiment .
[0028]
When the swi tching control uni t 204 judges that i t is necessary to
bypass the service t raf fic or extra t raf fic, the swi tching control uni t 204
selects a wi reless t ransmission path for bypassing the service traf fic or
14
extra t raf fic. The method for select ing a wireless t ransmission path for
bypassing the service t raf fic or extra t raf fic (hereinafter , cal led as a
“bypass t ransmission path”) is described later in detai l in the sect ion
“(6-2) Operat ion of swi tching ci rcui t uni t 203/swi tching cont rol uni t 204 ”) .
The swi tching cont rol uni t 204 that has se lected a bypass transmission pat5 h
outputs swi tching control informat ion (represent ing that the output
dest inat ion t ransmission path=selected bypass t ransmission path, and the
input source t ransmission path=present t ransmission path) . When a
wireless transmission path for bypassing the extra traffic is not avai lable,
10 the swi tching cont rol uni t 204 checks whether i t is possible to bypass the
extra t raf fic wi th use of a faul ty l ine even at a lower speed, based on the
input SNR value or modulat ion method of a faul ty l ine. Specif ical ly,
when the input modulat ion method of the faul ty l ine is a modulat ion
method whose mul t i -value number is not larger than a predetermined value,
15 and the input SNR value of the faul ty l ine is not lower than a
predetermined value, the swi tching control uni t 204 judges that i t is
possible to transmi t the extra t raf fic by the faul ty l ine at a low speed, and
i t is possible to bypass the extra t raf fic. The user of the wi reless
transmission system in the present exemplary embodiment is al lowed to set
20 the above-described predetermined value and the predetermined
mul t i -value number in the swi tching cont rol uni t 204. When i t is possible
to t ransmi t the extra traf fic by the faul ty l ine, the swi tching control uni t
204 selects the wireless t ransmission path in which a faul t has occurred, as
a wireless t ransmission path for bypassing the extra t raf fic. The
25 swi tching control uni t 204 outputs swi tching control informat ion
represent ing that the output dest inat ion t ransmission path=faul ty l ine, and
the input source transmission path=present t ransmission path.
[0029]
Next , the funct ions of the ring map storage uni t 205 and the radio
15
l ink control uni t 206 are descr ibed.
[0030]
The r ing map storage uni t 205 stores an input ring map. The ring
map is input f rom the supervisory cont rol device. Further, the ring map
storage uni t 205 stores an input modulat ion method and SNR value for eac5 h
of the wireless transmission paths.
[0031]
The radio l ink cont rol uni t 206 selects a modulat ion method of each
of the wireless transmission paths in accordance wi th an input SNR value
10 of each of the wireless t ransmission paths by a wel l -known technique, in
other words, by adapt ive modulat ion. The radio l ink control uni t 206
outputs data represent ing a selected modulat ion method. Further , the
radio l ink cont rol uni t 206 also outputs data represent ing an input
modulat ion method. Furthermore, the radio l ink cont rol uni t 206 outputs
15 the input SNR value of each of the wireless t ransmission paths.
[0032]
The receiving antennas 211, 221, 231, and 241 receive radio signals
to be input f rom the respect ive wireless t ransmission paths P1 to P4,
ampl i fy the radio signals, and output the ampl i fied signals.
20 [0033]
The radio receiving uni ts 212, 222, 232, and 242 convert the inp ut
radio signals into IF ( Intermediate Frequency) signals, demodulate the IF
signals, and output the demodulated signals. Further, the radio receiving
uni ts 212, 222, 232, and 242 measure input SNR values of the radio signals,
25 and output the measured values.
[0034]
The radio ci rcui t ext ract ion uni ts 213, 223, 233, and 243 extract the
service t raf fic or extra traff ic f rom the input demodulated radio signals in
accordance wi th the format of a radio f rame, and output the extracted
16
service t raf fic or extra traff ic. Further, the radio circui t extract ion uni ts
213, 223, 233, and 243 extract the overhead port ion of the radio f rame
from the input demodulated radio signals in accordance wi th the format of
the radio frame, and output the extracted overhead port i on of the radio
frame5 .
[0035]
The radio ci rcui t mul t iplexer uni ts 214, 224, 234, and 244 mul t iplex
the data represent ing the input modulat ion method, and the service t raf fic
or extra t raf fic in the radio f rame, and output the mul t iplex ed data.
10 [0036]
The radio t ransmission uni ts 215, 216, 217, and 218 modulate the
input signals, and output the modulated signals as radio signals. The
radio transmission uni ts 215, 216, 217, and 218 output radio signals in
frequency bands di fferent from each other so as to avoid inter ference.
15 Further, the radio transmission uni ts 215, 216, 217, and 218 extract data,
which is mul t iplexed in the input data and represents the modulat ion
method, and store the extracted data.
[0037]
The t ransmission antennas 216, 226, 236, and 246 ampl i fy the input
20 radio signals, and output the ampl i fied signals to the respect ive wi reless
transmission paths P1 to P4.
[0038]
The components other than the ring map storage uni t 205 are
implemented wi th use of an elect ronic circui t , a DSP (Digi tal Signal
25 Processor) or the l ike. The ring map storage uni t 205 is implemented
wi th use of a storage device such as an RAM (Random Access Memory) .
[0039]
The receiving antennas 211, 221, 231, and 241, the radio receiving
uni ts 212, 222, 232, and 242, and the radio circui t extract ion uni ts 213, 223,
17
233, and 243 are hereinafter generical ly cal led as “ radio receiving
processing uni ts” . Further, the radio ci rcui t mul t iplexer uni ts 214, 224,
234, and 244, the radio t ransmission uni ts 215, 216, 217, and 218, and the
transmission antennas 216, 226, 236, and 246 are hereinafter cal led as
“radio t ransmission processing uni ts ” . Furthermore, the radio receivin5 g
processing uni ts, the radio t ransmission processing uni ts , and the radio
l ink control uni ts 206 are generic al ly cal led as a “ radio t ransmi t t ing and
receiving uni t ” .
[0040]
10 (4) Supervisory cont rol device
In this sect ion, the funct ion of the uni l lustrated supervisory control
device is described.
[0041]
The supervisory cont rol device col lects a communicat ion path
15 present ly set in the wireless t ransmission system by a wel l -known funct ion,
and outputs the col lected communicat ion path to the ring map storage uni t
205 of each of the wi reless t ransmission devices, as a ring map. The ring
map is informat ion represent ing how a communicat ion path is set on a
wireless transmission path of the wi reless transmission system.
20 [0042]
Further, the supervisory cont rol device measures a t raf fic amount of
service t raf fic or extra traff ic to be input from the wi red l ine side to t he
wireless transmission system (hereinafter , cal led as a “t r a n smi s s i o n traff ic
amount ”) wi th use of a wel l -known technique. The supervisory control
25 device recognizes, from the ring map, a wireless t ransmission path and a
wireless transmission device in which a communicat ion path (a
transmission path for use in t ransmi t t ing input service t raf fic or extra
traf fic) is set , and outputs the t ransmission traff ic amount to the swi tching
control uni t 204 of the recognized wi reless t ransmission device. When
18
the t ransmission traf fic amount is output to the recognized wi reless
transmission device, the supervisory control device outputs the
transmission t raf fic amount in associat ion wi th the wi reless t ransmission
path. Speci fical ly, the supervisory control device ou tputs the recognized
transmission t raf fic amount regarding a wireless transmission path i5 n
which a communicat ion path is set , and outputs the t ransmission t raf fic
amount of zero regarding a wi reless t ransmission path in which a
communicat ion path is not set , out of the wireless transmission paths
connected to the recognized wi reless t ransmission device.
10 [0043]
Further, the supervisory cont rol device receives, f rom the swi tching
control uni ts 204 of the wi reless t ransmission devices 1 to 5, informat ion
represent ing a faul ty l ine, and a faul t status. When informat ion
represent ing a faul ty l ine, and a faul t status are received, the supervisory
15 control device obtains a faul ty sect ion by connect ing the received faul ty
l ines, and outputs the faul ty sect ion and the faul t status to the swi tching
control uni ts 204 of the wi reless t ransmission devices 1 to 5 as a faul t
informat ion not i ficat ion. Fur ther , the supervisory cont rol device outputs
an input SNR value to the swi tching cont rol uni t 204. The supervisory
20 cont rol device has a funct ion of output t ing, to the swi tching control uni t
204, a set value set by the user of the wi reless transmission system in the
present exemplary embodiment .
[0044]
[Descript ion on Operat ion of Wi reless Transmission Device]
25 The wi reless transmission device in the present exemplary
embodiment transmi ts and receives service t raf fic and ext ra traf fic to and
from another wi reless t ransmission device via a wireless t ransmission path.
Further, when a l ine faul t has occurred, the wireless t ra nsmission device in
the present exemplary embodiment bypasses the service t raf fic or extra
19
traf fic so as to cont inue transmission of the service t raf fic or extra t raf fic.
[0045]
Fi rst of al l , an operat ion of transmi t t ing and receiving service
traf fic and extra traf fic is described refer ring to Fig. 2A, Fig. 2B, Fig. 2C,
Fig. 3A, and Fig. 3B. Fig. 3A and Fig. 3B are diagrams for represent in5 g
adapt ive modulat ion to be per formed by a wi reless t ransmission device in
the fi rst exemplary embodiment of the present invent ion.
[0046]
(5) Operat ions of t ransmi t t ing and receiving service t raf fic and
10 extra t raf fic
Out of the t ransmi t t ing operat ion and the receiving operat ion, the
receiving operat ion is per formed by each of the radio receiving processing
uni ts, and the t ransmi t t ing operat ion is performed by each of the radio
transmission processing uni ts . Further, the modulat ion method for use in
15 the transmi t t ing operat ion (modulat ion process) of the wireless
transmission processing uni t , and in the receiving operat i on (demodulat ion
process) of the radio receiving processing uni t is calculated by the radio
l ink control uni t 206. In the fol lowing, the receiving operat ion, the
transmi t t ing operat ion, and the calculat ing operat ion of the modulat ion
20 method are descr ibed. Since the receiving operat ion, the t ransmi t t ing
operat ion, and the calculat ing operat ion of the modulat ion method, which
are per formed for each of the wi reless t ransmission paths , are the same
among al l the wireless t ransmission paths, those of the wi reless
transmission path P1 are descr ibed as a representat ive of the wireless
25 transmission paths.
(5-1) Receiving operat ion
Fi rst of al l , the receiving operat ion is described refer ring to Fig. 2A
and Fig. 2B.
[0047]
20
Fi rst , the receiving antenna 211 receive s a radio signal D210 on the
wireless transmission path P1 output from the opposing wi reless
transmission device, ampl i fies the radio signal D210, and thereafter,
outputs the ampl i fied signal to the radio receiving uni t 212 as a radio
signal D2115 .
[0048]
Subsequent ly, the radio receiving uni t 212 converts the radio signal
D211 into an IF signal , demodulates the IF signal , and thereaf ter , outputs
the demodulated signal to the radio circui t extract ion uni t 213 as radio
10 frame data D212. Further, the radio re ceiving uni t 212 measures an SNR
value of the radio signal D211, and outputs the measure d value to the radio
l ink control uni t 206 as SNR informat ion C210. The radio l ink control
uni t 206 outputs the SNR value input from the radio receiving uni t 212 to
the ring map storage uni t 205. The r ing map storage uni t 205 stores the
15 SNR value for each of the wireless transmission paths.
[0049]
Subsequent ly, the radio ci rcui t extract ion uni t 213 extracts service
traf fic or extra t raf fic D213 from the radio f rame da ta D212 in accordance
wi th the format of the radio f rame, and outputs the extracted t raf fic D213
20 to the swi tching circui t 203. Further, the radio circui t extract ion uni t 213
separates overhead C211 of the radio frame f rom the radio f rame data D212,
and outputs the separated overhead data C211 to the radio l ink control uni t
206. Data represent ing a modulat ion method used by the opposing
wireless transmission device at the t ime of modulat ion (hereinafter , cal led
25 as “modulat ion method informat ion”) , and data represent ing a modulat ion
method used by the present wireless t ransmission device at the t ime of
modulat ion (hereinaf ter , cal led as an “adapt ive modulat ion request ” ) are
mul t iplexed in the overhead by the opposing wireless t ransmission device .
[0050]
21
The radio l ink cont rol uni t 206 extracts and acqui res the modulat ion
method informat ion and the adapt ive modulat ion request that have been
mul t iplexed in the overhead data C211. Further , the radio l ink control
uni t 206 stores the acquired modulat ion method informat ion.
(5-2) Transmi t t ing operat io5 n
In this sect ion, the t ransmi t t ing operat ion is described refer ring to
Fig. 2A and Fig. 2C.
[0051]
Fi rst of al l , the radio ci rcui t mul t iplexer uni t 214 mul t iplexes
10 service t raf fic or extra traff ic D214 to be input from the swi tching ci rcui t
uni t 203, and an adapt ive modulat ion request C212 and modulat ion method
informat ion C213 to be input from the radio l ink control uni t 206 in a radio
frame. When the mul t iplexing operat ion is performed, the radio ci rcui t
mul t iplexer uni t 214 mul t iplexes the service traffic or extra t raffic D214 in
15 a data port ion of the radio f rame, and mul t iplexes the adapt ive modulat ion
request C212 and the modulat ion method informat ion C213 in the overhead
port ion of the radio f rame. The radio ci rcui t mul t iplexer uni t 214 outputs
the mul t iplexed data to the radio t ransmission uni t 215 as radio f rame data
D215.
20 [0052]
Subsequent ly, the radio t ransmission uni t 215 ext racts and stores
the modulat ion method informat ion C213 that has been mul t iplexed in the
radio f rame data D215. The radio t ransmission uni t 215 modulates the
radio f rame data D215 wi th use of the modulat ion method informat ion
25 C213 (modulat ion method) stored at a t ime earl ier by a predetermined t ime,
and outputs the modulated data to the t ransmission antenna 216 as a radio
signal D216. The predetermined t ime may be set in the radio
transmission uni t 215 by the user of the wireless t ransmission system in the
present exemplary embodiment , or may be a t ime equal to a mul t iple of the
22
radio f rame length.
[0053]
The t ransmission antenna 216 ampl i fies the radio signal D216, and
outputs the ampl i fied signal to the wi reless t ransmission path P1.
(5-3) Calculat ing operat ion of modulat ion metho5 d
The radio l ink cont rol uni t 206 in the present exemplary
embodiment per forms a wel l -known adapt ive modulat ion for each of the
wireless transmission paths. The radio l ink control uni t 206 outputs, to
the ring map storage uni t 205, an adapt ive modulat ion request , which is a
10 resul t of per forming a wel l -known adapt ive modulat ion. In the fol lowing,
an operat ion to be performed unt i l the radio l ink control uni t 206 outputs
an adapt ive modulat ion request to the r ing map storage uni t 205 is
described refer ring to Fig. 3A and Fig. 3B. The node A in Fig. 3A and
the node B in Fig. 3B are respect ively a wi reless t ransmission device in the
15 present exemplary embodiment . Further, whi le the receiving antenna 211
of the node A is i l lustrated as a receiving antenna A211, and the receiving
antenna 211 of the node B is i l lust rated as a receiving antenna B211 to
simpl i fy the descript ion, in Fig. 3A and Fig. 3B, t he operat ion and the
configurat ion do not dif fer between the receiving antennas A211 and B211.
20 The above idea is also appl ied to the other components.
[0054]
First of al l , the receiving antenna A211 of the node A receives a
radio signal AD210 f rom the opposing node B, and outputs the received
radio signal AD210 to a radio receiving uni t A212. Subsequent ly, the
25 radio receiving uni t A212 est imates the SNR value of the radio signal
AD210, and outputs SNR informat ion AC210 to a radio l ink control uni t
A206. The radio l ink control uni t A206 of the node A selects a
modulat ion method whose mul t i -value number is smal l , as the modulat ion
method (adapt ive modulat ion request) of the wireless transmission path P1,
23
when the value of the SNR informat ion AC210 is smal ler than a
predetermined threshold value; and selects a modulat ion method whose
mul t i -value number is large, as the modulat ion method (adapt ive
modulat ion request ) of the wireless transmission path P1, when the value
of the SNR informat ion AC210 is larger than the predetermined threshol5 d
value. The predetermined threshold value is set in the radio l ink control
uni t A206 by the user of the wi reless transmission syst em in the present
exemplary embodiment . Subsequent ly, the radio l ink control uni t A206
of the node A def ines the selected modulat ion method as an adapt ive
10 modulat ion request AC222. Subsequent ly, the radio l ink control uni t
A206 of the node A outputs the adapt ive modulat ion request AC222 to a
radio ci rcui t mul t iplexer uni t A224 in order to request the t ransmission
device of the node B which t ransmi ts the radio signal AD210 to change the
modulat ion method. The radio circui t mul t iplexer uni t A224 mul t iplexe s
15 the adapt ive modulat ion request AC222 in the overhead port ion of a radio
signal AD227, and outputs the mul t iplexed data to the wi reless
transmission device of the node B.
[0055]
A radio ci rcui t extract ion uni t B223 of the opposing node B
20 separates the overhead port ion of the radio signal AD227, and outputs the
separated overhead port ion to the radio l ink control uni t 206. The radio
l ink control uni t 206 extracts the adapt ive modulat ion request AC222 f rom
the overhead port ion, and outputs the extracted a dapt ive modulat ion
request AC222 to a r ing map storage uni t B205.
25 [0056]
The operat ion to be performed unt i l an adapt ive modulat ion request
is output to the ring map storage uni t B205 is as described above. The
wireless transmission device in the present exemplary embodiment also
performs the fol lowing operat ion regarding the adapt ive modulat ion
24
request AC222.
[0057]
Fi rst of al l , a radio l ink control uni t B206 outputs the extracted
adapt ive modulat ion request AC222 to a radio circui t mul t iplexer uni t
B214 as modulat ion method informat ion BC213. The radio circui 5 t
mul t iplexer uni t B214 mul t iplexes the modulat ion method informat ion
BC213 in the overhead port ion of a radio f rame, and the mul t iplexed radio
frame is output to the respect ive wireless transmiss ion path P1 via the
radio ci rcui t mul t iplexer uni t B214, a radio t ransmission uni t B215, and a
10 transmission antenna B216.
[0058]
As described above regarding the receiving operat ion, the radio l ink
control uni t A206 of the node A stores the modulat ion method informat ion
BC213 extracted from the overhead data C211, and not i fies the radio
15 receiving uni t A212 of the modulat ion method informat ion BC213 stored at
a t ime earl ier by a predetermined t ime. The radio receiving uni t A212
performs demodulat ion, based on the modulat ion method informat ion
BC213 f rom the radio l ink cont rol uni t A206 .
[0059]
20 (6) Traf fic bypass operat ion to be per formed when faul t has
occurred
The wi reless transmission device in the present exemplary
embodiment performs a process of bypa ssing service t raf fic or ext ra t raf fic
so as to cont inue transmission of the service traffic or extra t raf fic, when a
25 l ine faul t has occur red in a transmission path. Detai ls of the operat ion to
be per formed by the swi tching ci rcui t uni t 203, the swi tching control uni t
204, and the ring map storage uni t 205 that implement the process are
described in the fol lowing refer ring to Fig. 4 to Fig. 10.
[0060]
25
Fig. 4 is a diagram i l lustrat ing an example of a communicat ion path
set in the wi reless transmission syst em in the f irst exemplary embodiment
of the present invent ion. Fig. 4 i l lust rates a manner , in which a
communicat ion path is set among the wireless transmission devices 1-5-4,
and service traffic S301 input from the wireless t ransmission device 1 i5 s
transfer red to the wi reless t ransmission device 4 via the act ive system
transmission path P4 in the counterclockwise di rect ion. Fur ther, Fig. 4
i l lust rates a manner, in which a communicat ion path is also set among the
wireless transmission devices 4-5-1, and service t raf fic S302 input f rom
10 the wi reless t ransmission device 4 is t ransfer red to the wi reless
transmission device 1 via the act ive system transmission path P2 in the
clockwise direct ion. Furthermore, Fig. 4 i l lustrates a manner, in which a
communicat ion path is set among the wireless transmission devices 5-4-3,
and ext ra traffic E301 is transfer red f rom the wireless transmission device
15 5 to the wi reless transmission device 3 via the standby system transmission
path P1 in the counterclockwise di rect ion .
[0061]
Fig. 5 is a diagram i l lustrat ing a set t ing example of a
communicat ion path when a faul t has occur red in an act ive system
20 transmission path of the wi reless t ransmission system in the present
exemplary embodiment . Fig. 5 i l lust rates a set t ing exampl e of a
communicat ion path when a faul t has occur red in the act ive system
transmission path P2 between the wi reless transmission devices 1 -5 from
the state in Fig. 4. Further, Fig. 6 is a diagram i l lust rat ing a set t ing
25 example of a communicat ion path when a faul t has occur red in the act ive
system and standby system t ransmission paths of the wi reless t ransmission
system in the present exemplary embodiment . Fig. 6 i l lustrates a set t ing
example of a communicat ion path when a faul t has occur red in the act ive
system and standby system t ransmission paths P2 and P3 between the
26
wireless transmission devices 1-5 from the state in Fig. 4. Fig. 7 is a
flowchart i l lustrat ing a traff ic bypass operat ion to be per formed by a
wireless transmission device in the fi rst exemplary embodiment of the
present invent ion.
[00625 ]
(6-1) Operat ion of ring map storage uni t 205
The operat ion to be performed by the ring map storage uni t 205 is
summarized as fol lows. As described above in the sect ion “ (4)
Supervisory cont rol device ”, the ring map storage uni t 205 receives and
10 stores a ring map (set t ing status of the present ly set communicat ion path)
from the supervisory control device. Further , as described above in the
sect ion “(5-3) Calculat ing operat ion of modulat ion method” , the ring map
storage uni t 205 receives a modulat ion method (adapt ive modulat ion
request ) from the radio l ink control uni t 206, and stores the modulat ion
15 method for each of the wi reless t ransmission paths. Furthermore, as
described above in the sect ion “(5-1) Receiving operat ion” , the ring map
storage uni t 205 receives the SNR value of each of the wi reless
transmission paths from the radio l ink control uni t 206, and stores the SNR
value for each of the wi reless t ransmission paths.
20 [0063]
(6-2) Operat ion of swi tching circui t uni t 203/swi tching control
uni t 204
In this sect ion, an operat ion to be per formed by the swi tching
circui t uni t 203/swi tching control uni t 204 is described refer ring to Fig. 7.
25 [0064]
Fi rst of al l , the respect ive swi tching cont rol uni ts 204 of the
wireless transmission devices 1-5 moni tor the connected wireless
transmission paths, and detect a wireless t ransmission path in which a l ine
faul t has occurred (Step S901).
27
[0065]
Specif ical ly, the swi tching control uni t 204 measures a received
traf fic amount for each of the wireless t ransmission paths. Subsequent ly,
when a t ransmission traf fic amount of each of the wi reless t ransmission
paths is input , the swi tching control uni t 204 checks whether the rat io o5 f
the received t raf fic amount wi th respect to the t ransmission t raf fic amount
is not larger than a predetermined value for each of the wireless
transmission paths for a predetermined period. As a resul t of the
checking, when there is a wireless t ransmission path whose rat io of the
10 received traff ic amount wi th respect to the transmission t raf f ic amount is
not larger than the predetermined value, the swi tching cont rol uni t 204
detects that the wi reless transmission path is a wi reless t ransmission path
in which a l ine faul t has occur red. The swi t ching control uni t 204 may
use a modulat ion method (adapt ive modulat ion request ) to be calculated by
15 the radio l ink control uni t A206, in place of using the received traff ic
amount of each of the wireless t ransmission paths. In the above
modi ficat ion, the swi tching control uni t 204 checks whether there is a
wireless transmission path whose rat io of the t raf fic amount t ransmi t table
by a modulat ion method (adapt ive modulat ion request ) wi th respect to the
20 transmission t raf fic amount is not larger than a prede termined value. As
a resul t of the checking, when there is such a wi reless t ransmission path as
described above, the swi tching control uni t 204 detects the wi reless
transmission path as a wireless t ransmission path in which a l ine faul t has
occurred. The swi tching control uni t 204 judges a wireless t ransmission
25 path whose transmission t raf fic amount is zero, as a wi reless t ransmission
path having no l ine faul t .
[0066]
Subsequent ly, when the swi tching cont rol uni t 204 detects a l ine
faul t , the swi tching control uni t 204 acqui res, f rom the ring map storage
28
uni t 205, the SNR value of the wi reless t ransmission path in which a l ine
faul t has occurred. The swi tching cont rol uni t 204 not i fies the
supervisory cont rol device of informat ion represent ing the wi rele ss
transmission path in which a l ine faul t has occur red (hereinafter , cal led as
a “faul ty l ine” ), and a faul t status of the faul ty l ine. The faul t statu5 s
includes the SNR value of the faul ty l ine acqui red f rom the r ing map
storage uni t 205.
[0067]
Subsequent ly, the supervisory control device not i fied of the
10 informat ion represent ing the faul ty l ine and the faul t status obtains a faul ty
sect ion by connect ing the faul ty l ines, and not i fies the respect ive swi tching
control uni ts 204 of the wi reless t ransmissi on devices 1 to 5 of the faul ty
sect ion and the faul t status, as a faul t informat ion not ificat ion. Each of
the swi tching cont rol uni ts 204 receives the faul t informat ion not i ficat ion
15 to thereby recognize what faul t has occurred in which sect ion of the
wireless transmission paths .
[0068]
Subsequent ly, each of the swi tching cont rol uni ts 204 that has
received the faul t informat ion not i ficat ion reads out a ring map f rom the
20 ring map storage uni t 205, and recognizes a communicat ion path set t ing
status (Step S902).
[0069]
(Swi tching cont rol of service t raf fic)
Subsequent ly, each of the swi tching cont rol uni ts 204 judges
25 whether i t is necessary to bypass the service t raf fic (Step S903).
[0070]
Specif ical ly, each of the swi tching control uni ts 204 checks, from
the faul t informat ion not i ficat ion and the ring map, whether there is a
faul ty sect ion on a wireless t ransmission path in which a communicat ion
29
path for use in transmi t t ing service traffic (hereinafter, cal led as a “service
communicat ion path” ) is set , out of the communicat ion paths. When
there is a faul ty sect ion on the wi reless t ransmission path in which the
service communicat ion path is set , the swi tching cont rol uni t 204 judges i t
is necessary to bypass the service t raf fic. Further, al though no5 t
illust rated, each of the swi tching cont rol uni ts 204 checks, f rom the faul t
informat ion not i ficat ion and the ring map, whether a l ine faul t has
occurred in al l the wireless t ransmission paths in the same di rect ion as the
faul ty sect ion.
10 [0071]
When each of the swi tching cont rol uni ts 204 judges that i t is
necessary to bypass the service t raf fic, each of the swi tching control uni ts
204 bypasses the service t raf fic to a wireless transmission path that does
not pass the faul ty sect ion, as described in the fol lowing sect ions ( I) and
15 (II) (Step S904).
[0072]
( I) Fi rst of al l , each of the swi tching cont rol uni ts 204
recognizes to which one of the wi reless t ransmission devices 1 to 5, it
belongs, from a predetermined set value. The predetermined set value is
20 a value represent ing the wi reless t ransmission devices 1 to 5, and is set in
advance in the swi tching cont rol uni t 204 by the user of the wireless
transmission system in the present exemplary embodiment . The
predetermined set value may be set in the supervisory cont rol device by the
user of the wireless t ransmission system in the present exemplary
25 embodiment , and may be not i fied to the swi tching control uni t 204 by the
supervisory cont rol device. Subsequent ly, the swi tching control uni t 204
checks, f rom the ring map and the faul t informat ion not i ficat ion, whether it
direct ly connects wi th a wi reless transmission path in which a faul t has
occurred and transmi t s service traffic to the wi reless t ransmission path
30
(hereinafter , cal led as a “ t ransmission side condi t ion”) . When the
transmission status of service t raf fic coincides wi th the transmission side
condi t ion, the swi tching control uni t 204 checks whether a faul t has
occurred in a wi reless transmission path in the same direct ion as the
wireless transmission path in which the faul t has occur red, f rom the faul 5 t
informat ion not i ficat ion and the ring map. When a faul t has not occur red,
the swi tching cont rol uni t 204 selects the wireless transmission path in
which a faul t has not occur red. Subsequent ly, the swi tching control uni t
204 not i fies the swi tching ci rcui t uni t 203 of the swi tching control
10 informat ion represent ing that the selected wi reless t ransmission path
serves as an output dest inat ion transmission path. The swi tching ci rcui t
uni t 203 swi tches the output dest inat ion t ransmission path to a wireless
transmission path represented by the swi tching control informat ion. As a
resul t of the swi tching operat ion, even when a faul t has occur red in a
15 wireless transmission path to be connected, the wi reless t ransmissi on
device is al lowed to swi tch the service t raf fic to the wi reless transmission
path in the same direct ion (hereinafter , cal led as “span swi tching” ) for
avoiding a faul ty sect ion. For instance, in the case of Fig. 5, the wi reless
transmission device 5 per forms span swi tching to the standby system
20 transmission path P3 in the same di rect ion as the act ive system
transmission path P2 in which a faul t has occurred for avoiding a faul ty
sect ion.
[0073]
(II) In Step S903 as described above, when i t is checked th at a
25 faul t has occurred in al l the wireless t ransmission paths in the same
direct ion as the faul ty sect ion, the swi tching control uni t 204 of the
wireless transmission device which receives the service t raf fic from the
wired l ine side checks whether i t is possible to bypass the service t raf fic to
a wireless t ransmission path in the opposi te direct ion to the di rect ion of
31
the service communicat ion path. Hereinafter, the swi tching control uni t
204 of the wireless t ransmission device which receives the service traffic
from the wi red l ine side is cal led as a “ transmission source swi tching
control uni t 204” . Specif ical ly, the t ransmission source swi tching
control uni t 204 checks, f rom the faul t informat ion not i ficat ion and th5 e
ring map, whether i t is possible to bypass the service traff ic to a wi reless
transmission path in the opposi te di rect ion to the di rect ion of the wi reless
transmission path in which a service communicat ion path is set . When i t
is possible to bypass the service traff ic, the transmission sour ce swi tching
10 control uni t 204 selects the wireless transmission path. The swi tching
control uni t 204 not i fies the swi tching circui t uni t 203 of the swi tching
control informat ion represent ing that the selected wireless t ransmission
path serves as an output dest inat ion t ransmission path. The swi tching
circui t uni t 203 swi tches the output dest inat ion t ransmission path to the
15 selected wireless t ransmission path. As a resul t of the swi tching
operat ion, the wireless t ransmission device in the present exemplary
embodiment swi tches the service t raf fic to the wi reless t ransmission path
in the opposi te direct ion (hereinafter , cal led as a “ring swi tching”) for
avoiding a faul ty sect ion. For instance, in the case of Fig. 6, the wi reless
20 communicat ion t ransmission device 4 as a t ransmission source outputs the
service t raf fic S302 to the standby system transmission path P1 in the
opposi te di rect ion to the di rect ion of the act ive system and standby system
transmission paths P2 and P3 in which a faul t has occurred for avoiding a
faul ty sect ion.
25 [0074]
When the span swi tching is per formed, the extra t raf fic that has
been transmi t ted by the transmission path to evacuate service t raf fic is cut
of f. When a communicat ion path of ext ra traff ic is cut off , the swi tching
control uni t 204 sets a communicat ion path again in a sect ion which does
32
not af fect the service traf fic by a wel l -known funct ion, and cont inues
communicat ion.
[0075]
(Swi tching cont rol of extra t raf fic)
Subsequent ly, the swi tching cont rol uni t 204 judges wheth er i t i5 s
necessary to bypass the extra t raf fic (Step S905).
[0076]
Specif ical ly, the swi tching control uni t 204 checks, f rom the faul t
informat ion not i ficat ion and the r ing map, whether there is a faul ty sect ion
10 on a wireless t ransmission path in which a communicat ion path for use in
transmi t t ing extra traffic (hereinafter, cal led as “extra communicat ion
path” ) is set , out of the communicat ion paths. The swi tching control uni t
204 judges that i t is necessary to bypass the extra t raf fic, when there is a
faul ty sect ion on the wireless transmission path in which the extra
15 communicat ion path is set .
[0077]
When the swi tching control uni t 204 judges that i t is necessary to
bypass the extra t raf fic, the swi tching control uni t 204 checks, f rom the
faul t informat ion not ificat ion and the r ing map, whether an unused
20 transmission path for use in transmi t t ing the extra t raf fic is avai lable (Step
S906).
When an unused transmission path for use in t ransmi t t ing the extra
traf fic is avai lable, the swi tching cont rol uni t 204 bypasses the extra
traf fic to the t ransmission path, wi th use of the swi tching ci rcui t uni t 203
25 (Step S907).
[0078]
The concrete methods of Steps S906 and S907 are the same as the
methods ( I) and ( II) as described above. However, the “service
communicat ion path” is read as the “extra communicat ion path” , and the
33
“service traffic” is read as t h e “extra traf fic” . Further, the ”wireless
transmission path in the same di rect ion” is read as the “unused wi reless
transmission path in the same di rect ion ” , and the “wireless transmission
path in the opposi te direct ion” is read as the “unused wireless transmission
path in the opposi te direct ion” 5 .
[0079]
Fig. 8 is a diagram i l lustrat ing a set t ing example of a
communicat ion path, when a faul t has occur red in the s tandby system
transmission path of the wi reless t ransmission system in the present
10 exemplary embodiment . Fig. 8 i l lust rates a set t ing example of a
communicat ion path, when a faul t has occur red in the counterclockwise
standby system t ransmission path P1 ( among the wireless transmission
devices 5-4-3) along which the extra t raf f ic E301 is transmi t ted, from the
communicat ion path set t ing state in Fig. 4. As the clockwise standby
15 system t ransmission path P3 is an unused wireless transmission path, the
swi tching control uni t 204 of the wi reless transmission device 5 per forms
ring swi tching, and bypasses the ext ra traffic to the clockwise standby
system t ransmission path P3 for avoiding a faul ty sect ion.
[0080]
20 (Swi tching cont rol when path for bypassing extra t raf fic is not
avai lable)
Fig. 9 is a diagram i l lustrat ing a set t ing example of a
communicat ion path, when a path for bypassing extra t raf fic by the
wireless transmission system in the fi rst exemplary embodiment of the
25 present invent ion is not avai lable. Fig. 9 i l lustrates a case, in which a
l ine faul t has occur red in the standby system t ransmission path P1 and the
act ive system t ransmission path P4 between the wireless transmission
devices 4-5, f rom the communicat ion path set t ing state in Fig. 4, and an
unused transmission path for bypassing the extra t raf fic E301 is not
34
avai lable.
[0081]
When an unused transmission path for bypassing is not avai lable as
i l lust rated in Fig. 9, the swi tching cont rol uni t 204 of the wi reless
transmission device for t ransmi t t ing the extra t raf fic to a wi reles5 s
transmission path in which a faul t has occur red judges whether i t is
possible to t ransmi t the extra traff ic along the t ransmission path in which a
l ine faul t has occur red even at a lower speed (Step S908).
[0082]
10 Speci f ical ly, the swi tching control uni t 204 acqui res a modulat ion
method (adapt ive modulat ion request ) of the transmission path in which a
faul t has occurred f rom the ring map storage uni t 205, and acquires the
SNR value of the t ransmission path in which the f aul t has occur red from
the faul t informat ion not i ficat ion. Subsequent ly, the swi tching control
15 uni t 204 checks that the acquired modulat ion method is a modulat ion
method whose mul t i -value number is not larger than a predetermined
number and that the acqui red SNR value is not lower than a predetermined
value (hereinaf ter, cal led as a “ low-speed l ine use condi t ion” ). The
swi tching control uni t 204 judges that the transmission path in which a l ine
20 faul t has occurred is usable as a low-speed l ine when the low-speed l ine
use condi t ion is sat isfied, and selects the transmission path as the
low-speed l ine.
[0083]
In the case of Fig. 9, the swi tching control uni t 204 of the wireless
25 transmission device 5 acqui res the modulat ion method and the SNR value
of the t ransmission paths P1 and P4 in which a l ine faul t has occur red f rom
the ring map storage uni t 205 and the faul t informat ion not ificat ion. The
swi tching control uni t 204 of the wi reless transmission device 5 checks,
regarding each of the transmission paths P1 and P4, that the acquired
35
modulat ion method is a modulat ion method whose mul t i -value number is
not larger than a predetermined number, and that the SNR value is not
lower than a predetermined value, in other words, the low-speed l ine use
condi t ion is sat isfied. The swi tching control uni t 204 judges that the
transmission path that sat isfies the low-speed l ine use condi t ion is 5 a
wireless transmission path capable of t ransmission even at a lower speed.
The wi reless transmission path capable of transmission even at a lower
speed is hereinafter cal led as a “t r an smi s s i o n path usable as a low-speed
l ine” . When there are two or more t ransmission paths usable as a
10 low-speed l ine, the swi tching control uni t 204 selects a l ine whose l ine
speed is faster, in other words, a transmission path of a modulat ion method
whose mul t i -value number is the largest , as a wi reless t ransmission path
usable as a low-speed l ine.
[0084]
15 Subsequent ly, the swi tching cont rol uni t 204 per forms an operat ion
of swi tching a transmission path to which the extra t raf fic is output , to a
transmission path usable at a low speed (hereinafter, cal led as a
“ low-speed t ransmission path”) (Step S909) .
[0085]
20 Specif ical ly, the swi tching control uni t 204 not i fies the swi tching
circui t uni t 203 of the swi tching control informat ion represent ing that the
output dest inat ion t ransmission path is a low-speed t ransmission path.
The swi tching circui t uni t 203 swi tches the output dest inat ion t ransmission
path to the low-speed transmission path. In the case of Fig. 9, the
25 swi tching control uni t 204 of the wi reless transmission device 5 bypasses
the extra traffic E301 to one of the t ransmission paths P1 and P4, when the
transmission paths P1 and P4 in which a l ine faul t has occur red sat isfy the
low-speed l ine use condi t ion.
[0086]
36
[Descript ion of Advantageous Effects]
According to the present exemplary embodiment , the t ransmission
system is capable of cont inuing transmission of extra t raf fic, wi thout
af fect ing transmission of service t raf fic, even when an unuse d and
bypassable transmission path is not avai lable at the t ime of l ine faul 5 t
(hereinafter , this case is cal led as a “case where there is no bypass ” ).
[0087]
The reason for the above is as fol lows. The transmission system
in the present exemplary embodiment is const i tuted of transmission paths
10 wi th use of radio l ines. Even when there is no bypass at the t ime of l ine
faul t , the t ransmission system judges whether the extra traffic is
transmi t table along a transmission path in which a faul t has occurred.
When the transmission system judges that the ext ra t raf fic is t ransmi t table,
the transmission system bypasses the extra t raf fic to the t ransmission path.
15 [0088]
Further, the t ransmission system in the present exemplary
embodiment uses a faul ty t ransmission path along which service t raf fic is
not t ransmi t ted. This makes i t possible to cont inue t ransmission of extra
traf fic wi thout affect ing the service traffic.
20 [0089]
[Second Exemplary Embodiment]
In the fol lowing, the second exemplary embodiment of the present
invent ion is descr ibed.
[0090]
25 [Descript ion of Conf igurat ion]
Fig. 10 is a diagram i l lust rat ing a configurat ion example of a
wireless transmission system in the second exemplary embodiment of the
present invent ion. The wi reless transmission system in the second
exemplary embodiment of the present invent ion is a wireless t ransmission
37
system in which a plural i ty of wireless t ransmission devices are connected
via a plural i ty of wireless t ransmission paths. Whereas Fig. 10 i l lust rates
five wireless t ransmission devices 21 to 25, the number of wi reless
transmission devices is not l imi ted to the above.
[00915 ]
Each of the wi reless transmission devices 21 to 25 is a wireless
transmission device for transmi t t ing traffic to the other one of the wi reless
transmission devices via a wireless transmission path selected f rom among
the connected wi reless t ransmission paths. Each of the wireless
10 transmission devices 21 to 25 is provided wi th a swi tching control uni t
which selects a wi reless transmission path for transmi t t ing t raffic f rom
among the wi reless t ransmission paths.
[0092]
The swi tching control uni t judges whether i t is possible to t ransmi t
15 the traffic wi th use of a wireless t ransmission path in which a faul t has
occurred, namely, wi th use of a faul ty transmission path, when the faul t
has occur red in the wireless transmission path for transmi t t ing the traffic.
Further, the swi tching cont rol uni t selects the faul ty transmission path, as a
wireless transmission path for transmi t t ing the traffic, when i t is possible
20 to t ransmi t the t raf fic wi th use of the faul ty t ransmission path.
[0093]
[Descript ion of Operat ion]
The swi tching control uni t judges whether i t is possible to t ransmi t
the traffic wi th use of a wireless t ransmission path in which a faul t has
25 occurred, namely, wi th use of a faul ty transmission path, when the faul t
has occur red in the wireless transmission path for transmi t t ing the traffic.
The t raf fic may be extra t raf fic.
[0094]
In order to judge whether i t is possible to transmi t the traffi c wi th
38
use of a faul ty transmission path, first of al l , the swi tching control uni t
receives, from the other one of the wi reless t ransmission devices di rect ly
connected via the faul ty t ransmission path, the modulat ion method and the
SNR value relat ing to the faul ty t ransmission path. Subsequent ly, the
swi tching control uni t judges that extra traf fic is t ransmi t table along th5 e
faul ty transmission path, when the received modulat ion method is a
modulat ion method whose mul t i -value number is not larger than a
predetermined number , and when the SNR value is not lower than a
predetermined value.
10 [0095]
Subsequent ly, the swi tching cont rol uni t selects the faul ty
transmission path as a wireless t ransmission path for t ransmi t t ing the
traf fic, when i t is possible to t ransmi t the traf fic wi th use of the faul ty
transmission path.
15 [0096]
The wi reless transmission system in the second exemplary
embodiment of the present invent ion is not l imi ted to a configurat ion, in
which the wi reless t ransmission devices 21 to 25 are co nnected in the form
of a ring. The wi reless transmission system in the second exemplary
20 embodiment of the present invent ion may be such that a plural i ty of
uni l lustrated wi reless transmission devices are connected in the form of a
star or in the form of a mesh.
[0097]
[Descript ion of Advantageous Effects]
25 According to the present exemplary embodiment , the t ransmission
system is capable of cont inuing transmission of extra t raf fic, wi thout
af fect ing transmission of service t raf fic, even when an unused and
bypassable transmission path is not avai lable at the t ime of l ine faul t
(hereinafter , this case is cal led as a “case where there is no bypass ”).
39
[0098]
The reason for the above is as fol lows. The transmission system
in the present exemplary embodiment is const i tuted of transmission paths
wi th use of radio l ines. Even when there is no bypass at the t ime of l ine
faul t , the t ransmission system judges whether i t is possible to transmi t th5 e
traf fic along a t ransmission path in which a faul t has occur red. When i t
is possible to t ransmi t the t raf fic, the t ransmission system bypasses the
extra t raf fic to the t ransmission path.
[0099]
10 The above-described exemplary embodiments are not l imi ted to the
embodiments, and may be modified in various ways when the invent ion is
car ried out , as far as such modi ficat ions do not depart f rom the gist of the
invent ion.
[0100]
15 This appl icat ion is based upon and claims the benefi t of prior i ty
from Japanese Patent Appl icat ion No. 2012-148403 fi led on July 2, 2012,
the disclosure of which is incorporated herein in i ts ent i rety by reference.
[0101]
20 The whole or part of the exemplary embodiments disclosed above
can be described as, but not l imi ted to, the fol lowing supplementary notes.
(Supplementary Note 1)
A wireless transmission device for t ransmi t t ing traffic to another
wireless transmission device via a selected one of a plural i ty of connected
25 wireless transmission paths, the wi reless transmission device comprising:
a swi tching control uni t which judges, when a faul t has occur red in
the wi reless t ransmission path for t ransmi t t ing the t raf fic, whether the
traf fic is transmi t table wi th use of the wi reless t ransmission path in which
the faul t has occur red, namely, a faul ty transmission path, and which
40
selects the faul ty t ransmis sion path, as the wireless t ransmission path for
transmi t t ing the t raf f ic, when judging that the t raf fic is transmi t table.
(Supplementary Note 2)
The wi reless transmission device according to Supplementary Note
1, wherei5 n
when there are a plural i ty of faul ty transmission paths capable of
transmi t t ing the t raf f ic, the swi tching control uni t selects the faul ty
transmission path whose transmission capaci ty is the largest , as the
wireless transmission path for transmi t t ing the traffic.
10 (Supplementary Note 3)
The wi reless transmission device according to any one of
Supplementary Notes 1 to 2, wherein
the swi tching cont rol uni t receives a modulat ion method and an
SNR (Signal to noise rat io) value relat ing to the faul ty t ransmission path
15 from the another wireless transmission device direct ly connected via the
faul ty transmission path, and judges that the traffic is t ransmi t table by the
faul ty transmission path, when the modulat ion method is the modulat ion
method whose mul t i -value number is not larger than a predetermined
number , and when the SNR value is not lower than a predetermined value.
20 (Supplementary Note 4)
The wi reless transmission device according to any one of
Supplementary Notes 1 to 3, wherein
the swi tching cont rol uni t judges whether the traffic is
transmi t table wi th use of the faul ty transmission path, when t ransmission
25 of the t raf fic by the wireless transmission path other than the faul ty
transmission path is disabled.
(Supplementary Note 5)
The wi reless transmission device according to any o ne of
Supplementary Notes 1 to 4, wherein
41
the traffic is low pr iori ty informat ion, namely, extra t raf fic.
(Supplementary Note 6)
A wireless transmission system compr ising two or more wi reless
transmission devices connected via a plural i ty of wireless t r ansmission
paths, wherei5 n
each of the wi reless transmission device is the wireless
transmission device according to any one of Supplementary Notes 1 to 5.
(Supplementary Note 7)
The wi reless transmission system according to Supplementary Note
10 6, wherein
the two or more wi reless transmission devices are connected in the
form of a ring.
(Supplementary Note 8)
A communicat ion l ine select ion method for select ing a wireless
15 transmission path f rom a plural i ty of wireless transmission paths so as to
transmi t t raf fic to a communicat ion dest inat ion, comprising:
judging, when a faul t has occur red in the wireless t ransmission path
for t ransmi t t ing the t raf fic, whether the traf fic is t ransmi t table wi th use of
the wi reless t ransmission path in which the faul t has occurred, namely, a
20 faul ty transmission path, and select ing the faul ty transmission path as the
wireless transmission path for transmi t t ing the traffic, when judging that
the traffic is t ransmi t table.
(Supplementary Note 9)
The communicat ion l ine select i on method according to
25 Supplementary Note 8, wherein
when there are a plural i ty of faul ty transmission paths capable of
transmi t t ing the t raf f ic, select ing the faul ty t ransmission path whose
transmission capaci ty is the largest as the wireless t ransmission path for
transmi t t ing the t raf f ic.
42
(Supplementary Note 10)
The communicat ion l ine select ion method according to
Supplementary Notes 8 to 9, wherein
receiving a modulat ion method and an SNR value relat ing to the
faul ty t ransmission path, and judging that the t raf fic is transmi t table by th5 e
faul ty transmission path, when the modulat ion method is the modulat ion
method whose mul t i -value number is not larger than a predetermined
number , and when the SNR value is not lower than a predetermined value .
(Supplementary Note 11)
10 The wi reless transmission device according to any one of
Supplementary Notes 3 to 5, wherein
the faul ty t ransmission path whose transmission capaci ty is the
largest is the faul ty t ransmission path of the modulat ion method whose
mul t i -value number is the largest .
15 (Supplementary Note 12)
The wi reless transmission device according to any one of
Supplementary Notes 1 to 5, or 11, wherein
the swi tching cont rol uni t measures a t raf fic amount of t raf fic to be
received f rom the wi reless t r ansmission path for each of the wireless
20 transmission paths, and
in response to input of a traffic amount of traffic to be received by a
wireless transmission system const i tuted of the wireless transmission
devices, namely a transmission traffic amount , the swi tching control uni t
judges that the faul t has occur red in the wireless transmission path for
25 transmi t t ing the t raf f ic, when there is the wireless transmission path whose
rat io of the received traf fic amount wi th respect to the transmission traff ic
amount is not larger than a predetermined value for a predetermined
period.
(Supplementary Note 13)
43
The wi reless transmission system according to any one of
Supplementary Notes 6 to 7, wherein
the wi reless t ransmission path is a duplex wi reless t ransmissi on
path const i tuted of an act ive system wireless transmission path and a
standby system wireless transmission path5 .
(Supplementary Note 14)
The communicat ion l ine select ion method according to
Supplementary Note 10, wherein
the faul ty t ransmission path whose transmission capaci ty is the
10 largest is the faul ty t ransmission path of the modulat ion method whose
mul t i -value number is the largest .
(Supplementary Note 15)
The communicat ion l ine select ion method according to any one of
Supplementary Notes 8 to 10, or 14, wherein
15 judging whether the traf fic is transmi t table wi th use of the faul ty
transmission path, when transmission of the traffic by the wireless
transmission path other than the faul ty t ransmission path is disabled.
(Supplementary Note 16)
The communicat ion l ine select ion method according to any one of
20 Supplementary Notes 8 to 10, or 14 to 15, wherein
the traffic is low pr iori ty informat ion, namely, extra t raf fic.
[Reference Signs List ]
[0102]
1, 2, 3, 4, 5 Wireless t ransmission device
25 21, 22, 23, 24, 25 Wireless t ransmission device
201, 202 IF circui t uni t
203 Swi tching circui t uni t
204 Swi tching cont rol uni t
205 Ring map storage uni t
44
206 Radio l ink control uni t
211, 221, 231, 241 Receiving antenna
212, 222, 232, 242 Radio receiving uni t
213, 223, 233, 243 Radio circui t extract ion uni t
214, 224, 234, 244 Radio circui t mul t iplexer uni 5 t
215, 225, 235, 245 Radio t ransmission uni t
216, 226, 236, 246 Transmission antenna

WE CLAIMS:-
1. A wireless transmission device for t r ansmi t t ing traffic to another
wireless transmission device via a selected one of a plural i ty of connected
wireless transmission paths, the wi reless transmission device comprising5 :
a swi tching control uni t which judges, when a faul t has occur red in
the wi reless t ransmission path for t ransmi t t ing the t raf fic, whether the
traf fic is transmi t table wi th use of the wi reless t ransmission path in which
the faul t has occur red, namely, a faul ty transmission path, and which
10 selects the faul ty t ransmission path, as th e wireless t ransmission path for
transmi t t ing the t raf f ic, when judging that the t raf fic is transmi t table.
2. The wi reless transmission device according to Claim 1, wherein
when there are a plural i ty of faul ty transmission paths capable of
15 transmi t t ing the t raf f ic, the swi tching control uni t selects the faul ty
transmission path whose transmission capaci ty is the largest , as the
wireless transmission path for transmi t t ing the traffic.
3. The wi reless transmission device according to any one of Claims 1
20 to 2, wherein
the swi tching cont rol uni t receives a modulat ion method and an
SNR (Signal to noise rat io) value relat ing to the faul ty t ransmission path
from the another wireless transmission device direct ly connected via the
faul ty transmission path, and judges that the traffic is t ransmi t table by the
25 faul ty transmission path, when the modulat ion method is the modulat ion
method whose mul t i -value number is not larger than a predetermined
number , and when the SNR value is not lower than a predetermined value.
4. The wi reless transmission device according to any one of Claims 1
46
to 3, wherein
the swi tching cont rol uni t judges whether the traffic is
transmi t table wi th use of the faul ty transmission path, when t ransmission
of the t raf fic by the wireless transmiss ion path other than the faul ty
transmission path is disabled5 .
5. The wi reless transmission device according to any one of Claims 1
to 4, wherein
the traffic is low pr iori ty informat ion, namely, extra t raf fic.
10
6. A wireless transmission system compr ising two or more wi reless
transmission devices connected via a plural i ty of wireless t ransmission
paths, wherein
each of the wi reless transmission device s is the wi reless
15 transmission device according to any one of Claims 1 to 5.
7. The wi reless transmission system according to Claim 6, wherein
the two or more wi reless transmission devices are connected in the
form of a ring.
20
8. A communicat ion l ine select ion method for select ing a wireless
transmission path f rom a plural i ty of wireless transmission paths s o as to
transmi t t raf fic to a communicat ion dest inat ion, comprising:
judging, when a faul t has occur red in the wireless t ransmission path
25 for t ransmi t t ing the t raf fic, whether the traf fic is t ransmi t table wi th use of
the wi reless t ransmission path in whic h the faul t has occurred, namely, a
faul ty transmission path, and select ing the faul ty transmission path as the
wireless transmission path for transmi t t ing the traffic, when judging that
the traffic is t ransmi t table.
47
9. The communicat ion l ine select ion me thod according to Claim 8,
wherein
when there are a plural i ty of faul ty transmission paths capable of
transmi t t ing the t raf f ic, select ing the faul ty t ransmission path whos5 e
transmission capaci ty is the largest as the wireless t ransmission path for
transmi t t ing the t raf f ic.
10. The communicat ion l ine select ion method according to Claims 8 to
10 9, wherein
receiving a modulat ion method and an SNR value relat ing to the
faul ty t ransmission path, and judging that the t raf fic is transmi t table by the
faul ty transmission path, when the modulat ion method is the modulat ion
method whose mul t i -value number is not larger than a predetermined
15 number , and when the SNR value is not lower than a predetermined value .
11. The wi reless transmission device according to any o ne of Claims 3
to 5, wherein
the faul ty t ransmission path whose transmission capaci ty is the
20 largest is the faul ty t ransmission path of the modulat ion method whose
mul t i -value number is the largest .
12. The wi reless transmission device according to any o ne of Claims 1
to 5, or 11, wherein
25 the swi tching cont rol uni t measures a t raf fic amount of t raf fic to be
received f rom the wi reless t ransmission path for each of the wireless
transmission paths, and
in response to input of a traffic amount of traffic to be received by a
wireless transmission system const i tuted of the wireless transmission
48
devices, namely a transmission traffic amount , the swi tching control uni t
judges that the faul t has occur red in the wireless transmission path for
transmi t t ing the t raf f ic, when there is the wireless transmission path whose
rat io of the received traf fic amount wi th respect to the transmission traff ic
amount is not larger than a predetermined value for a predetermine5 d
period.
13. The wi reless transmission system according to any one of Claims 6
to 7, wherein
10 the wi reless t ransmission path is a duplex wi reless t ransmission
path const i tuted of an act ive system wireless transmission path and a
standby system wireless transmission path.
14. The communicat ion l ine select ion method according to Claim 10,
15 wherein
the faul ty t ransmission path whose transmission capaci ty is the
largest is the faul ty t ransmission path of the modulat ion method whose
mul t i -value number is the largest .
20 15. The communicat ion l ine select ion method ac cording to any one of
Claims 8 to 10, or 14, wherein
judging whether the traf fic is transmi t table wi th use of the faul ty
transmission path, when transmission of the traffic by the wireless
transmission path other than the faul ty t ransmission path is disab led.
25 16. The communicat ion l ine select ion method according to any one of
Claims 8 to 10, or 14 to 15, wherein
the traffic is low pr iori ty informat ion, namely, extra t raf fic.