Ti t l e of Inv ent ion
COMMUNICATION APPARATUS, TIME SYNCHRONIZATIO5 N
SYSTEM, AND TIME SYNCHRONIZATION METHOD
Te chni c a l Fi e ld
10 [0001]
The pr e s ent invent ion r e l a t e s to a communi c a t ion a ppa r a tus , a
t ime s ynchroni z a t ion s ys t em, and a t ime s yn c hroni z a t ion me thod,
pa r t i cul a r l y a communi c a t ion appa r a t us , a t ime s ynchron i z a t ion
s ys t em, and a t ime s ynch roni z a t ion me thod for t ime s ynch roni z a t ion
15 in a t r ansmi s s ion sys t em havin g a s ymme t r i c a l de l a y cha r a c t e r i s t i c s in
whi ch t r ansmi s s ion de l a y t ime i s di f f e r ent dependin g on t he di r e c t ion
of t r ansmi s s ion.
Ba ck ground Ar t
20 [0002]
Gen e r a l l y, in a ba s e s t a t ion of a mobi l e communi c a t ion,
a c cur a c y of t ime s ynchroni z a t ion of s eve r a l mi c ro s e cond s or l e s s i s
r equi r ed. A t ime s ynch roni z a t ion s ys t em, l ike GNSS (Gl oba l
Naviga t ion Sa t e l l i t e Sys t em) , i s the r e f or e u s ed. IEEE (The Ins t i tut e
25 of El e c t r i c a l and El e c t roni c s En gine e r s ) 1588 whi ch de f in e s the
me thod for s ynchro ni z ing a devi c e on a ne twork wi th a c c ur a c y of l e s s
than a mi c ro s e con d, c an a l so be us ed for t ime s ynch roni z a t ion .
[0003]
PTL 1 di s c lo s e s a t e chnolo g y on the t ime s ynchroni z a t ion
3
ne twork and the communi c a t ion appa r a tus whi ch a chi ev e t ime
s ynch roni z a t ion wi thin r equi r ed a c cur a c y wi thout inc r e a s i ng a
ne twork load or wi thout inc r e a s in g cos t o f mount ing a highl y a c cu r a t e
os c i l l a tor , when a b a s e s t a t ion whi ch c a r r i e s out t ime s ync hroni z a t ion
on the ba s i s of GPS (Globa l Pos i t ioning S ys t em) and a b a s e s t a t io5 n
whi ch c a r r i e s out t ime s ynch roni z a t ion on the ba s i s of GPS throu gh a
pa cke t ne twork us i ng protocol , l ike IEEE 1588 ex i s t in the s ame
ne twork.
[0004]
10 PTL 2 di s c lo s e s the t e chnolo gy r e l a t ed to the t ime
s ynch roni z a t ion s ys t em whi ch s yn chron i z e s a t ime a t a s l av e node to a
t ime a t a ma s t e r no de us ing protocol , l ike IEEE 1588.
Ci t a t ion Li s t
15 Pa t ent Li t e r a tur e
[0005]
PTL 1: J apane s e Pa t ent Appl i c a t ion La id -Open No. 2010 -278546
PTL 2: J apane s e Pa t ent Appl i c a t ion La id -Open No. 2011 -135482
Summa r y of Inv ent ion
20 Te chni c a l Probl em
[0006]
Howev e r , PTLs 1 and 2 inc lude a probl em in whi ch t ime
s ynch roni z a t ion be come inde f ini t e wh en a t r ansmi s s ion pa th ha s
a s ymme t r i c a l de l a y cha r a c t e r i s t i c s . The r e a son i s de s c r ibed be low.
25 [0007]
In ord e r to s t abl y c a r r y out t ime s yn chroni z a t ion in GNSS, sk y
vi ew ha s to be suf f i c i ent l y s e cur ed. Howeve r , s inc e ful l sk y vi ew
ma y not be obt a ine d in an urban a r e a due to bui lding wa l l pl a c ement
or sur rounding obs t a c l e s , s t abi l i t y pro bl em ex i s t s . Us ing a
4
broadc a s t in g wav e f rom a s a t e l l i t e , GNSS i s a s ys t em wh i ch i s not
r e l a t ive l y subj e c t ed to di s turbanc e f rom the o ut s ide . Ho ldove r
s i tua t ion howeve r ma y oc cur and t ime s ynch roni z a t ion ma y b e los t
be c aus e o f suspens ion of GNSS, shi e ld ing of a t r ansmi s s ion pa th,
int e r f e r enc e b y an int e r rupt ing wav e , f a i lur e of a r e c e ivin g appa r a tus 5 ,
or the l ike . Hen c e , f aul t - tol e r an c e h a s to be improved.
[0008]
The r e for e , a GNSS r e c e ive r i s r equi r ed to ke ep t ime
s ynch roni z a t ion b y i t s e l f ev en in Holdove r s i tua t ion . In orde r to
10 ke ep t ime s yn chron i z a t ion for a pr a c t i c a l - l eve l pe r iod of t ime a s
de s c r ibed abov e , a l a rge and ex pens i ve f r equen c y sour c e , such a s
OCXO (Oven Cont r ol l ed Xt a l Os c i l l a to r ) wi th hi gh lon g - t e rm s t abi l i t y,
an a tomi c os c i l l a tor , or the l ike , ha s t o be us ed.
[0009]
15 Ac cordin gl y i n orde r to r educ e c os t of GNSS, a s di s c los ed in
PTL 1 or 2, IEEE 1 855 s ys t em, l ike NTP (Ne twork Time Protocol ) or
PTP (Pr e c i s ion Time Protocol ) , whi ch c a r r i e s out t ime
s ynch roni z a t ion b y supe r impos ing on a t r ansmi s s ion s ys t em, i s us ed.
Sinc e the above s ys t em i s supe r impos e d on the t r ansmi s s ion s ys t em,
20 f luc tua t ion of de l a y amount be twe en t r ansmi s s ion appa r a tus e s ma y
va r y dependin g on t r ansmi s s ion pa th e nvi ronment or de l a y amount
ma y be di f f e r ent de pending on a t r ansmi s s ion pa th. The r e for e , t ime
s ynch roni z a t ion be come s inde f ini t e .
[0010]
25 He r e , t he f lu c tua t ion of de l a y amount c an be cor r e c t ed to some
ex t ent b y ave r a ging a r r iva l t ime s or pu l l ing the sho r t e s t a r r iva l .
Howeve r , t ime s ync hroni z a t ion be twe e n appa r a tus e s c ann ot be c a r r i e d
out a s de s c r ibed be low, i f de l a y s o f bi -di r e c t iona l t r ansmi s s ion pa th s
a r e di f f e r ent .
5
[0011]
A s i tua t ion in whi ch a t ime of a s l ave devi c e i s s yn chroni z ed
wi th a t ime of a ma s t e r devi c e i s ex pl a ined be low. Ini t i a l l y the
ma s t e r devi c e t r ansmi t s a pa ck e t inc luding informa t ion of a t ime A1
in the ma s t e r devi c e to the s l ave devi c e . The t ime A1 i s , fo5 r
ex ampl e , a t r ansmi t t ing t ime of the pa c ke t . The s l av e de vi c e whi ch
ha s r e c e ived the pa cke t c an c a l cul a t e i t s own t ime B1 b y us ing a
t r ansmi s s ion de l a y t ime X f rom the ma s t e r devi c e to the s l ave devi c e
on the ba s i s of the fol lowing equa t ion (1) .
10 B 1 = A 1 + X … (1)
[0012]
At thi s t ime , howeve r , s inc e the t ime s of the ma s t e r devi c e and
the s l ave devi c e do not s ynchroni z e , the t r ansmi s s ion de l a y t ime X
c annot be c a l cul a t e d a c cur a t e l y. Thu s , a pa cke t t r ansmi s s ion de l a y
15 t ime Y of the oppos i t e d i r e c t ion i s fur the r us ed, tha t i s , when the
pa cke t i s t r ansmi t t ed f rom the s l ave de vi c e to the ma s t e r d evi c e .
Tha t i s to s a y, pa ck e t s having informa t ion on the t r ansmi t t ing t ime a r e
s ent ba ck b y r e turn be twe en the ma s t e r devi c e and th e s l a ve devi c e
whos e t ime s a r e de t e rmined. Th e r eb y the bidi r e c t iona l de l a y amount
20 i s c a l cul a t ed and a ha l f the r eof i s e s t ima t ed a s the t r ansmi s s ion de l a y
t i m e X ’ ( e . g. equa t i on (2) ) . The t ime B of the s l ave d evi c e i s
c a l cul a t ed on the b a s i s of the fol lowing equ a t ion (3) and
s ynch roni z a t ion wi th the t ime A of the ma s t e r devi c e b e come s
pos s ibl e .
25 X ’ = ( X + Y ) / 2 … (2)
B = A + X ’ … (3)
[0013]
He r e , i n the above de s c r ipt ion, de l a y t ime X = de l a y t ime Y i s
pr emi s ed. I f the de l a ys o f bi-di r e c t i ona l l y t r ansmi s s ion pa ths a r e
6
di f f e r ent , t ime di f f e r enc e be twe en X a nd Y be come s an of f s e t e r ror o f
the t ime B and auto nomous r e solut ion i s impos s ibl e . The r e for e ,
t ime s ynchroni z a t ion be twe en the ma s t e r devi c e and the s l ave devi c e
c annot be c a r r i ed o ut and t ime s ynchro ni z a t i on be come s i nde f ini t e .
[00145 ]
The invent io n i s made in cons id e r a t ion of the abov e probl em,
and an obj e c t the r e of i s to provide a c ommuni c a t ion appa r a tus , a t ime
s ynch roni z a t ion s ys t em, and a t ime s yn chroni z a t ion me tho d whi ch
ke ep t ime s yn chron i z a t io n a c cur a c y in a t r ansmi s s ion s ys t em having
10 a s ymme t r i c a l de l a y cha r a c t e r i s t i c s in whi ch a t r ansmi s s ion de l a y t ime
i s di f f e r ent dependi ng on the di r e c t ion of t r ansmi s s ion.
Solut ion to Probl em
[0015]
15 A communi c a t ion appa r a tus of a f i r s t a spe c t of th e invent ion
inc lude s a s tor a ge uni t tha t s tor e s in a dvanc e di f f e r en c e i nforma t ion
be twe en f i r s t t ime informa t ion and s e c ond t ime informa t i on, the f i r s t
t ime informa t ion be ing r e c e ived f rom a s ynch roni z a t ion sour c e
communi c a t ion appa r a tus , a s a t ime s ynchroni z a t ion sour c e ,
20 conne c t ed to a t r an smi s s ion s ys t em wh e r e in a t r ansmi s s ion de l a y t ime
i s di f f e r ent depending on the di r e c t ion of t r ansmi s s ion and the s e cond
t ime informa t ion o bt a ined f rom a t ime s ynch roni z a t ion or igin othe r
than the t r ansmi s s ion s ys t em, and t ime s yn chroni z a t ion me ans for
c a r r yin g out , when the s e cond t ime informa t ion c annot be obt a ined
25 f rom the t ime s ync hroni z a t ion or igin , t ime s ynchroni z a t ion wi th the
s ynch roni z a t ion sour c e communi c a t io n appa r a tus us in g the di f f e r enc e
informa t ion r e ad ou t f r om the s tor a ge u ni t .
[0016]
A t ime s yn c hroni z a t ion s ys t em of a s e cond a spe c t of the
7
invent ion inc lude s a t r ansmi s s ion s ys t em in whi ch a t r ansmi s s ion
de l a y t ime i s di f f e r ent dependin g on the di r e c t ion of t r ansmi s s ion, a
f i r s t communi c a t ion appa r a tus t ha t i s conne c t ed to the t r ansmi s s ion
s ys t em, a s a t ime s yn ch roni z a t ion sour c e , a t ime s ynch ro ni z a t ion
or igin othe r than th e t r ansmi s s ion s ys t em, and a s e con5 d
communi c a t ion appa r a tus tha t i s conne c t ed to the t r ansmi s s ion s ys t em
and the t ime s ynch r oni z a t ion or igin an d c a r r i e s out t ime
s ynch roni z a t ion on the ba s i s of t ime informa t ion of the f i r s t
communi c a t ion appa r a tus . Th e s e con d communi c a t ion appa r a tus
10 inc lude s a s tor a ge uni t tha t s tor e s in a dvanc e di f f e r en c e i nforma t ion
be twe en f i r s t t ime informa t ion r e c e ive d f rom the f i r s t communi c a t ion
appa r a tus and s e co nd t ime informa t io n obt a ined f rom the t ime
s ynch roni z a t ion or igin , and t ime s ynch roni z a t ion me ans fo r c a r r yin g
out , when the s e con d t ime informa t ion c annot be obt a ined f rom the
15 t ime s ynchroni z a t ion or igin , t ime s yn c hroni z a t ion wi th the f i r s t
communi c a t ion appa r a tus us ing the di f f e r en c e informa t ion r e ad out
f rom the s tor a ge un i t .
[0017]
A t ime s yn c hroni z a t ion me thod of a thi rd a spe c t o f the
20 invent ion inc lude s r e c e ivin g f i r s t t ime informa t ion f rom a
synch roni z a t ion sour c e communi c a t io n appa r a tus , a s a t ime
s ynch roni z a t ion sour c e , conn e c t ed to a t r ansmi s s ion s ys t em whe r e in
t r ansmi s s ion de l a y t ime i s di f f e r ent de pending on the di r e c t ion of
t r ansmi s s ion, obt a ining s e cond t ime in forma t ion f rom a t ime
25 s ynch roni z a t ion or igin othe r than the t r ansmi s s ion s ys t em,
c a l cul a t in g di f f e r en c e informa t ion be twe en the f i r s t t ime informa t ion
and the s e cond t ime informa t ion, s tor ing the di f f e r enc e inf orma t ion in
a s tor a ge uni t , a f t e r tha t , r e adin g out the di f f e r enc e in fo rma t ion f rom
the s tor age me ans when the s e cond t ime informa t ion c an not be
8
obt a ined f rom the t ime s ynchroni z a t ion or igin , and c a r r yi ng out t ime
s ynch roni z a t ion wi th the s ynch roni z a t ion sour c e communi c a t ion
appa r a tus us in g the di f f e r en c e informa t ion r e ad o ut f rom the s tor a ge
uni t .
5
Advant a geous Ef f e c t s of Invent ion
[0018]
The invent io n i s made in cons id e r a t ion of the abov e probl ems ,
and c an provide a c ommuni c a t ion appa r a tus , a t ime s yn chr oni z a t ion
10 s ys t em, and a t ime s ynch roni z a t ion me thod whi ch ke ep t ime
s ynch roni z a t ion a c cur a c y in a t r ansmi s s ion s ys t em h aving
a s ymme t r i c a l de l a y cha r a c t e r i s t i c s in whi ch a t r ansmi s s ion de l a y t ime
i s di f f e r ent dependi ng on the di r e c t ion of t r ansmi s s ion.
15 Br i e f De s c r ipt ion of Dr awin gs
[0019]
[Fig. 1] i s a block di agr am i l lus t r a t ing a conf i gur a t ion o f a t ime
s ynch roni z a t ion s ys t em of an ex empl a ry embodiment 1 of the
invent ion .
20 [Fig. 2] i s a block di agr am i l lus t r a t ing a conf i gur a t ion o f a t ime
s ynch roni z a t ion s ys t em of an ex empl a ry embodiment 2 of the
invent ion .
[Fig. 3] i s a block di agr am i l lus t r a t ing a conf i gur a t ion o f a s l ave
devi c e of the ex empl a r y embodiment 2 of the invent ion .
25 [Fig. 4] i s a f lowch a r t ex pl a ining a f low of a t ime s yn chro ni z a t ion
proc e s s of the ex empl a r y embodiment 2 of the invent ion .
[Fig. 5] i s a block di agr am i l lus t r a t ing a conf i gur a t ion o f a s l ave
devi c e of an ex empl a r y embodiment 3 of the invent ion.
9
De s c r ipt ion of Embodiment s
[0020]
Spe c i f i c ex empl a r y embodiment s to whi ch the invent ion i s
appl i ed a r e d e s c r ib ed be low in de t a i l b y r e f e r r in g to dr awings . In
e a ch of d r awin gs , t he s ame e l ement h a s the s ame s ign, an d r epe a t 5 ed
ex pl ana t ions a r e omi t t ed a s ne c e s s a r y in orde r to c l a r i f y the
ex pl ana t ions .
[0021]
10
Fi g. 1 i s a bl ock di agr am i l lus t r a t ing a c onf i gur a t io n of a t ime
s ynch roni z a t ion s ys t em 100 of an ex empl a r y embodiment 1 of the
invent ion. The t ime s ynch roni z a t ion s ys t em 100 inc lud e s a
s ynch roni z a t ion sour c e communi c a t io n appa r a tus 11, a t r ansmi s s ion
15 s ys t em 12, a communi c a t ion appa r a tus 13, a nd a t ime s yn chroni z a t ion
or igin 14. In the t r ansmi s s ion s ys t em 12, a t r ansmi s s ion de l a y t ime
i s di f f e r ent dependi ng on the di r e c t ion of t r ansmi s s ion. Tha t i s to
s a y, t he t r ansmi s s ion s ys t em 12 inc lu de s a s ymme t r i c a l t r ansmi s s ion
de l a y cha r a c t e r i s t i c s . The s ynchroni z a t ion sour c e communi c a t ion
20 appa r a tus 11 i s con ne c t ed to the t r ansmi s s ion s ys t em 12 and i s a f i r s t
communi c a t ion app a r a tus a s a s ynchro ni z a t ion sour c e of a t ime . Th e
s ynch roni z a t ion sour c e communi c a t io n appa r a tus 11 i s , for ex ampl e , a
ma s t e r devi c e in t ime s ynch roni z a t ion. The t ime s ynchr oni z a t ion
or igin 14 i s a communi c a t ion appa r a t us , a t r ansmi s s ion sys t em, a
25 s a t e l l i t e pos i t ioning s ys t em, s a t e l l i t e naviga t ion s ys t em, or the l ike ,
whi ch i s a t ime s yn chroni z a t ion or igin othe r than the t r an smi s s io n
s ys t em 12.
[0022]
The commun i c a t ion appa r a tus 1 3 i s a s e cond communi c a t ion
10
appa r a tus whi ch i s conne c t ed to the t r ansmi s s ion s ys t em 12 and the
t ime s ynchroni z a t ion or igin 14 and c a r r i e s out t ime s ynch roni z a t ion
on the ba s i s of f i r s t t ime informa t i on t1 of the s ynch roni z a t ion sour c e
communi c a t ion appa r a tus 11. Th e communi c a t ion appa r a tus 13 i s a
s l ave devi c e in t ime s yn chroni z a t ion5 .
[0023]
The commun i c a t ion appa r a tus 1 3 inc lude s a s tor a ge uni t 131
and a t ime s yn chro ni z a t ion uni t 132. The s t or a ge uni t 1 31 s tor e s in
advanc e di f f e r enc e informa t ion 1311 be twe en the f i r s t t ime
10 informa t ion t1 r e c e ived f rom the s yn c hroni z a t ion sour c e
communi c a t ion appa r a tus 11 and s e con d t ime informa t ion t2 obt a ined
f rom the t ime s ynch roni z a t ion or igin 14. I f the t ime s ync hroni z a t ion
uni t 132 c annot obt a in the s e cond t ime informa t ion t2 f rom the t ime
s ynch roni z a t ion or igin 14, the uni t 132 c a r r i e s out t ime
15 s ynch roni z a t ion wi th the s ynch roni z a t ion sour c e communi c a t ion
appa r a tus 11 us in g the di f f e r en c e info rma t ion 13 11 r e ad o ut f rom the
s tor age uni t 131.
[0024]
Ca r r yin g out t ime s ynchroni z a t ion wi th the s ynchro ni z a t ion
20 sour c e communi c a t ion appa r a tus 11 vi a the t r ansmi s s ion s ys t em 12
having an a s ymme t r i c a l t r ansmi s s ion de l a y t ime , the t ime s yn ch ronous
s ys t em 10 0 and communi c a t ion appa r a tus 13 of the ex empl a r y
embodiment 1 of the invent ion us e the s e cond t ime informa t ion t2
obt a ined f rom the t ime s yn chroni z a t ion or igin 14 whi ch give s a s t abl e
25 t ime . By s tor in g in advanc e th e di f f e r enc e info rma t ion 1311
be twe en th e f i r s t t ime informa t ion t1 and the s e cond t ime informa t ion
t2, i t i s a l so pos s ibl e to c a r r y out t ime s ynch roni z a t ion us ing the
di f f e r en c e informa t ion 1311 whi ch i s a l r e ad y s tor ed ev en though the
l a t e s t s e cond t ime informa t ion t2 c ann ot be obt a ined f rom th e t ime
11
s ynch roni z a t ion or igin 14. Th e r e for e , i n a t r ansmi s s ion s ys t em
having a s ymme t r i c a l de l a y cha r a c t e r i s t i c s in whi ch a t r an smi s s ion
de l a y t ime i s di f f e r ent dependin g on the di r e c t ion of t r ansmi s s ion,
a c cur a c y of t ime s ynchroni z a t ion c an be ma int a ined.
[00255 ]

Fi g. 2 i s a bl ock di agr am i l lus t r a t ing a conf i gur a t io n of a t ime
s ynch roni z a t ion s ys t em 200 of an ex empl a r y embodiment 2 of the
invent ion. The t ime s ynch roni z a t ion s ys t em 200 i s one ex ampl e of
10 the ex empl a r y emb odiment 1. The t ime s ynch roni z a t ion s ys t em 200
inc lude s a GNSS 21, a ma s t e r devi c e 22, a t r ansmi s s ion s ys t em 23, a
GNSS 24, and a s l ave devi c e 25. The t ime s ynchroni z a t ion s ys t em
200 s ynchroni z e s t ime informa t ion 250 of the s l ave devi c e 25 w i th
t ime informa t ion 2 20 of the ma s t e r de vi c e 22.
15 [0026]
The GNSS 2 1 and the GNSS 24 a r e a s a t e l l i t e pos i t ioning
s ys t ems or s a t e l l i t e naviga t ion s ys t ems whi ch a r e di f f e r en t f rom e a ch
othe r . The GNSS 21 inc lude s a GNSS s a t e l l i t e 211 and a GNSS
r e c e iv e r 212. Th e GNSS r e c e ive r 212 r e c e iv e s a s ign a l f rom the
20 GNSS s a t e l l i t e 211 and t r ansmi t s t ime / t iming pul s e output p1. The
GNSS 24 inc lude s a GNSS s a t e l l i t e 24 1 and a GNSS r e c e ive r 242.
The GNSS r e c e ive r 242 r e c e ive s a s i gn a l f rom the GNSS s a t e l l i t e 241
and t r ansmi t s t ime / t iming pul s e output p2. The GNSS 2 4 i s an
ex ampl e of the t ime s yn chroni z a t ion or igin 14 above d e s c r ibed.
25 [0027]
The GNSS 2 1 inc lude s f aul t - tol e r anc e such a s r edu ndanc y.
On the othe r hand, i n the GNSS 24, r edundanc y and f aul t tol e r anc e for
low cos t and mini a tur i z a t ion a r e in a l ow l eve l , compa r ed wi th the
GNSS 21. Sinc e t he GNSS 21 and the GNSS 24 c an emp lo y publ i c l y
12
known t e chnologi e s i f the y c an be t ime r e f e r enc e , de t a i l ed
ex pl ana t ions the r eo f a r e omi t t ed. As the GNSS 21 and t he GNSS 24,
a t ime s ynch roni z a t ion s ys t em, l ike GPS, Ga l i l eo (Ga l i l eo
(pos i t ioning s ys t em) ) , GLONASS (Glo ba l Naviga t ion Sa t e l l i t e
Sys t em) , or Be idou (Be iDou Navi ga t ion Sa t e l l i t e Sys t em) c an b5 e
emplo yed.
[0028]
The ma s t e r devi c e 22 i s one ex ampl e of the s yn chr oni z a t ion
sour c e communi c a t ion appa r a tus 11 ab ove de s c r ibed. Th e ma s t e r
10 devi c e 22 a cqui r e s the t ime / t iming pul s e output p1 whi ch i s t ime
r e f e r enc e f rom the GNSS r e c e ive r 212, and holds a s the t ime
informa t ion 220. The ma s t e r devi c e 22 i s conne c t ed to the
t r ansmi s s ion s ys t em 23 in orde r to t r a nsmi t and r e c e ive a pa cke t for
t ime s ynchroni z a t ion wi th the s l ave d e vi c e 25 cont rol l ed the r eb y.
15 Sinc e t he othe r con f igur a t ions in the ma s t e r devi c e 22 c a n us e
publ i c l y known t e c hnologi e s , de t a i l ed ex pl ana t ions the r eo f a r e
omi t t ed.
[0029]
The t r ansmi s s ion s ys t em 23 i s o ne ex ampl e of the t r ansmi s s ion
20 s ys t em 12 de s c r ibe d above . Th e t r an smi s s ion s ys t em 23 inc lude s
communi c a t ion r e l a yi n g appa r a tus e s 23 1 to 233. A t r ansmi s s ion
pa th f rom the ma s t e r devi c e 22 to the s l ave devi c e 25 i s r out ed
through the commu ni c a t ion r e l a yin g a ppa r a tus 231. On the othe r
hand, a t r ansmi s s ion pa th f rom the s l a ve devi c e 25 to the ma s t e r
25 devi c e 22 i s rout ed through the commu ni c a t ion r e l a yin g a ppa r a tus e s
233 and 232. Tha t i s to s a y, i n the t r ansmi s s ion s ys t em 23,
bidi r e c t iona l t r ansmi s s ion pa ths be twe en the ma s t e r devi c e 22 and the
s l ave devi c e 25 a r e di f f e r ent e a ch othe r . In the t r ansmi s s ion s ys t em
23, the r e for e , bidi r e c t iona l t r ansmi s s ion de l a y t ime s a r e di f f e r ent
13
e a ch othe r , th a t i s , a s ymme t r i c a l de l a y cha r a c t e r i s t i c s ex i s t . Fi g. 2
shows a c a s e in whi ch, in the t r ansmi s s ion s ys t em 23, the
bidi r e c t iona l t r ansmi s s ion pa ths a r e d i f f e r ent f rom e a ch othe r .
Spe c i f i c a l l y, a c a s e i s shown, in whi ch the numbe r of the
communi c a t ion r e l a yi n g appa r a tus e s whi ch i s loc a t ed be twe en th5 e
ma s t e r devi c e 22 an d the s l ave devi c e 2 5 i s di f f e r ent dep en ding on the
di r e c t ion of t r ansmi s s ion. Howeve r , a rout e of the t r ansmi s s ion
s ys t em 23 i s not l imi t ed the r e to. Fo r ex ampl e , l ike ADSL
(As ymme t r i c Digi t a l Subs c r ibe r Lin e ) , one whi ch inc lude s
10 a s ymme t r i c a l de l a y cha r a c t e r i s t i c s in whi ch ups t r e am communi c a t ion
spe ed i s di f f e r ent f rom downs t r e am communi c a t ion spe ed in the s ame
bidi r e c t iona l t r ansmi s s ion pa th ma y b e emplo ye d . Sinc e publ i c l y
known t e chn ologi e s a r e emplo yed for t he t r ansmi s s ion s ys t em 23 and
the communi c a t ion r e l a yin g appa r a tus e s 231 to 233 , de t a i l ed
15 ex pl ana t ions the r eo f a r e omi t t ed. As the t r ansmi s s ion s ys t em 23, a
bidi r e c t iona l ne two rk s ys t em, l ike Eth e rne t ( t r ade ma rk) , c an be us ed .
[0030]
The s l ave d e vi c e 25 i s one ex ampl e of the communi c a t ion
appa r a tus 13 abov e de s c r ibed. The s l ave devi c e 25 i s c onne c t ed to
20 the t r ansmi s s ion s ys t em 23 and r e c e iv e s the t ime informa t i on f rom the
s l ave devi c e 25. Fur the r , t he s l av e d evi c e 25 a cqu i r e s , s epa r a t e l y
f rom the t r ansmi s s ion s ys t em 23, the t ime / t iming pul s e ou tput p2
whi ch i s t ime r e f e r enc e f rom the GNSS r e c e ive r 242. Fur the rmor e ,
the s l ave devi c e 25 c a l cul a t e s di f f e r en c e informa t ion be twe en the
25 t ime informa t ion 2 20 and the t ime / t iming p ul s e output p2, and s tor e s
the di f f e r en c e info rma t ion in the s tor a ge uni t . Then, t he s l ave
devi c e 25 c a l cul a t e s and holds the t ime informa t ion 250 on the ba s i s
of the t ime informa t ion 220 and the t ime / t iming pul s e ou tput p2.
Be s ide s , t he s l ave devi c e 25 output s , a s an int e r f a c e to t r ans f e r to a
14
wi r e l e s s ba s e s t a t io n, or the l ike (not shown) , t ime / t iming pul s e
output p3 r e gen e r a t ed f rom the ma s t e r devi c e 22 or the GNSS 24.
[0031]
He r e a f t e r , when the s l ave devi c e 25 c annot a cqui r e the
t ime / t iming pul s e output p2 f rom the GNSS 24, the s l ave d evi c e 25 5
r e ads out di f f e r enc e informa t ion f rom the s tor age uni t , c a r r i e s out
t ime s ynchroni z a t ion wi th the ma s t e r d evi c e 22 us ing th e r e ad
di f f e r en c e informa t ion, and output s the t ime / t iming pul s e output p3.
[0032]
10 Whi l e s ynch roni z a t ion protocol us ed b y the ma s t e r devi c e 22
and the s l ave devi c e 25 a r e not spe c i f i ed i n the ex ampl e a bove
de s c r ibed , a t ime · t iming t r ansmi s s ion s ys t em such a s IEEE 1588v2 or
NTP protocol c an b e us ed .
[0033]
15 Fi g. 3 i s a bl ock di agr am i l lus t r a t ing a conf i gur a t io n of the
s l ave devi c e 25 of t he ex empl a r y embodiment 2 of the invent ion.
Sinc e con f igu r a t ion s othe r than the s l a ve devi c e 25 in Fig. 3 a r e
equiva l ent to Fig. 2 , the ex pl ana t ions a r e omi t t ed. The s l ave devi c e
25 inc lude s a t iming co r r e c t ion informa t ion holding uni t 251, a
20 s ynch roni z a t ion protocol t e rmina t ion uni t 252 and a t iming
compa r a tor 253.
[0034]
The s yn chro ni z a t ion protocol t e rmina t ion uni t 252 t e rmina t e s a
pa cke t fo r t ime s yn chroni z a t ion f rom the ma s t e r d evi c e 22 , c a l cul a t e s
25 t r ansmi s s ion de l a y t ime s td1 and td2 b e twe en the ma s t e r d evi c e 22 and
the s l ave devi c e 25 and output s the r e gen e r a t ed t ime / t iming pul s e
output p3. Be s ide s , t he s ynch roni z a t ion protocol t e rmina t ion uni t
252 c a l cul a t e s a t ime in the s l ave dev i c e 25 in cons ide r a t ion of an
a s ymme t r i c a l t r ansmi s s ion de l a y t ime of the t r ansmi s s ion s ys t em 23.
15
Publ i c l y known t e c hnologi e s c an b e us ed for th e s ynch ron i z a t ion
protocol t e rmina t ion uni t 252.
[0035]
The t iming c ompa r a tor 253 c a l c ul a t e s t ime / t iming di f f e r en c e
informa t ion d us ing the t ime informa t i on 250 of the s l ave devi c e 25 5
c a l cul a t ed wi thout cons ide r ing a s ymme t r i c a l t r ansmi s s ion de l a y t ime
for e a ch t r ansmi s s ion pa th ( t ime / t iming pul s e output p3) and a
r e f e r enc e t ime on the ba s i s of the t ime / t iming pul s e outpu t p2
a cqui r ed f rom the GNSS 24. Then, t he s yn chroni z a t ion protocol
10 t e rmina t ion uni t 252 c a l cul a t e s the t r a nsmi s s ion de l a y t ime for e a ch
t r ansmi s s ion pa th td1 and td2 and s tor e s the r e sul t in the t iming
cor r e c t ion informa t ion holding uni t 25 1. Publ i c l y known
t e chnologi e s c an be emplo yed fo r t he t iming compa r a tor 2 53.
[0036]
15 The t iming c or r e c t ion informa t i on holding uni t 251 i s a s tor a ge
appa r a tus whi ch s to r e s the t r ansmi s s ion de l a y t ime s td1 and td2. Fo r
ex ampl e , t he t r ansmi s s ion de l a y t ime td1 i s a de l a y t ime in the
t r ansmi s s ion f rom t he ma s t e r devi c e 22 to the s l ave devi c e 25, and th e
t r ansmi s s ion de l a y t ime td2 i s a de l a y t ime in the t r ansmi s s ion f rom
20 s l ave devi c e 25 to t he ma s t e r devi c e 2 2. Tha t i s to s a y, t he
s ynch roni z a t ion protocol t e rmina t ion u ni t 252 s tor e s the b idi r e c t iona l
t r ansmi s s ion de l a y t ime s be twe en the s l ave devi c e 25 and the ma s t e r
devi c e 22 into the t imin g cor r e c t ion informa t ion holding uni t 251, a s
di f f e r en c e informa t ion.
25 [0037]
He r e , t he t iming compa r a tor 2 53 and the s yn chro ni z a t ion
protocol t e rmina t ion uni t 252 ma y be di f f e r en c e informa t ion
c a l cul a t ion me ans whi ch c a l cul a t e s th e di f f e r enc e info rma t ion
( t ime / t iming di f f e r enc e informa t ion d) be twe en the f i r s t t ime
16
informa t ion ( t ime informa t ion 220) an d the s e cond t ime informa t ion
( t ime / t iming pul s e output p2) , and s tor e s the di f f e r enc e in forma t ion
into the t iming cor r e c t ion informa t ion holding uni t 2 51. Tha t i s to
s a y, t he s yn chroni z a t ion protocol t e rmina t ion uni t 252 may s tor e the
di f f e r en c e informa t ion i t s e l f into the t iming cor r e c t ion informa t io5 n
holding uni t 251.
[0038]
When the t ime / t iming pul s e ou tput p2 c an be a cqu i r ed f rom th e
GNSS 24 , the s ync hroni z a t ion protoco l t e rmina t ion uni t 252 c a r r i e s
10 out t ime s yn chroni z a t ion wi th the ma s t e r devi c e 22 on the ba s i s of the
t ime / t iming pul s e output s p1 and p2.
[0039]
Fi g. 4 i s a f l owcha r t ex pl a ining a f low of a t ime
s ynch roni z a t ion proc e s s of the ex empl a r y embodiment 2 of the
15 invent ion. Ini t i a l l y, the s ynchroni z a t ion protocol t e rmi na t ion uni t
252 r e c e ive s th e f i r s t t ime informa t ion ( e . g. t ime informa t ion 220)
f rom the ma s t e r dev i c e 22 (S11) . The t iming compa r a tor 253 t r i e s to
a cqui r e the s e c ond t ime informa t ion ( e .g. t ime / t iming pul s e output p2 )
f rom the GNSS r e c e ive r 242 whi ch i s a t ime s ynch roni z a t ion or igin
20 (S12) . Whe the r o r not a cqui s i t ion of the s e cond t ime informa t ion
f rom the GNSS r e c e ive r 242 be come s suc c e s s ful i s de t e rmined a t thi s
point (S13) .
[0040]
I f the GNSS 24 i s norma l , a cqui s i t ion of the s e cond t ime
25 informa t ion i s suc c e s s ful (YES in s t ep S13) , and the t iming
compa r a tor 253 c a l cul a t e s the t ime / t iming di f f e r enc e inf orma t ion d,
a s the di f f e r enc e in forma t ion (S14) . The s yn c hroni z a t ion protocol
t e rmina t ion uni t 252 s tor e s the di f f e r e nc e informa t ion in the t iming
cor r e c t ion informa t ion holding uni t 25 1 (S15) . In addi t i on, t he
17
s ynch roni z a t ion protocol t e rmina t ion uni t 252 c a r r i e s out t ime
s ynch roni z a t ion wi th the ma s t e r devi c e 22 us ing the di f f e r enc e
informa t ion (S17) .
[0041]
On the othe r hand, when i t i s de t e rmined tha t a cqui s i t ion of th5 e
s e cond t ime informa t ion f rom the GNSS r e c e ive r 242 f a i l s in s t ep S13,
the s ynchroni z a t ion protocol t e rmina t ion uni t 252 r e ads out the
di f f e r en c e informa t ion f rom the t iming cor r e c t ion informa t ion holding
uni t 251 (S16) . The c a s e tha t the GNSS 24 f a i l s and the c a s e tha t the
10 s l ave devi c e 25 c an not ful l y r e c e ive th e t ime / t iming pul s e output s p2
due to a r adio wav e condi t ion, e t c . a r e ex empl i f i ed.
[0042]
The s ynch ro ni z a t ion protocol t e rmina t ion uni t 252 c a r r i e s out
t ime s ynchroni z a t ion wi th the ma s t e r d evi c e 22 us ing th e r e ad
15 di f f e r en c e informa t ion (S17) .
[0043]
Subs equent ly, c a l cul a t ion of the t r ansmi s s ion de l ay t ime in the
s l ave devi c e 25 of t he ex empl a r y embodiment 2 i s de s c r ib ed be low.
The t r ansmi s s ion de l a y t ime td1 i s a t ime whi ch i s r equi r e d for
20 t r ansmi s s ion of a s pe c i f i c pa cke t f rom the ma s t e r devi c e 22 to the
s l ave devi c e 25. He r e , s uppos e a t r a nsmi t t ing t ime of the pa cke t in
t h e m a s t e r d e v i c e 2 2 i s “ A 1 ” .
[0044]
The s yn chro ni z a t ion protocol t e rmina t ion uni t 252 r e c e iv e s the
25 pa cke t inc luding th e t r ansmi t t ing t ime A1 f rom the ma s t e r devi c e 22.
Next , the s yn chroni z a t ion protocol t e rmina t ion uni t 252 r egene r a t e s
the t ime / t iming pul s e output s p3 ba s ed on the t r ansmi t t ing t ime A1.
Be s ide s , t he s l ave devi c e 25 a cqui r e s the r e f e r enc e t ime B1 ba s ed on
the t ime / t iming pul s e output s p2 f rom the GNSS r e c e ive r 242. Then,
18
the t iming compa r a tor 253 c an c a l cul a t e the t r a nsmi s s ion de l a y t ime
td1 a s the t ime / t iming di f f e r en c e informa t ion d b y compa r ing the
t r ansmi t t ing t ime A1 wi th the r e f e r enc e t ime B1. He r e , t he
t r ansmi s s ion de l a y t ime td1 c an be c a l cul a t ed us ing the f ol lowing
equa t ion (4) 5 .
td1 = B1 – A1 ……(4)
[0045]
The s l ave d e vi c e 25 in the ex empl a r y embodiment 2 s tor e s the
t r ansmi s s ion de l a y t ime td1 into the t iming cor r e c t ion inf orma t ion
10 holding uni t 251. The r e for e , e ven th ough the t ime r e f e r enc e ba s ed
on the GNSS 24 i s los t , the s l ave devi c e 25 c an c a l cu l a t e a t i m e B 1 ’ o f
the s l ave devi c e 25 f rom the t r ansmi t t ing t ime A1 us ing th e
t r ansmi s s ion de l a y t ime td1 whi ch i s a l r e ad y he ld in the t iming
cor r e c t ion informa t ion holding uni t 25 1. The r e for e , i t i s pos s ibl e to
15 ke ep t ime s yn chron i z a t ion. He r e , t he t ime B 1 ’ o f t h e s l a v e d e v i c e
25 c an be c a l cul a t e d b y the fol lowin g equa t ion (5) .
B 1 ’ = A 1 + t d 1 ……( 5 )
[0046]
Be s ide s , t he t r ansmi s s ion de l a y t ime td2 i s a t ime whi ch i s
20 r equi r ed for t r ansmi s s ion of a sp e c i f i c pa cke t f rom the s l a ve devi c e 25
to the ma s t e r devi c e 22. He r e , s uppo s e a t r ansmi t t ing t ime of the
p a c k e t i n t h e s l a v e d e v i c e 2 5 i s “ B 2 ” .
[0047]
Ini t i a l l y, t h e s l ave devi c e 25 t r a nsmi t s the pa cke t i nc luding the
25 t r ansmi t t ing t ime B2 to the ma s t e r d ev i c e 22. Next , b y compa r in g a
t ime A2 a t whi ch th e pa cke t i s r e c e ive d wi th the t r ansmi t t ing t ime B2
inc luded in the pa c ke t , the ma s t e r devi c e 22 c an c a l cul a t e the
t r ansmi s s ion de l a y t ime td2. The s e t e chnique s c an b e a chi eved on
the ba s i s of IEEE 1 588. The t r ansmi s s ion de l a y t ime td2 c an be
19
c a l cul a t ed b y the f ol lowing equa t ion ( 6) .
td2 = A2 – B2 ……(6)
[0048]
Af t e r tha t , the ma s t e r devi c e 2 2 informs the s l ave devi c e 25 of
the t r ansmi s s ion de l a y t ime td2. Th e s l ave devi c e 25 s to r e s th5 e
t r ansmi s s ion de l a y t ime td2 into the t iming cor r e c t i on inf orma t ion
holding uni t 251. The r eb y appropr i a t ene s s c an be ex amined even
though a t r ansmi s s ion pa th of the t r ansmi s s ion s ys t em 23 i s chan ged.
The r e a son i s ex pl a ined be low.
10 [0049]
Ini t i a l l y, i n the t ime s ynchroni z a t ion s ys t em, t r ansmi s s ion
de l a y amount be twe en the ma s t e r devi c e 22 and the s l ave devi c e 25
c an b e c a l cul a t ed o n the ba s i s o f a rou nd - t r ip t ime Z of a pa cke t . In
thi s c a s e , wh en a ro und - t r ip t ime of a p a cke t fo r t ime s ync hroni z a t ion
15 i s r epr e s ent ed a s Z, i t c an be shown a s the fol lowin g equ a t ion (7) .
Z = X + Y …… (7)
[0050]
For th a t r e a s on, i t i s p o t e n t i a l l y c o n s i d e r e d t h a t t h e t i m e B 2 ’ o f
the s l ave devi c e 25 c an be c a l cul a t ed wi thout us ing the t r ansmi s s ion
20 de l a y t ime td2 whe n the t ime r e f e r enc e ba s ed on the GNSS 24 i s los t .
Howeve r , th e t r ansmi s s ion de l a y amou nt change s i f a t r an smi s s ion
pa th in the t r ansmi s s ion s ys t em 23 i s changed. In thi s c a s e , the
round- t r ip t ime Z a l so chan ge s . The r e for e , a c c u r a c y o f t h e t i m e B 2 ’
c annot be kept i f Z i s us ed. The s l av e devi c e 25 c an not ex amine
25 appropr i a t en e s s of the t r ansmi s s ion de l a y amount ba s ed o nl y on the
t r ansmi s s ion de l a y t ime td1. The r e fo r e , a s de s c r ibed ab ove , the
s l ave devi c e 25 h a s to s tor e the t r ansmi s s ion de l a y t ime td2 in the
t iming co r r e c t ion informa t ion holding uni t 2 51.
[0051]
20
As de s c r ib ed above , the t ime s yn chroni z a t ion s ys t em 200 of the
ex empl a r y embodiment 2 inc lude s the fol lowing adv ant a geous e f f e c t s .
Ini t i a l l y, i n the t ime s yn chroni z a t ion sys t em havin g a s ymme t r i c a l
de l a y in the t r ansmi s s ion pa th the r eof , b y me a su r ing an a s ymme t r i c a l
de l a y t ime of th e t r ansmi s s ion pa th us ing t ime informa t io n a s 5 a
r e f e r enc e , a c cur a c y of t ime s ynch roni z a t ion c an be kept even though a
f a i lur e of the t ime informa t ion a s a r e f e r en c e oc cur s . Be s ide s , even
though a f a i lur e of the t ime informa t io n whi ch i s a r e f e r e nc e for
GNSS oc cur s , s inc e the r e f e r enc e t ime i s kept in the t ime
10 s ynch roni z a t ion s ys t em, a low- cos t f r e quenc y sour c e c an be us ed.
[0052]

An ex empl a r y embodiment 3 of the i nvent ion i s a modi f i ed
ex ampl e of the abo ve embodiment 2. The di f f e r enc e f rom the
15 ex empl a r y embodiment 2 i s to us e the t r ansmi s s ion s ys t em in whi ch
bidi r e c t iona l t r ansmi s s ion de l a y t ime s a r e s ymme t r i c a l a s a
s ynch roni z a t ion or igin of the s l av e dev i c e ins t e ad of GNSS.
[0053]
Fi g. 5 i s a bl ock di agr am i l lus t r a t ing a conf i gur a t io n of a s l ave
20 devi c e 25a of th e e xempl a r y embodiment 3 of the invent ion. The
s ame conf i gur a t ion s a s thos e of Fi g. 3 a r e indi c a t ed wi th the s ame
s igns and ex pl ana t ions the r eon a r e omi t t ed. Ini t i a l l y, a ma s t e r
devi c e 27 i s a communi c a t ion appa r a t us whi ch i s a s ynch roni z a t ion
sour c e whi ch i s di f f e r ent f rom the ma s t e r devi c e 22. Th e ma s t e r
25 devi c e 27 i s one ex ampl e of the t ime syn ch roni z a t ion or i gin 14 of Fi g.
1. In a t r ansmi s s ion s ys t em 26, the bidi r e c t iona l t r ansmi s s ion de l a y
t ime s a r e s ymme t r i c a l .
[0054]
The s l ave d e vi c e 25a inc lude s a s ynch roni z a t ion pr otocol
21
t e rmina t ion uni t 254 and a t iming cor r e c t ion informa t ion holding uni t
255 in addi t ion to the t iming co r r e c t ion info rma t ion holding uni t 251 ,
the s ynch roni z a t ion protocol t e rmina t ion uni t 252, and the t iming
compa r a tor 253. The s yn chroni z a t ion protocol t e rmina t ion uni t 254
t e rmina t e s a pa ck e t for t ime s ynch roni z a t ion f rom the ma s t e r devi 5 c e
27, c a l cul a t e s t r ansmi s s ion d e l a y t ime s td3 and td4 be twe e n the
ma s t e r devi c e 27 a nd the s l ave devi c e 25, and output s r egen e r a t ed
t ime / t iming pul s e . Fur the r , t he s yn chr oni z a t ion protocol t e rmina t ion
uni t 254 s tor e s the t r ansmi s s ion de l a y t ime s td3 and td4 in the t iming
10 cor r e c t ion info rma t ion holding uni t 25 5. Sinc e the t r ansmi s s ion
s ys t em 26 inc lude s the s ymme t r i c a l t r a nsmi s s ion de l a y t ime s , the
s ynch roni z a t ion protocol t e rmina t ion uni t 254 c an c a l cul a t e the
t r ansmi s s ion de l a y t ime s td3 and td4 by us in g ex i s t ing t e c hnique s .
The t imin g cor r e c t i on informa t ion holding uni t 255 i s equiva l ent to
15 the t iming cor r e c t ion informa t ion holding uni t 251.
[0055]
For thi s r e a s on, even i f the t r an smi s s ion s ys t em 23 inc lude s
a s ymme t r i c a l de l a y cha r a c t e r i s t i c s , the s l ave devi c e 25 a c an s t abl y
acqui r e the r e f e r en c e t ime f rom the t r ansmi s s ion s ys t em 26. In
20 pa r t i cul a r , ev en i f the r e f e r en c e t ime i s not a cqui r ed f rom the ma s t e r
devi c e 27, b y us in g the t r ansmi s s ion de l a y t ime s td3 and t d4 s tor ed in
advanc e in the t iming co r r e c t ion informa t ion holding uni t 255, i t i s
pos s ibl e to giv e r ed undanc y to the s l av e devi c e 25 a .
[0056]
25 Even t hough the t r a nsmi s s ion s ys t em 2 6 inc lude s a s ymme t r i c a l
de l a y ch a r a c t e r i s t i c s in Fi g. 5, b y holding in advanc e the t r ansmi s s ion
de l a y t ime s td3 and td4 in the t iming c or r e c t i on informa t i on holding
uni t 255, equiva l en t r edundanc y c an b e kept .
[0057]
22

A conv ent iona l t ime s ynchroni z a t ion s ys t em ha s th e fol lowing
probl ems . A f i r s t probl em i s tha t cor r e c t t ime s yn chroni z a t ion
c annot be c a l cul a t e d due to a s t a t e o f a s ymme t r i c a l d e l a y of a ne two rk
communi c a t ion pa th in the t ime s yn ch roni z a t ion s ys t em. A s e con5 d
probl em i s tha t s inc e f aul t - tol e r anc e o f GNSS ha s to be inc r e a s ed
when cor r e c t t ime s yn ch roni z a t ion c annot be c a l cul a t ed, a t ime
s ynch roni z a t ion e r ror ha s to be minimi z ed b y us ing an ex pens ive
f r equen c y sour c e wi th high a c cu r a c y.
10 [0058]
The r e for e , t he ex empl a r y embodiment 1 and the l ike of the
invent ion de s c r ibed above improve the probl em tha t a c cur a c y o f
s ynch roni z a t ion r e f e r enc e c annot b e a c qui r ed due to the t r ansmi s s ion
a s ymme t r y of th e t ime s ynch roni z a t ion s ys t em, and provid e a me ans
15 of solving us ing th e t ime s ynch roni z a t ion s ys t em for impr ovement of
f aul t - tol e r anc e of GNSS. Tha t i s to s a y, i n the t ime s yn chroni z a t ion
s ys t em in whi ch th e t r ansmi s s ion pa th ha s the a s ymme t r i c a l de l a y
t ime , anoth e r r e f e r e nc e t ime i s s e t , the a s ymme t r i c a l de l a y t ime of th e
t r ansmi s s ion pa th i s me a sur ed us in g the r e f e r en c e t ime to be us ed for
20 c a l cul a t ion of the t ime s ynchroni z a t ion s ys t em. Th e r eb y unc e r t a int y
of t ime s ynchroni z a t ion in whi ch the t r ansmi s s ion pa th ha s
a s ymme t r i c a l de l a y cha r a c t e r i s t i c s c an be r e solved in adv anc e .
[0059]
The s l ave de vi c e 25 in Fig. 3 , in pa r t i cul a r , inc lude s the t iming
25 cor r e c t ion informa t ion holding uni t 25 1. Fur th e r , t he s l ave devi c e
25 c a l cul a t e s the t ime / t iming di f f e r en c e informa t ion d of a
r e gene r a t ion t ime of the ma s t e r devi c e 22 ba s ed on the r e f e r enc e t ime ,
us ing the t ime / t iming pul s e output p2 of the GNSS 24 and the
t ime / t iming pul s e output p3 r e gen e r a t e d f rom the t ime informa t ion
23
r e c e iv ed f rom the ma s t e r devi c e 22. Af t e r tha t , the s l a ve devi c e 25
c a l cul a t e s in adv an c e a s ymme t r i c a l t r a nsmi s s ion de l a y t ime s td1 and
td2 for e a ch t r ansmi s s ion pa th in the t r ansmi s s ion s ys t em 23 b y us in g
the t ime / t iming di f f e r enc e informa t ion d.
[00605 ]
By c a l cul a t i ng in advan c e the a s ymme t r i c a l t r ansmi s s ion de l a y
t ime s for e a ch t r an smi s s ion pa th, i t i s r e solved tha t unc e r t a int y of
t ime s ynchroni z a t ion oc cur s onl y b y the t ime s ynch roni z a t ion s ys t em
when the t r ansmi s s ion de l a y t ime fo r e a ch t r ansmi s s ion pa th i s
10 di f f e r ent . The r eb y the r e f e r enc e t ime c an be k ept onl y b y the t ime
s ynch roni z a t ion s ys t em even when GNSS go e s wron g.
[0061]
The ex empl a r y embodiment 1, e t c , c a l cul a t e a tot a l of de l a y
t ime s of r e sp e c t ive t r ansmi s s ion pa ths in the t ime s yn chro ni z a t ion
15 s ys t em us ing the t ime informa t ion f rom a t ime s ynch roni z a t ion sour c e
of GNSS, e t c . and the t ime informa t ion c a l cul a t ed in the t ime
s ynch roni z a t ion s ys t em in whi ch the t r ansmi s s ion pa th inc lude s
a s ymme t r i c a l de l a y. The t ime s ynchr oni z a t ion s ys t em i s ope r a t ed
us ing the tot a l of the de l a y t ime s in c ons ide r a t ion of a s ymme t r y of
20 e a ch t r ansmi s s ion pa th, so tha t a c cur a c y of t ime s ynchroni z a t ion in
the t ime s ynchroni z a t ion s ys t em havin g a s ymme t r i c a l de l a y in the
t r ansmi s s ion pa th i s gua r ant e ed.
[0062]
As a spe c i f i c ex ampl e , in a s i tua t ion in whi ch r e c e pt ion
25 a c cur a c y i s gu a r ant e ed b y a GNSS r e c e ive r in the s l av e de vi c e , a t ime
of an appa r a tus i s de t e rmined us ing a t iming pul s e whi ch i s
s ynch roni z ed wi th GNSS and t ime inf orma t ion. On the othe r hand,
the t ime s ynchroni z a t ion s ys t em i s a l so ope r a t ed and a
s ynch roni z a t ion ope r a t ion wi th a di f f e r ent appa r a tus s yn c hroni z ed
24
wi th GNSS i s c a r r i ed out . He r e , i n o rde r to c a l cul a t e a de l a y t ime
for e a ch t r ansmi s s io n pa th, the t ime in forma t ion c a l cul a t e d f rom the
GNSS r e c e ive r , th e s ynch roni z a t ion t ime c a l cul a t ed in th e t ime
s ynch roni z a t ion s ys t em and the bidi r e c t iona l de l a y t ime a r e us ed.
Thus, when the t ime informa t ion c ann ot be a cqui r ed f rom GNSS, th5 e
t ime s ynchr oni z a t ion s ys t em i s us ed b y us ing de l a y t ime i nforma t ion
for e a ch t r ansmi s s ion pa th whi ch i s c a l cul a t ed in a norma l s t a t e .
The r eb y t ime s ynch roni z a t ion a c cu r a c y c an be kept .
[0063]
10 The ex empl a r y embodiment s 1 to 3 c an be appl i ed to a wi r e l e s s
ba s e s t a t ion appa r a tus whi ch i s r equi r ed to a c cur a t e l y us e the t ime
s ynch roni z a t ion, such a s 3G (3rd Gene r a t ion) , LTE (Lon g Te rm
Evolut ion) , WiMAX (Wor ldwide Int e r ope r abi l i t y fo r Mi c rowave
Ac c e s s ) , o r PHS (Pe r sona l Hand y -pho ne Sys t em) , and wh i ch i s
15 di f f i cul t t o s t abl y us e the GNSS s ynch r oni z a t ion s ys t em.
[0064]
The invent io n of the pr e s ent ap pl i c a t ion i s not l imi t ed to the
above ment ioned ex empl a r y embodime nt s . I t i s to be un de r s tood
tha t to the conf i gur a t ions and de t a i l s of the invent ion of the pr e s en t
20 appl i c a t ion, va r iou s chan ge s c an be made wi thin the s cop e of the
invent ion of the pr e s ent appl i c a t ion.
[0065]
A whol e pa r t or pa r t of the ex empl a r y embodiment s di s c los ed
above c an b e de s c r ibed a s , but not l imi t ed to, the fol lowing
25 suppl ement a r y not e s .
[0066]
(Suppl ement ary not e 1)
A communi c a t ion appa r a tus whi ch inc lude s
a s tor a ge uni t for s tor ing in advan c e d i f f e r en c e informa t ion be twe en
25
f i r s t t ime informa t i on and s e cond t ime informa t ion, the f i r s t t ime
informa t ion be ing r e c e ived f rom a s yn c hroni z a t ion sour c e
communi c a t ion appa r a tus a s a t ime s yn chroni z a t ion sour c e conne c t ed
to a t r ansmi s s ion sys t em whe r e in t r an smi s s ion de l a y t ime i s di f f e r ent
depending on th e di r e c t ion of t r ansmi s s ion and the s e cond t im5 e
informa t ion obt a ined f rom a t ime s yn c hroni z a t ion or igin othe r than
the t r ansmi s s ion s ys t em, and
t ime s ynchroni z a t ion me ans for c a r r yin g out , when the s e c ond t ime
informa t ion c annot be obt a ined f rom th e t ime s ynch roni z a t ion or igin ,
10 t ime s ynchroni z a t ion wi th the s ynchron i z a t ion sour c e communi c a t ion
appa r a tus us in g the di f f e r en c e informa t ion r e ad out f rom the s tor a ge
uni t .
[0067]
(Suppl ement ary n ot e 2)
15 The commun i c a t ion appa r a tus d e s c r ibed in the sup pl ement ary
not e 1 whi ch i s cha r a c t e r i z ed in fur the r inc luding di f f e r en c e
informa t ion c a l cu l a t ion me ans for c a l c ul a t ing the di f f e r en c e
informa t ion be twe e n f i r s t t ime informa t ion and s e cond t ime
informa t ion and for s tor ing the di f f e r e nc e informa t ion in the s tor age
20 uni t .
[0068]
(Suppl ement ary n ot e 3)
The communi c a t ion appa r a tus de s c r ibe d in the suppl ement ary
not e 2 whi ch i s cha r a c t e r i z ed in tha t the t ime s ynch roni z a t ion me ans
25 c a r r i e s out t ime s ynchroni z a t ion wi th the s ynch roni z a t ion sour c e
communi c a t ion appa r a tus on the ba s i s of the f i r s t t ime informa t ion
and the s e cond t ime informa t ion when the s e cond t ime informa t ion
c an be obt a ined f rom the t ime s yn chro ni z a t ion or igin .
[0069]
26
(Suppl ement ary n ot e 4)
The commun i c a t ion appa r a tus d e s c r ibed in the sup pl ement ary
not e 2 whi ch i s cha r a c t e r i z ed in tha t the di f f e r enc e info rma t ion
c a l cul a t ion me ans s tor e s bidi r e c t iona l t r ansmi s s ion de l a y t ime s of th e
me ans i t s e l f and the s yn chroni z a t ion sour c e communi c a t ion appa r a tus 5 ,
a s the di f f e r enc e in forma t ion, into the s tor age uni t .
[0070]
(Suppl ement ary not e 5)
The commun i c a t ion appa r a tus o f an y one of t he su ppl ement ary
10 not e s 1 to 4 whi ch i s cha r a c t e r i z ed in tha t the t ime s ynch roni z a t ion
or igin i s a s a t e l l i t e pos i t ioning s ys t em.
[0071]
(Suppl ement ary n ot e 6)
The communi c a t ion appa r a tus of an y o ne of the suppl eme nt ary
15 not e s 1 to 4 whi ch i s cha r a c t e r i z ed in tha t the t ime s yn chr oni z a t ion
or igin i s a t r ansmi s s ion s ys t em in whi ch bidi r e c t iona l t r an smi s s ion
de l a y t ime s a r e s ymme t r i c a l .
[0072]
(Suppl ement ary not e 7)
20 A t ime s yn c hroni z a t ion s ys t em, inc luding,
a t r ansmi s s ion s ys t em in whi ch t r ansmi s s io n de l a y t ime i s
di f f e r ent dep endin g on the di r e c t ion of t r ansmi s s ion,
a f i r s t communi c a t ion appa r a tus tha t i s conne c t ed to the
t r ansmi s s ion s ys t em, a s a t ime s ynch r oni z a t ion sour c e ,
25 a t ime s ynch roni z a t ion or igin ot he r than the t r ansmi s s ion
s ys t em, and
a s e cond communi c a t ion appa r a tus tha t i s conne c t ed to the
t r ansmi s s ion s ys t em and the t ime s yn chroni z a t ion or igin and c a r r i e s
out t ime s yn chroni z a t ion on the ba s i s of t ime informa t ion of the f i r s t
27
communi c a t ion appa r a tus ,
the s e cond commun i c a t i on appa r a tus in c lude s
a s tor a ge uni t for s tor ing in adv anc e di f f e r en c e inf orma t ion
be twe en f i r s t t ime informa t ion r e c e ive d f rom the f i r s t communi c a t ion
appa r a tus and s e co nd t ime informa t io n obt a ined f rom the t im5 e
s ynch roni z a t ion or igin , and
time s yn chro ni z a t ion me ans for c a r r yin g out , when the s e cond
t ime informa t ion c a nnot be obt a ined f r om the t ime s yn chr oni z a t ion
or igin, t ime s yn chr oni z a t ion wi th the f i r s t communi c a t ion appa r a tus
10 us ing the di f f e r enc e informa t ion r e ad out f rom the s tor age uni t .
[0073]
(Suppl ement ary not e 8)
The t ime s yn chroni z a t ion s ys t em de s c r ibed in the
suppl ement ary not e 7 cha r a c t e r i z ed in tha t the s e cond communi c a t ion
15 appa r a tus fu r the r in c lude s di f f e r enc e i nforma t ion c a l cul a t ion me ans
for c a l cul a t ing the di f f e r en c e info rma t ion be twe en f i r s t t ime
informa t ion and s e c ond t ime informa t i on and for s tor in g the
di f f e r en c e informa t ion in the s tor a ge u ni t .
[0074]
20 (Suppl ement ary n ot e 9)
The t ime s yn chroni z a t ion s ys t em de s c r ibed in the
suppl ement ary not e 8 cha r a c t e r i z ed in tha t the t ime s ynch roni z a t ion
me ans c a r r i e s out t ime s ynch roni z a t ion wi th the f i r s t communi c a t ion
appa r a tus on the ba s i s of the f i r s t t ime informa t ion and the s e cond
25 t ime informa t ion when the s e cond t ime informa t ion c an b e obt a ined
f rom the t ime s ync hroni z a t ion or igin .
[0075]
(Suppl ement ary not e 10)
The t ime s yn chroni z a t ion s ys t em de s c r ibed in the
28
suppl ement ary not e 8 cha r a c t e r i z ed in tha t the di f f e r en c e informa t ion
c a l cul a t ion me ans s tor e s bidi r e c t iona l t r ansmi s s ion de l a y t ime s of th e
me ans i t s e l f and the f i r s t communi c a t ion appa r a tus , a s th e di f f e r enc e
informa t ion, into the s tor a ge uni t .
[00765 ]
(Suppl ement ary n ot e 11)
A t ime s ynchroni z a t ion me thod, inc luding
r e c e ivin g f i r s t t ime informa t ion f rom a s ynchroni z a t ion sour c e
communi c a t ion appa r a tus a s a t ime s yn chroni z a t ion sour c e conne c t ed
10 to a t r ansmi s s ion sys t em whe r e in t r an smi s s ion de l a y t ime i s di f f e r ent
depending on th e di r e c t ion of t r ansmi s s ion,
obt a ining s e cond t ime informa t i on f rom a t ime s yn c hroni z a t ion
or igin othe r than th e t r ansmi s s i on s ys t em,
c a l cul a t ing d i f f e r en c e informa t ion be twe en the f i r s t t ime
15 informa t ion and the s e cond t ime informa t ion,
s tor ing the d i f f e r en c e informa t ion in a s tor age me a ns ,
a f t e r tha t , r e ading out the di f f e r enc e informa t ion f r om the
s tor age me an s wh e n the s e cond t ime informa t ion c annot be obt a ined
f rom the t ime s ync hroni z a t ion or igin , and
20 c a r r yin g out t ime s ynchroni z a t ion wi th the s ynchron i z a t ion
sour c e communi c a t i on appa r a tus us in g the di f f e r enc e info rma t ion r e ad
out f rom the s tor age me ans .
[0077]
The invent ion of the pr e s ent ap pl i c a t ion i s ex pl a ined b y
25 r e f e r r in g to the ex empl a r y embodiment s . The invent ion of the
pr e s ent appl i c a t ion i s not l imi t ed to the above de s c r ipt ion. I t i s to
be unde r s tood tha t to the conf igu r a t ions and de t a i l s of the invent ion
of the pr e s ent appl i c a t ion, a pe r son or dina r i l y ski l l ed in the a r t c an
make va r ious chan ge s wi thin the s cope of the invent ion of the pr e s ent
29
appl i c a t ion.
[0078]
Thi s appl i c a t ion i s ba s ed upon and c l a ims the bene f i t of pr ior i t y
f rom J apane s e Pa t e nt Appl i c a t ion No. 2012 -166669 fi led on J uly 2 7 ,
2012, the di s c losur e of whi ch i s incor por a t ed he r e in in i t s ent i r e t y b 5 y
r e f e r enc e .
Re f e r en c e Signs Li s t
[0079]
10 100 t ime s ynchroni z a t ion s ys t em
11 s ynchroni z a t ion sour c e communi c a t ion appa r a tus
12 t r ansmi s s ion s ys t em
13 communi c a t ion appa r a tus
131 s tor age uni t
15 1311 di f f e r en c e inf orma t ion
132 t ime s ynchroni z a t ion uni t
14 t ime s ynchroni z a t ion sour c e
t1 f i r s t t ime informa t ion
t2 s e cond t ime informa t ion
20 200 t ime s ynchroni z a t ion s ys t em
21 GNSS
211 GNSS s a t e l l i t e
212 GNSS r e c e ive r
22 ma s t e r devi c e
25 220 t ime informa t i on
23 t r ansmi s s ion s ys t em
231 communi c a t ion r e l a yin g appa r a tus
232 communi c a t ion r e l a yin g appa r a tus
233 communi c a t ion r e l a yin g appa r a tus
30
24 GNSS
241 GNSS s a t e l l i t e
242 GNSS r e c e ive r
25 s l ave devi c e
25a s l ave devi c 5 e
250 t ime informa t i on
251 t iming co r r e c t ion informa t ion holding uni t
252 s ynchroni z a t ion protocol t e rmina t ion uni t
253 t iming compa r a tor
10 254 s ynchroni z a t ion protocol t e rmina t ion uni t
255 t iming co r r e c t ion informa t ion holding u ni t
26 t r ansmi s s ion s ys t em
27 ma s t e r devi c e
p1 t ime / t iming pul s e output
15 p2 t ime / t iming pul s e output
p3 t ime / t iming pul s e output
d t ime / t iming di f f e r enc e info rma t ion
td1 t r ansmi s s ion de l a y t ime
td2 t r ansmi s s ion de l a y t ime
20 td3 t r ansmi s s ion de l a y t ime
td4 t r ansmi s s ion de l a y t ime
31
WE CLAIM:
Cl a im 1. A communi c a t ion devi c e , compr i s ing:
s tor age me ans fo r s tor ing in advan c e d i f f e r en c e informa t ion
be twe en f i r s t t ime informa t ion and s e c ond t ime informa t i on, the f i r s t
t ime informa t ion be ing r e c e ived f rom a s ynch roni z a t ion sour 5 c e
communi c a t ion appa r a tus a s a t ime s yn chroni z a t ion sour c e conne c t ed
to a t r ansmi s s ion sys t em whe r e in t r an smi s s ion de l a y t ime i s di f f e r ent
depending on th e di r e c t ion of t r ansmi s s ion and the s e cond t ime
informa t ion obt a ined f rom a t ime s yn c hroni z a t ion or igin othe r than
10 the t r ansmi s s ion s ys t em; and
t ime s ynchroni z a t ion me ans for c a r r yin g out , when the s e c ond
t ime informa t ion c a nnot be obt a ined f r om the t ime s yn chr oni z a t ion
or igin, t ime s yn chr oni z a t ion wi th the s ynch roni z a t ion sour c e
communi c a t ion appa r a tus us ing the di f f e r en c e informa t ion r e ad out
15 f rom the s tor a ge me ans .
Cl a im 2. Th e communi c a t ion appa r a tus of c l a im 1, fur the r
compr i s ing: d i f f e r en c e informa t ion c a l cul a t ion me a ns for
c a l cul a t in g the di f f e r enc e informa t ion be twe en f i r s t t ime informa t ion
20 and s e cond t ime inf orma t ion and for s tor ing the di f f e r en c e
informa t ion in the s tor age me ans .
Cl a im 3. Th e communi c a t ion appa r a tus of c l a im 2, whe r e in the
t ime s ynchroni z a t ion me ans c a r r i e s out t ime s ynchroni z a t ion wi th the
25 s ynch roni z a t ion sour c e communi c a t io n appa r a tus on the ba s i s of the
f i r s t t ime informa t i on and the s e cond t ime informa t ion when the
s e cond t ime informa t ion c an be obt a in ed f rom the t ime
s ynch roni z a t ion or igin .
32
Cl a im 4. Th e communi c a t ion appa r a tus of c l a im 2, whe r e in the
di f f e r en c e informa t ion c a l cul a t ion me a ns s tor e s bidi r e c t iona l
t r ansmi s s ion de l a y t ime s of the me ans i t s e l f and the s yn ch roni z a t ion
sour c e communi c a t ion appa r a tus , a s th e di f f e r enc e info rma t ion, into
the s tor age me ans 5 .
Cl a im 5. The communi c a t ion app a r a tus of an y one of c l a ims 1 to 4,
whe r e in the t ime s ynchroni z a t ion or igin i s a s a t e l l i t e pos i t ioning
s ys t em.
10
Cl a im 6. The communi c a t ion app a r a tus of an y one of c l a ims 1 to 4,
whe r e in the t ime s ynchroni z a t ion or igin i s a t r ansmi s s ion s ys t em in
whi ch bidi r e c t iona l t r ansmi s s ion de l a y t ime s a r e s ymme t r i c a l .
15 Cl a im 7. A t ime s ynch roni z a t ion s ys t em, compr i s ing:
a t r ansmi s s ion s ys t em in whi ch t r ansmi s s ion de l a y t ime i s
di f f e r ent dep endin g on the di r e c t ion of t r ansmi s s ion;
a f i r s t communi c a t i on appa r a tus tha t i s conne c t ed to the
t r ansmi s s ion s ys t em, a s a t ime s ynch r oni z a t ion sour c e ;
20 a t ime s ynch roni z a t ion or igin ot he r than the t r ansmi s s ion
s ys t em; and
a s e cond communi c a t ion appa r a tus tha t i s conne c t ed to the
t r ansmi s s ion s ys t em and t he t ime s yn chroni z a t ion or igin and c a r r i e s
out t ime s yn chroni z a t ion on the ba s i s of t ime informa t ion of the f i r s t
25 communi c a t ion appa r a tus , whe r e in the s e cond communi c a t ion
appa r a tus compr i s e s :
s tor a ge me a ns for s tor ing in ad vanc e di f f e r en c e in forma t io n
be twe en f i r s t t ime informa t ion r e c e ive d f rom the f i r s t communi c a t ion
appa r a tus and s e co nd t ime informa t io n obt a ined f rom the t ime
33
s ynch roni z a t ion or igin ; and
t ime s yn chro ni z a t ion me ans for c a r r yin g out , when the s e cond
t ime informa t ion c a nnot be ob t a ined f r om the t ime s yn chr oni z a t ion
or igin, t ime s yn chr oni z a t ion wi th the f i r s t communi c a t ion appa r a tus
us ing the di f f e r enc e informa t ion r e ad out f rom the s tor age me ans 5 .
Cl a im 8. Th e t ime s ynch roni z a t ion s ys t em of c l a im 7, whe r e in the
s e cond communi c a t ion appa r a tus fur th e r compr i s e s di f f e r enc e
informa t ion c a l cul a t ion me ans for c a l c ul a t ing the di f f e r en c e
10 informa t ion be twe e n f i r s t t ime informa t ion and s e cond t ime
informa t ion and for s tor ing the di f f e r e nc e informa t ion in the s tor age
me ans .
Cl a im 9. Th e t ime s ynch roni z a t ion s ys t em of c l a im 8, whe r e in the
15 t ime s ynchroni z a t ion me ans c a r r i e s out t ime s ynchroni z a t ion wi th the
f i r s t communi c a t ion appa r a tus on the ba s i s of the f i r s t t ime
informa t ion and the s e cond t ime informa t ion when the s e cond t ime
informa t i on c an be obt a ined f rom the t ime s ynchroni z a t ion or igin .
20 Cl a im 10. A t ime s yn chroni z a t ion me thod, compr i s ing:
r e c e ivin g f i r s t t ime informa t ion f rom a s ynchroni z a t ion sour c e
communi c a t ion appa r a tus , a s a t ime s ynchroni z a t ion sour c e ,
conne c t ed to a t r ansmi s s ion s ys t em whe r e in t r ansmi s s ion de l a y t ime i s
di f f e r ent dep endin g on the di r e c t ion of t r ansmi s s ion;
25 obt a ining s e cond t ime informa t i on f rom a t ime s yn c hroni z a t ion
or igin othe r than th e t r ansmi s s ion s ys t em;
c a l cul a t ing d i f f e r en c e informa t io n be twe en the f i r s t t ime
informa t ion and the s e cond t ime informa t ion;
s tor ing the d i f f e r en c e informa t ion in s tor a ge me an s ;
34
a f t e r tha t , r e ading out the di f f e r enc e informa t ion f r om the
s tor age me ans wh e n the s e cond t ime informa t ion c annot be obt a in ed
f rom the t ime s ync hroni z a t ion or igin ; and
c a r r yin g out t ime s ynchroni z a t ion wi th the s ynchron i z a t ion
sour c e communi c a t ion appa r a tus us ing the di f f e r en c e informa t ion r e 5 a d
out f rom the s tor age me ans .