Systems and methods of optical path protection for distributed antenna systems

A.[.!|DUO![.3Un;[ 23D}J2J,UI \D / % v Q E Z 5% N\ N/‘ 2 N A E , £2 8/4 N "_-.1‘-A; 1.0 E“ 8 K 2 \ / N LO 43 —| |— —| |— , 3 Q Q) /> H 8 Km, U. N / 0/ /J O / 8 N 0 0\-II ] E B E I I A V 1 R; I M A1!|Duo!1Oun:I 2oD;Na1u1

32 Qzgmm L \ 1% M L / 3. R22 \§ L M L >1 L E; \ U Q H.242; h E; =3 S S L S S N: S / ZS WA WA WA IL . \ X: H_<z<_H X_:Q.mV_P. H_<z<_H x? Q H_<z<Hx_: 4N2: H E \ %é.% \ x? ...,.% \ X? ...+%% I >1 L 5% 2% ES 5 / >1 2453 SLM SI 1 _, <51 _~>~_ £2 E is X: W S IMIW 5 in n \ 2” _S>U_>L__S:S_S=v_m~=\_..mHm $3 6 J X_:...+N=+s Mi N: 2 3; WI...16..J / S S _ NC I Gm LWIKKIIII. _S>S_ r___S_S _2m_m s A T S/\eM0 .4 gm 2 MW _ .1 <3 223 Wm. A -m\ lflim 5?. +~_?.=U w \ / ONM fit S E

mm GE

\38 N \c23R \ Nemm N/I _H—u 4 _i_ HMM , _i_ N -x: Ea Z<~_ \ N ._e\ 2 V A h 56> H En z<~_ N % 2 ~38 Na z<~_ 2.8% NU N: BNM BNM N Ndwm \— \C \Z-omm x: i x:Eo0\x=<< x:+ +N=+H= _ Rm \\ J I. - . 2 as , 5e 5? +N_e :0 _ \\ pN Z BM 8 NM ONN

410 transmitting a downlink optical signal to a downlink fiber of one of 0 first \ fiber path and a second fiber path.

415 combining any downlink optical signal received on the downlink fiber of \ The first fiber path and any downlink optical signal received on the

downlink fiber of the second fiber path in order to output the downlink optical signal

420 splitting an uplink optical signal for transmission on an uplink fiber of the \ first fiber path and an uplink fiber of the second fiber path

430 I
\ determining a signal quality of the downlink optical signal

440
\ determining a signal quality of the uplink optical signal

45O\ switching between a normal state and backup state based on one or both

of the signal quality of the uplink optical signal and the signal quality of the downl ink optical signal

FIG. 4

(5111 512-1 r 513 514 I 95 % d1 d1+d2+... +dx P: I,’ u1—|— WDM u1+u2+...+u>< ' I Hi MUX/ ‘ A51 \ 112 > 5\ Ll \ ,2 u2 | / H E I : 5122 u1 siqnal quality level \ 511_X J; 515: u2 signal quality level \ \ SE "X HOM I HE uxsignal quality level I 516 Hub \ 510 1 \ [ RAN #N 1 550-1 5502 X I pnmary 534 ( (550 M _Y I O 522\ PI d1+d2+...+dx'] L d2+...+dx 1 L d(x-1)+dx'] [ dx [ 524 J u1+u2+..,+ux AD M u2+,..+ux AM/[: O 3(;_1)+uX ADN[ ux 30 NJ \ secondary ,_[ ]_, ,_ ]_, ,_‘ 5 _ /‘ 112 112 d(><-1) RAN #2 I Cable U1 d1 _Y RAN #N I X VGUII - -Y - X I 531) RAN #1 , 11(><-1) I § ‘ - / I 530 2 530(N1)) I \ 530-IJ

\