Automatic analysis and warning method of optical connection between BBU combination and RRU of radio station
An Automated Analysis and Warning of Optical Transmission (AWOT) between BBU unit and RRU of radio transmitting station accurately and quickly identifies errors on an optical transmission line, thereby reducing costs in terms of labor and equipment, and at the same time reducing service downtime of mobile communication systems.
1. A method to automatically analyze and warn optical connection status between a BBU (Base Band Unit) and a RRU (Remote Radio Unit) in an Automated Analysis and Warning of Optical Transmission (AWOT) includes the following steps:
(i) read a warning status of a CPRI (Common Public Radio Interface) and an optical power of a photoelectric converter module on the BBU;
(ii) connect to the RRU via an Ethernet interface, in case of a successful connection, perform step (iii), otherwise, if connection is unsuccessful, perform step (v);
(iii) read an optical power of the photoelectric converter module on the RRU;
(iv) calculate an attenuation on an optical link from BBU to RRU and vice versa, from RRU to BBU using the following formula:
Δ
1
=
1
0
log
(
P
BBU
_
TX
P
RRU
_
RX
)
Δ
2
=
1
0
log
(
P
RRU
_
TX
P
BBU
_
RX
)
(
1
)
wherein,
Δ1 (dB) is the attenuation on the optical path from BBU to RRU,
Δ2 (dB) is the attenuation on the optical path from the RRU to the BBU,
P BBU_TX (mW) is an emitted optical power of SFP on the BBU,
P BBU_RX (mW) is an obtained optical power of SFP on the BBU,
P RRU_TX (mW) is an emitted optical power of SFP on the RRU,
P RRU_RX (mW) is an obtained optical power of SFP on the RRU;
(v) analyze an optical transmission fault and give the following warnings:
Connect
CPRI
Situation
P BBU _TX
P BBU _RX
P RRU _TX
P RRU _RX
the RRU
warnings
1
normal
normal
normal
normal
yes
no
2
normal
normal
normal
x
yes
yes
3
normal
x
normal
normal
yes
yes
4
normal
normal
normal
normal
yes
yes
5
normal
normal
normal
normal
yes
yes
6
error
x
x
x
x
x
7
normal
error
NA
NA
are not
no
8
normal
normal
NA
NA
are not
yes
9
normal
normal
NA
NA
are not
no
Situation
Δ1
Δ2
Error code
1
0 < Δ1 ≤
0 < Δ2 ≤
OPT_CONN_NORMAL
attenuation
attenuation
threshold
threshold
2
Δ1 >
x
OPT_CABLE_BROKEN
Attenuation
threshold
3
x
Δ2 >
OPT_CABLE_BROKEN
Attenuation
threshold
4
Δ1 < 0
0 < Δ2 ≤
OPT_SFP_BROKEN
attenuation
threshold
5
0 < Δ1 ≤
Δ2 < 0
OPT_SFP_BROKEN
attenuation
threshold
6
x
x
OPT_SFP_BBU_BROKEN
7
NA
NA
OPT_CONN_ERROR_1
8
NA
NA
OPT_CABLE_BROKEN
9
NA
NA
ETH_CONN_ERROR
wherein,
Optical power P BBU_TX , P BBU_RX , P RRU_TX and P RRU_RX 3 thresholds are normal, warning and error,
x is an occurrence of any possible event,
NA is not applicable,
attenuation threshold is an allowable attenuation on the optical transmission line, attenuation threshold is calculated by a product of the attenuation coefficient α (dB/km) with an optical wire length L (km), α is defined in accordance to the ITU Telecommunication standardization and summarized in the following table:
Attenuation
Wavelength
coefficient α
Fiber type
(nm)
(dB/km)
G.652.A
1310
0.5
1550
0.4
G.652.B
1310
0.4
1550
0.35
1625
0.4
G.652.C, G.652.D
1310-1625
0.4
G.653.A, G.653.B
1550
0.35
G.655.C, G.655.D,
1550
0.35
G.655.E
1625
0.4
Error code is defined in the following table:
Error code
Describe
OPT_CONN_NORMAL
Optical connection is in normal condition,
without errors
OPT_CABLE_BROKEN
The optical cable is damaged
OPT_SFP_BROKEN
SFP on RRU or SFP on BBU fails
OPT_SFP_BBU_BROKEN
The SFP on the BBU is broken
OPT_CONN_ERROR_1
It can happen in one of the following
3 cases: -
Failure of optical cord from RRU to
BBU - SFP on RRU failure - RRU off
ETH_CONN_ERROR
The Ethernet communication has an error.