522
13 Fiber Optic Communication Networks
structure for SDH is shown in Fig. 13.8b. An STM-N frame has a 125-μs duration
and consists of nine rows, each of which has a length of 270 × N bytes. Because
the line and section overhead bytes differ somewhat between SONET and SDH, a
translation mechanism is needed to interconnect SONET and SDH equipment.
Drill Problem 13.3 Using Fig. 13.8 and Table 13.1, show that 37152 voice
channels (64-kb/s per voice channel) can be carried by an STM-16 SDH system.
13.3.2 Optical Interfaces in SONET/SDH
To ensure interconnection compatibility between equipment from different manufacturers, the SONET and SDH specifications provide details for the optical source
characteristics, the receiver sensitivity, and transmission distances for single-mode
fibers. Seven transmission ranges are defined with different terminology for SONET
and SDH, as Table 13.2 indicates. The ITU-T G.957 Recommendation also designates the SDH categories by codes such as I-1, S-1.1, L-.1, and so on as indicated
in the table. Table 13.3 shows the wavelength and attenuation ranges specified for
transmission distances up to 80 km.
Depending on the attenuation and dispersion characteristics for each hierarchical
level shown in Table 13.2, feasible optical sources include LEDs, multimode lasers,
and various single-mode lasers. The system objectives are to achieve a bit-error rate
(BER) of less than 10
−10 for rates less than 1 Gb/s and 10
−12 for higher rates and/or
higher-performance systems.
Table 13.2 Transmission
distances and their SONET
and SDH designations, where
x denotes the STM-x level
Transmission
distance
SONET terminology SDH terminology
≤2 km
Short-reach (SR)
Intraoffice (I-1)
15 km at
1310 nm
Intermediate-reach
(IR-1)
Short-haul (S-x.1)
15 km at
1550 nm
Intermediate-reach
(IR-2)
Short-haul (S-x.2)
40 km at
1310 nm
Long-reach (LR-1)
Long-haul (L-x.1)
80 km at
1550 nm
Long-reach (LR-2)
Long-haul (L-x.3)
120 km at
1550 nm
Very long-reach
(VR-1)
Very long (V-x.3)
160 km at
1550 nm
Very long-reach
(VR-2)
Ultra long (U-x.3)
13 Fiber Optic Communication Networks
structure for SDH is shown in Fig. 13.8b. An STM-N frame has a 125-μs duration
and consists of nine rows, each of which has a length of 270 × N bytes. Because
the line and section overhead bytes differ somewhat between SONET and SDH, a
translation mechanism is needed to interconnect SONET and SDH equipment.
Drill Problem 13.3 Using Fig. 13.8 and Table 13.1, show that 37152 voice
channels (64-kb/s per voice channel) can be carried by an STM-16 SDH system.
13.3.2 Optical Interfaces in SONET/SDH
To ensure interconnection compatibility between equipment from different manufacturers, the SONET and SDH specifications provide details for the optical source
characteristics, the receiver sensitivity, and transmission distances for single-mode
fibers. Seven transmission ranges are defined with different terminology for SONET
and SDH, as Table 13.2 indicates. The ITU-T G.957 Recommendation also designates the SDH categories by codes such as I-1, S-1.1, L-.1, and so on as indicated
in the table. Table 13.3 shows the wavelength and attenuation ranges specified for
transmission distances up to 80 km.
Depending on the attenuation and dispersion characteristics for each hierarchical
level shown in Table 13.2, feasible optical sources include LEDs, multimode lasers,
and various single-mode lasers. The system objectives are to achieve a bit-error rate
(BER) of less than 10
−10 for rates less than 1 Gb/s and 10
−12 for higher rates and/or
higher-performance systems.
Table 13.2 Transmission
distances and their SONET
and SDH designations, where
x denotes the STM-x level
Transmission
distance
SONET terminology SDH terminology
≤2 km
Short-reach (SR)
Intraoffice (I-1)
15 km at
1310 nm
Intermediate-reach
(IR-1)
Short-haul (S-x.1)
15 km at
1550 nm
Intermediate-reach
(IR-2)
Short-haul (S-x.2)
40 km at
1310 nm
Long-reach (LR-1)
Long-haul (L-x.1)
80 km at
1550 nm
Long-reach (LR-2)
Long-haul (L-x.3)
120 km at
1550 nm
Very long-reach
(VR-1)
Very long (V-x.3)
160 km at
1550 nm
Very long-reach
(VR-2)
Ultra long (U-x.3)