Chapter 7 Microwave Engineering Design Requirement
7.4 Technical Requirement of Digital Microwave Relay Communication Engineering Design113
7.4.1 PDH Microwave Engineering Design Technical Requirement
I. Assumed reference channel of digital microwave relay communication system
(1) Advanced assumed reference digital channel of microwave relay communication system, used to transmit digital microwave relay larger than secondary group, 2500 km long.
(2) Intermediate assumed reference digital channel of microwave relay communication system, used to transmit digital microwave relay larger than secondary group, 1250 km long.
(3) User-level assumed reference digital channel of microwave relay communication system, used to transmit digital microwave relay larger than secondary group, 50 km long.
(4) Advanced digital microwave channel is used between level-2 and higher toll exchange centers. Intermediate digital microwave channel is used between level-2 exchange center and local exchange center. User-level digital microwave channel is used to the relay line between local network terminal office and users.
II. Bit Error Performance Index of Digital Microwave Relay Communication System
(1) Considering fading inside the system, interference and other bad factors, bit error performance of the 64kbit/s output end of the advanced assumed reference digital channel should meet the following requirements:
¾ In any month, in 0.4% or more of the total time, average bit error rate of one minute should be not more than 1*10-6
¾ In any month, in 0.054 % or more of the total time, average bit error rate of one second should be not more than 1*10-3
¾ In any month, total time of the bit error should be not more than 0.32% of the entire month.
(2) Considering fading inside the system, interference and other bad factors, bit error performance of the 64kbit/s output end of the intermediate assumed reference digital channel should meet the following requirements:
¾ In any month, in 1.5% or more of the total time, average bit error rate of one minute should be not more than 1*10-6
¾ In any month, in 0.04 % or more of the total time, average bit error rate of one second should be not more than 1*10-3
¾ In any month, total time of the bit error should be not more than 1.2% of the entire month.
(3) Considering fading inside the system, interference and other bad factors, bit error performance of the 64kbit/s output end of the user-level assumed reference digital channel should meet the following requirements:
¾ In any month, in 1.5% or more of the total time, average bit error rate of one minute should be not more than 1*10-6
¾ In any month, in 0.015 % or more of the total time, average bit error rate of one second should be not more than 1*10-3
¾ In any month, total time of the bit error should be not more than 1.2% of the entire month.
III. When there is only one transport method of digital microwave channel, those indexes are applicable.
(4) Assumed reference digital section of 5 or 280 km, based on different types, considering fading inside the system, interference and other bad factors, bit error performance of the 64kbit/s output end should meet the following requirement.
Table 7.2 Assumed reference digital section bit error performance index
Assumed
Bit error rate larger than 1×10-3
(second)
Bit error rate Residual bit error rate
Type 1 280 0.045% 0.006% 0.036% 5.6×10-10
Type 2 280 0.2% 0.0075% 0.16% 2.5×10-9
Type 3 50 0.2% 0.002% 0.16% 2.5×10-9
Type 4 50 0.55% 0.005% 0.4% 6×10-10
Note: assumed reference digital section of type 1 is suitable to constitute advanced assumed reference digital channel of 2500 km, type 2, between advanced and intermediate circuits, type 3 and 4, between intermediate and user-level circuits.
(5) For advanced actual digital microwave channel with the circuit length L not less than 280 km, and the intermediate actual digital microwave channel with circuit length L larger than two digital sections, based on the difference of circuit structure between actual and assumed digital microwave channel, considering fading inside the system, interference and other bad factors, bit error performance of the 64kbit/s output end should meet the following requirements. (For advanced actual digital microwave channel with circuit length less than 280 km, the bit error performance indexes are as same as that with length of 280 km.) Table 7.3 Advanced and intermediate actual digital microwave
channel bit error performance index Channel quality level
Time percentage of the entire month (%) Bit error performance item
Advanced circuit Intermediate circuit
Degrading score with bit error ratio larger than 1×10-6 ≤0.4L/2500 ≤1.5L/1250 SES with bit error ratio larger than 1×10-3 (second) ≤0.054L/2500 ≤0.04L/1250
Bit error rate ≤0.32L/2500 ≤1.2L/1250
Residual bit error rate ≤5×10-9L/2500 ≤1.8×10-8L/1250
(6) When the length of user-level actual digital microwave channel, L, is larger than 50 km, for error rate performance index, refer to that of L=50 km.
(7) When the length of actual digital microwave channel of type 2, 3 and 4 is not more than two digital sections, and the digital section length L and the length of assumed reference digital section L0 of relevant type has the following relation: “n L0< L< (n+1) L0”, the bit error performance of 64kbit/s output end, should be n+1 times of that of the assumed reference section of relevant type.
IV. Unavailability index of microwave relay communication system (1) The unavailability index of advanced assumed reference digital microwave channel (bidirectional), in any year, should be not more than 0.3%, among this, caused by propagation is 1/3.
(2) The unavailability index of intermediate assumed reference digital microwave channel (bidirectional), in any year, should be not more than 0.2%–0.5%, among this, that caused by propagation is 1/3.
(3) The unavailability index of user-level assumed reference digital microwave channel (bidirectional), in any year, should be not more than 0.08%–1%, among this, that caused by propagation is 1/3.
(4) For principles of unavailability index of actual circuit, make linear distribution based on circuit length.
(5) Unavailability index of assumed reference digital section (bidirectional) should meet the following requirement.
Table 7.4 Unavailability index of assumed reference digital section Digital section type Unavailability index (bidirectional)
Type 1 (280 Km) 0.033%
Type 2 (280 Km) 0.05%
Type 3 (50 Km) 0.05%
Type 4 (50 Km) 0.1%
7.4.2 SDH Microwave Engineering Design Technical Requirement
I. SDH Microwave Relay Communication System Assumed Reference Channel
(1) Connecting length of international circuit of national L1 backbone line that uses microwave relay with transmission basic group and higher constant bit rate is 5000 km.
(2) For the SDH microwave relay communication system with each IF channel at transmission basic group and higher constant bit rate, based on its position in the network, can be classified into inter-provincial backbone, provincial backbone, local network and access network.
(3) Inter-provincial backbone is used between toll exchange centers and between exchange center and international interface office. Provincial backbone connects provincial toll exchange center. Local network is used to connect local network terminal office (or transit exchange) and toll exchange center. Access network is used to connect user to local network terminal office (or transit exchange).
II. Bit Error Performance Index of SDH Microwave Relay Communication System
(1) Considering fading inside the system, interference and other bad factors, error performance index of inter-provincial backbone channel, in any direction and any month, should not exceed the following standard value.
Table7.5 bit error performance index of inter-provincial backbone channel Channel rate
(Kbit/s) 1500–5000 >15000–
55000
>55000–
160000
>160000–
3500000
Bits/block 2000–8000 4000–20000 6000–20000 15000–30000
ESR 0.04×A 0.075×A 0.16×A (to be defined)
SESR 0.002×A 0.002×A 0.002×A 0.002×A
BBER 2×10-4×A 2×10-4×A 2×10-4×A 2×10-4×A
In the table: A=6%×L/5000 L: actual length of the circuit
(2) Considering fading inside the system, interference and other bad factors, error performance index of provincial backbone channel, in any direction and any month, should not exceed the following standard value.
Table7.6 bit error performance index of provincial backbone channel Channel rate
Bits/block 2000–8000 4000–20000 6000–20000 15000–30000
ESR 0.04×B 0.075×B 0.16×B (to be defined)
SESR 0.002×B 0.002×B 0.002×B 0.002×B BBER 2×10-4×B 2×10-4×B 2×10-4×B 10-4×B
In the table: B=2.5%+1%×L/500 L: actual length of the circuit
(3) Considering fading inside the system, interference and other bad factors, error performance index of local network channel, in any direction and any month, should not exceed the following standard value.
Table7.7 bit error performance index of local network channel Channel rate
Bits/block 2000–8000 4000–20000 6000–20000 15000–30000
ESR 0.04×C 0.075×C 0.16×C (to be defined)
SESR 0.002×C 0.002×C 0.002×C 0.002×C
BBER 2×10-4×C 2×10-4×C 2×10-4×C 10-4×C
In the table: C=5%
(4) Considering fading inside the system, interference and other bad factors, error performance index of access network, in any direction and any month, should not exceed the following standard value.
Table7.8 bit error performance index of access network channel Channel rate
(Kbit/s) 1500–5000 >15000–
55000 >55000–
160000 >160000–
3500000
Bits/block 2000–8000 4000–20000 6000–20000 15000–30000 ESR 0.04×D 0.075×D 0.16×D (待定)
SESR 0.002×D 0.002×D 0.002×D 0.002×D
BBER 2×10-4×D 2×10-4×D 2×10-4×D 10-4×D
In the table: D=8%
(5) For inter-provincial and provincial backbones, actual bit error performance design index should be distributed in direct proportion based on actual channel length by referencing the standard value in the previous table.
III. Unavailability Index of SDH Microwave Relay Communication System
(1) Unavailability index of toll assumed reference digital channel, in any year, should not exceed 0.06% in every 500 km, and that caused by propagation occupies 1/3.
(2) Unavailability index of actual circuit is linearly distributed based on circuit length.
7.4.3 Access Network Technical Requirement—26 GHz Local Multiple-point Distribution System (LMDS)
Based on PRC communication industry standard (YD/T1186-2002) “Access Network Technical Requirement—26 GHz Local Multiple-point Distribution System (LMDS)”
(1) Bit error performance index:
1) Bit error performance
¾ Bit error performance of Nx64 Kbit/s digital connection
Between the SNI and UNI of LMDS fixed radio access system, bit error performance of digital connection should meet requirements in the following table.
Table 7.9 Bit error performance index of Nx64 Kbit/s digital connection
Rate ESR SESR
Nx64kbit/s 1.2×10-2 1.5×10-4
¾ Bit error performance of 2048 Kbit/s channel
As to high bit rate channel, when radio access is used in the access network, the total bit error performance indexes should reach 7.5% of all the indexes of 27,500 km.
Between the SNI and UNI of LMDS fixed radio access system, bit error performance of 2048 Kbit/s digital connection should meet requirements in the following table.
Table 7.10 Bit error performance index of 2048 Kbit/s digital connection
Rate ESR SESR BBER Equivalent BER
2048kbit/s 3.0×10-3 1.5×10-4 1.5×10-5 1.46×10-9 (2) Availability Index
¾ Intermediate quality requirement, annual availability: 99.8%
¾ Advanced quality requirement, annual availability: 99.99%
7.4.4 Access Network Technical Requirement—3.5 GHz Fixed Radio Access
Based on PRC communication industry standard (YD/T11586-2001) “Access Network Technical Requirement—3.5 GHz Fixed Radio Access”
(1) Bit error performance index:
1) Bit error performance
¾ Bit error performance of Nx64 Kbit/s digital connection
Between the SNI and UNI of 3.5G fixed radio access system, bit error performance of Nx64 Kbit/s digital connection should meet requirements in the following table.
Table 7.11 Bit error performance index of Nx64 Kbit/s digital connection
Rate ESR SESR
Nx64kbit/s 1.2×10-2 1.5×10-4
¾ Bit error performance of 2048 Kbit/s channel
As to high bit rate channel, when radio access is used in the access network, the total bit error performance indexes should reach 7.5% of all the indexes of 27,500 km.
Between the SNI and UNI of 3.5 G fixed radio access system, bit error performance of 2048 Kbit/s digital connection should meet requirements in the following table.
Table 7.12 Bit error performance index of 2048 Kbit/s digital connection
Rate ESR SESR BBER Equivalent BER
2048kbit/s 3.0×10-3 1.5×10-4 1.5×10-5 1.46×10-9 (2) Availability Index
¾ Intermediate quality requirement, annual availability: 99.9%
¾ Advanced quality requirement, annual availability: 99.99%
Have a think
What do you learn in this chapter?
1. Basic requirements of microwave engineering route and cross section design 2. Microwave frequency band selection and polarization arrangement
3. Technical requirement of digital microwave relay communication engineering design
7.5 Conclusion
This chapter mainly describes microwave engineering design requirement in three parts: first part is about the basic requirements of microwave engineering route and cross section design, second part is about microwave frequency band selection and polarization arrangement, and the third part describes technical requirement of digital microwave relay communication engineering design.