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Beijing
suburban telephone network has 1.9 million lines capacity and 1.45
million households and some 40 switching systems at present. The
switching system has four modes, i.e. S1240, EWSD, CC08 and E10B，among
them, S1240 has 10 systems, EWSD has 26, CC08 has 3 and E10B has
1 switching system. Other than these, the suburban network has also
equipped with some access equipment for Hua Wei and Zhong Xing companies.
The current switching point has reached to 700, and covering 15,000
km2 suburban area，providing telecommunication services for the 6
million suburban households.
1. Network Profile
Beijing
has 10 suburban areas and counties, among them，the big 5 areas (Da
Xing, Fang Shan, Shun Yi, Tong Zhou and Chang Ping) have 5-6 switching
systems on the average, and the 5 small areas (Yan Qing, Huai Rou,
Mi Yun, Ping Gu and Men Tou Gou) have 2-3 switching systems on the
average. Each system has 50, 000 capacities. Generally speaking,
the parent office has the capacity of 10, 000 to 20, 000 lines，while
others like the remote module or V5 access will spread to each counties
or villages. From this network structure，we can see clearly that
each area has 2-3 district or county central offices (or we can
call it auxiliary tandem offices) and some end offices. These central
offices have connected to tandem offices directly, and undertaken
the outgoing calls, while the outgoing calls of other end offices
be connected to other auxiliary tandem offices by the load sharing.
The Beijing suburban area has 22 auxiliary tandem offices to undertake
the outgoing calls of the 40 switching systems. Take the Chang Ping
for example, the incoming and outgoing calls of the 8970 office
be connected to T2X（T21、T22、T23、T24） to undertake the incoming and
outgoing calls of the switching system. See the exhibition 1.
2. Main Issues
With the
development of increasing households and various multi-network services,
such as the dial-up and campus card, as well as the urban population
migration，especially after the abandon of the suburban calling tariff,
the suburban traffic volume increased distinctly. Take Chang Ping,
Shun Yi and Tong Zhou areas for example. The trunking lines from
Sha He Bureau to city T21, T22 and T23 has been 10E1 respectively
at the beginning of 2001. And now it has been increased to 18,18,
and 29E1 respectively, and there are 40% overflow. From the analysis
of the traffic volume and direction, it has found that the traffic
volume of Sha He Bureau has also increased other volumes that has
tandemed the Sha He Bureau. With the destination code analysis,
it has been found that the 6975 bureau to the urban volume (one
way) is 540Erl, the 6977 bureau to the urban volume (one way) is
480Erl, and the 6178 bureau nearly 200Erl, plus the urban voice
traffic volume of the incoming calls, the 6973 bureau and the 6970
bureau has tandemed the voice traffic volume nearly 1000Erl. This
has increased the auxiliary tandem office voice load, and at the
same time, increased the demand for the trunking lines and has made
pressure on the trunk module of the areas and counties.
See the
suburban voice traffic volume in exhibition 1 (destination code
analysis).
3. Suggestions
According
to the statistical analysis, it is suggested that we should add
5 direct trunk lines from the end offices (6975, 6977, 8049, 8959
and 6957) to the urban tandem offices to relay the voice traffic.
This will help to reduce the pressure of the auxiliary tandem offices.
Owning
to the network structure of the transactions from the outgoing calls
to incoming calls, we therefore suggested that to transfer these
5 bureaus to the city network, i.e. 6975 and 6977 bureau be merged
into T21, T23, T24, T12 and T6, 8049 bureau be merged into T42,
T43, T44, T32 and T5, 8959 and 6957 bureau be merged into T42, T43,
T44, T32 and T5. These direct trunking lines are used only for the
tandem of the suburban traffic of this end office and its inter-network
calls, while the long distance calls are dealt with by the auxiliary
tandem office.
The detailed
steps are shown as follows:
(1). Add
inter-office trunk lines from the end office to tandem office
(2). Transfer
the suburban outgoing traffic volume to the new routing path
(3). The
tandem office will direct this office number to the new rout.
The above-mentioned
need the co-operation between Network Departments and Tandem Offices.
If other end offices have rapid increase in the suburban traffic
volume, this suggestion can be used with some adjustment, and the
new added switching system also be transferred into city network
based on incoming and outgoing calls.
With the
development of suburban economy and city migration, the differences
between city and suburb has become smaller and smaller. The suburban
voice traffic should increase rapidly. We therefore should reinforce
the statistic analysis on the voice traffic and direction, to get
the changing information and find the new business. By doing these,
we can adjust the unreasonable factors timely and to make the suburban
network into a more secure, economy and reasonable direction.
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