METHODS OF MODERNIZATION OF THE PRIMARY RURAL NETWORKS,
PROVIDING CONVERGENCE IN NGN

The complex of the equipment of manufacture of company " Selsoft " and the schemes of its application providing economic modernization of primary networks with their subsequent inclusion in NGN is described. Ways of transfer of traffic NGN and TGU on site MS-TS and methods of its optimum distribution in a primary narrow-band network are considered.

 

1. Transfer of traffic NGN on site MS-TS

Let's consider transport opportunities of primary networks in two widespread cases: in the first - on a site there is a cable with S = 1,2 mm2, in the second - the cable is not present and it is necessary to build a radiorelay line (RRL). We shall define possible speeds of transportation of the general traffic to OS on distance from 20 up to 50 km on a cable or on RRL without served reclaiming items. The widespread and inexpensive technology of linear coding TC-PAM 16 allows to reach on a cable with S = 1,2 mm2 next speeds of transfer:
- Up to 4 MBit/s on one pair on technology TC-PAM 32 with a reclaiming site of 3 km with six far off fed regenerators - 20 km;
- Up to 2 MBit/s on one pair with a reclaiming site of 8 km with six regenerators - 50 km.
Regenerators eat far off on alarm pair, on three from each party. On two pairs in a cable with S = 1,2 mm2 the total traffic makes 8 MBit/s (up to 20 km) or 4 MBit/s (up to 50 km).
Probably, soon there will be new technologies of linear coding, but the increase in speed of transfer and the general length of a site hardly considerably will change.

The scheme of transfer of the traffic 2x2 MBit/s on site MS-TS
on a cable with S = 0,9 mm2 on distance of 50 km

The scheme of transfer of the traffic 2x4 MBit/s on site MS-TS
on a cable with S = 0,9 mm2 on distance of 20 km

The opportunity of organization RRL to small village (up to 100 subscribers) until recently in practice was not considered in view of dearness of the equipment, complexity of its installation and service, and also long terms of coordination. Last decade there was enough of the import and domestic inexpensive radiorelay equipment, however, it on former seldom is applied on sites MS-TS. Principal causes of it are known.

Not demanding direct radio visibility and, hence, expensive mast constructions digital RRS and radio extensions of frequency ranges 150, 300 and 400 MHz in rural networks until recently also met seldom. Import systems of such class are very dear (them let out only the European and American companies), domestic in view of the military origin hardly adapted for the peace purposes. Only there were domestic digital RRS " a civil origin " for everyone above the listed range, including, and systems of our manufacture: "R-150", "RT-300" and "R-6" accordingly. They are compact, inexpensive and simple in installation. They can be let out and mounted so much, how many it is necessary for the market. Their speeds are low, but it is an obligatory payment for range of action provided by them at absence of direct radio visibility.

The statistical data who have been saved up by us within several years of work above specified RRS in all regions of the country, give following figures of real speed and range of their work: 2 MBit/s on range up to 30 km and 1 MBit/s - up to 50 km.
These data are received under the average geographical conditions and height of rise of aerials above a level of a ground no more than 15 m.
So, in the most widespread, average case, on copper cable lines or a radio channel it is possible to provide with above described equipment of transfer transfer of the traffic on site MS-TS:
- at length up to 20 km:
- at presence of a cable with S = 0,9 mm2 - 8 MBit/s;
- on RRL - 2 MBit/s;
- at length from 20 km up to 50 km:
- at presence of a cable - 4 MBit/s;
- on RRL - 1 MBit/s.
Not so it is a lot of, but - it is real and it is accessible to all. We also shall make a start from this fact in the further reasoning’s. Certainly, will have to save the traffic and to take measures on its rational distribution between systems TGU and NGN. This problem is carried out also with described below multiplexers.

 

2. Distribution of the general traffic between TGU and NGN

Optimistically adjusted experts speak, that now, before coming NGN, already there is no sense in installation instead of old ATE on 200 numbers as OS of digital automatic telephone exchange - it is necessary to establish at once Softswith. Pessimists consider, that in primary, narrow-band networks NGN in general never will be, and now it is not necessary to mix channels of transfer TGU with Internet. The reliable and economic telephony in the signal system should function separately from other systems. What to do to the operator today? If to wait arrival NGN with the old equipment, last subscribers can run up.

Now it is not known, what situation with introduction NGN will develop the nearest years in rural networks. Where it will be established Softswith, and at what level it will have "sluice" with TGU? Probably optimists also are right are there will be level TS. Much depends not in the last instance on by what - local or "visitor" the content - all will be more demanded on village. It is not excluded, that it will be local videonews, virtual corporate or family networks, and it is not enough Internet. In the reasonings and schemes we assume, that "high-grade" Softswith will be established on MS and in the same place to have sluices with TGU, local networks of departments, the organizations and the enterprises, and on TS will establish the simple IP-switchboard. By the way speaking as in this scheme and delays, and other minuses of an IP-telephony are excluded, and all pluss remain, who knows - the truth can also, in three years rural subscribers (before city) - will run across all in NGN from usual TGU. One only an opportunity simultaneously to communicate to all relatives from all villages of area costs in the winter evening of that. And new opportunities for the organization of corporate communication in area, from meetings of chapters of rural administrations (with the web-chamber in a cabinet of the chapter). But it while assumptions, and what in rural networks in view of the narrow strip traffic NGN and TGU will be compelled to mix up long at a transport level, obviously already now. It also is a question which we suggest to solve in the optimum ways described below, on examples of optimization of distribution of traffic Internet and TGU.
We offer arranging, we hope, all the parties participating in discussion a variant of modernization of rural networks. It is replacement analog TS on the universal flexible user's multiplexer with G.HDSL the module of a linear path for communication with MS, in a consequence easily integrated in NGN. At the first stage it carries out functions of the universal user's multiplexer, transferring some tens user's telephone channels and traffic Internet in village. At the subsequent stage-by-stage switching subscribers in NGN resources of system of transfer "IKM-6a/30", liberated from disconnected in favour of NGN telephone channels, will automatically pass to transfer of stream Ethernet. The multiplexer becomes more system of transfer of traffic NGN, than TGU. It is especially actual in many cases, when on site MS-TS only one narrow-band physical channel of transfer, for example, one pair or (below examples of such cases are resulted).
At installation as TS digital ATE such flexibility to reach more difficultly. At reduction of quantity borrowed timeslots in connecting stream E1 terminal ATE to share free with traffic NGN (and now with Internet) does not become, and dynamic, "fair" distribution of the general modest traffic it will not turn out. So it will not turn out also an effective utilization of lines that allows one more occasion to pessimists to speak, that NGN in village will be never.
Now some details of our decisions. At the basic loading from TGU user's multiplexers in common with multiplexer " MK--5/8 " concentrating useful loading will provide user's carrying out of " direct numbers " available in regional ATE Si2000 capacities with concentration of loading in stream E1 (by the way, reducing cost for number), and also transfer of small traffic Internet, for example, in school. On a case of damage of a linear path, economy of the traffic of interstation communication networks (ICN) between MS and TS and it is simple for convenience the concentrator possesses an internal switching field. It, by the way, does its attractive to the agricultural enterprises - it can be used and as simple departmental ATE.

The scheme of application of a complex of user's multiplexers at replacement
terminal analog ATE. From MS 120 subscribers with concentration and
loading 0,25 Erl on one pair and traffic Ethernet 2 MBit/s on other pair are born.

Thus, the considered complex of the equipment of series "IKM-6A" (user's multiplexers with the module of linear path G.HDSL), "MC-115" (universal multiplexers with the module of linear path G.HDSL) and "MK-5" (the concentrator of streams E1) represents the flexible multiservice concentrator providing stage-by-stage, evolutionary development of primary networks, their initial "digital" and the subsequent connection to NGN.

3. Specificity of distribution of the traffic on a rural user's network

On TS where there is a cable user's network, it is applied ADSL or HDSL where symmetric access is required. Though extent can make user's lines and on 5 km where "city" ADSL will not work on range and storm protection. Not always it can approach and on functionality - often it is required to bear on one pair in the remote farm or on an agricultural production simultaneously with traffic Internet and the telephone channel on G.711 (for a fax, for example).

The scheme of the organization of carrying out on a cable with S = 0,7 mm2
on distance of 3 subscribers of 6 km on G.711 and traffic Ethernet.

Now we shall consider variants of transfer of distribution of traffic NGN and TGU on a radio channel from OS, being in village.
Under standard IEEE 802.1x range of transfer over several hundreds meters does not provide the equipment of a radio access. It, as well as more long-range DECT (up to 5 km), demands all that direct radio visibility at the ranges GHz and, hence, long and complex procedure of installation of a high-altitude mast in village. Therefore such systems can be applied effectively only in compact settlements.
For distribution of the traffic for subscribers in the majority of domestic spacious villages and the farms scattered around of them are necessary, as well as at its delivery there, the narrow-band low-frequency systems providing demanded range without presence of direct radio visibility. Besides systems of a radio access for rural networks should have corresponding interfaces and other user characteristics considering realities of today. The complex of the radial and directed, sectional and individual systems of a radio access, simple in the installation, based on one hardware platform is necessary. Strips of their radio frequencies should correspond to the table of distribution of frequencies in ranges 150, 300 and 400 MHz which in a countryside are free. Proceeding from it we also have developed a series of systems of transfer on a radio channel. It refers to " a digital multichannel radio extension of model RT-300 ". In it is, as a matter of fact, and RRS with speed of transfer from 512 kBit/s up to 2 MBit/s, and inexpensive micropowerful (100 mW with range of action up to 10 km) integrated " phone+Ethernet 64 kBit/s " a radio extension of one user's channel (RT-300/1E), and its more powerful versions (1 W, 30 km).
To the regional operator will enough receive strips of 307,5-308,0 and 343,5-344,0 MHz on all region for a complex above the specified equipment and to distribute it in view of frequency-territorial arrangements, orientations of aerials, capacities of transmitters.

The scheme of radiocarrying out of 27 subscribers (on G.711) and traffic
Internet (dynamically) with a speed up to 2048 kBit/s (at free telephone channels).
Radio extension RT-300, 2 MBit/s and multiplexer MC-115T/27E.

The scheme of radiocarrying out of 1 subscriber and Ethernet 64 kBit/s.
Radio extension RT-300/1E.

The conclusion

Application of a complex above the described equipment and typical decisions for modernization of primary rural networks will allow stage by stage, with small expenses, to carry out their subsequent inclusion in NGN, effectively to use available narrow-band copper lines of "copper" and to create lines on the basis of specialized RRS.
Advantages of its application already now, at a stage of " maintenance with digital communication " local networks - providing of access in Internet, unification of the equipment of terminal stations, a linear path and user's carrying out, simplification of schemes of primary networks and technology of service of the equipment.