The Goodwin Borodino DECT standard radio access system
1. The organization of communication scheme and principles of work of the Goodwin Borodino system
The circuit of communication organization in the Goodwin Borodino system is shown in Fig. 1.
The structure of the Goodwin Borodino system consists of:
1.1.1. Base Station Controller
The base station controller (BSC) provides functions for organizing the interface with ISDN, the protocol support for the radio channel (establishment of the connection, identification, etc.), and assuring the functioning of the DECT network (subscriber search, procedure of hand-over in one cluster, roaming in multicluster system, etc.).
The BSC contains functional blocks for managing the entire Goodwin Borodino system.
One E1 interface provides 30 communication links. Thus, in the Goodwin Borodino system, from 30 to 120 subscribers simultaneously can have access to ISDN.
The BSC-E1 has 8 E1 lines of which from 1 to 4 lines can be used for communication with an automatic telephone exchange and the rest for communication with the base stations.
The BSC is placed in a standard 19" rack (fig. 2) and draws its power from a 60-watt direct current network. To assure trouble-free operation of the BSC in a situation when there is a loss of voltage in an initial network, an uninterruptible power supply (UPS) should be used.
The BSC is installed inside rooms, besides that it can be installed in the rooms of an automatic telephone exchange or it can be operated remotely, using the transfer systems available to the operator.
1.1.2. Base Stations
The base stations (BS) are intended for organization of the radio channel providing access of subscribers' Cordless Terminal Adapters to the Goodwin Borodino system.
The base station with the E1 interface provides 12 conversation channels. Thus, through one BS-E1 12 subscribers can have simultaneous access to the communication system.
The recommended number of subscribers that can be served by one BS-E1 is 30…80 subscribers.
1.1.3. Base Station Multiplexer
The base station multiplexer (BSM) is intended for division/unification of the ?1 flow from BSC to several BS.
For connection with the BSC all the multiplexers use the E1 interface.
The base station multiplexer with the E1 interface is intended for dividing/ unifying the ?1 flow extending from the BSC and containing 30 B-channels into three separate 12 B-channel paths. Thus, three BS-E1 can be connected to one BSM-E1.
The BSM feed is sourced from an external power supply (an uninterruptible power source is recommended).
1.1.4. Regenerator of E1 digital flows
The digital flow regenerator (RDF) is intended to increase the range of the BS location from the BSC. The RDF provides for transfer of one or two ?1 flows in both directions.
An RDF feed can be extended from the BS controller (at a distance of up to 1 km), and from an external power source. In the latter case, an uninterruptible power source is recommended.
1.1.5. Base Station Repeater
The base station repeater (BSR) is intended for the relaying of signals from the base station (BS) to the cordless terminal adapter (CTA) and back for the purpose of increasing the range of a CTA site from the BS as well as for the purpose of creating zones of local mobility for a subscriber with a handset (to a radius of up to 200 meters from the BSR). The BSR feed can be extended from external sources (it is recommended to use an uninterruptible power source).
1.1.6. Cordless Terminal Adapters
The cordless terminal adapter (CTA) is intended for maintenance of the user's radio access to the base station. The CTA is a DECT-GAP standard stationary device which has a subscriber's double-wire ending (a/b interface) for connection of subscribers' devices (SD) certificated by the Ministry of Communication and Information of the Russian Federation (see Fig. 2). The CTA used are Goodwin-Taroussa-S DECT/GAP standard manufactured by the Goodwin group.
Fig.2. Structure of subscriber equipment
Handsets (HS) are intended for maintaining radio access of mobile users to BS-E1 and represent a DECT Standard GAP-type wireless radio telephone receiver. As HS it is possible to use GAP-type DECT standard receivers, which have been awarded the conformity certificate of the Ministry of Communication and Information of the Russian Federation.
1.1.8. Data Transfer Controller
The structure of the BSC includes an additional module — data transfer controller (DTC ) in order to assure data transfer.
1.1.9. Subscriber Devices
Telephone sets of various types and manufacturers with proper frequency and pulse set, as well as faxes and modems, can be used as subscriber devices (SD). Even the use of some kinds of pay phone is possible. SDs are connected to the CTA through the same two-wire subscriber lines as a standard telephone network. The link speed of the data is 32 kbit/s.
1.2. Operator Workplace
The operator workplace (WPO) is for the use and convenience of the systems management operator in fulfilling system requirements (configuring of the system, registration/deregistration of subscribers, etc.), maintenance service, and equipment diagnostics. The WPO computer is connected to the BSC through the modem or Ethernet network.
1.3. Antenna-feeder Devices
The base stations have two HF-sockets for connection of antenna-feeder devices (AFD).
Antennas may be built in the case of BS (inside antennas) as well as placed outside the case (outside antennas). The BS-Upn has inside antennas meanwhile the BS-E1 and BS-DSL have outside antennas.
In the Goodwin Borodino system certificated antennas, feeders and sockets of foreign companies such as Huber & Suhner, Kathrein, AMP, Amphenol as well as of domestic producers are used.
2. Connection of the Goodwin Borodino system to a public telephone network
The Goodwin Borodino system is connected to ISDN through the E1 interface with the EDSS1 or QSIG signal protocol. At the connection to a basic automatic telephone exchange of PSTN with the 2VSK(R1.5) interface, it is necessary to use the 2VSK/?DSS1 interface converter; for example, the CSM converter manufactured by LONIIS, which has a conformance certificate from the Ministry of Communication and Information of the Russian Federation.
3. Goodwin Borodino system access control
The Goodwin Borodino system has two types of registration for subscriber equipment:
Each DECT standard CTA and hand set also has its own code. The CTA and handsets retain the system codes under which they were registered. The BSC retains the individual codes of the registered CTAs. The identification of codes by certain algorithm is performed at each search. Thus the codes which the BSC and CTA (or HS) exchange are broadcast only after the addition of random numbers to these codes in compliance with standard DECT procedure. This prevents unauthorized receiving and usage of the data at the current control of the air interface. The operator can manage the access process by registration and deregistration (connecting and disconnecting from service) of system subscribers. The number of registered subscribers in the system is determined by the software configuration of the BS controller and can be changed upon upgrade of the system.
4. The parameters of the Goodwin Borodino system radio interface
The parameters of the DECT Goodwin Borodino communication system radio interface are given in Table 1.
5. The intensity of failures in the Goodwin Borodino system
Table 2 shows the intensity of failures (Bit Error Rate — BER) in the radio channel of the Goodwin Borodino DECT communication system.
6. The characteristics of the Goodwin Borodino-G system
Information about the capacity of the communication system, consisting of one cluster, is provided in Table 3.
7. Reliability of the equipment of the Goodwin Borodino system
8. Characteristics of the main equipment of the Goodwin Borodino system
The cordless terminal adapter Goodwin-Taroussa-S
The Goodwin-Taroussa-S ( see Fig.1) is a telephone radio jack for use in DECT standard WLL systems, developed according to the requirements of the international DECT digital standard. Goodwin-Taroussa-S allows you to quickly connect your telephone, fax machine, modem or answering machine to PSTN or a data network without any additional telephone cabling.
Advantages of Goodwin-Taroussa-S:
The mode of SD operations -- pulse or tone -- is automatically distinguished by the CTA. CTA management is accomplished via an SD connected to it with tone dialing.
The CTA modes of operation are presented on an LED display on the case and by various sound signals heard through the connected SD. The maximum number of CTAs that can be connected to the DECT system is determined by the parameters of the system.
RJ-11 sockets are used to connect power supplies to the SD. CTA has a high frequency (HF) socket of the SMA type for connection of the external aerial, and a clamp for connecting a ground wire (lightning rod).
The Goodwin-Taroussa-S provides a range of communication on the radio channel up to 12 km with maintenance of the necessary level of energy (application of subscriber's aerials). The Goodwin-Taroussa-S can be completed by subscriber antenna.
An uninterruptible power source is used to maintain a constant power supply from a stable main voltage (and/or in case of loss of main voltage).
Goodwin-Taroussa-S CTA characteristics are given in Table 1.
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