Изучение технологий доступа для широкополосной электросвязи (стр. 41 )

The DRG Element Manager enables an operator or service provider to manage and configure up to 200 000 installed DRG units remotely. An operator can set parameters regarding e. g. VLAN, IP-telephony and packet filter using SNMPv1 messages as well as initiate remote software updates.

The residential network in Figure 29 is connected across copper wire to a Digital Subscriber Line Access Multiplexer (DSLAM) using an Ethernet connection between the xDSL modem and the DRG22 unit. The Exchange terminal (ET) signals are transmitted on a fibre net to the IP router and Virtual LAN. The operators management system controls the DRG and DSLAM managers to secure end-to–end management.

Figure 29 – Example of DRG im­ple­men­ta­tion

The Broadband Telephone Enabler (BTE) is the central component in an end-to-end VoIP solution, consisting of a carrier class Gatekeeper, Gateway and Element Manager. The solution is based on the most common standards today. Some of the outstanding facilities are scalability, capacity, redundancy and range of services.

A number of Ericsson/42 Networks solutions can be integrated with the end-to-en VoIP solution product portfolio, including Public Ethernet equipment, active and passive equipment for fibre networks and Ethernet xDSL Access solutions.

The DRG and BTE Systems together with the DRG/BTE Element Managers are one of the few solutions for broadband telephony and services on the market focusing on the network aspects to achieve a high level of security, high quality of service (QoS) and a business case based on remote management and software updates of the Customer Premises Equipment (CPE).

III.4.5        Israel: 802.16 Deployment in Rural Areas

IEEE 802.16a is a high capacity standard utilizing OFDM/OFDMA technology on both the Upstream/return and Downstream/forward, with the potential of delivery of a high aggregated data rate in excess of 18 Mbit/s on a channel of 8 MHz bandwidth (average of 2.2 bit/(s*Hz)). Compared to known advanced generation system in stationary applications (2 Mbit/s), IEEE 802.16a has tenfold capacity which can be shared by a large community of users, spread over a wide geographical area, ideally used in rural areas or in highly populated areas.

The system is a highly adaptive system, employing different modulation schemes (nQAMs) and error correction codes (Viterbi, RS and Turbo Codes) with different coding rates. Dynamic resource allocation ensures optimal allocation of the required bandwidth, which fits current user application. The system can support a wide range of tele­com­mu­ni­cation applications, such as fast internet, video conferencing, VoIP, e‑commerce, VoD, etc. The following contribution describes a typical multi-phase deployment of the infra­struc­ture for developing countries, where the laid down infra­struc­ture – of Base Stations (BS) and networking among Base Stations– is optimised to keep infra­struc­ture cost to a minimum level, while supplying IP telephony and reliable Internet services. In addition, the design is modular and scalable in order to allow multiplication of the deployment to additional areas without resorting to any changes, on the system level design and/or the frequency planning.

Basic assumptions for rural deployment:

•        Deployment in a typical rural area in low populated where 100-200 people live per sq. km (20‑40 households), a penetration rate of 80%, and 25% of the subscribers (households) are active in the same time (4-8 households per sq. km).

•        Suppose that the total area of coverage extends over 125 km by 125 km divided into four 62.5 km radius areas. Initial launch will start in one of the four areas.

•        The Infrastructure should support an initial launch for 31 250 active households (in two phases).

•        The Infrastructure should be scalable to support up to 125 000 households in the four regions. Data rate allocated for each household is 128 kbit/s.

•        In Phase-1, 15 625 households in one area will be serviced by 31 Base Stations (providing full tele­com­mu­ni­cation services); each deployed in a cell of 6.3 km radius. Four channels in the 2.4-2.6 GHz band (each 8 MHz bandwidth) will be needed for the Downlink, and an additional 4 channels (8 MHz each) on the Uplink.

•        In Phase-2, Additional Base Stations will be deployed in the same region to extend services to additional 15 625 households and to support full symmetric services, within certain parts of the coverage area; each one of them will cover a 3 km radius.

•        The CPE (Customer Premises Equipment) supplied to subscribers will have to use out-door directional antenna;

•        A minimum data rate between 128 kbit/s will be committed at peak hours;

•        An average data rate between 160 to 425 kbit/s will be delivered at off-peak hours;

•        Up to 18 Mbit/s burst peak rate will be achieved in some CPE’s.

System Description

The deployment is designed to start with one out of four areas, assume a gradual growth of subscribers community, starting with the initial launch of 15 625, followed by successive deployments of Base Stations, to cope with the increase of the number of subscribers (Households), where more than one user is expected in some percentage of households.

The area is divided into four large regions with comparable area size. The area spans an area of 125 × 125 km, which when divided into four regions we get a region extending to a radius of 31.25 km.

Figure 30 – Typical deployment in rural and sub-urban areas

System Deployment considerations

Optimal design – to achieve a full coverage of one of the areas and keep number of the Base Station to a minimum – is based on cellular approach where the Base Stations are installed in cells of 6.3 km radius. Total number of Base Stations needed to achieve full coverage of one area serving 31 250 users is 62 BSs (assuming 25% active households in the same time).

Each Base station is comprised of two parts from the spectrum partition and services provided point of view as described below:

Part 1 – The first deployment of Base Stations in one of the four areas will target 15 650 households. The aggregated data rate achievable on DL or UL is 64 Mbit/s, which is shared among 500 subscribers (households). Total number of subscribers with the deployment of 31 BSs can reach 15 625 households.

Part 2 – A second phase of BSs deployment will be followed to extend system capacity for the delivery of symmetric services to additional subscribers in the same region. The second tier of BSs will be based on same type of Base Station. Each BS is deployed in a denser network of cells, each 3 km radius. Deployment of additional BSs, within the larger cells of 6.3 km radius will also support delivery of 64 Mbit/s/Base Station.

Assuming average simultaneous usage of 25%, a data rate of 128 kbit/s can be committed, subscribers with favourable link budget will be able to enjoy data rates 2.5 times faster, and by utilizing statistical multiplexing techniques the factor can grow to 20 times faster.

Design Consideration

•        Frequency band:                2.4-2.6 GHz

•        BST transmit power:                37 dBm

•        BST Tx, Rx Antenna gain:        16 dBi

•        CPE Transmit power:                23 dBm

•        CPE Tx, Rx Antenna gain:        18 dB

•        UL, DL propagation model:        near LOS

•        DL, UL aggregated data rate:        18 Mbit/s

•        No diversity is attempted on BS or CPE

Economical Aspect

BWA system based on IEEE 802.16a has a potential for deployment in rural or underserved areas, for delivery of a wide range of telecommunication services. An initial investment of less than 350 USD/ household will be required for the supply of CPE`s and deploying infra­struc­ture for the first 31 250 subscribers in one area (rural, suburban), the Return on Investment (ROI) is estimated to be less than 2 years. This calculation does not take into account expenses such as: spectrum license cost, and the cost of the equipment needed to supply the services such as routers, gateways, switches and intra-cell networking equipment.

III.5        Asia Pacific

III.5.1        Niue: Wi-Fi in Niue, South Pacific

The South Pacific island of Niue is about 100 square miles, has 1 750 residents, and its economy suffers from the typical Pacific island problems of geographic isolation, few resources, and a small population. Tourism is an import source of revenue and until recently, has declined severely. Additionally, the island in recent years has suffered a serious loss of population because of its economic downturn. In an effort to revive its tourism, economy, and population the tiny island of Niue has launched the world’s first nationwide WiFi Internet access service. After introducing free email service to Niue in 1997, The Internet Users Society of Niue launched free Internet access service for the island in 1999. The group was initially set up to fund the high cost of satellite-based Internet connections on the remote island. However, WiFi was chosen as a better fit for the island, where harsh weather conditions of rain, lightning, salt water, and high humidity causes major problems with satellite and underground copper lines.