Compex Last Miles Solution for Melnik Region

Background 

Located about 30km away from Prague, Melnik is a UNESCO World Heritage site rich in its history and culture. The district town of Melnik is undoubtedly the most important place in the surrounding area. Due to its location and history, it was predestined to be the leader of the district. Since the beginning of its history, it was part of the lives of many important Czech kings, queens, and other nobility because it was one of the country's oldest dowry towns, revenues of which belonged to the Czech queens.  

Internet access to the population living in the region has also become a necessity. However, due to the high costs of cabling over long distances of tens of kilometers to provide such a service, ISPs have sought to look for more cost effective solutions. Currently, the towns and villages in the region of Melnik enjoy Internet access served by a Microwave link connection at Melnik from Prague.

In general, the Melnik region has flat land all around its main town, which is based on a hilltop. Nevertheless, achieving a perfect line of sight with varying landscape may not be a breeze. 

On the technical aspects, uptime is very critical to customers of the ISP. Unlike ADSL lines that have physical connections, Internet services provided by wireless connections have uncertainties due to various factors. To be definite and confident of a prolonged uptime, stable and professional equipment has to be used. In addition, with the incidence of a few radio hops, the total latency may sum up to be very significant.

The Challenge 

Situated in the centre of Bohemia, the Czech Republic and Melnik possess a typical temperate climate with temperatures ranging from a low of -20deg Celsius to a high of 30deg Celsius. The temperature changes may not be very drastic but may potentially pose a problem to sensitive electronic equipment to be placed outdoors. 

Varying temperatures is just one of the external factors which might affect performance and equipment. Others include humidity, moisture conditions and air density variation.

Melnik and Citov Solution 

Due to the high cost of laying a leased cable for Internet, a third party microwave link originating from Prague, is utilized to provide as an Internet connection feed to the region of Melnik. The feed point is located at the top of Melnik’s town hall.

Base Station at Melnik 

With a Compex SXP2224WM switch, with bandwidth control feature, two units of Compex Access Points are connected. To address the issue of overcrowding channels, one of the units is based on the 2.4GHz freuquency (802.11b/g), while the other is based on 5GHz.  

WPE54G is used together with a 15dBi omni-directional antenna to serve businesses and residences within the town of Melnik. CPEs of these business and residential customers of the WISP are typically located with the radius of 800m of the antenna, with a line-of-sight to the antenna. It is interesting to note that Compex Power-over-Ethernet (PoE) kits were used to provide power supply to the access points over the Cat 5 or Ethernet cable, which saves cabling costs of power cables. 

The other unit of access point, WPE54AG functions as a wireless bridge in Access Point mode. A 21dBi directional, dish antenna is connected to it, pointing in the direction of the town, village Citov.

Fig 2.0 Network Diagram of Melnik and Citov

Sub-base Station at Citov 

On the top of Citov’s elementary school, 5km away from Melnik’s base station, a sub-base station is set up with three Compex Access Points connect to another SXP2224WM. The first access point is a WPE54AG in the Access Point Client Mode with a 21dBi directional antenna connected, pointing in the direction of Melnik’s town hall functions as the other end of the wireless bridge from Melnik. 

The last access point is another unit of WPE54AG, acting as a second bridge connection to another neighboring village, functioning in the 5GHz frequency again. 

Typical CPEs 

CPEs (Customer Premises Equipment) consist of 12dBi panel directional antennas are used, connected to WPE54G units set in the Access Point Client Mode. These access point clients are in-turn connected either directly to PCs (Personal Computers), another switch or another access point to serve the business or residence. 

Last Miles Application

Since the 802.11a/b/g standards, or WiFi were not designed for outdoor use, it was a challenge to utilize them in the outdoor environment. Timeouts and retries were encountered frequently, which caused instability and poor reliability. To be able to attain distances of up to 8km as in the case of Melnik to Citov, Compex Access Points incorporate Atheros chipsets which allow for manual adjustment of ACK timeout and RX sensitivity. By setting ACK timeouts to higher values, retries are reduced and connectivity is improved. Our proprietary algorithm also provides recommended values for the parameters and at the same time allows for manual fine-tuning for optimal performance. Compex Wireless Access Points can then be configured for use in outdoor long-range environments in a cost effective solution. Configuration of Compex Access Points for long-range solution can be done through the web-based Uconfig application. Long distance parameters can be adjusted under “WLAN Advanced Setup”. 

An additional tool is packaged with the Access Points that makes it easy to deploy APs for long-range applications. The tool calculates slot time, ACK timeout and CTS timeout values based on input distance. By entering the distance between two points, the tool automatically recommends values, which you can fine tune to improve performance based on the environmental conditions.

Last Miles Solutions Application 

Compex wireless access points and other networking products can be used by system integrators and ISPs as a total product solution for implementing wireless last miles solutions for geographically challenged countries. Countries like Czech Republic, Russia, India, New Zealand and Indonesia have already realized the potential of wireless communication and have implemented it today to bridge the connectivity for remotely located towns and villages. 

Compex’s unique long distance algorithm calculation feature for parameter setting, will enable faster and easier deployment for last miles solutions. 

With Compex’s proprietary technologies like Pseudo VLAN, Parallel Broadband for bandwidth aggregation and a unique Spanning Tree Protocol algorithm, we are prepared to take on and re-invent Enterprise solutions to improve and further streamline business operations.

Results 

Using very reliable and stable Compex access points and equipment, the network supporting the Internet services to hundreds of satisfied households has been up and running for the last four years.  The various Internet Service Providers also attribute this success to the careful planning and selection of equipment. 

Despite the temperate weather conditions, Compex access points have managed to endure the changes and have a very low failure rate.   

To be able to take on ADSL service providers with cheap Internet services sprouting in the market, an edge over them had to realized. Wireless Internet Service Providers take pride in the much lower latency rate achieved with Compex Access Points and exploit it as a key advantage over the ADSL providers.

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