WiMAX part 2

Introduction
Setting up a wireless network requires much planning and different areas of technology. This lecture will firstly look at a local WiMAX provider's current network then will examine the steps that such a company would need to go through to install their infrastructure in a new area.

Case Study - Telabria/Orbital.net
Offered Products
Network Infrastructure
Setting up a WiMAX Network - the Stages
Financial Planning
Site Survey
Network Design
Site Planning and Construction
Monitoring of Devices
Device Maintenance
Conclusion
References

Case Study
Telabria/ Orbital.net
In order to understand the reason for setting up a WiMAX network, it is necessary to know something about the region. The area under discussion is Kent, an area of high population with much countryside. There are many people who live outside of the range of ADSL equipped telephone exchanges in rural areas. These people have had slow modem connections to the Internet until the advent of WiMAX. The lack of broadband internet connections had also stifled small business growth outside of towns and therefore there was a large demand for this technology.

Original website http://www.telabria.com however the company was bought in 2006 by Orbital.net who have continued to offer the wireless backhaul originally set up by Telabria.

Telabria was a local company that began by providing wireless backhaul in the Kent area for WiFi hotspots. In the Canterbury area, they had worked with the local council and given them wireless access in return for access to the rooftops of their buildings. This has allowed the setting up of their backhaul network at very low cost.

Telabria were a young company that used the 5.8 GHz band to form their local network. This waveband is neither totally LOS, nor NLOS and provides for multipath propagation. This gives advantages in the transmission characteristics at this frequency.

Offered Products
The products available for consumers are :
Skylink Home 1.5M (1.5Mbps / 512Kbps, 50:1)
Skylink Home 3M (3Mbps / 512Kbps, 50:1)

Commercial customers may have :



	Skylink Pro		Skylink Ultra
Speed (Up/Down)	1.5Mbps	3Mbps	5Mbps	10Mbps
Contention	20:1	20:1	10:1	10:1
Service Level Agreement (SLA)
Unlimited* Traffic
Free Telabria Wi-Fi hotspot use
Skylink Voice Business (1 line)	Optional	Optional
Skylink Voice PBX (10 lines)			Optional	Optional
Email accounts	10	10	50	50
FTP space	100MB	100MB	1GB	1GB
Static IP addresses	1	1	4	4
Setup (ex.VAT)	£99	£99	£199	£199
Monthly (ex. VAT)	£49.99	£79.99	£249	£379

Network Infrastructure

As can be seen from the diagram above, there are two tiers of this network, backhaul and the local service. The local service runs at 5.8 GHz in the unlicensed spectrum. This means that other companies or individuals could be using equipment operating at this frequency. This could be a problem so a proper site survey must be carried out in each proposed area before setting up the communication infrastructure.

In contrast, the backhaul part of the network that provides the link between populated areas and the Internet is running at a higher power in the licensed spectrum, using microwave transmission.

The diagram below depicts the (Nov 2005) extent of their network. This frequency is in the licensed portion of the spectrum and therefore a licence has been obtained from Ofcom to operate this.

Currently, the company is deploying infrastructure in the Chatham area. This is challenging as the area is interesting from a topological point of view following the river Medway as it meanders along its valley. Again, the company is working with the local council and has access to the rooftops of over 100 buildings.

After Telabria was taken over in late 2006, the network owners have continued to expand the network as shown below.

Image courtesy of http://www.orbital.net/?l=wireless/wlcoverage

Setting up a WiMAX Network -the stages
Financial Planning
It is necessary to conduct a thorough investigation into the financial viability of deploying a WiMAX network before any physical work is carried out. The following link will describe the first part of the investigation. http://wimax.com/deployment/financial_model
Various business models are available for a WiMAX network. Among these are:
City or town owned network
Network partnership with company and local council/ government
Privately owned network

For each of these there must be compelling financial opportunities to ensure the success of the network in financial terms.

If the network is privately owned, it must be ensured that there will be a sufficient market for the service among domestic customers, business customers and perhaps local government.

Other issues to consider at this stage are an inventory of :
The current and proposed fixed connectivity options offered by local providers
Current and future frequencies that are/ will be available
An inventory of assets such as buildings, towers etc. to set up the wireless hardware

Once this is in place, estimates of the proposed use of the network will help to define bandwidth requirements. These can include:

Fixed best efforts or carrier class data connectivity
Fixed voice over IP via wireless services
Mobile data services
Business video surveillance or public safety video surveillance

A five year plan for customer take-up should now be considered to help define the charge for the service. Costs to be included at this stage are the network cost itself, Internet backhaul, billing costs, technical support costs, maintenance and monitoring costs.

If the network is to include surveillance, hidden savings such as crime reduction, fire watching etc. this should also be factored into the business planning.

Site Survey
Secondly it is necessary to carry out a site survey to ensure that the geography and topology and desired spectrum are to be suitable. See http://wimax.com/deployment/network_survey for the second step. The site survey is carried out to ensure that the location for the wireless installation will be suitable for deployment. The following list is by no means exhaustive.

A spectral analysis of the planned area will need to be carried out to ensure that the spectrum that is planned is not currently in use and also to ensure safety of the team who will carry out the actual installation from existing wireless installations.
Documentation of the tower(s) or building(s) that the planned hardware is to be placed upon and documenting this on maps.
Checking that the proposed feeder tower has line of sight. If this is in doubt, a test rig should be set up to verify this.
Check for power, space requirements and cable runs.

Network Design
Next, network design needs to be considered. Details can be found at http://wimax.com/deployment/network_design.
A comprehensive network design should be drawn up including:

A summary of the overall network objectives, goals, expectations, advantages and challenges from a user and network architecture perspective. This overview should include bandwidth considerations, link availability, frequency selection, number of sites and sectors, type of systems recommended, etc.
A network blueprint that shows all components that will be required and vendors of these parts e.g. antennae, cabling, switches etc.
A complete costing of the installation including testing training, installation costs etc.
A power budget and analysis of each link that is proposed within the design
Results of the site survey
Physical dimensions of the tower or building so that correct brackets etc. can be obtained
Detailed hardware-specific multipoint propagation analysis with coverage estimates superimposed on geographic, political or satellite backdrops; these maps can be later used to show potential customers what the theoretical coverage footprint looks like.

Site Planning and Construction
Site planning and construction can go ahead. Details at http://wimax.com/deployment/siteplanning. For a point to multipoint network to be constructed, it is necessary to have access to tall buildings, towers or other high points in the coverage area. Sometimes it will be necessary to lease these sites if an alternative agreement cannot be found.
The following points must also be considered and carried out during this part of the installation cycle.

Site plans and engineering drawings must be submitted to the site owner for approval. Weight, cable runs, ice bridges, huts, power termination and other critical information must be supplied in addition to frequency and physical dimensions.
Permission must be sought from local planning authority for the installation of the antennae. This can be a time consuming and costly process if the operator does not have expertise in this process.
Site Walk: Once a site lease has been obtained, a site visit is in order. During this visit to the site all parties including electrical, site owner, integrator, riggers and other key personnel should inspect each site to make final decisions about the system installation and remaining work to be done. Electrical Considerations: if the service operator cannot use existing power at the site, power will need to be provisioned. Solar power may be a viable option in some regions.
Spectrum Licence: in the UK, Ofcom will need to supply a licence for the frequency in use.
Staging: During power installation, the actual wireless hardware should be bought, shipped, staged, programmed and tested. Out-of-box failure rates can be surprisingly high, so quality testing processes must be put in place to insure the radio, cabling and antenna systems work properly. Often the equipment can be faulty on arrival and it is costly to have an installation team on standby, paid by the hour, so the pre-testing is essential. Once the hardware is configured, the installation process can begin.
Installation: various teams will be required for different aspects of the installation including cabling, provisioning of racks, connection to switches, routers, power and integration with other networks e.g. fibre optic.
Rigging: This is installation of the dish itself and cell site riggers, depending on dish size, require 1-3 days on site per location.
Testing: A thorough set of tests must be carried out once installation is complete.
Weather and other unforeseen issues can delay the installation and these factors must be taken into account.

Monitoring of Devices
Once the equipment is in place, it is crucial that the equipment is monitored and maintained to ensure proper network operation. Details at http://wimax.com/deployment/networkmonitoring. Within the network are routers, switches, access points, CSU/DSUs, point-to-point links and other hardware. All of these need to be checked on a regular basis to ensure proper operation. At customer premises a server running SNMP will usually be deployed to allow remote monitoring.

Different hardware vendors method of monitoring will vary so it is not always possible to use the same solution for all hardware. With potentially hundreds of hardware appliances to monitor, it is vital to have central monitoring available for as much of the network as possible.

The first level of monitoring checks whether the device is functional or not and reports non-functional devices.
The second level involves performance baselines for each radio device. At setup, the performance should be logged so that performance deterioration can be checked for.
Threshold traps of 25% are then set up so that an alarm will be triggered if a device's performance drops by this margin. This allows the poor performing device to continue operating while triggering the alarm to keep the network running during deterioration. When this trap is triggered, the Network Operations Centre is notified and perhaps key staff will be called/ paged.
Network collisions and data loss should also be tracked to ensure deterioration does not take place un-noticed.

Device Maintenance
Sometimes a poorly operating device can be reset remotely or reconfigured to bring it back to original performance. Other problems will require a truck roll. These include firmware updates and visual inspections. Staff carrying out remote maintenance should have the ability to log into the hardware at the remote sites, often by serial or Ethernet connection and the maintenance staff should have data on how to gain access to the hardware 24/ 7.

Conclusion
The case study has shown that Telabria are actively engaging in setting up wireless networking in the local area and the design process is a lengthy process. There are many stages that need to be gone through before any equipment is actually installed. Financial planning, site survey, network design, site planning and construction, maintenance of the equipment.
If these stages are not carefully followed, a network may fail either due to technical or financial reasons.

References
http://www.telabria.com taken over in 2006 by Orbital.net
http://wimax.com