This is the second part of solar power article by Robert Ndlovu
WHEN considering solar power a thorough and detailed site survey to establish if a particular technology will work for a certain community or not will need to be carried out.
The site survey must collect relevant data like weather patterns, temperature extremes, elevation, wind speeds, security, distance from interconnection, population density, etc.
This is because some solar-powered equipment might fare better in Lupane than Nyanga.
These are facts relevant to a specific geographic area. This is not a one size fits all solution.
Use of solar-powered wireless equipment addresses two problems inherent in most developing countries – lack of reliable electricity (Zesa) and cost of laying copper.
Solutions that can be solar powered remove power- related obstacles in rolling out basic telephone services and even internet via 3G which is hot property these days!
This approach provides a vehicle to implement, say, tele-medicine and other healthcare delivery services as well as agricultural education and extension services.
Other services include distance learning and mass education programmes.
This means that the local rural clinic, police, school, shops have access to a dial tone and email within a reasonable walking distance. This means teachers based in remote areas are able to access resources that can aid their curriculum.
This means that health workers can disseminate HIV/Aids info at the click of a mouse. I thought that this was common sense! But I could be wrong.
In Zimbabwe’s case like most African countries, we have farmers with the most fertile land that DO NOT have access to information resources regarding commercial farming as a business. This is a serious matter.
Most of the new farmers do not have access to an email address!
Having phone and internet at community centres and even growth points, will mean that not everyone in that area needs to buy his or her own computer to access basic communication services but can use the public access system.
This eliminates the excuse of computer cost being a major obstacle to development by default.
Lack of access to information contributes heavily to an extent similar to the perennial food shortages to a country that has NOT been experiencing any drought because of lack of information. Lack of information is directly proportional to poverty levels.
The Bible says ” . . . people perish because of lack of knowledge . . . “
I will not expand on this self-explanatory verse from the book of Hosea.
Telecom Centre (Phone & Internet Centre)
Think of a telecom centre as a set-up with phone, e-mail and internet services.
This model is pretty common in urban set-ups. This model could be used for remote and even some urban centres whose electricity supply is more often off than on.
As such the telecom centre will have three distinct elements: phone centre, internet centre and the control system. This test system is for eight phones and eight workstations.
The essential building blocks for the rural phone centre would be based along these guidelines:
l Housing booths – to house telephone handsets.
l Solar module – this is a 3m long pole with a solar panel, a charger and batteries.
l Wireless module – this could be CDMA or WiFi or GSM depending on what wireless technology is available.
l Phone devices – these are the handsets that will be plugged into the switch on the local network.
l Metering units – these could either be stand-alone devices or incorporated within the telephony devices to regulate usage.
The following make up the data side of the community communications centre:
l Mini PCs – these are fully functional computer systems that consume less electricity but provide enough processor speed and capacity to be used for tasks like wordprocessing and internet browsing and printing.
l LCD monitors – these have a lower power consumption rates.
l Switch – this is in the form of a PoE (Power over Ethernet) switch in which the phones can be plugged in directly with no separate power source as they are powered inline by the switch.
l Accessories – ethernet cables and power strips.
l Software – free tried and tested Linux operating system like Ubuntu.
Basically, this is the logical term for the systems that bring and or enable services to the end user stations, namely the telephone centre and the internet centre.
l Internet server – this is a Pentium 4 computer with at least 2G of memory running FREE open source Ubuntu Linux operating system. In short, this system acts as the intermediary between the end users (stations) on one side and the internet and satellite dish on the other hand.
l Telephony server – this is the call routing and call processing system that literally performs call origination and termination and all transcoding functions where audio signals have to be converted for GSM or landline systems. Typically this system is a dual core Pentium 4 kicking on at least 3 G memory.
l VSAT system – this is a solar-powered satellite dish maybe 1,2m wide with 1,5Mb/s down and 384kps up and again its size is determined by the size of the centre. The VSAT option is the wireless option if there is no GSM or WiMax alternative in that area.
I know someone out there is about to point out that the bandwidth requirements for both voice and data might not be enough. Well, VSAT and VoIP technologies have leapfrogged with time.
Five years ago when I started thinking of this project, Facebook was not so popular then. But today it’s a different story. My point is that what you know NOT today could be a hit tomorrow. Present satellite systems do carry voice at lower bandwidth capacities than ever imagined possible – yes at 4kb/s. GSM uses 13 kb/s.
The beauty of IP telephony is that modern and efficient and cost-effective voice compression schemes are now available that enable a number of voice calls to be squeezed into a smaller pipe than before – an interesting analogy would be like packing 20 people into a kombi originally designed to seat 12 people.
VSAT systems have an option for CIR (Committed Information Rate), which literally guarantees a minimum bandwidth allocation for the end user – the community centre. Of course, CIR means a little bit extra dollars.
l Solar system – this is an array of solar panels, chargers and batteries that are installed and sized according to the expected load of the deployment.
This is measured in KWh (kilowatt hours).
This depends on the sunlight and on the size of the panel’s surface area.
Batteries are sized in such a way that the system can function even during days of low sunlight, in which case wind energy can be used by use of windmills in areas with low light. Usually areas that have low sunshine and more cloud cover will have higher wind speeds to make sense of considering windmills.
Use of VoIP
If the system described is deployed, then to make calls some telephoning system must be used. NOT Econet, NOT TelOne but some technology that allows you to carry voice over an IP network – VoIP – Voice Over Internet Protocol. Ever heard of Skype ? That’s VoIP.
This is how it is set up. Let’s say we want to have four telephones in our remote site in Gokwe to enable farmers to sell their cotton online and be able to make and receive calls locally and internationally. Four VoIP devices are installed to provide the dialling tone on site.
The actual phones won’t need any electricity as they are powered inline by the network switch. The devices will get their dial tone from the telephone server located locally on the same local area network.
But the local switch is linked to other switches nationwide over IP and can communicate with the larger providers like Econet and NetOne. This is using the VSAT option where the GSM is unavailable.
But for other settings a WiMax backhaul is used to connect directly to Econet. This could either use LOS (Line of Sight) or NLOS (Non-Line of Sight) to propagate the signals. LOS refers to a direct point to point line between a transmitter and a receiver with NO obstruction in between such as trees, mountains or buildings. WiMax, which is another wireless technology, has the capability of good connectivity for up to 50km.
Calls made within the VoIP network from one farmer in Gokwe to another one in Wedza are almost free. Because the phone call path does NOT leave the private network based on open standard and open source technologies.
Naturally established telecom operators do NOT like open source-based VoIP when used by potential competitors BUT they themselves use the same technology to lower their origination and termination costs which they don’t pass to the consumer.
The project management teams is more interested in this one. The costs obviously include all of the above plus labour, security installations, transport, meals, airtime, etc. Nothing is new here. But of importance to note are the monthly recurring costs that should be built into the budget when this is planned.
l Connectivity – if the VSAT is used then there is a monthly service fee that goes with use of the service. This depends on the amount of traffic that traverses the network.
l Telephony – calls made between similar systems on the IP network are free, but not really free since their connectivity portion takes care of it. OK let me break it down to simpler terms. If a system community communications is deployed in Jambezi, Gokwe, Wedza, Guruve and Madla-mbuzi for argument’s sake, calls made between these centres are technically FREE.
l To be continued next week
l Robert Ndlovu is an ICT consultant based in Bulawayo in Zimbabwe formerly based in Silicon Valley in California. He writes in his personal capacity and provides limited FREE consultancy to individuals ,companies and organizations in Southern Africa via SMS, Phone and E-Mail. Zimbabwe (071) 310 0000 : (077) 600 2065; USA + 1 (650) 200 0250 : SA + 27 (031) 100 2337 : UK + 44 (12) 2580 8338; [email protected]
Solar power solution to communication
This is the second part of solar power article by Robert Ndlovu