White space and it’s possible impact on broadband in Kenya
White space refers to frequencies that are allocated for telecommunications but are not used in active transmission. They however play a crucial role in enabling interference free communication. In layman’s terms, if there are two adjacent FM radio stations say Hope FM at 93.30Mhz and BBC-Africa at 93.90Mhz, the two are separated by white space bandwidth equal to the difference of the two (93.90Mhz-93.30Mhz = 0.6Mhz or 600Khz). If you look at the entire FM or TV spectrum, there is a lot of white space frequencies not in active use but is used as guard band to enable listeners tune clearly and avoid hearing two radio channels at the same time. The same is true also for Television (TV) transmission.
TV transmission uses the UHF frequency range of 470Mhz-806MHz (for example KTN Kenya transmits at 758-764Mhz which is channel 62 on the ITU chart. Remember this logo here? that rainbowy 62 wasn’t a fashion statement). Each TV station is allocated 6Mhz out of which only three points are used for picture, color and audio, the rest is white space. Taking the KTN example, 759.25Mhz is used for video, 762.83Mhz is used for color while 763.75Mhz is used for the audio in the TV channel. The rest is what is known as white space and just lies in waste though serving as guard bands.
It is this wasteful nature of analog TV and radio broadcast that there is a concerted push by CCK to move to digital transmission which unlike analog, does not have white spaces and therefore doesn’t waste precious frequencies. The push to digital TV is informed by the fact that if all stations transmit digital signals, they will free up the white spaces for other uses.
From the consumer’s perspective, the push for analog to digital transmission is because they will also benefit from clearer and rich content that it will bring along (such richness includes being able to set reminders on future programs, scroll what’s next e.t.c just as you are able to do now on satellite TV such as DStv but not on the local free to air stations).
Kenya has set a target of 2012 to complete the analog to digital TV migration and there is already a lot of progress being made on that front. Once the migration is complete, it will have released the UHF band for other uses such as broadband internet, SCADA and remote metering systems and many more. However, once released, these frequencies will be unlicensed meaning anyone can use them without prior approval by CCK. In the USA for example the fact that white space will be unlicensed has seen the FCC face legal proceedings by wireless microphone manufacturers (which use white space) because it would mean that they will be interfered with by more powerful transmission sources such as white space base stations on tall buildings etc. The FCC has however gone ahead and allowed the use of white space for other uses.
The fact that white space is at lower frequency (470Mhz-806MHz ) compared to existing last mile solutions such as Wimax (2000Mhz and 5000Mhz ranges) or Wi-Fi, the white space can travel much farther and around physical objects. It is estimated that a Wi-Fi hotspot that changes to use white space frequency range can increase its coverage area by 16 times hence enabling wide reach. The lower frequencies will also make detection of white space signals easier and less power-hungry (This is because the higher the frequency detected, the more complex the equipment and the more power required, this explains why your phone’s battery drains faster if Wi-Fi or blue-tooth (Higher freq)is turned on than if you tune to FM stations (lower freq) on the same phone).
The wide coverage, cheaper equipment and lower power requirements will present endless possibilities of extending broadband coverage beyond towns or areas with Wimax, Wi-Fi, or GSM coverage. The use of white space will also lead to cheaper internet as investment in infrastructure will be minimum as one base station will be enough to cover the entire city and beyond making last mile infrastructure CAPEX lower. This is unlike Wimax which to cover a city like Nairobi would need about 5-10 base stations.
The Institute of Electrical and Electronic Engineers (IEEE) recently announced the finalization of 802.22TM white space standard known as the Wireless Regional Area Networks (WRAN) or Super-Wi-Fi (Microsoft calls its version White-Fi) that will deliver speeds of up to 22Mbps per channel. This paves way for equipment manufacturers to design interoperable white space transceivers and I believe we will soon see them in phones, laptops and tablet computers. Last April, A test white space network was established at Rice University in Houston in which one base station was able to provide broadband connectivity to 3,000 residents of East Houston.
White space use for broadband connectivity will be a game changer in the country when it comes to last mile connectivity as the current networks are not very extensive in reach and neither do they offer reliable and affordable connectivity. The new white space systems will offer wide coverage especially in rural Kenya that has low population density that has made investors shun extending services to them due to CAPEX required to set-up networks to serve the rural folk. White space utilization will now make it possible for these investors to recoup their investments in rural areas as they will now cover larger areas cheaply.