On October 23rd, 2014, we updated our
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The problem: Spectrum and format (air interface) fragmentation
We get used to things. Familiarity breeds myopia as well.
But an alien arriving on planet earth and looking at our accumulated baggage of radio communication formats and frequency bands would think, “Huh?”
Multi-format evolution 1990 - 2011 W-LAN Technology evolution Market evolution GSM (Europe) IS-136 (US TDMA) PDC (Japan) IS-95A (US CDMA) 802.11b 2G 802.11a/g HSCSD GPRS iMODE IS-95B (US CDMA) 2.5G 802.11h TD-SCDMA (China) W-CDMA(FDD & TDD) E-GPRS (EDGE) cdma2000 (1x RTT) 3G 802.11n 802.16d (Fixed WiMAX) HSDPA HSUPA EDGE Evolution 1x EV-DO 0 A B 3.5G Increasing efficiency, bandwidth and data rates WiBRO(Korea) 802.16e (Mobile WiMAX) HSPA+ /E-HSPA LTE (R8/9 FDD & TDD) 3.9G/4G 802.11ac 802.11ad LTE-Advanced (R10 & beyond) 802.16m / WiMAX2 WirelessMAN-Advanced 4G / IMT-Advanced By 2012 only two mainstream technologies will have been obsoleted in 20 years!
LTE FDD Frequency bandsBased on 36.101 va.2.0 Table 5.5-1 Duplex spacing Width Width Gap Uplink Band Downlink Band Frequency Points of note
There is a lot of overlap between band definitions for regional reasons
The Duplex spacing varies from 30 MHz to 799 MHz
The gap between downlink and uplink varies from 10 MHz to 680 MHz
Narrow duplex spacing and gaps make it hard to design filters to prevent the transmitter spectral regrowth leaking into the receiver (self-blocking)
Bands 13, 14, 20 and 24 are reversed from normal by having the uplink higher in frequency than the downlink
Bands 15 and 16 are defined by ETSI (not 3GPP) for Europe only – these bands combine two nominally TDD bands to create one FDD band
LTE TDD Frequency bandsBased on 36.101 va.2.0 Table 5.5-1 Width Transceive Band Points of note
For TDD there is no concept of duplex spacing or gap since the downlink and uplink frequencies are the same
As such, the challenge of separating transmit from receive does not require a duplex filter for the frequency domain but a switch for the time domain
Future LTE/UTRA Frequency bands The work on defining new frequency bands shows no sign of slowing up. These are the bands currently being considered by 3GPP:
Band 22 3410/3490 + 3510/3590 – UMTS/LTE 3500 MHz
Band 23 2000/2020 + 2180/2200 - S band additional terrestrial component (ATC) of the mobile satellite systems (MSS)
Band 25 1850/1915 + 1930/1995 - Extended 1900 band – has issues with GPS co-existence
Band 26 814/849 MHz + 859/894 – Extended 850 upper band
Band 27 806/824 + 851/869 – Extended 850 lower band
Other possibilities identified by the ITU:
790−862 MHz band (European digital dividend)
4.4-4.99 GHz band
US 700 MHz band plan Revised 700 MHz Band Plan for Commercial Services You need some organization, ‘cause ... Damn!
The industry solution – do it all? VoIP LTE Multi-band (13?) HSPA+ TD-SCDMA High batteryefficiency High spectralefficiency LTE-Advanced MIMO 1xEV-DO(B) Low cost Interferencecancellation 802.16m Operator’s Radio equirements Wants: Everything When: Now! Greenwireless Bluetooth Multi-Carrier TD-LTE EDGE-Evolution 802.16e Dongle or phone Wi-FI A-GPS MBMS Multi-RAT
All options available for no extra cost size or weight! Why we don’t have multi-format motor cars today Weight and padding for sound-proofing and ride User-switchable left/right hand drive for roaming Petrol engine for range Diesel engine for economy Light-weight for fuel economy Solar panels for ecology Electric engine for ecology Supercharger for power 4WD for grip
The industry solution - Multi-band multi-format devices
On paper these are conceptually simple, especially when using the SDR word.
Software Defined Radio is a noble goal – especially for narrow band base stations with sufficient design and cost margins
For user devices it is not so simple
Has anyone seen a software-defined PA or antenna? What we do have is SDB - software defined baseband.
Tuneable antennas are being worked on but are no panacea
Multiplex filter design is also a struggle – can’t violate physics
Multi-band + carrier aggregation + MIMO = Antenna nightmare!
An alternative “anti-competitive” solution
Wireless comms relies on a shared and limited natural resource – Radio Spectrum
Industries that rely on such precious resources - like water and power - need to be carefully planned
Consider the history of power in the UK
Back in the 1920’s strong “competition” meant great choice:
DC or a variety of AC frequencies
A variety of voltages
A variety of independent unconnected generating companies
But to exercise choice of supply you would have to move house since any one generator would only supply the local market with their unique offering. “Devices” could not roam.
The alternative “anti-competitive” solutionCreation of the UK national grid
Then some rare visionary in government proposed the creation of a national grid
This required standardization of frequency and voltage: 240V at 50 Hz was chosen.
The industry fought back strongly on anti-competitive grounds but were over ruled
In the 1950s the government nationalized the generating companies creating the Central Electricity Generating Board
This was again strongly opposed but it created huge scale resulting in lower costs and better coordination of generation capability for continuity of supply
Who would roll back the clock now?
Examples of fragmented infrastructure
Japan standardized its national grid at 100V but:
The west of the country influenced by Europe runs on 50 Hz The east influenced by the US runs on 60 Hz Recent consequence: The loss of generating capacity in the east due to the tsunami cannot be mitigated by excess capacity in the west
Australian has three different gauges of railway and have had to develop unique bogey switching equipment
Edinburgh used to be served from London by two railway companies each with their own set of tracks and matching hotels at either end of the city centre
The alternative “anti-competitive” solutionWhat about cellular communications
Cellular communications have come a long way in 20 years and are no longer considered a luxury
The history of regional regulation and competition have led to today’s often highly fragmented market which has many inherent inefficiencies
In many countries, competition laws require that relatively narrow bands are split between several operators, all required to build their own networks – Is this really sensible any more?
Governments did to cellular what they already did to power?
Instead of trying to sell off public assets to the highest bidder how about taking a more holistic approach?
But is this not just another flawed socialist idea!Is it not Adam Smith vs. Karl Marx? GSM is the most successful wireless technology ever, owned by more than 5 billion people.
It was created by an “anti-competitive” memorandum of understanding by 17 European countries
Compare this with what happened with 2G in the US – a fragmented competitive mess of five systems which eventually led to just two systems with no interoperability.
There was a quote on the White House web site some time ago praising the FCC. It went something like this: “Why can’t all our agencies emulate the FCC and generate money rather than just spend it”.
The wireless lifecycle is long, requires heavy capital investment and benefits from mobility. All this requires careful planning. In recent times regulators have taken an increasingly soft touch – this is now backfiring. Competition is needed - once the direction is set.
An alternative “anti-competitive” solutionWhat about cellular communications
Network sharing is becoming more common – the industry is figuring out the economics for themselves
The most ambitious example is Yota in Russia who have formed a consortium with competitors MegaFon, MTS, Rostelecom and VimpelCom to build a single shared LTE network.
From an engineering perspective it should be evident that if each country’s wireless assets were pooled the potential scale and benefits could look similar to the impact of the national grid
A single regulated operating company could maximize coverage and performance while reducing format and band fragmentation
The rest of us could get on with designing optimal hardware and applications just like we do with the national grid!
“But they’re communists!”
The role of central planning
Have we reached an inflection with spectrum when it makes sense to move towards more central planning?
The need for planning and regulation is almost always retrospective when less formal methods fail
Even the ten commandments came after the fact! We should not get hung up that the regulatory regime needs to evolve
Land ownership is a prime example. In the early days you just claimed it. Now it is legally traded and in denser areas is subject to planning permission to control usage and impact
Spectrum is recognized as the sovereign property of a country. It is leased and has exclusivity. Much of its legal regulation is based on real estate law.
An example of green field central planning Denver
An example of chaotic evolution 1G 3G 5G 2G 4G Heathrow! Page 21
The role of central planning
The need for central planning varies during the lifecycle:
In the 1970s wireless communications was a luxury In the 1980s it was an emerging market In the 1990s it entered a phase of massive growth Today it is ubiquitous and an essential service
Sometimes having a green field situation presents too many variables.
In any case, wireless has too much invested to start from scratch. We are crowded and need to think laterally.
Leave it alone and let the Market find its own way
Apply a gentle-but-deliberate hand to move things toward some more organized situation
Apply a regulatory hammer and sickle to re-apportion spectrum and dictate common interfaces