The Revolution of Telephony Provision

The Revolution of Telephony Provision Wireless Solutions Workshop 1-3 Oct 2005, Khartoum

Where it all began – The Telephone An irascible Scots immigrant and an imaginative Italian immigrant working during the 1870s in America (and for a short period in the same laboratory) together invented what we now know as the telephone. Ironically Mr. Bell’s work was a development of the telegraph; essentially a digital method of sending messages. Alexander Graham Bell is credited with the invention (patent number 174,465) though it is now recognised that much of the foundation work was provided by Antonio Meucci and his family’s long standing claim that he was a co-inventor of the telephone has been upheld by the United States Congress Elisha Gray of course also invented the telephone but was beaten by just a few hours to the patent office – but that’s another story

Rapid Progress Alexander Graham Bell went on to invent the “Photophone” which was a device to transmit the human voice by light – he demonstrated a system which successfully transmitted voice by light over a distance of about 200m – the precursor to optical fibre transmission. In 1896 Gugliemo Marconi was granted a patent (in England) for his wireless telegraphy apparatus. He improved the apparatus by making it tuneable and then in December 1901, to prove that wireless waves were not affected by the curvature of the Earth, he transmitted the first wireless signals 2100 miles across the Atlantic between Poldhu, Cornwall, and St. John's, Newfoundland.

Telephone networks The telephone continued to evolve and improve and by connecting several instruments through an operator’s “switchboard” (a manual arrangement of plugs and sockets) any two telephone instruments could be connected together making the telephone an indispensable tool for communicating long distances with anyone else who had a telephone. In Kansas, the story goes, an undertaker (Almon B. Strowger or Strowager) was frustrated because the wife of his competitor worked at the manual telephone exchange and passed all calls for an undertaker to her husband. Strowger decided to create an automatic switchboard to remove the manual operator and level the playing field. He produced the first viable switch in 1888.

Telephone networks In order to create nationwide networks there was obviously a need to build “exchanges” as they became known, but also to run large quantities of cabling between these exchanges. Calculating just how many cables were required was a complex probability problem based on waiting and queuing theory. In Denmark Agner Erlang had a particular interest in this area of mathematics and was persuaded to apply his knowledge and skill to the benefit of the Copenhagen Telephone Company and he created tables which can be easily used to calculate the capacity or loading of telecommunications circuits – the Erlang Tables.

Telephones on the move - divergence Radio and telephones seem almost instinctively to go together and the radio telephone (simply a radio connection to an operator who connected the caller to a chosen destination telephone through the telephone network) provided a small number of people with “mobile communications” for many years. The number of radio channels required to provide service to a given number of customers would, to a large extent, determine the cost of deployment of a mobile network and Erlang’s tables were once again employed to great effect. In fact this basic system continued in use until the 1980s when the first analogue mobile networks were built. But before a mobile network as we know it today could be built a few advances elsewhere were required. Reduction in power consumption and size of transmitters of course but as a concept, perhaps the most important was the idea of “frequency re-use” where a limited number of radio channels could be used over and over again covering a large geographical area.

Digital Telecoms And the rapid shrinking of footprint and cost has opened the floodgates to a wide range of wireless (interesting how that word has become popular again..) technologies offering Wireless Local Loop (where it’s difficult to get wires to the customer), Wireless LAN as already discussed, wireless headsets, PCs, PDAs…..all with a common basis in the provision of telecommunications. The success of the analogue mobile phone provided the necessary impetus for the 2nd generation of mobile phones – digital. Now much greater efficiencies could be employed making better use of scarce resources.

Convergence Mobile phones and fixed phones offer different experiences while basically providing the same service. However there is perceived to be a need to converge mobile and fixed to give the customer a greater flexibility (and better balance for his wallet) than either fixed or mobile can provide on their own. The technical argument for convergence is clear – we can do it and it is certainly convenient. But the financial argument is much more cloudy and it is difficult to see how operators can compete and offer converged services. BT makes its money by delivering fixed network services – encouraging its customers to use a mobile operated by Vodafone could be a great risk. And similarly Vodafone would be better off if its customers simply used their mobiles all the time. BT certainly seems to believe in convergence and perhaps it should or it could get left behind in the wireless world. BT Fusion offers a mobile service which switches automatically to landline (well broadband via ADSL into the home) when at home, and the customer has just one handset which looks and feels like a conventional mobile phone.

Today • Telecommunications delivery technology • Fixed telephone networks • Mobile telephone networks • Broadband • Wireless • Convergence • Digital multi-media devices (cameras, mp3 players…) • Personal Digital Assistants (PDAs) • Cordless telephony • Fixed/mobile convergence

The technology • Telecommunications is a range of services and it is not defined by the technology delivering it • However it is worth quickly reviewing the current technologies to see how they are utilised in the delivery of telecommunication services and how they might influence the types of services made available • In addition to the basic POTS (Plain Old Telephone System) we have: • Fixed Wireless Access • Mobile • Mobile Broadband • WiMAX • VoIP • And some minor players such as Bluetooth which can add another layer of flexibility

Fixed Wireless Access • Substitution for copper at the point of delivery • Great for delivering fixed services to a moderate coverage area where providing copper would be expensive • A good solution to an expensive problem - But it doesn’t always deliver……

Fixed Wireless Access • Limited range • Manufacturers claim up to 30km but 8 to 10 is more realistic • Subject to weather and other environmental conditions • New building projects can obscure line of sight • Trees can do the same! • BUT….newer technology is renewing interest in wireless delivery over a wide area and we shall discuss WiMAX later

Mobile Networks The technology of mobile networks and the limitations

2G (GSM) Network Architecture • 2G – GSM • There are elements supporting the radio subsystem • BTSs • Cells • Macro • Micro • Pico • Hierarchies • BSCs • Elements supporting switching (traffic routing) • MSCs • GMSC • Other non-radio elements • HLR • VLRs • SMSC • Authentication Centre

BTS BTS Base Transceiver Station “A bis” link to BSC Each BTS can support many mobiles simultaneously depending upon number of transceivers installed

BTS BTS BTS BTS BSC Base Station Controller Link to MSC (the “A” interface) BSC Links to BTS (the “A bis” interface) The BSC is connected to many BTSs (50+) but only one MSC

MSC Mobile Switching Centre Traffic to be routed MSC Signalling to other network elements

GMSC Gateway Mobile Switching Centre Other network (possibly in other country) GMSC To switches within network

HLR Home Location Register Incoming call Onward routed call Switch Customer location (routing info) HLR Where is customer?

Which VLR? Customer location? VLR Visitor Location Register HLR Actual customer location VLR Incoming call Onward routed call Switch

SMSC Short Message Service Centre SMSC Message is sent from mobile to SMSC and then from SMSC to mobile, all via the fixed and wireless parts of the network

SIM Authentication Centre Before any other transaction can occur in support of a customer’s service request, the customer must be “authenticated” to ensure that SIM card has not been stolen and that customer is permitted access to network AUC IMEI Billing info Other

BTS BTS BTS BTS BTS BTS BTS SIM Complete Network SMSC HLR GMSC Other Network(s) VLR MSC MSC VLR AUC BSC BSC BSC BSC BSC

Cells Various cell types can be deployed for most efficient and cost effective network rollout • Macro • Micro • Pico • Hierarchies

Macro Cells Wide area coverage Omni Omni cell is equipped with a vertically orientated antenna that radiates in a 360° pattern A sectored cell has, Typically, 3 antennas each with a directional propagation pattern Sectored

Micro Cells Small area or local coverage Strict definition requires antennas to be mounted below average roof height and usually wall mounted Wall-mounted panel antenna ensures RF energy is largely contained in spaces between buildings permitting frequencies to be more easily re-used and transmitters located close to each other without causing excessive interference

Pico Cells “Hotspot” coverage Often indoors at shopping malls, airports, railway stations etc • Coverage from these cells is very localised • Frequencies can be re-used very frequently, and often part of the allocated spectrum is set aside by the operator for pico cells • Pico cell coverage is similar to WLAN coverage and the two technologies may converge in this area

Hierarchical Cells In order to provide handover between cell types, a hierarchy of cells is required with management software within the BSC or MSC Street Micro-cell coverage Macro-cell coverage Shopping Mall Pico-cell coverage

2G limitations • Primarily designed for voice carried at 16kbps • Data at 9.6kbps on basic system • Increased to 56kbps in good coverage with GPRS though rarely achieved in practice • Re-use of frequencies reaches limits creating an upper limit of the quantity of base stations that can be deployed and thus the number of customers that can be supported in a given area (subscriber density)

Mobile Broadband • 3rd Generation mobile networks - 3G • 2G/3G differences: • 3G is based on Code Division Multiple Access (CDMA) whereas GSM is based on Time Division Multiple Access (TDMA) • The difference allows multiple 3G users to use the same frequency at the same time • CDMA is inherently resistant to self interference • A network can be implemented with just one RF channel • Wide band CDMA (W-CDMA) can theoretically deliver 2Mbps to the user as long as he doesn’t move quickly • More users per MHz are possible with 3G – greater spectral efficiency • Network planning is considerably more difficult with 3G as coverage area changes with traffic load (cell breathing)

Mobile Broadband • 3G should give us mobile broadband, but • In countries where wireline broadband (ADSL and cable) have been available for several years, the available bandwidth for a given cost has risen substantially • Thus the perception of what is broadband has changed to be 1Mbps or greater • A typical installation will now offer almost unlimited downloads at 1Mbps with upgrades to 2 and 3Mbps available • 3G will not realistically give more than 384kbps and only to static users in towns

Mobile Broadband • 3G will therefore provide • So called “clips” – short movies – good for advertising and seeing a good football goal • Music downloads – really only useful if you can then play them immediately (on the mobile) • Games - generally interactive, but difficult for any but the simplest games because of the small screen size • These all seem to be great for the provider (operator) but does the customer really want them?

Nomadic Wireless Broadband • WiMAX wide area wireless services • IEEE 802.16; is the standard for the delivery of wireless broadband: • Cellular backhaul • WiFi (802.11) backhaul • Broadband wireless local loop (direct to homes and businesses) • Direct broadband to mobile devices when operating outside “hotspots” (usually delivered by 802.11) • Nomadic suggests moving from place to place and wirelessly working at each place without necessarily supporting “mobile” which would imply working “on the go” and handover • …however handover is quite possible too, in the future

802.11 802.11 Access point wiMax wiMax Bluetooth Nomadic Wireless Broadband wiMax provides a wide-area “backhaul” for other, short-range, protocols such as Bluetooth (for voice) and 802.11x (for Internet and LAN access), and can also offer an alternative to microwave for backhauling from cellular base stations Gateway functionality (including telephone number to I/P address translation) will be included here wiMax Access point Internet connection

Voice over IP • What it is… • IP is the delivery mechanism • Used for all forms of data transfer • Data is in “packets” not a continuous stream • Packets are subject to loss for a variety of reasons • Routes can change while two devices are communicating • Time delays from origin to destination can vary from session to session and during a session • IP is “connectionless” • Voice over IP is simply another data service where the original data happens to be a converted analogue signal • Ideally voice requires a good quality continuous connection

Voice over IP • Technology vs Services • The words “Voice” and “IP” in the same sentence get people, including regulators, excited. They should get excited but not for the wrong reasons • Operators are justifiably concerned if a competitor offers equivalent services at a much lower cost to the customer; lower perhaps than it is possible for them to compete with. • Operators are also concerned if it seems that a service is being provided by un-licensed competitors • VoIP appears to allow both of these, but this is a misconception. • VoIP is only a technology which can be used to deliver a voice service. It is low cost because the infrastructure it uses is readily available to everyone (and hence does not undercut other operators because they can use it too) • Voice services cannot be delivered without a licence (legally at least) – this is true whether the service is delivered by a Strowger exchange or IP

Voice over IP • It is easy to get technology and services confused, but VoIP is just a technology employed to deliver a service – voice. • For anyone to provide a voice delivery service on a commercial basis requires them to hold an appropriate licence • The licence is for the provision of a voice service, not the technology providing the delivery mechanism

Convergence The coming together of two or more applications into one device

Types of Convergence • Mobile phones and cameras • Mobile phones and mp3 players • PDAs and other functions • VoIP and 3G mobile phones • Mobile and fixed phones • The future of convergence: Everything is IP

Mobile phones and cameras • The increase in processor power… • …and the reduction in size and cost of memory devices… • …has led to the almost natural convergence of digital cameras and phones • Low resolution to begin with, but already 2Mp cameras are available integrated with mobile phones • The advantages to the user are obvious: • Mobile phones are with us all the time, so including a camera means that “special” moment can always be captured because there’s always a camera available too • Only the top-of-the-range phones produce pictures which can be printed as easily as conventional digital cameras

Mobile phones and mp3 players • mp3 was developed as a an alternative to CDs to: • Reduce the size of the player • Make the player more resilient to knocks when carried • Increase the playing time by: • Decreasing power consumption, and • Increasing the number of tracks which can be carried around • It required development of processors and memory • The same as digital cameras and mobile phones… • If you’re going to carry your phone around, and your favourite music, you might as well do both in the same device

PDAs • Personal Digital Assistants… • …have taken convergence in a slightly different direction • From being a simple diary to a handheld computer • They can now provide web surfing as well as geographic location • With wireless internet connectivity and VoIP they can almost replace the mobile phone… • …except that broadband wireless access to the internet is not (and probably will not be for a while) as widespread as mobile

Convergence is happening • By now the phone carrying public is getting used to the idea of their phone being more than a device to carry voice based conversations • With the developments already discussed this single device can; • Send text messages • Take pictures, and send them to other phone users • Record sounds • Play mp3 (and other format) music tracks • Oh yes, and make voice calls • This is convergence of several technologies and “services”. The next step, to converge fixed and mobile telecoms seems almost trivial by comparison

VoIP and 3G • An area of convergence which is happening but not driven by the operators • 3G offers broadband on the move • Broadband offers the potential to access the internet • VoIP requires a moderately wide channel and access to the internet • A VoIP terminal connected to a 3G phone (or a 3G phone with VoIP software loaded) offers voice calls at data call rates (potentially cheaper and therefore undercutting the voice call premium) • A combination of a technology and a service which is likely to be resisted by the 3G operators to protect their revenue streams

Fixed and Mobile • Convergence traditionally meant combining the advantages of fixed services (cheap) with mobile (available anywhere) • It should not be confused with substitution where the mobile provides all of the service offering meaning that customers make 100% of their calls on the mobile network • A mobile phone equipped with a method of accessing the fixed network… • Using a cordless technology like DECT or VoIP utilising ADSL and broadband… • …would provide true convergence… • …and if that same mobile took pictures, played music, provided location information, and managed your diary…

Everything is IP • The Internet Protocol (IP) is very suited to the delivery of almost all forms of data, and with all information sources (including speech and video) originating as data, delivery mechanisms are going all IP • Internally to telephone networks all routes are IP • WLAN is a wireless form of Ethernet – IP based • Internet access is of course IP • This greatly helps the move to convergence because no translation from one format to another is needed

Everything is IP • However IP is not currently suited to mobility • Mobility requires that communication can continue when the terminal is moving • Two factors affect this: • Doppler effects as the terminal speed increases • Handover • Neither of these are well supported by wireless systems (other than true mobile) currently • Even nomadicity is not well supported by IP because a new IP address is issued at each location where an IP terminal connects – this makes it difficult or impossible to receive incoming messages • Mobile IP seeks to address this latter problem

Mobile IP • Mobile IP offers true nomadicity • By issuing a single IP address which is “known” by others • Providing a mechanism by which a mobile device always connects to a “home” device (which uses the single IP address) • Delivery of data can take longer because the route is always extended • Giving fixed IP addresses consumes numbers – already in short supply • IPv6 will increase the number of available addresses from 232 to 2128 and usage will be much more efficient

IP: 65.32.1.1 Local server (NAT) Local LAN (10. Sub net) Internet IP: 192.168.1.1 “Home” device Data store Mobile IP “Roaming” location Incoming message “Mobile” device Fixed IP address (IPv4 format) IP: 10.0.12.5 (temp IP address) 1.Mobile device makes contact with “home” informs home of new temp IP address 2. Home device records new temp IP address 3. Incoming message is “tunnelled” by home device with onward routing to temporary location

Summary • We have seen how the humble telephone has developed into a powerful, indispensable private and business tool • With the help of radio the service delivery diverged into two main branches of telecommunications (wired and mobile) • Further radio (wireless) development has increased the functionality delivered wirelessly • Advances in switching and networking have advanced services delivered both in wired and wireless environments • Fixed and wireless systems finally appear to be converging once again providing the customer with good quality calls, wherever his location and at a cost which is encouraging growth

The Revolution of Telephony Provision