Networks and Protocols CE Week 7b Network technologies 2.5G & 3 rd generation 2.5G, GPRS Contents: Why do we need it Details of GPRS Details of EDGE GPRS Value Added Services Operators have seen the use of data as a new source of revenue The potential for data use is To sell the users the data applications To charge them for data needed to use them To charge other developers to allow the applications on to the network 3G data use Although the UK operators have bought licensees to use 3G the infrastructure was not ready to be used The operators paid a lot for the radio spectrum licenses This left little available for infrastructure upgrades Also devices were not ready to be used with 2 Mbps LicenseCompany Paid (Pounds) ATIW (3)4,384,700,000 BVodafone5,964,000,000 CMM024,030,100,000 DOne2One (T-Mobile)4,003,600,000 EOrange4,095,000,000 GPRS General Packet Radio Service (GPRS) This standard was agreed by ETSI March 1998 It is designed to allow data communication to take place within the existing GSM infrastructure and technology A few additional servers are added to the network to allow this and these will be discussed later This is described as being a 2.5G technology To use GPRS you will need a GPRS enabled device Existing GSM devices will not be able to make use of the additional features GPRS General Packet Radio Service (GPRS) Features Higher connections speeds Theoretical Maximum of 171 Kbps Interference Distance from transmitter All GSM channels would have to be dedicated to GPRS communications This speed also does not take into account any error-correction Does not consider a device uploading data Actually speeds with conditions taken into account is theoretically a maximum of 53.6 Kbps Studies have show the average is usually about 30 40 Kbps Always on Data communications No delay in setting up a data communication? GPRS Is it always on In the GSM infrastructure to make a data call your device would phone the data centre which would make the data connection This is a part of the circuit switched infrastructure and as such you were paying for every second you were connected no matter if you were communicating or not Within GPRS you are always attached to the data infrastructure When you first turn on your device you are authorised for GPRS communications When you need to use data services you no longer have to dial a number Your device will make a request to the SGSN to allow data communications via the BS Once setup your device can then start sending packets across the infrastructure There will be a delay but this is very small in comparison to the GSM infrastructure GPRS Always on? GPRS Devices In the standard there are three types of GPRS devices A Capable of Simultaneous data transfer and voice communications B Automatic switching between voice and data calls. This will need to be configured on the device itself C Switching between data and voice operated by the device user manually. All of these standards are backwards compatible with the GSM networks for voice communications GPRS Relies on the fact that Internet communications are bursty in nature A large amount of data will be received and the user will process it before requesting more i.e. a web page A single voice circuit from GSM will be broken into smaller parts and the GPRS data is sent on this circuit. All data is sent in packets Data must be broken into small packets These packets are re-assembled at the destination These packets add an overhead in the form of the packet header Lower resource requirements than circuit switched communications GPRS GPRS Channel Breakdown ChannelUse of the Channel 0Voice 1AAAABBABBAAAAFA 2Voice 3AAABAABAAAFAAAA 4AAAFAFAFFFAFFFFB 5BBBBABABAFFFFFFF 6Voice 7FFAFFAFFABABBBBB Data Users A = User 1 B = User 2 F = User 3 In this instance we have 3 voice calls and 5 users receiving data GPRS GPRS Channel Breakdown Continued A channel which is being used for GPRS data Can only be shared between other GPRS users It can not be allocated in that time slot for GSM voice calls Even if part of the time slot is available The use of GPRS will reduce the amount of voice calls that can be made on that cell With enough data calls a cell will become useless for voice callers, which require exclusive access to the time slots GPRS GPRS Multi slot classes ClassDownlinkUplinkMaximum Active GPRS GPRS coding schemes Depending on environment one of the following coding schemes are used SchemeMax Throughput per 1 Time Slot Error Checking CS-18 KbpsGood CS-212 KbpsGood CS KbpsModerate CS-420 KbpsPoor Schemes CS-1 and CS-2 are usually used GPRS GPRS Infrastructure As discussed earlier GPRS build upon the GSM network. One network element need changing Base stations Requires a software upgrade Base station controller Requires a software upgrade New parts need adding Serving GPRS Support Node (SGSN) Has VLR functionality Authorise attached users Details recorded of data packets to be charged for Session Management Router for packets which may be lost during a handover during a data call GPRS GPRS Infrastructure continued Gateway GPRS Support Node (GGSN) Is the connection into the GPRS network It carries out all translations that area required Firewall for the network Collates data regarding the amount of packets received Potentially in the future this will allow for competing GGSNs in a network! Free market choosing either the cheapest or most reliable GGSN! There are 3 types of GGSN A Near Future/Now The GGSN becomes part of its own ISP and provides Internet services. The devices will be assigned IP address using DHCP. B Now The SSGN always selects the same GGSN to do the Internet work. The configuration will be done dynamically and on a temporary basis C Future This allows a private company to have its own GGSN, with an encryption key so that only authorised devices can gain access. i.e. a VPN into a network, constantaccess etc Packet Control Unit (PCU) Logically part of the Base station controller Responsible for the radio interface of GPRS GPRS and SMS SMS messages are sent in GPRS as a part of the normal data channels In GSM they are usually sent via the control channels Why This changes has taken place ready for the Multimedia Messaging service (MMS) Due to the size of the messages The size limits of SMS are removed with MMS GPRS Current Supported Protocols IP Internet Protocol Connectionless protocol, which delivers based on best effort Widely used in most networks X.25 Connection orientated communications Reliability built in with error checking the header Uses Virtual circuits Intended for terminal services Still used but is being replaced by other technologies GPRS IP Address As you connect and disconnect you will be given a new IP Address Using Dynamic Host Configuration Protocol (DHCP) Consider if you disconnect because an handover does not work What happens to your packets, does another device get them ? Addresses Issues Two options Private - only available within the network Uses Network address translator (NAT) to get data from the Internet Public Available from outside of the network Effectively the node is a part of the Internet All of the PC security issues are still valid GPRS General Packet Radio Service Problems Initial problems existed in respect to the GPRS device When launched there was only a few compatible devices These had poor features and terrible battery life There was nothing to use the increased data rate Limited advertising of the features of GPRS Potentially this was an issue around how much the advertising of the WAP services cost operators This is now changing Vodafone has published for half % increase in data revenue In the UK it is 383 Million ar File.dat/2008_Annual_Report_FINAL.pdfar File.dat/2008_Annual_Report_FINAL.pdf Messaging made the group 923 Million GPRS EDGE Newer Technology Enhanced Data Rate for the GSM Environment (EDGE) EDGE was another step towards the holy grail of 3G It was developed by Erricson for the losers of the 3G auctions EDGE builds upon the infrastructure which is installed for GPRS QOS supported Improved air interface technology Increased throughput from the new encoding method 384 Kbps (theoretical) 80 100 Kbps (closer to reality) EDGE UK usage There are three operators using this technology Orange T-Mobile O2 These have upgraded there infrastructure to EDGE to support the use of the apple i-phone Apple listed one of the reasons for EDGE was the relatively large availability of EDGE rather than 3G communications at this time In addition to the reduced battery requirements of EDGE Apple have now released the 3G version and as such the technology is moving towards that EDGE Changes The changes to the infrastructure The BS will need a new transceiver This is to deal with the 8 Phase shifting Key (8 PSK) encoding used This method will encode 3 bits in each modulation This is the one of the reasons why it is 3 times faster than GPRS New software on the BS This is to deal with the new encoding method The other required changes would have been carried out during the GPRS upgrades EDGE QOS QOS classes The classes which are supported by EDGE are the same as UMTS Conversational Real-Time communications highest priority Two way communications Streaming Video audio files, time dependent One way communication Interactive WWW usage, telnet etc Reduced request response time Background SMS,, MMS Best effort delivery Each of the communications will be issued with one of these classes. This will depend ion the technology being used for EDGE EDGE QOS Air Interface Improvements Improved Retransmission procedures Lower modulation quality techniques can be used Packets can then be resent at the new level Addressing of frames has been increased to 2048 from the 128 of GPRS Improved Forward error checking Measurements for correct sending rate are carried out continuously The coding technique can then be changed to the appropriate rate EDGE 3G? EDGE and 3G The International Telecommunication Union (ITU) made some definitions for 3G Moving slowly a minimum speed of 384 Kbps to be classed as 3G EDGE does meet this requirement and as such can be considered as a 3G technology Others describe it as a 2.5G or 2.75G technology! EDGE Roll out Rollout Stages Phase 1 Introduce single and multi-slot packet switched services Introduce single and Multi-slot circuit switched services Phase 2 Web UseReal-time services VOIP Video Conferencing GPRS Key Points of lecture GPRS increases the data rate of GSM Kbps Uses current GSM infrastructure, with small changes Additional servers How GPRS operates Dividing the time slots between multiple users EDGE Technology What is it What is needed Issue of IP packets in a network Changing IP Addresses 3G UMTS Why 3G? UMTS (Universal Mobile Telecommunication system) Use of 3G at the moment 3G Third Generation (3G) We have looked at current and older technologies over the last couple of lectures TACS GSM GPRS EDGE 3G is the currently widely available state of the art technology In terms of high speed data access over a cellular environment The user can get access anywhere any time! 3G UMTS The Dream (intention) 2G and 2.5G systems are incompatible around the world Although GSM is dominant there are still lots of other technologies Worldwide devices need to have multiple technologies inside of them, i.e. tri-band phones, dual-mode phones To develop a single standard that would be accepted around the world One device should be able to work anywhere ! Access to Information from Anyplace, Anytime 3G UMTS The Dream (continued) Worldwide positioning available Able to pinpoint a device and direct services to it. Mostly to be used for Push services Increased data rate Maximum 2048Kbps Operational in Europe by 2002 Japan 2001 (this was achieved) Worldwide usage by 2005 (Did not happen) 3G UMTS The reality Different standards with some operators in difference countries and the rest of the world For example In the US market forces dictate the adopted technologies in Europe this is done by the EU with the agreement of the member states In the future market forces may move towards a single standard i.e. VHS and Betamax video tapes, currently being seen in the new DVD standards Difficulties World wide identical available spectrum Agreement on the encoding/decoding technique used Local influence groups Manufacturers who have invested in one technology 3G UMTS Standard The 3G standard was written by the International Telecommunication Union (ITU) The standard was referred to as IMT-2000 The key to the standards was the available data over the air interface 2Mbps in fixed or in-building environments 384 kbps in pedestrian or urban environments 144 kbps in wide area mobile environments Variable data rates in large geographic area systems (satellite) 3G UMTS Other parts of the standard Frequency Spectrum Technical Specification Radio and Network components Tariffs and Billing Technical Assistance 3 Main technical implementations were agreed UMTS - Europe CDMA America TD-SCDMA China 3G Standards Added Confusion Two specification groups create the standards within the ITU specifications 3GPP Developed the standards for the UMTS system which is built upon GSM 3GPP2 Developed the standards building upon the US CDMA networks, specifically the CDMA-2000 standard The Chinese group is referred to as Chinese Academy of Telecommunications Technology (CATT) 3G UMTS Universal Mobile Telecommunication system (UMTS) UMTS Builds upon the successful European GSM network Incorporates the developments made for the GPRS and EDGE networks Five areas of standardisation Radio Core Network Terminals Services 3G UMTS The core network Asynchronous Transfer Method (ATM) Has been defined as the core networking technology ATM allows circuit switched transfer of data using packets. High speed data transfer currently maximum 10 Gbps Guarantee of quality of service for the duration of packet transfer Small packets used called cells for the transfer of data to minimise the impact on the routers, network and switches. IPv6 Arguments are being pushed for the core network to allow IPv6 RFC3314, September 2002 RFC3314 This would allow packets to be transferred directly from the internet to the device with no translation IPv6 does contain QOS headers, which can be used with the correctly configured hardware All 3G devices could have a single IP address that would not need to change 3G UMTS UMTS Full packet driven architecture For voice and for data transmissions. Packet based networks allow for an increased amount of traffic on a medium. The only time part of that medium is blocked is when a device is transmitting or receiving. Consider how often in your phone calls you actually say nothing Natural pause between words Taking a breath Waiting for a response Thinking of something to say 3G UMTS UMTS Offers voice and data services the same as EDGE Services offered will be classed into one of the following From these classes certain defined Quality of Service (QOS) specifications are guaranteed like packet delay time ConversationalStreamingInteractiveBackground Real-TimeBest-effort, guarantee of quality delivery VoiceStreaming VideoWeb PagesMMS, SMS,s 3G UMTS Intended Data Rates Actual data rates will be effected by Interference (other devices, background, buildings) Over use of the frequency Weather! Amount of other traffic Base station / cell actually attached to Speed you are moving at ! 3G UMTS Types of Cells and Base station to use them Macro Cell These cover a large area and will give slow access 144 Kbps max speed of 500 Km/h Micro Cell These should cover a medium area 384 Kbps max speed 120 Km/h Pico Cell Less than 100 metres 2 Mbps max speed of 10 Km/h Difficult to predict Actual distances and bandwidth depend on local conditions 3G UMTS Types of Cells and Base station to use them Cells will operate in a hierarchy overlaying each other Satellite Macro-Cell Micro-Cell Urban In-Building Pico-Cell Global Suburban 3G UMTS Consider These data rates are in Mega Bits per Second and Kilo Bits In terms of data rate the measure of a kilo bit is 1000 bits Not the 1024 which is used for data storage So 2 Mega Bits per Second = 244 Kilo Bytes per second (roughly) 3G UMTS Hierarchy of Cells 3G UMTS What transmitters/base stations look like Pictures taken from (http://www.scotland.gov.uk/library/pan/pan62-05.asp, 2009)http://www.scotland.gov.uk/library/pan/pan62-05.asp 3G Base Station Locations A database of all cellular base stations is provided by OFCOM in the UK This database contains the locations of all Base stations and discuss the details of them Here is a screen grab of Stafford, UK 3G UMTS Radio Interface: Allocated Frequencies 3G - UK 3G spectrum auction License shows the size of the spectrum with A being the largest Part of the auction rules was a new company in the UK won the License type A Auction closed on the 27 th April 2000 Original estimates were for a total selling value of 1.5 billion ()The license is allocated until the 31 st December 2021 The operators must have 80% uk coverage by the 31 st December 2007 otherwise they will be fined The UK phone companies in June, 2003 said that they would claim the VAT back on the license purchases! About 3.3 Billion pounds European Court case started in 2004 This claim though was dismissed though in June 2007 (http://www.theregister.co.uk/2007/06/26/no_vat_on_3g/)http://www.theregister.co.uk/2007/06/26/no_vat_on_3g/ LicenseCompany Paid (Pounds) ATIW (3)4,384,700,000 BVodafone5,964,000,000 CMM024,030,100,000 DOne2One (T-Mobile)4,003,600,000 EOrange4,095,000,000 3G UMTS UK 3G Winners ?? 3G UMTS Radio Interface UMTS uses Wideband-Code Division Multiple Access (W-CDMA) Also known as IMT-2000 Direct Spread Extremely complex algorithms Uses 10x the current 2G processing power! Modulation is done with Quadrature phase shift keying (QPSK) This encodes 2 bits with each change Supports two modes of operation Frequency Division Duplex (FDD) Time Division Duplex (TDD) 3G UMTS W-CDMA Operates in the same manner as the CDMA used in the US CDMA allows multiple users to communicate at the same time over the same frequency Each of the devices is given a Chipping code this is known by the device and the base station. This chipping code is then used to identify the signal and allows the BS to receive the signal The chipping code is used to adjust the frequency of data transferred during the transfer The essential point of CDMA is the use of power control 3G UMTS W-CDMA Wideband CDMA operates the same but this takes place over a wider area of frequency UMTS uses 5MHz for the signal CDMA (narrowband) uses 200 KHz These communications are secure by the nature that unless the chipping code is known, the sequence of the data can not be known Communications can take place as soon as the device is ready and frequency reuse factor is now one 3G UMTS W-CDMA Frequency Reuse Factor This is the distance which needs to be left between cells As the same frequency is reused and the chipping code which is used is change and unique to a BS The frequency can be reused in adjoining cells Temporary Base stations can be added to the infrastructure if required, as long as the chipping code was unique 3G UMTS Power Control If you consider a group of people speaking, Chinese, English and Italian If these all speak at the same volume you can then listen for the parts which you understand. If the English person starts talking louder than the rest, the all you will hear is English The other languages will be drowned out CDMA Works on the same basis One point of CDMA is the power control, so that the power sent out is just enough to allow data transfer to take place. As a side effect of this technology this controlling of the power that the radio interface uses, also saves the battery on the device 3G UMTS W-CDMA, Infrastructure 3G UMTS W-CDMA UTRAN The core network for 3G will remain the same as GSM This is a purely cost issue, in the future the infrastructure will be upgraded GSMUMTS Mobile device/station (MS)User Equipment (UE) Base Station (BS)Node-B Base Station Controller (BSC)Radio Network Controller (RNC) 3G UMTS W-CDMA UMTS Terrestrial Radio Access Network (UTRAN) A device which wishes to communicate needs to request access to the network This is to prevent too many devices communicating at once Although CDMA will theoretically allow a very large number of user to communicate at once What actually happens is the quality of the calls is reduced considerably This is a issue for voice but is a disaster for data calls 3G UMTS W-CDMA Handover UMTS will use a soft handover technique GSM used a hard handover technique In a handover the device is always attached to at least one BS Node-B 3G UMTS - WCDMA The technology which UMTS is based upon (WCDMA) has some patented content On this basis any manufacturer who builds a handset needs to pay royalties to Qualcomm On the 1 st of October 2007 the European Community started looking into this to investigate if Qualcomm was overcharging"If the other patent holders were to do as Qualcomm is doing, royalties could raise the cost of WCDMA handsets considerably - thus raising the prices to consumers. In October 2008 Nokia paid $2.3 Billion for the use of the technology This will settle worldwide court cases which were ongoing 3G UMTS 3G UMTS was tested in the Isle of Man for Europe The equipment was run and operated by O2 The license spectrum used on this island was given free by the government The actual devices used were given to some of the islanders The idea was to trial the equipment in a limited manner Also they wanted to see if there was a pattern of usage for the technology i.e. the killer app A single killer app, like SMS was for GSM, is unlikely It is more likely a series of applications will be popular 3G is now widely available Most of the operators started to get the infrastructure working in 2004 and this is continuing to cover the country The devices to make use of the technology are also now widely available and the cost is coming down. PCMCIA cards are available for laptops to give data access Japan When we consider Japan for the killer app it was! 3G bandwidth is not needed for! 3G UMTS Increasing usage of this technology now it is rolled out is being developed Mobile broadband as an alternative to DSL connections from phone companies Increasing number of devices which can make use of this technology with USB dongles or inbuilt technology All of this allows for 3G to be rolled out increasingly to devices which are beyond the original consideration of just a mobile phone On the 30 th of September 2008 a number of companies have linked with the GSMA to produce a symbol to rival the Wi-Fi logo Mobile Broadband to be put onto Laptops which support 3G connectivity Also interesting if the government statistics on this technology That 19% of mobile phone users had used it to connect to the Internet in the last 3 months UMTS Links Details of the 3G license auction (UK) UMTS standards documents