1 Global System for Mobile communications (GPRS, EDGE, UMTS, LTE and…) 2 GSM History Year Events 1982 CEPT establishes a GSM group in order to develop the standards for a pan-European cellular mobile system 1985 Adoption of a list of recommendations to be generated by the group 1986 Field tests were performed in order to test the different radio techniques proposed for the air interface 1987 TDMA is chosen as access method (in fact, it will be used with FDMA) Initial Memorandum of Understanding (MoU) signed by telecommunication operators (representing 12 countries) 1988 Validation of the GSM system 1989 The responsibility of the GSM specifications is passed to the ETSI 1990 Appearance of the phase 1 of the GSM specifications 1991 Commercial launch of the GSM service 1992 Enlargement of the countries that signed the GSM- MoU> Coverage of larger cities/airports 1993 Coverage of main roads GSM services start outside Europe 1995 Phase 2 of the GSM specifications Coverage of rural areas 3 GSM world coverage map 4 5 Differences Between First and Second Generation Systems • Digital traffic channels – first-generation systems are almost purely analog; second-generation systems are digital • Encryption – all second generation systems provide encryption to prevent eavesdropping • Error detection and correction – second-generation digital traffic allows for detection and correction, giving clear voice reception • Channel access – second-generation systems allow channels to be dynamically shared by a number of users 6 7 GSM network The GSM network can be divided into four subsystems: • The Mobile Station (MS). • The Base Station Subsystem (BSS). • The Network and Switching Subsystem (NSS). • The Operation and Support Subsystem (OSS). 8 GSM Network Architecture Mobile Station • Mobile station communicates across Um interface (air interface) with base station transceiver in same cell as mobile unit • Mobile equipment (ME) – physical terminal, such as a telephone or PCS – ME includes radio transceiver, digital signal processors and subscriber identity module (SIM) • GSM subscriber units are generic until SIM is inserted – SIMs roam, not necessarily the subscriber devices 10 Base Station Subsystem (BSS) • BSS consists of base station controller and one or more base transceiver stations (BTS) • Each BTS defines a single cell – Includes radio antenna, radio transceiver and a link to a base station controller (BSC) • BSC reserves radio frequencies, manages handoff of mobile unit from one cell to another within BSS, and controls paging • The BSC (Base Station Controller) controls a group of BTS and manages their radio ressources. A BSC is principally in charge of handovers, frequency hopping, exchange functions and control of the radio frequency power levels of the BTSs. 11 Network Subsystem (NS) • NS provides link between cellular network and public switched telecommunications networks – Controls handoffs between cells in different BSSs – Authenticates users and validates accounts – Enables worldwide roaming of mobile users • Central element of NS is the mobile switching center (MSC) 12 Mobile Switching Center (MSC) Databases • Home location register (HLR) database – stores information about each subscriber that belongs to it • Visitor location register (VLR) database – maintains information about subscribers currently physically in the region • Authentication center database (AuC) – used for authentication activities, holds encryption keys • Equipment identity register database (EIR) – keeps track of the type of equipment that exists at the mobile station 13 The Operation and Support Subsystem (OSS) • The OSS is connected to the different components of the NSS and to the BSC, in order to control and monitor the GSM system. It is also in charge of controlling the traffic load of the BSS. • However, the increasing number of base stations, due to the development of cellular radio networks, has provoked that some of the maintenance tasks are transferred to the BTS. This transfer decreases considerably the costs of the maintenance of the system. 14 GSM Channel Types • Traffic channels (TCHs) carry digitally encoded user speech or user data and have identical functions and formats on both the forward and reverse link. • Control channels (CCHs) carry signaling and synchronizing commands between the base station and the mobile station. Certain types of control channels are defined for just the forward or reverse link. 15 How a Cellular Telephone Call is Made • All base stations continuously send out identification signals (ID) of equal, fixed strength. When a mobile unit is picked up and goes off-hook, it senses these identification signals and identifies the strongest. This tells the phone which cell it is in and should he associated with. The phone then signals to that cell's base station with its ID code, and the base station passes this to the MSC, which keeps track of this phone and its present cell in its database. The phone is told what channel to use for talking, is given a dial tone, and the call activity proceeds just like a regular call. All the nontalking activity is done on a setup channel with digital codes. 16 • • • • • • Mobile unit initialisation Mobile-originated call Paging Call accepted Ongoing call Handoff 17 GSM Radio interface • Frequency allocation • Two frequency bands, of 25 Mhz each one, have been allocated for the GSM system: • The band 890-915 Mhz has been allocated for the uplink direction (transmitting from the mobile station to the base station). • The band 935-960 Mhz has been allocated for the downlink direction (transmitting from the base station to the mobile station). 18 Multiple access scheme • In GSM, a 25 MHz frequency band is divided, using a FDMA, into 124 carrier frequencies spaced one from each other by a 200 kHz frequency band. • Each carrier frequency is then divided in time using a TDMA. This scheme splits the radio channel into 8 bursts. • A burst is the unit of time in a TDMA system, and it lasts approximately 0.577 ms. • A TDMA frame is formed with 8 bursts and lasts, consequently, 4.615 ms. • Each of the eight bursts, that form a TDMA frame, are then assigned to a single user. 19 GSM bands 20 21 Maximum number of simultaneous calls = [(124) × 8] / N = 330 (if N=3) 22 Multiframe components 23 GSM frame format 24 TDMS format Trail bits: synchronisation between mobile and BS. Encrypted bits: data is encrypted in blocks, Two 57-bit fields Stealing bit: indicate data or stolen for urgent control signaling Training sequence: a known sequence that differs for different adjacent cells. It indicates the received signal is from the correct transmitter and not a strong interfering transmitter. It is also used for multipath equalisation. 26 bits. Guide bits: avoid overlapping, 8.25 bits 25 26 Data rate • channel data rate in GSM (1/120 ms) × 26 × 8 × 156.25 = 270.8 33Kbps • User data rate Each user channel receives one slot per frame 114 bits/slot 24 slots/multiframe 22.8kbps 120 ms/multifram With error control 65data bits/slot 24 slots/mult iframe 13kbps 120 ms/multifr am 27 Traffic Channels full rate channels offer a data rate of 22.8 kBit/s: • speech data: used as 13 kBit/s voice data plus FEC data • packet data: used as 12, 6, or 3.6 kBit/s plus FEC data half rate channels offer 11.4 kBit/s: • speech data: improved codecs have rates of 6.5 kBit/s, plus FEC • packet data: can be transmitted at 3 or 6 kBit/s Two half rate channels can share one physical channel Consequence: to achieve higher packet data rates, multiple logical channels have to be allocated =) this is what GPRS does 28 Speech coding There are 260 bits coming out of a voice coder every 20 ms. 260 bits/20ms = 13 kbps These 260 bits are divided into three classes: • Class Ia having 50 bits and are most sensitive to errors 3-bit CRC error detection code 53, then protected by a Convolutional (2,1,5) error correcting code. • Class Ib contains 132 bits which are reasonably sensitive to bit errors--protected by a Convolutional (2,1,5) error correcting code. • Class II contains 78 bits which are slightly affected by bit errors– unprotected • After channel coding: 260 bits 456bits 29 Channel coding: block coding Then Convolutional coding 30 31 32 33 Evolution from 2G 2G 2.5G IS-95 GSM- GPRS IS-95B HSCSD Cdma2000-1xRTT 3G IS-136 & PDC EDGE W-CDMA EDGE Cdma2000-1xEV,DV,DO TD-SCDMA Cdma2000-3xRTT 3GPP2 3GPP • Newer versions of the standard were backward-compatible with the original GSM phones. • Release ‘97 of the standard added packet data capabilities, by means of General Packet Radio Service (GPRS). GPRS provides data transfer rates from 56 up to 114 kbit/s. • Release ‘99 introduced higher speed data transmission using Enhanced Data Rates for GSM Evolution (EDGE), Enhanced GPRS (EGPRS), IMT Single Carrier (IMT-SC), four times as much traffic as standard GPRS. accepted by the ITU as part of the IMT-2000 family of 3G standards • Evolved EDGE standard providing reduced latency and more than doubled performance e.g. to complement High-Speed Packet Access (HSPA). Peak bit-rates of up to 1Mbit/s and typical bitrates of 400kbit/s can be expected. 35 GSM-GPRS 36 • the Base Station Subsystem (the base stations and their controllers). • the Network and Switching Subsystem (the part of the network most similar to a fixed network). This is sometimes also just called the core network. • the GPRS Core Network (the optional part which allows packet based Internet connections). all of the elements in the system combine to produce many GSM services such as voice calls and SMS. 37 ITU’s View of Third-Generation Capabilities • Voice quality comparable to the public switched telephone network • High data rate. 144 kbps data rate available to users in highspeed motor vehicles over large areas; 384 kbps available to pedestrians standing or moving slowly over small areas; Support for 2.048 Mbps for office use • Symmetrical / asymmetrical data transmission rates • Support for both packet switched and circuit switched data services • An adaptive interface to the Internet to reflect efficiently the common asymmetry between inbound and outbound traffic • More efficient use of the available spectrum in general • Support for a wide variety of mobile equipment • Flexibility to allow the introduction of new services and technologies 38 Third Generation Systems (3G) The dream of 3G is to unify the world's mobile computing devices through a single, worldwide radio transmission standard. However, 3 main air interface standards: W-CDMA(UMTS) for Europe CDMA2000 for North America TD-SCDMA for China (the biggest market) 39 40 UMTS (Universal Mobile Telecommunications System ) Services UMTS offers teleservices (like speech or SMS) and bearer services, which provide the capability for information transfer between access points. It is possible to negotiate and renegotiate the characteristics of a bearer service at session or connection establishment and during ongoing session or connection. Both connection oriented and connectionless services are offered for Point-to-Point and Point-toMultipoint communication. Bearer services have different QoS parameters for maximum transfer delay, delay variation and bit error rate. Offered data rate targets are: 144 kbits/s satellite and rural outdoor 384 kbits/s urban outdoor 2048 kbits/s indoor and low range outdoor 41 UMTS Architecture 42 Core Network The Core Network is divided in circuit switched and packet switched domains. Some of the circuit switched elements are Mobile services Switching Centre (MSC), Visitor location register (VLR) and Gateway MSC. Packet switched elements are Serving GPRS Support Node (SGSN) and Gateway GPRS Support Node (GGSN). Some network elements, like EIR, HLR, VLR and AUC are shared by both domains. The Asynchronous Transfer Mode (ATM) is defined for UMTS core transmission. ATM Adaptation Layer type 2 (AAL2) handles circuit switched connection and packet connection protocol AAL5 is designed for data delivery. 43 W-CDMA Parameters 44 Summary of UMTS frequencies: Universal Mobile Telephone System (UMTS) • 1920-1980 and 2110-2170 MHz Frequency Division Duplex (FDD, W-CDMA) Paired uplink and downlink, channel spacing is 5 MHz and raster is 200 kHz. An Operator needs 3 - 4 channels (2x15 MHz or 2x20 MHz) to be able to build a high-speed, high-capacity network. 1900-1920 and 2010-2025 MHz Time Division Duplex (TDD, TD/CDMA) Unpaired, channel spacing is 5 MHz and raster is 200 kHz. Tx and Rx are not separated in frequency. 1980-2010 and 2170-2200 MHz Satellite uplink and downlink. 45 OFCOM: The Office of Communications www.ofcom.org.uk 46 47 Global Wireless Frequency Bands 48 Base station finder: http://www.sitefinder.ofcom.org.uk/ 49 Frequency Spectrum in UK(Sep 2007) 900MHz Vodafone O2 Restricted to 2G services only 1800MHz Vodafone O2 2100MHz ( 3G ) Vodafone O2 T-Mobile T-Mobile Orange Orange Three Restricted to 3G services only 50 GSM frequency allocations Mobile phone transmit frequency MHz Base station transmit frequency MHz Vodafone GSM 900 O2 (BT) GMS 900 Vodafone GSM 900 890 - 894.6 -23 chs 894.8 - 902 902 - 910 935 - 939.6 939.8 - 947 947 - 955 O2 (BT) GMS 900 910 - 915 955 - 960 Vodafone GSM 1800 & O2 GSM 1800: T Mobile GSM 1800 Orange GSM 1800: 1710 - 1721.5 1805 - 1816.5 1721.5 - 1751.5 1751.5 - 1781.5 1816.5 - 1846.5 1846.5 - 1876.5 51 The UMTS/3G frequency allocations Frequency (MHz) 1900 - 1900.3 1900.3 - 1905.2 1905.2 - 1910.1 1910.1 - 1915.0 1915.0 - 1919.9 1919.9 - 1920.3 1920.3 - 1934.9 1934.9 - 1944.9 1944.9 - 1959.7 1959.7 - 1969.7 1969.7 - 1979.7 2110 - 2110.3 2110.3 - 2124.9 2124.9 - 2134.9 2134.9 - 2149.7 2149.7 - 2159.7 2159.7 - 2169 2169.7 - 2170 Bandwidth (MHz) licence 4.9 4.9 4.9 4.9 licence D licence E licence C licence A 14.6 10 14.8 10 10 licence A licence C licence B licence D licence E 14.6 10 14.8 10 10 licence A licence C licence B licence D licence E holder Guard band T-Mobile Orange O2 3 Guard band 3 O2 Vodafone T-Mobile Orange Guard band 3 O2 Vodafone T-Mobile Orange Guard band 52 3G downlink Signal level measured at T701 3 O2 Vodafone T-Mobile Orange EE 53 3G download Signal level measured at T714 54 3G Uplink signal level Uplink signal monitoring without 3G calls Uplink signal monitoring with an Vodafone 3G call 55 MVNO A mobile virtual network operator (MVNO) is a mobile phone operator that provides services directly to their own customers but does not own key network assets such as a licensed frequency allocation of radio spectrum and the cell tower infrastructure. The UK mobile market has 5 main mobile network operators and has a total of more than 20 MVNOs (virgin, tesco, asda, lyca…). http://en.wikipedia.org/wiki/List_of_United_Kingdom_mobile_virt ual_network_operators 56 57 58 59 International Mobile Telecommunications (IMT) Advanced Key features of ´IMT-Advanced´ • a high degree of commonality of functionality worldwide while retaining the flexibility to support a wide range of services and applications in a cost efficient manner; • compatibility of services within IMT and with fixed networks; • capability of interworking with other radio access systems; • • • • • high quality mobile services; user equipment suitable for worldwide use; user-friendly applications, services and equipment; worldwide roaming capability; and, enhanced peak data rates to support advanced services and applications (100 Mbit/s for high and 1 Gbit/s for low mobility were established as targets for research)*. 60 3.5G (HSPA) High Speed Packet Access (HSPA) is an amalgamation of two mobile telephony protocols, High Speed Downlink Packet Access (HSDPA) and High Speed Uplink Packet Access (HSUPA), that extends and improves the performance of existing WCDMA protocols 3.5G introduces many new features that will enhance the UMTS technology in future. 1xEV-DV already supports most of the features that will be provided in 3.5G. These include: - Adaptive Modulation and Coding - Fast Scheduling - Backward compatibility with 3G - Enhanced Air Interface What is 4G 4th Generation of Mobile communications First Gen Analog, AMPS 2G, Digital, IncreaseVoice Capacity- TDMA, GSM & 1xRTT 3G High Speed Data; EVDO, UMTS, HSPA ITU defines 4G as 100 Mbps mobile, 1 Gbps stationary LTE-Advanced & WiMax 2.0 4G certified, theoretically capable Realistic? Nokia lab demo w/ 8 antennas, 60 MHz & 1 user Market 4G defined as ~10X 3G or 5-10+ Mbps Current gen WiMax, LTE & HSPA+ 62 4G (LTE) • • • • LTE stands for Long Term Evolution Promises data transfer rates of 100 Mbps Based on UMTS 3G technology Optimized for All-IP traffic LTE Link Budget Comparison Uplink Budget Comparison LTE Encyclopedia https://sites.google.com/site /lteencyclopedia/lte-radiolink-budgeting-and-rfplanning/lte-link-budgetcomparison 64 LTE Link Budget Comparison Downlink Budget Comparison 65 Mapping of Path Losses to Cell Sizes https://sites.google.com/site/lteencyclopedia/lte-radio-link-budgetingand-rf-planning 66 Advantages of LTE Comparison of LTE Speed Major LTE Radio Technogies • Uses Orthogonal Frequency Division Multiplexing (OFDM) for downlink • Uses Single Carrier Frequency Division Multiple Access (SCFDMA) for uplink • Uses Multi-input Multi-output(MIMO) for enhanced throughput • Reduced power consumption • Higher RF power amplifier efficiency (less battery power used by handsets) LTE Physical Channels Physical Channels used in Long Term Evolution (LTE) downlink and in uplink Downlink Channels: Physical Downlink Control Channel (PDCCH) Physical Downlink Shared Channel (PDSCH) Common Control Physical Channel (CCPCH) Uplink Channels: Physical Uplink Shared Channel (PUSCH) Physical Uplink Control Channel (PUCCH) 70 Commercial LTE Speed evolution 2015 2010 2009 50 Mbps 150 Mbps LTE Advanced Radio Systems 1000 Mbps Peak rate ~50 ~50Mbps Mbps ~150 ~150Mbps Mbps ~1000 ~1000Mbps Mbps Typical user rate downlink 5-30 8-30Mbps Mbps 10-100 10-100Mbps Mbps Operator Operatordependent dependent Typical user rate uplink 3-10 Mbps 1-10 Mbps 10 MHz 5-50 Mbps 5-50 Mbps 20 MHz Operator dependent Operator dependent >20 MHz Bandwidths LTE brings excellent user and network experience Release schedule & RAN features 1999 Release 99 2001 W-CDMA 2003 2005 2009 2007 LCR TDD Release 5 HSDPA Release 6 HSUPA, MBMS only main RAN 3GPP aligned to ITU-R IMT process WI 3GPP Releases evolve to meet: listed • Future Requirements for IMT Release 7 • HSPA+ (MIMO, etc.) Release 8 2013 LTE Release 9 LTE enhancements Release 10 Future operator and end-user requirements LTE-Advanced Release 11 Further LTE enhancements ITU-R M.2012 [IMT.RSPEC] Dr. Joern Krause 2015 3GPP work is structured in releases (REL) of 1-3 years duration each release consists of several work items (WI) and study items (SI) even if a REL is completed corrections are possible later existing features of one REL can be enhanced in a future REL ITU-R M.1457 IMT-2000 Recommendation Release 4 2011 IMT-Advanced Recommendation Release 12 ??? Main Features in LTE-A Release 10 100 MHz Support of wider bandwidth (Carrier Aggregation) • Use of multiple component carriers (CC) to extend bandwidth up to 100 MHz • Common L1 parameters between component carrier and LTE Rel-8 carrier Improvement of peak data rate, backward compatibility with LTE Rel-8 f CC Advanced MIMO techniques • • • eNB Extension to up to 8-layer transmission in downlink (REL-8: 4-layer in downlink) Introduction of single-user MIMO with up to 4-layer transmission in uplink Enhancements of multi-user MIMO Improvement of peak data rate and capacity UE Heterogeneous network and eICIC (enhanced Inter-Cell Interference Coordination) macro eNB • Interference coordination for overlay deployment of cells with different Tx power Improvement of cell-edge throughput and coverage Relay • Relay Node supports radio backhaul and creates a separate cell and appears as Rel. 8 LTE eNB to Rel. 8 LTE UEs Improvement of coverage and flexibility of service area extension Minimization of Drive Tests • replacing drive tests for network optimization by collected UE measurements Reduced network planning/optimization costs Dr. Joern Krause micro/pico eNB Donor eNB Relay Nod UE LTE/LTE-A REL-11 features • Coordinated Multi-Point Operation (DL/UL) (CoMP): – • • Power Preference Indicator (PPI): informs NW of mobile’s power saving preference Interference avoidance for in-device coexistence (IDC): – • • • Optical fiber Minimization of Drive Tests (MDT): QoS measurements (throughput, data volume) Self Optimizing Networks (SON): inter RAT Mobility Robustness Optimisation (MRO) Carrier Aggregation (CA): multiple timing advance in UL, UL/DL config. in inter-band CA TDD Machine-Type Communications (MTC): EAB mechanism against overload due to MTC Multimedia Broadcast Multicast Service (MBMS): Service continuity in mobility case Network Energy Saving for E-UTRAN: savings for interworking with UTRAN/GERAN Inter-cell interference coordination (ICIC): assistance to UE for CRS interference reduction Location Services (LCS): Network-based positioning (U-TDOA) Home eNode B (HeNB): mobility enhancements, X2 Gateway RAN Enhancements for Diverse Data Applications (eDDA): – • Coordination Enhanced physical downlink control channel (E-PDCCH): new Ctrl channel with higher capacity Further enhancements for – – – – – – – – – • cooperative MIMO of multiple cells to improve spectral efficiency, esp. at cell edge FDM/DRX ideas to improved coexistence of LTE, WiFi, Bluetooth transceivers, GNSS receivers in UE High Power (+33dBm) vehicular UE for 700MHz band for America for Public Safety Additional special subframe configuration for LTE TDD: for TD-SCDMA interworking In addition: larger number of spectrum related work items: new bands/band combinations Dr. Joern Krause Generations of Mobile Communication Systems • • • • • 1G: analogue systems from 1980s (e.g. NMT, AMPS, TACS, C-Netz) 2G: first digital systems of 1990s (e.g. GSM, CDMAone, PDC, D-AMPS) 3G: IMT-2000 family defined by ITU-R (e.g. UMTS, CDMA2000) 4G: fulfilling requirements of IMT-Advanced defined by ITU-R (e.g. LTE-A, WiMAX) 5G: ? – too early to be a topic in standardization, further 4G enhancements expected before – driven by requirements from customers & network operators – restricted by spectrum limitations – often influenced by new technologies/applications Dr. Joern Krause Ofcom (The Office of Communications) awards 4G licences in £2.34 billion auction Feb 2013 Everything Everywhere, Hutchison 3G UK, Telefonica (O2), Vodafone (VOD) and BT (BT.A)'s Niche Spectrum Ventures secured the 4G licences. Vodafone was the highest bidder at £791 million, securing five chunks of 4G spectrum. When mobile operator EE, a joint venture between T-Mobile and Orange, became the first to launch a 4G service in October 2012 in a brief monopoly, it struggled to attract users. It was forced to cut its prices in January, lowering its entry price to £31 from £36 a month. Ofcom: Independent regulator and competition authority for the UK communications industries. 77 Ofcom announces winners of the 4G mobile auction February 20, 2013 http://consumers.ofcom.org.uk/4g-auction/ Winning Spectrum won Base price bidder Everything Everywhere Ltd 2 x 5 MHz of 800 MHz (796-801; 837-842MHz) and 2 x 35 MHz of 2.6 GHz (2535-2570; 2655-2690MHz) £588,876,000 Hutchison 3G UK 2 x 5 MHz of 800 MHz (791-796; 832-837MHz) Ltd £225,000,000 Niche Spectrum 2 x 15 MHz of 2.6 GHz (2520-2535; 2640-2655MHz) Ventures Ltd (a and £186,476,000 subsidiary of BT 1 x 25 MHz of 2.6 GHz (unpaired) (2595-2620MHz) Group plc) Telefónica UK Ltd (O2) 2 x 10 MHz of 800 MHz (811-821; 852-862MHz) (coverage obligation lot) Vodafone Ltd 2 x 10 MHz of 800 MHz, (801-811; 842-852MHz) 2 x 20 MHz of 2.6 GHz (2500-2520; 2620-2640MHz) £790,761,000 and 1 x 25 MHz of 2.6 GHz (unpaired) (2570-2595MHz) Total £550,000,000 £2,341,113,000 78 Frequencies are in use for LTE in the UK Three different frequency bands are used for 4G LTE in the UK. • 800MHz, • 1.8GHz , • 2.6GHz band. 79 Vodafone O2 Measured signal strength of LTE in 800MHz in T718 LSBU Vodafone Vodafone Vodafone BT Measured signal strength of LTE in 2.6 GHz in T718 LSBU 80 4G coverage in UK, 2014 http://opensignal.com/ 81 EE, 4G coverage in the UK, March 2015 http://opensignal.com/ 82 The State of LTE (February 2013) What is the difference between LTE and 4G? 4G: 100Mbp/s while on moving transport and 1Gbp/s when stationary. While LTE is much faster than 3G, it has yet to reach the International Telecoms Union's (ITU) technical definition of 4G. LTE does represent a generational shift in cellular network speeds, but is labelled 'evolution' to show that the process is yet to be fully completed. 83 The Global Rollout 76 Countries with LTE 18 LTE scheduled Australia (24.5Mbps) Fastest Country With LTE Claro Brazil (27.8Mbps) Fastest Network With LTE Japan (66% LTE improvement) Most Improved country for LTE Speed Tele2 Sweden (93% coverage) Network With Best Coverage South Korea (91% average coverage) Country with Best Coverage 84 Feb 2013; http://opensignal.com/reports/state-of-lte/ 85 Feb 2014; http://opensignal.com/reports/state-of-lte-q1-2014/ 86 87 88 On average LTE is the fastest wireless technology worldwide, representing a real increase in speed on both 3G and HSPA+. 4G LTE is over 5x faster than 3G and over twice as fast as HSPA+ and represents a major leap forward in wireless technology. 89 References • Dr. Joern Krause, ”Future 3GPP RAN standardization activities for LTE” ppt, Oct 2012. • http://www.ofcom.org.uk/ • http://www.4g.co.uk/4g-lte-advanced/ 90