UMTS LTE. Topic 5 EPL657. Part of this lecture is adapted from: UMTS LTE Lawrence Harte Althos Publishing web:

Transcription

1 UMTS LTE Topic 5 EPL657 Part of this lecture is adapted from: UMTS LTE Lawrence Harte Althos Publishing web: 1

2 UMTS LTE Universal mobile telecommunications system - UMTS - Long Term Evolution - LTE set of projected improvements to the 3rd generation wireless systems - 3G, including: 100 Mbps+ data transmission rates, reduced transmission delays (reduced latency), increased system capacity and shorter transmission latency times IP-based OFDMA technology Address increase mobile data usage and new multimedia applications 2

3 UMTS LTE SYSTEM allows cellular carriers to offer a very efficient (more subscribers per cell site) mix of multimedia services (voice, data, and video) for existing (mobile telephone) and new (Internet and television) customers. designed to permit advanced and reliable services including media streaming and large file transfers. new services offer potential of higher average revenue per user than existing 1 st and 2 nd generation mobile customers. for existing mobile carriers that upgrade to LTE, marketing is geared towards acquiring new data-only and mobile television customers. 3

4 UMTS LTE natural evolution of 3GPP GSM and UMTS WCDMA networks. Since LTE provides services above the original 3rd generation (3G) requirements, but does not provide service levels for 4th generation (4G) requirements, it is sometimes called Beyond 3G. key attributes include a variable bandwidth (1.25 MHz up to 20 MHz) OFDM radio channel, the co-existence of multiple physical channels on the same frequency using channel codes, many logical (transport) channels, separate signaling channels, multiple service QoS types, multi-system operation, and other advanced operational features. Each wide (20 MHz) UMTS LTE RF channel can have more than 800 simultaneous communication channels. Some of the channels are used for control purposes, while others are used for voice (audio) and user data transmission. 4

5 UMTS LTE Performance Metrics LTE, in addition to be based on OFDMA, it includes MIMO techniques and smart antennas. Peak data rate Full Mobility Latency in control/user plane Capacity Cell size Spectrum DL/UL: 100/50 Mbps for 20MHz Up to 500km/h <100ms(idle to active)/ 5ms >200 users per cell (5MHz) 5-100km 1.25, 2.5, 5, 10, 15, 20MHz Optimal performance at 0-15km/h High performance at km/h Maintain mobility at km/h 5

6 Recall: what is UMTS Mobile Communication System - Universal Mobile Telephone System - UMTS - is a wide area broadband wireless communications system that uses digital radio transmission to provide voice, data, and multimedia communication services. 6

7 Recall: What is UMTS? A UMTS system coordinates communication between mobile devices (user equipment), radio access radio sites (UTRAN), and uses a packet switching core network to connect UMTS devices to other devices or networks. Digital Media Formats - LTE is designed to transfer digital information in packet data format through the Evolved-UTRAN; supported by the Evolved Packet Core. Functional Sections - The LTE architecture is composed of three key parts: User Equipment (UE) - A device that converts media to and from UMTS LTE radio signals. Evolved UMTS Terrestrial Radio Access Network (E-UTRAN) - Assemblies that convert digital signals to radio signals that can be sent to mobile devices and receive radio signals that can be converted back to their digital form. Contains solely base stations (aka enodeb or enb) Evolved Packet Core Contain a mobility management entity, a system architecture evolution gateway and a packet data network gateway. 7

8 LTE architecture MME S-GW PDN GW Internet epdg enb enb non 3GPP trusted IP access non 3GPP nontrusted IP access UE UE UE enb UE UE 8

9 UMTS LTE key features UMTS LTE key features include high speed data transmission, low latency packet data transmission, flexible frequency allocation, selfconfiguration capability, all IP core network, and multibeam transmission. UMTS LTE data transmission rates can reach up to 100 Mbps for the downlink and up to 50 Mbps for the uplink. UMTS LTE packet data transmission is significantly low allowing for low latency applications (such as VoIP Internet Telephony). The UMTS LTE system can use a mix of radio channel frequency bandwidths and duplex transmission types allowing for UMTS to be deployed in small amounts of spectrum. The UMTS LTE system was designed for automatic configuration and radio transmission optimization reducing the operational complexity and cost. The UMTS LTE switching system (the core network) only uses IP connections between network components simplifying design and deployment. This standardizes the equipment and service requirements simplifying design complexity and lowering support costs. UMTS LTE can use multibeam transmission to increase distance, reliability, and provide more capacity. 9

10 LTE: UMTS evolution 10

11 LTE: UMTS evolution UMTS LTE natural evolution of 3GPP GSM and UMTS WCDMA networks. Because LTE provides services above the original 3 rd generation (3G) requirements but does not provide service levels for 4th generation (4G) requirements, it is sometimes called Beyond 3G. 0G - Mobile Telephone before cellular 1G - Analog Cellular 2G - Digital Cellular 2.5G - High Speed Packet Data 3G UMTS WCDMA - Multimedia 3G UMTS LTE - Ultra Broadband Packet Data (cellular) mobile communication evolved from single user per radio channel (analog) to shared high-speed multimedia broadband channels. One key benefit of evolution is ability of a mobile carrier to provide more services in same amount of radio channel bandwidth. If carrier upgrades system radio equipment and adds customers with new mobile technologies (and eventually gets rid of the old), they lower service costs (or make more money). 11

12 UMTS LTE services 12

13 UMTS LTE services GSM voice service started as a full rate voice service that allowed 8 users per GSM radio channel. The original design allowed for the use of a half rate voice service (lower quality audio) to increase the number of simultaneous GSM voice users to 16 per radio channel. GSM Data services started as low speed circuit switched data (9.6 kbps). The GSM system evolved to allow the combination of multiple circuit switched data connections to provide high speed circuit switched data services - HSCSD. GSM short messaging service - SMS messaging service for extremely short text messages (140 characters). SMS evolved into executable messages that allow for advanced two-way messaging features. GSM Multicast - GSM has capabilities of one to many type services such as group call (dispatch type services) and voice broadcast (such as traffic alerts). GSM Packet Data - GPRS - The GSM system evolved allowing users to dynamically share packet data resources on one or more GSM channels for services such as Internet browsing. 13

14 UMTS LTE devices 14

15 UMTS LTE devices UMTS LTE devices range from fixed adapters (e.g. home network termination units) to network termination adapters that allow a mix of device types to connect to the UMTS LTE system. UMTS LTE mobile telephones may include the capability to use UMTS LTE radio channels and other types of radio signals (such as WCDMA, GSM, CDMA2000, and WiMAX) 3 iphone 5 models for LTE. Multimode UMTS LTE mobile device allows service providers to gradually migrate users in their systems to areas that can provide UMTS LTE radio services. Mobile Telephones - Portable devices that can be used for voice communication. PCMCIA Air Cards - Cards that can slide into computers to provide data services. Embedded Radio Modules - Radio assemblies that can be built-in or installed in devices such as laptop computers, video cameras, or digital signage displays. 15

16 UMTS LTE devices External Radio Modems - Assemblies that can be connected to other devices through USB, Ethernet, or other connection types to provide data services. Network Termination Units (NTUs) - A receiver assembly that can produce one or more outputs that can be connected to devices such as home telephones, computers, or television sets. Media Players - Portable devices that can receive and display multimedia. Location Devices - Devices that can capture and/or display position location information. 16

17 UMTS LTE Radio 17

18 UMTS LTE Radio UMTS LTE radio is the transmission of control and user information in packet data format through a wide RF channel which usually operate on frequency bands around the world ranging from 800 MHz to 2 GHz. UMTS LTE was designed as a Multimode system which allows mobile devices to transfer between the UMTS LTE system and other types of systems such as GSM, WCDMA, or even CDMA2000. Multiple Types of Modulation - The UMTS system can transmit using different types of modulation - QPSK and QAM - to allow the system to increase the data transmission rate when low distortion radio conditions exist. 18

19 UMTS LTE Radio Multiple Input Multiple Output (MIMO) - UMTS systems can use multiple transmission paths to increase the distance and reliability of radio transmission. Variable Channel Bandwidth - The RF channel bandwidth can be dynamically assigned to allow LTE THE flexibility for bandwidth assignment (narrow channels) and increasing data transmission rates when bandwidth is available. FDD or TDD Operation LTE system can used paired frequencies - FDD - or shared single frequencies - TDD to allow systems to operate in a mix of frequency bands. The UMTS LTE system can use multiple types of modulation. The lowest level modulation type (and most robust) is Quadrature Phase Shift Keying - QPSK modulation. When radio conditions permit, 16- QAM can be used to increase transmission capacity. If radio conditions permit, 64-QAM may be used. Complexity and cost of 64-QAM, mobile devices may not include a 64-QAM transmission option. 19

20 UMTS LTE MIMO radio transmission UMTS LTE system can use multiple input multiple output - MIMO - radio transmission to provide increased transmission reliability and higher data transmission rates. A multiple input multiple output (MIMO) transmission system transmits signals over multiple paths to a receiver where they are combined to produce a higher quality signal. example shows that a single beam transmission signal can have deep signal fade levels. When two or more beams are used, the signal fades are minimized, resulting in a more even (error free) signal. 20

21 UMTS LTE dynamic bandwidth configuration UMTS LTE system can dynamically change its transmission bandwidth up to 20 MHz by adding or removing sub-carrier channels. Figure shows how UMTS LTE system can dynamically assign bandwidth through the allocation of sub-carriers. This diagram shows that the RF channel bandwidth can be up to 20 MHz wide. The RF channel can be divided into 15 khz sub-channels and bandwidth configuration (allocated sub-carriers) is a portion of the RF channel. 21

22 UMTS LTE system The key parts of a UMTS LTE system include the user equipment - UE - can be many types of devices ranging from simple mobile telephones to digital televisions. radio access network RAN, can use a mix of radio transmission technologies which may include GSM, WCDMA, and UMTS LTE wide radio channels evolved packet core EPC, uses an IP packet system which can connect to other types of networks such as the public switched telephone network - PSTN through the use of gateway - GW - devices. 22

23 UMTS LTE system simplified diagram of a UMTS LTE system, includes mobile communication devices (user equipment - UE) that can communicate through an evolved node B (enb) enhanced packet core (EPC) packet switching system. UMTS LTE system is compatible with both the new variable width LTE channels, 5 MHz wide WCDMA radio channels, and narrow 200 khz GSM channels. This example also shows that the UMTS LTE system can provide broadcast video, multimedia (mixed data), and voice services. 23

24 UMTS LTE evolved Node B (enb) An evolved Node B - enb - is the radio access part of the UMTS LTE system. Each enb contains at least one radio transmitter, receiver, control section and power supply. In addition to radio transmitters, and receivers, enbs contain resource management and logic control functions that have been traditionally separated into base station controllers (BSCs) or radio network controllers (RNCs). This added capability allows enbs to directly communicate with each other, eliminating the need for mobile switching systems (MSCs) or controllers (BSCs or RNCs). 24

25 UMTS LTE evolved Node B (enb) enb functions include radio resource management - RRM, radio bearer control, radio admission control - access control, connection mobility management, resource scheduling between UEs and enb radios, header compression, link encryption of user data stream, packet routing of user data towards its destination (usually to EPC or other enbs), scheduling and transmitting paging messages (incoming calls and connection requests), broadcast information coordination (system information), and measurement reporting (to assist in handover decisions). Each enb is composed of an antenna system (typically a radio tower), building, and base station radio equipment. Base station radio equipment consists of RF equipment (transceivers and antenna interface equipment), controllers, and power supplies. 25

26 UMTS LTE Gateways UMTS LTE gateways are devices that adapt media transmission between the LTE system and other systems such as the Internet or the public switched telephone network - PSTN. 26

27 UMTS LTE Gateways UMTS LTE system uses serving gateways - S-GW and packet gateways - P-GW A serving gateway, S-GW is a device or assembly that coordinates the control and adapts data transmission between a device and a system. may adapt communication processes and underlying data to access method used by device or system with which it is communicating. also functions as a mobility anchor point (fixed connection route during a communication session) for handovers between enbs (inter-enb handovers), and an anchor point for inter-3gpp mobility. A packet gateway is a device or assembly that coordinates the control and adapts packet data transmission between a communication connection and another system. may adapt data formats and communication processes to the system that it is communicating with. may allocate IP addresses or filter packets (deep packet inspection). 27

28 UMTS LTE Serving Gateway SGW provides routing and forwarding of user data packets SGW connects to PDN GW and gets instructions from MME SGW is responsible for data paths, handles IP header compression, encryption of user data streams, etc Provides handover functions when terminal handovers between LTE and other 3GGP/2 technologies In case of lawful interception, it also performs replication of user traffic 28

29 UMTS LTE Packet Data Network GW PDN GW provides connectivity to external data networks Connected to Policy and Charging Rules Function It s the interface to the Internet and other services including: IMS (IP Multimedia Subsystem) PSS (Packet-Switched Streaming Service) Performed deep packet inspection For QoS, packet marking is used Anchor between 3GPP and non-3ggp technologies 29

30 LTE Mobile management entity A mobile management entity - MME - is a processing element within the UMTS LTE can be used to help find, route, and maintain and transfer communication connections to e.g. WiMAX wireless devices. The MME can perform end to end connection signaling and security services between core networks (Inter CN node signaling). It can perform mode access control to the UE when it is not connected. The MME can maintain location information about devices and determine which gateway will be used to connect mobile devices to other networks. Selecting SGW for a UE at the network entry Performing intra-lte handover Paging-distribution of messages to enbs Handling security key management Providing mobility support in idle state Allocating temporary IDs to UEs Ciphering and integrity protection of NAS signaling 30

31 LTE Evolved Packet Core The UMTS LTE system uses two basic types of network elements; enhanced node B - enb base stations and media gateways. No switch is needed as network elements can communicate with each other to setup connections and connection transfers (handovers). The UMTS system uses an evolved packet core - EPC - to receive, process, and forward packets towards their destinations. The use of an EPC allows for the rapid processing of packets, which increases data throughput while reducing packet delays. 31

32 LTE Evolved Packet Core-EPC Figure shows the key functional parts of an evolved packet core - EPC - system. Example shows several types of packet flows (voice, Internet browsing, and video) that are transferred to a user equipment device in a UMTS LTE system. The serving gateway categorizes each incoming packet and routes it to a mobility tunnel that reaches the enb (base station). The enb maps and manages the data transmission to the UE on appropriate radio bearer channels. 32

33 LTE network architecture key network elements include user equipment (UE) base stations (enbs) serving gateway (S-GW) and mobile management entity (MME) subscriber databases (HSS) and packet gateway (P-GW). UEs communicate with enbs (base stations) through the Uu radio interface. enbs can directly communicate with each other using an X2 interface or with MMEs using the S1 interface. The MME sets up and manages mobile connections using information from HSS. Calls are controlled by an S-GW and the call or session event information from the S-GW is provided to a policy control and charging function (PCRF) which translates the information into billing records. The S-GW can also link to a serving general packet radio service support node (SGSN) to allow the UMTS system to interoperate with other mobile communication systems including GSM, GPRS, and WCDMA. 33

34 LTE network architecture The UMTS LTE network architecture uses a modular system design called the system architecture evolution - SAE, which is composed of separate components that may be added, removed, or connected together to evolve or improve the capabilities of an existing system. The LTE system uses SAE to transition from a voice centric switched network to a universal broadband communications access system. 34

35 LTE protocol architecture 35

36 LTE protocol architecture Control Plane User Data Plane 36

37 LTE protocol architecture The UMTS LTE can use multiple protocols that are divided into processing layers. Each protocol layer performs specific functions. Each protocol layer may also use one or more protocols. The layered approach simplifies for the adding of new functions without requiring significant changes to the system. Radio resource control - RRC - is a protocol used to coordinate the operation (control) of the radio. Packet data convergence protocol - PDCP - ensures that all the packets are transferred and placed in correct order. The radio link control - RLC - layer is concerned with maintaining the radio link between the mobile device and the base station. Medium access control layer - MAC - coordinates access requests and assignment from the system. Broadcast and multicast control - BMC -is responsible for receiving and processing broadcast messages. 37

38 LTE protocol layers Figure shows how the protocol layers of the UMTS LTE system can link the radio device, through the evolved node B (enb) base station. The UMTS LTE radio link is divided into layers where each layer performs its specific function and passes its data on to the next layer above or below. Physical Layer - The physical layer converts digital packets to and from RF signals that are sent between the UMTS LTE device and the access point. MAC Layer - The medium access control layer (MAC) is the process used to request and coordinate access to the system. RLC Layer - The radio link control layer is concerned with maintaining the radio link between the mobile device and the base station. PDCP Layer - Ensures that all packets are transferred and placed in correct order. 38

39 Communication Channel Structure 39

40 Communication Channel Structure Each channel is characterized by its functions and parameters. There are logical channels that are mapped to transport channels Transport channels are mapped to physical channels. Logical channels are distinguished by the information carried by them Transport channels are identified by their transmission characteristics Physical channels are characterized by the data protection method used Two types of logical channels: Control and traffic channels Logical Control channels are: BCCH: Broadcast control channel is to transmit broadcasting system control information PCCH: Paging Control Channel is to transmit paging information when UE is unlocated CCCH: Common Control Channel is used by UE when UE has no RRC connection MCCH: Multicast Control Channel is used to transmit MBMS control information DCCH: Dedicated Control Channel is a point-to-point bidirectional channel used by UE for RRC connection 40

41 Communication Channel Structure Logical Traffic channels are DTCH: Dedicated Traffic Channel is a point-to-point bidirectional channel dedicated to one UE to transfer user information MTCH: Multicast Traffic Channel is a point-to-multipoint Transport channels provide structure passing data, configuration of PHY mechanisms, status indicators and higher layer peer-to-peer signaling. They include: BCH: Broadcast Channel DL-SCH: Downlink Shared Channel used for HARQ, DRX, link adaptation PCH: Paging Channel MCH: Multicast Channel UL-SCH: Uplink Shared Channel RACH: Random Access Channel (collision risk) 41

42 Communication Channel Structure Physical Channels include: PDSCH: Physical Downlink Shared Channel used for data and multimedia transport. Adaptive modulation (QPSK, 16-, 64-QAM) PDCCH: Physical Downlink Control Channel conveys UE specific information CCPCH: Common Control Physical Channel conveys cell information PUSCH: Physical Uplink Shared Channel for data and multimedia upload using adaptive modulation PUCCH: Physical Uplink Control Channel carries uplink control information including uplink scheduling requests 42

43 LTE MAC Layer functionality Scheduling (controls time/frequency resources) depends on channel conditions and the following: QoS parameters Measurements Buffered Payloads Pending Retransmissions CQI reports from the UEs UE capabilities UE sleep cycles Measurement gaps/periods System parameters such as bandwidth and interference levels Types of schedulers include: Frequency Selective Scheduler Frequency Diverse Scheduler Proportional Fair Scheduling 43

44 LTE MAC Layer functionality HARQ Cell Search Power Control Intercell Interference Mitigation Inter-eNodeB synchronization Physical layer measurements Evolved Multicast Broadcast Multimedia Services Self Configuration 44

45 LTE PHY Layer functionality Offers data transport to higher layers Performs the following: Error detection on the transport channel FEC encoding/decoding Hybrid ARQ soft-combining Rate matching Mapping of the coded symbols to physical channels Power weighting of physical channels Modulation and demodulation Frequency and time synchronization Radio characteristics measurements MIMO/transmit diversity beamforming support RF processing 45

46 LTE network interfaces 46

47 LTE network interfaces This figure shows key UMTS LTE network elements and how they interface with each other. UMTS network interfaces define the characteristics and processes that are used to connect network elements to each other or to other systems. Uu Interface - User equipment - UE - communicate with evolved node B (enb) using the Uu interface. S1 Interface - is used to enbs to the serving gateway (S-GW). X2 Interface - allows enbs to directly connect with each other. S6 Interface - allows mobile management entity (MME) to connect with customer database (HSS). S3 Interface - is used to link to existing systems (such as GSM, GPRS, and WCDMA) to the UMTS LTE system. S5 Interface - connects the UMTS LTE system to packet data networks such as the Internet. S7 Interface - connects the UMTS LTE system to operations and support systems. 47

48 LTE system operation The UMTS LTE system operates by coordinating connections with mobile devices, managing connection transfers (mobility), setting up and managing service sessions, keeping track of the location of mobile devices, and coordinating the distribution of signals to groups (multicast) or to geographic areas (broadcast). Connection States - The LTE must identify and control the mode of each wireless device that is operating in its system. Connection Transfers (Mobility) - the LTE system coordinates the transfer of connections as wireless devices move to different radio coverage areas. Session Management (IMS) - The LTE system sets up, initializes, and manages communication services such as voice, data, and video. Location Based Services (LBS) - LTE systems maintain position location information for commercial services, system management, and emergency services. Muticasting and Broadcasting - LTE systems coordinate the distribution of signals to groups of users (multicast) or to geographic regions (broadcast). 48

49 UMTS LTE mobility states Mobility states are the status conditions of a mobile device as it relates to a communication network. Mobility states include detached (unknown), active (communicating), and idle (awaiting actions). This figure that UMTS LTE device starts in the detached (unknown status) state when it is turned on. After it registers with the system, it changes into the active state. If the device is inactive for a period of time (does not transfer information), it may be moved into the idle mode. If there is data to be transferred, the mode may be changed back to the active state. When a device is powered off, it informs the system (deregisters) and detaches. 49

50 UMTS LTE handover (HO) UMTS LTE Handover is performed by the user equipment devices connecting directly to each other through the enbs. No switching equipment is required for UMTS LTE handovers to other devices in the UMTS LTE system. UEs can handover within a system (intra-system), to other systems (intersystem), and to systems that use other radio access technologies (Inter-RAT handover). 50

51 UMTS LTE handover (HO) This figure shows the basic handover process that occurs in the UMTS LTE system where the system has determined that the signal strength and quality of the radio channel it is receiving and the serving enb (source enb) is below desired levels and handover is preferred. Process starts when the source enb commands the UE to start measuring the radio channel quality from a nearby base station (target enb). Using the information from the mobile, it is determined that the adjacent cell site is a candidate for the handover and the direct transfer process starts. The source enb informs the target enb using the X2 interface that a handoff request has been initiated. During the handover process, the source enb forwards the user data to the target enb. When the UE has successfully connected to the target enb, the connection is transferred and the target enb updates the MME of the transfer completion. The MME then informs the serving gateway to change the user s media path (path change) from the source enb to the target enb. 51

52 IP Multimedia Subsystem (IMS) 52

53 IP Multimedia Subsystem (IMS) IP multimedia subsystem - IMS - is a set of session based protocols that can be used to provide services using Internet protocol (IP). IMS has evolved from its first use in 3rd generation mobile telephone standards to other types of networks including voice over Internet protocol (VoIP) and IP television (IPTV). IMS can integrate devices and services across multiple types of networks. Set of Session Control Protocols - IMS defines the use of session control protocols (existing and tested protocols such as SIP) to negotiate and initialize protocols that are used for communication sessions. Integrates Systems and Services - The IMS system can be used to integrate different systems and services that can be addressed using IP connections. 53

54 IP Multimedia Subsystem (IMS) Started 3GPP and Evolved to VoIP and IPTV - IMS protocols are so flexible that they have been used in other types of systems such as Internet telephony and Internet protocol Television - IPTV. The figure on slide 52 shows the basic functions of the IMS system. This diagram shows that a user equipment device (a mobile phone in this example) is calling another device (a landline telephone). The UE sends its connection request (an invite) to the proxy call session control function (P- CSCF). The P-CSCF needs to find the call server so it sends a request to the interrogatory call session control sever (I-CSCF). The I-CSCF contacts the home subscriber server (HSS) which contains the service profile of the user and the location of the serving call session control function (S-CSCF). The S-CSCF will then manage the communication session with the UE through the P-CSCF. The IMS system can then connect a call through a media gateway (signaling processes not shown) so the connection can reach the landline telephone. 54

55 Location based Services (LBS) UMTS LTE can provide location information using different types of positioning systems including the system itself (network positioning) or through the use of global positioning system - GPS. 55

56 Location based Services (LBS) UMTS location services include: Commercial Location Services (Commercial LCS) - Value added services that are performed using location determination equipment and services such as mapping and advertising. Internal Location Services (Internal LCS) - Position discovery activities and data that are used for network or service operation (find and page the subscriber). Emergency Location Services (Emergency LCS) - Discovery and transfer device location information to emergency facilities or services. Emergency LCS provide agencies with the identification and location of a device that has dialed an emergency services number (such as 112 or 911). This figure shows how mobile communication systems can use GPS signals to provide location information. A mobile telephone has both mobile communication and GPS reception capability. When the user dials an emergency number, the GPS information can is sent to the public safety access point to allow emergency services to the location of the user s mobile telephone. Lawful Intercept Location Services (Lawful Intercept LCS) - Providing of identification and location information of a device to an authorized public safety agency. 56

57 Evolved MBMS UMTS LTE was designed to allow for shared (multicast) types of services such as digital broadcast radio and digital video broadcast. The embms feature can simultaneously transmit the same media signals using UMTS LTE enbs to multiple recipients in the same geographic region. In addition to the shared transmission capability, the two-way capabiltiy of the MBMS system allows users to dynamically interact with the broadcast network. This means that the MBMS system can provide one-way bearer services (multicasting and broadcasting media) and user controlled media streaming. 57

58 Evolved MBMS This figure shows how the MBMS system can be used to provide radio and television broadcast services. A television station (a or a video subscription channel) is broadcast to all the cells within the UMTS LTE system area. Each TV subscription viewer must use a key (previously provided) so they can receive and decode the television signal. A audio broadcast (local radio station) is also connected to some of the UMTS LTE cells. Voice broadcast (traffic alerts) are connected to a cells in the system area. 58

59 UMTS LTE summary 59

60 UMTS LTE summary UMTS LTE was designed to simultaneously provide a mix of services ranging from real time voice to high-speed Internet browsing.the use of a single IP type of interconnection simplifies deployment, maintenance, and reduces equipment cost. Base stations (enbs) can directly connect to each other with eliminates the need for a switching system. The radio structure is flexible (bandwidth, duplex types) which allows UMTS LTE to be deployed in different spectrums. IP Multimedia Subsystem - IMS - is used to setup and manage multimedia sessions with devices in and outside of the UMTS LTE system. Multiple types of location based services are integrated into the UMTS LTE system. UMTS LTE is an evolution of GSM, GPRS, and WCDMA. 60

61 LTE ADVANCED See SLIDES BY Toskala IEEE Tutorial 61

62 Orthogonal frequency-division multiplexing (OFDM) method of encoding digital data on multiple carrier frequencies. developed into a popular scheme for wideband digital communication, whether wireless or over copper wires, used in applications such as digital television and audio broadcasting, DSL broadband internet access, wireless networks, and 4G mobile communications. 62

63 Orthogonal frequency-division multiplexing (OFDM) is a frequency-division multiplexing (FDM) scheme used as a digital multi-carrier modulation method. A large number of closely spaced orthogonal sub-carrier signals are used to carry data. The data is divided into several parallel data streams or channels, one for each sub-carrier. Each sub-carrier is modulated with a conventional modulation scheme (such as quadrature amplitude modulation or phase-shift keying) at a low symbol rate, maintaining total data rates similar to conventional single-carrier modulation schemes in the same bandwidth. 63

64 Orthogonal frequency-division multiplexing (OFDM) primary advantage of OFDM over single-carrier schemes is ability to cope with severe channel conditions (for example, attenuation of high frequencies in a long copper wire, narrowband interference and frequency-selective fading due to multipath) without complex equalization filters. low symbol rate makes use of a guard interval between symbols affordable, making it possible to eliminate intersymbol interference (ISI) and utilize echoes and time-spreading (that shows up as ghosting on analogue TV) to achieve a diversity gain, i.e. a signalto-noise ratio improvement. This mechanism also facilitates the design of single frequency networks (SFNs), where several adjacent transmitters send the same signal simultaneously at the same frequency, as the signals from multiple distant transmitters may be combined constructively, rather than interfering as would typically occur in a traditional single-carrier system. 64

65 Supplementary slides based on ieee tutorial

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