Chapter 3.pdf

CCCN 422 Wireless Communication Networks Dr. Mohammed Balfaqih Assistant Professor [email protected] @modditto Lecture Outline ▪ Wide Area Wireless Access • • • • • • • Principle of cellular networks 1G: Analog 2G Network: GSM, IS-95(CDMA) 2.5G Network: GPRS / EDGE 3G Network: CDMA2000, WCDMA...

CCCN 422 Wireless Communication Networks Dr. Mohammed Balfaqih Assistant Professor [email protected] @modditto Lecture Outline ▪ Wide Area Wireless Access • • • • • • • Principle of cellular networks 1G: Analog 2G Network: GSM, IS-95(CDMA) 2.5G Network: GPRS / EDGE 3G Network: CDMA2000, WCDMA LTE and LTE-Advanced Networks 5G Network Dr. Mohammed Balfaqih CCCN 422: Wireless Communication Networks Introduction ▪ Wireless networks are classified based on coverage area into different categories including: - WWANS: Wireless Wide Area Networks These types of networks can be maintained over large areas, such as cities or countries, via multiple satellite systems or antenna sites looked after by an ISP - WMANS: Wireless Metropolitan Area Networks This technology allows the connection of multiple networks in a metropolitan area such as different buildings in a city, which can be an alternative or backup to laying copper or fiber cabling. - WLANS: Wireless Local Area Networks WLANS allow users in a local area, such as a university campus or library, to form a network or gain access to the internet. A temporary network can be formed by a small number of users without the need of an access point; given that they do not need access to network resources. Dr. Mohammed Balfaqih CCCN 422: Wireless Communication Networks Introduction - WPANS: Wireless Personal Area Networks The two current technologies for wireless personal area networks are Infra Red (IR) and Bluetooth (IEEE 802.15). These will allow the connectivity of personal devices within an area of about 30 feet. However, IR requires a direct line of site and the range is less. Type Wireless PAN Coverage Standards Application Within reach of a Wireless PAN Within reach of a person person Moderate Bluetooth, and IEEE 802.15 Within a building or IEEE 802.11, HiperLAN campus Cable replacement for peripherals Wireless MAN Within a city IEEE 802.16, WIMAX Fixed wireless between homes and businesses and the Internet Wireless WAN Worldwide CDPD and Cellular 2G, 2.5G, 4G Mobile access to the Internet from outdoor areas Wireless LAN Dr. Mohammed Balfaqih Mobile extension of wired networks CCCN 422: Wireless Communication Networks Principle of cellular networks ▪ Cellular Networks - Revolutionary development telecommunications. - Foundation of mobile wireless in data communications and Telephones, smartphones, tablets, wireless Internet, wireless applications - Supports locations not easily served by wireless networks or WLANs. - Five generations of standards 1G: Analog 2G: Still used to carry voice 3G: First with sufficient speeds for data networking, packets only 4G: Truly broadband mobile data up to 1 Gbps 5G Dr. Mohammed Balfaqih CCCN 422: Wireless Communication Networks Principle of cellular networks ▪ Cellular Network Organization - Use multiple low-power transmitters (100 W or less). - Areas divided into cells • • • • Each served by its own antenna Served by base station consisting of transmitter, receiver, and control unit Band of frequencies allocated Cells set up such that antennas of all neighbors are equidistant (hexagonal pattern) Dr. Mohammed Balfaqih CCCN 422: Wireless Communication Networks Principle of cellular networks Dr. Mohammed Balfaqih 13.1 CELLULAR GEOMETRIES CCCN 422: Wireless Communication Networks Principle of cellular networks ▪ Frequency Reuse - Adjacent cells assigned different frequencies to avoid interference or crosstalk. - Objective is to reuse frequency in nearby cells • 10 to 50 frequencies assigned to each cell • Transmission power controlled to limit power at that frequency escaping to adjacent cells • The issue is to determine how many cells must intervene between two cells using the same frequency Dr. Mohammed Balfaqih CCCN 422: Wireless Communication Networks Principle of cellular networks (b) Frequency reuse pattern for N = 7 (a) Frequency reuse pattern for N = 4 Dr. Mohammed Balfaqih (c) Black cells indicate a frequency reuse for N = 19 13.2 FREQUENCY REUSE PATTERNS CCCN 422: Wireless Communication Networks Principle of cellular networks ▪ Approaches to Cope with Increasing Capacity - Adding new channels. Frequency borrowing – frequencies are taken from adjacent cells by congested cells. Cell splitting – cells in areas of high usage can be split into smaller cells. Cell sectoring – cells are divided into a number of wedge-shaped sectors, each with their own set of channels. Network densification – more cells and frequency reuse • Microcells – antennas move to buildings, hills, and lamp posts • Femtocells – antennas to create small cells in buildings Interference coordination – tighter control of interference so frequencies can be reused closer to other base stations • Inter-cell interference coordination (ICIC) • Coordinated multipoint transmission (CoMP) Dr. Mohammed Balfaqih CCCN 422: Wireless Communication Networks Principle of cellular networks 13.3 CELL SPLITTING Dr. Mohammed Balfaqih CCCN 422: Wireless Communication Networks Principle of cellular networks ▪ Cellular Systems Terms - Base Station (BS) – includes an antenna, a controller, and a number of receivers - Mobile telecommunications switching office (MTSO) – connects calls between mobile units - Two types of channels available between mobile unit and BS • Control channels – used to exchange information having to do with setting up and maintaining calls • Traffic channels – carry voice or data connection between users Dr. Mohammed Balfaqih CCCN 422: Wireless Communication Networks Principle of cellular networks 13.5 OVERVIEW OF CELLULAR SYSTEM Dr. Mohammed Balfaqih CCCN 422: Wireless Communication Networks Principle of cellular networks ▪ Steps in an MTSO Controlled Call between Mobile Users • • • • • • Mobile unit initialization Mobile-originated call Paging Call accepted Ongoing call Handoff Dr. Mohammed Balfaqih CCCN 422: Wireless Communication Networks Principle of cellular networks 13.6 EXAMPLE OF MOBILE CELLULAR CALL CCCN 422: Wireless Communication Networks Principle of cellular networks ▪ Additional Functions in an MTSO Controlled Call • • • • Call blocking Call termination Call drop Calls to/from fixed and remote mobile subscriber Dr. Mohammed Balfaqih CCCN 422: Wireless Communication Networks Principle of cellular networks ▪ Mobile Radio Propagation Effects - Signal strength - Fading • Must be strong enough between base station and mobile unit to maintain signal quality at the receiver • Must not be so strong as to create too much co-channel interference with channels in another cell using the same frequency band • Signal propagation effects may disrupt the signal and cause errors Dr. Mohammed Balfaqih CCCN 422: Wireless Communication Networks Principle of cellular networks ▪ Handoff Performance Metrics • Handoff blocking probability – probability that a handoff cannot be successfully completed • Handoff probability – probability that a handoff occurs before call termination • Rate of handoff – number of handoffs per unit time • Interruption duration – duration of time during a handoff in which a mobile is not connected to either base station • Handoff delay – distance the mobile moves from the point at which the handoff should occur to the point at which it does occur Dr. Mohammed Balfaqih CCCN 422: Wireless Communication Networks Principle of cellular networks ▪ Handoff Strategies Used to Determine Instant of Handoff • Relative signal strength • Relative signal strength with threshold • Relative signal strength with hysteresis Dr. Mohammed Balfaqih CCCN 422: Wireless Communication Networks Principle of cellular networks Dr. Mohammed Balfaqih 13.7 HANDOFF BETWEEN TWO CELLS CCCN 422: Wireless Communication Networks 1G: Analog ▪ Advanced Mobile Phone Service (AMPS) – Two 25-MHz bands allocated to AMPS • One for transmission from base to mobile unit • One for transmission from mobile unit to base – Each band split in two to encourage competition – Frequency reuse exploited Dr. Mohammed Balfaqih CCCN 422: Wireless Communication Networks 1G: Analog ▪ AMPS Operation – Subscriber initiates call by keying in phone number and presses send key – MTSO verifies number and authorizes user – MTSO issues message to user’s cell phone indicating send and receive traffic channels – MTSO sends ringing signal to called party – Party answers; MTSO establishes circuit and initiates billing information – Either party hangs up; MTSO releases circuit, frees channels, completes billing Dr. Mohammed Balfaqih CCCN 422: Wireless Communication Networks 2G Network: GSM, IS-95(CDMA) ▪ Differences Between First and Second Generation Systems – Digital traffic channels – first-generation systems are almost purely analog; second-generation systems are digital. • Using FDMA/TDMA or CDMA – 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 Dr. Mohammed Balfaqih CCCN 422: Wireless Communication Networks 2G Network: GSM, IS-95(CDMA) Dr. Mohammed Balfaqih 2G Network: GSM, IS-95(CDMA) ▪ Global System for Mobile Communications (GSM) – FDMA/TDMA approach – Developed to provide a common second-generation technology for Europe • Over 6.9 billion subscriber units by the end of 2013 – Mobile station communicates across the Um interface (air interface) with base station transceiver in the 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 Dr. Mohammed Balfaqih CCCN 422: Wireless Communication Networks 2G Network: GSM, IS-95(CDMA) Dr. Mohammed Balfaqih 13.9 OVERALL GSM ARCHITECTURE CCCN 422: Wireless Communication Networks 2G Network: GSM, IS-95(CDMA) ▪ 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 Dr. Mohammed Balfaqih CCCN 422: Wireless Communication Networks 2G Network: GSM, IS-95(CDMA) ▪ Network Subsystem (NS) – NS provides link between telecommunications networks cellular network and public switched • 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) Dr. Mohammed Balfaqih CCCN 422: Wireless Communication Networks 2G Network: GSM, IS-95(CDMA) ▪ 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 Dr. Mohammed Balfaqih CCCN 422: Wireless Communication Networks 2G Network: GSM, IS-95(CDMA) ▪ GSM Radio Link – Combination of FDMA and TDMA – 200 kHz carriers – Each with a data rate of 270.833 kbps – 8 users share each carrier Dr. Mohammed Balfaqih CCCN 422: Wireless Communication Networks 2G Network: GSM, IS-95(CDMA) ▪ Advantages of CDMA for Cellular systems – Frequency diversity – frequency-dependent transmission impairments have less effect on signal – Multipath resistance – chipping codes used for CDMA exhibit low cross correlation and low autocorrelation – Privacy – privacy is inherent since spread spectrum is obtained by use of noise-like signals – Graceful degradation – system only gradually degrades as more users access the system Dr. Mohammed Balfaqih CCCN 422: Wireless Communication Networks 2G Network: GSM, IS-95(CDMA) ▪ Drawbacks of CDMA Cellular – Self-jamming – arriving transmissions from multiple users not aligned on chip boundaries unless users are perfectly synchronized – Near-far problem – signals closer to the receiver are received with less attenuation than signals farther away Dr. Mohammed Balfaqih CCCN 422: Wireless Communication Networks 2G Network: GSM, IS-95(CDMA) ▪ Mobile Wireless CDMA Design Considerations – RAKE receiver – when multiple versions of a signal arrive more than one chip interval apart, RAKE receiver attempts to recover signals from multiple paths and combine them – Soft Handoff – mobile station temporarily connected to more than one base station simultaneously • Requires that the mobile acquire a new cell before it relinquishes the old • More complex than hard handoff used in FDMA and TDMA schemes Dr. Mohammed Balfaqih CCCN 422: Wireless Communication Networks 2G Network: GSM, IS-95(CDMA) 13.10 IS-95 CHANNEL STRUCTURE Dr. Mohammed Balfaqih CCCN 422: Wireless Communication Networks 2G Network: GSM, IS-95(CDMA) ▪ IS-95 Forward Link – Most widely used CDMA cellular standard is IS-95, used mainly in North America – Forward link channels • Pilot (channel 0) - allows the mobile unit to acquire timing information, provides phase reference and provides means for signal strength comparison • Synchronization (channel 32) - used by mobile station to obtain identification information about cellular system • Paging (channels 1 to 7) - contain messages for one or more mobile stations • Traffic (channels 8 to 31 and 33 to 63) – the forward channel supports 55 traffic channels 9600 or 14,400 bps Dr. Mohammed Balfaqih CCCN 422: Wireless Communication Networks 2G Network: GSM, IS-95(CDMA) ▪ IS-95 Reverse Link – The reverse link consists of up to 94 logical CDMA channels, each occupying the same 1228-kHz bandwidth. – The traffic channels in the reverse link are unique to each mobile unit. Each mobile unit has a unique long code mask based on its electronic serial number. – The access channel is used by a mobile unit to initiate a call, to respond to a paging channel message from the base station, and for a location update. Dr. Mohammed Balfaqih CCCN 422: Wireless Communication Networks 2.5G Network: GPRS / EDGE ▪ Generalized Packet Radio Service (GPRS) – Phase 2 of GSM – Provides a datagram switching capability to GSM – Instead of sending data traffic over a voice connection which requires setup, sending data, and teardown – GPRS allows users to open a persistent data connection – Also has a new system architecture for data traffic – 21.4 kbps from a 22.8 kbps gross data rate – Can combine up to 8 GSM connections • Overall throughputs up to 171.2 kbps Dr. Mohammed Balfaqih CCCN 422: Wireless Communication Networks 2.5G Network: GPRS / EDGE ▪ Enhanced Data Rates for GSM Evolution (EDGE) – The next generation of GSM Not yet 3G, so called “2.G” by some – Three-fold increase in data rate • Up to 3 bits/symbol for 8-PSK from 1 bit/symbol for GMSK for GSM. • Max data rates per channel up to 22.8 × 3 = 68.4 kbps per channel • Using all eight channels in a 200 kHz carrier, gross data transmission rates up to 547.2 kbps became possible Actual throughput up to 513.6 kbps. – A later release of EDGE (3GPP Release 7) increased downlink data rates over 750 kbps and uplink data rates over 600 kbps Dr. Mohammed Balfaqih CCCN 422: Wireless Communication Networks 3G Network: CDMA2000, WCDMA ▪ ITU’s initial View of Third-Generation Capabilities – The ITU’s International Mobile Telecommunications for the year 2000 (IMT-2000) initiative – Voice quality comparable to the public switched telephone network – 144 kbps data rate available to users in high-speed 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 Much higher rates were developed – 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 Dr. Mohammed Balfaqih CCCN 422: Wireless Communication Networks 3G Network: CDMA2000, WCDMA – 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 Dr. Mohammed Balfaqih CCCN 422: Wireless Communication Networks 3G Network: CDMA2000, WCDMA ▪ Alternative interfaces – Five alternatives for smooth evolution from 1G and 2G systems – Two most prevalent • Wideband CDMA (WCDMA) • CDMA2000 – Both based on CDMA – Similar to but incompatible with each other Dr. Mohammed Balfaqih CCCN 422: Wireless Communication Networks 3G Network: CDMA2000, WCDMA Dr. Mohammed Balfaqih 13.11 IMT-2000 TERRESTRIAL RADIO INTERFACES CCCN 422: Wireless Communication Networks 3G Network: CDMA2000, WCDMA ▪ CDMA Design Considerations – Bandwidth – limit channel usage to 5 MHz – Chip rate – depends on desired data rate, need for error control, and bandwidth limitations; 3 Mcps or more is reasonable – Multirate – advantage is that the system can flexibly support multiple simultaneous applications from a given user and can efficiently use available capacity by only providing the capacity required for each service Dr. Mohammed Balfaqih CCCN 422: Wireless Communication Networks 3G Network: CDMA2000, WCDMA ▪ WCDMA and UMTS WCDMA is part of a group of standards from • IMT-2000 • Universal Mobile Telephone System (UMTS) • Third-Generation Partnership Project (3GPP) industry organization 3GPP originally released GSM • Issued Release 99 in 1999 for WCDMA and UMTS • Subsequent releases were “Release 4” and onwards • Many higher layer network functions of GSM were carried over to WCDMA Dr. Mohammed Balfaqih CCCN 422: Wireless Communication Networks 3G Network: CDMA2000, WCDMA – 144 kbps to 2 Mbps, depending on mobility – High Speed Downlink Packet Access (HSDPA) • Release 5 • 1.8 to 14.4 Mbps downlink • Adaptive modulation and coding, hybrid ARQ, and fast scheduling – High Speed Uplink Packet Access (HSUPA) • Release 6 • Uplink rates up to 5.76 Mbps – High Speed Packet Access Plus (HSPA+) • Release 7 and successively improved in releases through Release 11 • Maximum data rates increased from 21 Mbps up to 336 Mbps • 64 QAM, 2×2 and 4×4 MIMO, and dual or multi-carrier combinations 3GPP Release 8 onwards introduced Long Term Evolution (LTE) • Pathway to 4G Dr. Mohammed Balfaqih CCCN 422: Wireless Communication Networks 3G Network: CDMA2000, WCDMA Dr. Mohammed Balfaqih 13.13 EVOLUTION OF CELLULAR WIRELESS SYSTEMS CCCN 422: Wireless Communication Networks LTE and LTE-Advanced Networks ▪ Purpose, motivation, and approach to 4G • Ultra-mobile broadband access - For a variety of mobile devices • International Telecommunication Union (ITU) 4G directives for IMT-Advanced. - All-IP packet switched network. - Peak data rates Up to 100 Mbps for high-mobility mobile access Up to 1 Gbps for low-mobility access - Dynamically share and use network resources. - Smooth handovers across heterogeneous networks, including 2G and 3G networks, small cells such as picocells, femtocells, and relays, and WLANs. - High quality of service for multimedia applications. • No support for circuit-switched voice (Instead providing Voice over LTE (VoLTE)) • Replace spread spectrum with OFDM Dr. Mohammed Balfaqih CCCN 422: Wireless Communication Networks LTE and LTE-Advanced Networks ▪ Purpose, motivation, and approach to 4G Dr. Mohammed Balfaqih CCCN 422: Wireless Communication Networks LTE and LTE-Advanced Networks ▪ Third versus Fourth Generation Cellular Networks Dr. Mohammed Balfaqih CCCN 422: Wireless Communication Networks LTE and LTE-Advanced Networks ▪ LTE Architecture • Two candidates for 4G - IEEE 802.16 WiMax (described in the next chapter) Enhancement of previous fixed wireless standard for mobility - Long Term Evolution Third Generation Partnership Project (3GPP) Consortium of Asian, European, and North American telecommunications standards organizations • Both are similar in use of OFDM and OFDMA • LTE has become the universal standard for 4G - All major carriers in the United States • Some features started in the 3G era for 3GPP • Initial LTE data rates were similar to 3G • 3GPP Release 8 • 3GPP Release 10 Clean slate approach Completely new air interface OFDM, OFDMA, MIMO Dr. Mohammed Balfaqih Known as LTE-Advanced Further enhanced by Releases 11 and 12 CCCN 422: Wireless Communication Networks LTE and LTE-Advanced Networks Dr. Mohammed Balfaqih CCCN 422: Wireless Communication Networks LTE and LTE-Advanced Networks • evolved NodeB (eNodeB) - Most devices connect into the network through the eNodeB • Evolution of the previous 3GPP NodeB - Now based on OFDMA instead of CDMA - Has its own control functionality, rather than using the Radio Network Controller (RNC) eNodeB supports radio resource control, admission control, and mobility management Originally the responsibility of the RNC Dr. Mohammed Balfaqih eNodeB = evolved NodeB HSS = Home subscriber server MME = Mobility Management Entity PGW = Packet data network (PDN) gateway RN = relay node SGW = serving gateway S1 = interface between E-UTRAN and EPC UE = user equipment X2 = interface between eNodeBs CCCN 422: Wireless Communication Networks LTE and LTE-Advanced Networks ▪ Evolved Packet System • Overall architecture is called the Evolved Packet System (EPS) • 3GPP standards divide the network into - Radio access network (RAN) Core network (CN) • Each evolve independently. • Long Term Evolution (LTE) is the RAN - Called Evolved UMTS Terrestrial Radio Access (E-UTRA) Enhancement of 3GPP’s 3G RAN eNodeB is the only logical node in the E-UTRAN No RNC • Evolved Packet Core (EPC) - Operator or carrier core network It is important to understand the EPC to know the full functionality of the architecture Dr. Mohammed Balfaqih CCCN 422: Wireless Communication Networks LTE and LTE-Advanced Networks ▪ Evolved Packet System • Some of the design principles of the EPS - Clean slate design - Packet-switched transport for traffic belonging to all QoS classes including conversational, streaming, real-time, non-real-time, and background - Radio resource management for the following: end-to-end QoS, transport for higher layers, load sharing/balancing, policy management/enforcement across different radio access technologies - Integration with existing 3GPP 2G and 3G networks - Scalable bandwidth from 1.4 MHz to 20 MHz - Carrier aggregation for overall bandwidths up to 100 MHz Dr. Mohammed Balfaqih CCCN 422: Wireless Communication Networks LTE and LTE-Advanced Networks ▪ FUNCTIONS OF THE EPS • Network access control, including network selection, authentication, authorization, admission control, policy and charging enforcement, and lawful interception • Packet routing and transfer • Security, including ciphering, integrity protection, and network interface physical link protection • Mobility management to keep track of the current location of the UE • Radio resource management to assign, reassign, and release radio resources taking into account single and multi-cell aspects • Network management to support operation and maintenance • IP networking functions, connections of eNodeBs, E-UTRAN sharing, emergency session support, among others Dr. Mohammed Balfaqih CCCN 422: Wireless Communication Networks LTE and LTE-Advanced Networks ▪ Evolved Packet Core • Traditionally circuit switched but now entirely packet switched - Based on IP - Voice supported using voice over IP (VoIP) • Core network was first called the System Architecture Evolution (SAE) Dr. Mohammed Balfaqih CCCN 422: Wireless Communication Networks LTE and LTE-Advanced Networks ▪ EPC Components • Mobility Management Entity (MME) - Supports user equipment context, identity, authentication, and authorization • Serving Gateway (SGW) - Receives and sends packets between the eNodeB and the core network • Packet Data Network Gateway (PGW) - Connects the EPC with external networks • Home Subscriber Server (HSS) - Database of user-related and subscriber-related information • Interfaces - S1 interface between the E-UTRAN and the EPC For both control purposes and for user plane data traffic - X2 interface for eNodeBs to interact with each other Again for both control purposes and for user plane data traffic Dr. Mohammed Balfaqih CCCN 422: Wireless Communication Networks LTE and LTE-Advanced Networks ▪ Non-Access Stratum Protocols • For interaction between the EPC and the UE - Not part of the Access Stratum that carries data • EPS Mobility Management (EMM) - Manage the mobility of the UE • EPS Session Management (ESM) - Activate, authenticate, modify, and de-activate user-plane channels for connections between the UE, SGW, and PGW Dr. Mohammed Balfaqih CCCN 422: Wireless Communication Networks LTE and LTE-Advanced Networks ▪ LTE Resource Management • LTE uses bearers for quality of service (QoS) control instead of circuits • EPS bearers - Between PGW and UE - Maps to specific QoS parameters such as data rate, delay, and packet error rate • Service Data Flows (SDFs) differentiate traffic flowing between applications on a client and a service - SDFs must be mapped to EPS bearers for QoS treatment - SDFs allow traffic types to be given different treatment • End-to-end service is not completely controlled by LTE Dr. Mohammed Balfaqih CCCN 422: Wireless Communication Networks LTE and LTE-Advanced Networks 14.3 LTE QoS Bearers Dr. Mohammed Balfaqih CCCN 422: Wireless Communication Networks LTE and LTE-Advanced Networks ▪ Classes of bearers • Guaranteed Bit Rate (GBR) bearers - Guaranteed a minimum bit rate And possibly higher bit rates if system resources are available - Useful for voice, interactive video, or real-time gaming • Non-GBR (GBR) bearers - Not guaranteed a minimum bit rate - Performance is more dependent on the number of UEs served by the eNodeB and the system load - Useful for e-mail, file transfer, Web browsing, and P2P file sharing. Dr. Mohammed Balfaqih CCCN 422: Wireless Communication Networks LTE and LTE-Advanced Networks ▪ Bearer management • Each bearer is given a QoS class identifier (QCI) • Each QCI is given standard forwarding treatments - Scheduling policy, admission thresholds, rate-shaping policy, queue management thresholds, and link layer protocol configuration • For each bearer the following information is associated - QoS class identifier (QCI) value - Allocation and Retention Priority (ARP): Used to decide if a bearer request should be accepted or rejected • Additionally for GBR bearers - Guaranteed Bit Rate (GBR): minimum rate expected from the network - Maximum Bit Rate (MBR): bit rate not to be exceeded from the UE into the bearer Dr. Mohammed Balfaqih CCCN 422: Wireless Communication Networks LTE and LTE-Advanced Networks Dr. Mohammed Balfaqih CCCN 422: Wireless Communication Networks LTE and LTE-Advanced Networks ▪ EPC Functions • Mobility management - X2 interface used when moving within a RAN coordinated under the same MME - S1 interface used to move to another MME - Hard handovers are used: A UE is connected to only one eNodeB at a time • Inter-cell interference coordination (ICIC) - Reduces interference when the same frequency is used in a neighboring cell - Goal is universal frequency reuse (N = 1) Must avoid interference when UEs are near each other at cell edges Interference randomization, cancellation, coordination, and avoidance are used - eNodeBs send indicators Relative Narrowband Transmit Power, High Interference, and Overload indicators - Later releases of LTE have improved interference control Dr. Mohammed Balfaqih CCCN 422: Wireless Communication Networks LTE and LTE-Advanced Networks ▪ LTE Channel Structure and Protocols • Hierarchical channel structure between the layers of the protocol stack - Provides efficient support for QoS • LTE radio interface is divided - Control Plane - User Plane • User plane protocols - Dr. Mohammed Balfaqih Part of the Access Stratum Transport packets between UE and PGW PDCP transports packets between UE and eNodeB on the radio interface (Fig. 14.4) GTP sends packets through the other interfaces (Fig. 14.5) CCCN 422: Wireless Communication Networks LTE and LTE-Advanced Networks ▪ Protocol Layers • Radio Resource Control (RRC) - Performs control plane functions to control radio resources - Through RRC_IDLE and RRC_CONNECTED connection states • Packet Data Convergence Protocol (PDCP) - Delivers packets from UE to eNodeB - Involves header compression, ciphering, integrity protection, in-sequence delivery, buffering and forwarding of packets during handover • Radio Link Control (RLC) - Segments or concatenates data units - Performs ARQ when MAC layer H-ARQ fails Dr. Mohammed Balfaqih CCCN 422: Wireless Communication Networks LTE and LTE-Advanced Networks ▪ Protocol Layers • Medium Access Control (MAC) - Performs H-ARQ - Prioritizes and decides which UEs and radio bearers will send or receive data on which shared physical resources - Decides the transmission format, i.e., the modulation format, code rate, MIMO rank, and power level • Physical layer actually transmits the data Dr. Mohammed Balfaqih CCCN 422: Wireless Communication Networks LTE and LTE-Advanced Networks Dr. Mohammed Balfaqih CCCN 422: Wireless Communication Networks LTE and LTE-Advanced Networks Dr. Mohammed Balfaqih CCCN 422: Wireless Communication Networks LTE and LTE-Advanced Networks ▪ LTE Channel Structure • Three types of channels - Channels provide services to the layers above - Logical channels Provide services from the MAC layer to the RLC Provide a logical connection for control and traffic - Transport channels Provide PHY layer services to the MAC layer Define modulation, coding, and antenna configurations - Physical channels Define time and frequency resources use to carry information to the upper layers • Different types of broadcast, multicast, paging, and shared channels Dr. Mohammed Balfaqih CCCN 422: Wireless Communication Networks LTE and LTE-Advanced Networks Logical Channels: (BCCH) Broadcast Control Channel, (MCCH) Multicast Control Channel, (PCCH) Paging Control Channel, (CCCH) Common Control Channel, (DCCH) Dedicated Control Channel, (DTCH) Dedicated Traffic Channel, (MTCH) Multicast Traffic Channel. Transport channels: Downlink Shared Channel (DL-SCH), Broadcast Channel (BCH), Multicast Channel (MCH), Paging Channel (PCH), Uplink Shared Channel (UL-SCH), Random Access Channel (RACH). Physical Channels: Physical Downlink Shared Channel (PDSCH), Physical Uplink Shared Channel (PDSCH), Physical Broadcast Channel (PBCH), Physical Multicast Channel (PMCH), Physical Hybrid ARQ Indicator Channel (PHICH), Dr. Mohammed Balfaqih LTE and LTE-Advanced Networks ▪ LTE Radio Access Network • LTE uses MIMO and OFDM - OFDMA on the downlink SC-OFDM on the uplink, which provides better energy and cost efficiency for battery-operated mobiles • LTE uses subcarriers 15 kHz apart - Maximum FFT size is 2048 Basic time unit is Ts = 1/(15000×2048) = 1/30,720,000 seconds. Downlink and uplink are organized into radio frames Duration 10 ms., which corresponds to 307200Ts. Dr. Mohammed Balfaqih CCCN 422: Wireless Communication Networks LTE and LTE-Advanced Networks • LTE uses both TDD and FDD - Both have been widely deployed - Time Division Duplexing (TDD) Uplink and downlink transmit in the same frequency band, but alternating in the time domain - Frequency Division Duplexing (FDD) Different frequency bands for uplink and downlink • LTE uses two cyclic prefixes (CPs) Normal CP = 144 × Ts = 4.7 μs. Extended CP = 512 × Ts = 16.7 μs. For worse environments Dr. Mohammed Balfaqih CCCN 422: Wireless Communication Networks LTE and LTE-Advanced Networks ▪ FDD Frame Structure - Type 1 • Three different time units - The slot equals Tslot = 15360 × Ts = 0.5 ms - Two consecutive slots comprise a subframe of length 1 ms. Channel dependent scheduling and link adaptation (otherwise known as adaptive modulation and coding) occur on the time scale of a subframe (1000 times/sec.). - 20 slots (10 subframes) equal a radio frame of 10 ms. Radio frames schedule distribution of more slowly changing information, such as system information and reference signals. • Normal CP allows 7 OFDM symbols per slot • Extended CP only allows time for 6 OFDM symbols - Use of extended CP results in a 1/7 = 14.3% reduction in throughput - But provides better compensation for multipath Dr. Mohammed Balfaqih CCCN 422: Wireless Communication Networks LTE and LTE-Advanced Networks Dr. Mohammed Balfaqih CCCN 422: Wireless Communication Networks LTE and LTE-Advanced Networks ▪ TDD Frame Structure - Type 2 • Raio frame is again 10 ms. • Includes special subframes for switching downlink-to-uplink - Downlink Pilot TimeSlot (DwPTS): Ordinary but shorter downlink subframe of 3 to 12 OFDM symbols - Uplink Pilot TimeSlot (UpPTS): Short duration of one or two OFDM symbols for sounding reference signals or random access preambles - Guard Period (GP): Remaining symbols in the special subframe in between to provide time to switch between downlink and uplink Dr. Mohammed Balfaqih CCCN 422: Wireless Communication Networks LTE and LTE-Advanced Networks Dr. Mohammed Balfaqih CCCN 422: Wireless Communication Networks LTE and LTE-Advanced Networks ▪ Resource Blocks • A time-frequency grid is used to illustrate allocation of physical resources • Each column is 6 or 7 OFDM symbols per slot • Each row corresponds to a subcarrier of 15 kHz - Some subcarriers are used for guard bands - 10% of bandwidth is used for guard bands for channel bandwidths of 3 MHz and above • Resource Block - 12 subcarriers - 6 or 7 OFDM symbols - Results in 72 or 84 resource elements in a resource block (RB) Dr. Mohammed Balfaqih CCCN 422: Wireless Communication Networks LTE and LTE-Advanced Networks • For the uplink, contiguous frequencies must be used for the 12 subcarriers - Called a physical resource block • For the downlink, frequencies need not be contiguous - Called a virtual resource block • MIMO - 4×4 in LTE, 8×8 in LTE-Advanced - Separate resource grids per antenna port • eNodeB assigns RBs with channel-dependent scheduling • Multiuser diversity can be exploited - To increase bandwidth usage efficiency - Assign resource blocks for UEs with favorable qualities on certain time slots and subcarriers - Can also include Fairness considerations, Understanding of UE locations, Typical channel conditions versus fading, QoS priorities. Dr. Mohammed Balfaqih CCCN 422: Wireless Communication Networks LTE and LTE-Advanced Networks ▪ Power-On Procedures 1. 2. 3. 4. 5. 6. Power on the UE Select a network Select a suitable cell Use contention-based random access to contact an eNodeB Establish an RRC connection Attach: Register location with the MME and the network configures control and default EPS bearers. 7. Transmit a packet 8. Mobile can then request improved quality of service. If so, it is given a dedicated bearer Dr. Mohammed Balfaqih CCCN 422: Wireless Communication Networks LTE and LTE-Advanced Networks ▪ LTE-Advanced • So far we have studied 3GPP Release 8 - Releases 9-12 have been issued • Release 10 meets the ITU 4G guidelines - Took on the name LTE-Advanced • Key improvements - Carrier aggregation MIMO enhancements to support higher dimensional MIMO Relay nodes Heterogeneous networks involving small cells such as femtocells, picocells, and relays - Cooperative multipoint transmission and enhanced intercell interference coordination - Voice over LTE Dr. Mohammed Balfaqih CCCN 422: Wireless Communication Networks LTE and LTE-Advanced Networks ▪ Carrier Aggregation • Ultimate goal of LTE-Advanced is 100 MHz bandwidth - Combine up to 5 component carriers (CCs) - Each CC can be 1.4, 3, 5, 10, 15, or 20 MHz - Up to 100 MHz • Three approaches to combine CCs - Intra-band Contiguous: carriers adjacent to each other - Intra-band noncontiguous: Multiple CCs belonging to the same band are used in a noncontiguous manner - Inter-band noncontiguous: Use different bands Dr. Mohammed Balfaqih LTE and LTE-Advanced Networks ▪ Enhanced MIMO • Expanded to 8 × 8 for 8 parallel layers • Or multi-user MIMO can allow up to 4 mobiles to receive signals simultaneously - eNodeB can switch between single user and multi-user every subframe • Downlink reference signals to measure channels are key to MIMO functionality - UEs recommend MIMO, precoding, modulation, and coding schemes - Reference signals sent on dynamically assigned subframes and resource blocks Dr. Mohammed Balfaqih CCCN 422: Wireless Communication Networks LTE and LTE-Advanced Networks ▪ Relaying • Relay nodes (RNs) extend the coverage area of an eNodeB - Receive, demodulate and decode the data from a UE - Apply error correction as needed - Then transmit a new signal to the base station • An RN functions as a new base station with smaller cell radius • RNs can use out-of-band or inband frequencies Dr. Mohammed Balfaqih CCCN 422: Wireless Communication Networks LTE and LTE-Advanced Networks ▪ Heterogeneous networks • It is increasingly difficult to meet data transmission demands in densely populated areas • Small cells provide low-powered access nodes - Operate in licensed or unlicensed spectrum - Range of 10 m to several hundred meters indoors or outdoors - Best for low speed or stationary users • Macro cells provide typical cellular coverage - Range of several kilometers - Best for highly mobile users Dr. Mohammed Balfaqih CCCN 422: Wireless Communication Networks LTE and LTE-Advanced Networks • Femtocell - Low-power, short-range self-contained base station - In residential homes, easily deployed and use the home’s broadband for backhaul - Also in enterprise or metropolitan locations • Network densification is the process of using small cells - Issues: Handovers, frequency reuse, QoS, security • A network of large and small cells is called a heterogeneous network (HetNet) Dr. Mohammed Balfaqih CCCN 422: Wireless Communication Networks LTE and LTE-Advanced Networks ▪ Coordinated Multipoint Transmission and Reception • Release 8 provides intercell interference coordination (ICIC) - Small cells create new interference problems - Release 10 provides enhanced ICIC to manage this interference • Release 11 implemented Coordinated Multipoint Transmission and Reception (CoMP) - To control scheduling across distributed antennas and cells - Coordinated scheduling/coordinated beamforming (CS/CB) steers antenna beam nulls and mainlobes - Joint processing (JT) transmits data simultaneously from multiple transmission points to the same UE - Dynamic point selection (DPS) transmits from multiple transmission points but only one at a time Dr. Mohammed Balfaqih CCCN 422: Wireless Communication Networks LTE and LTE-Advanced Networks ▪ Voice over LTE • The GSM Association is the cellular industry’s main trade association - GSM Association documents provide additional specifications for issues that 3GPP specifications left as implementation options. • Defined profiles and services for Voice over LTE (VoLTE) • Uses the IP Multimedia Subsystem (IMS) to control delivery of voice over IP streams - IMS is not part of LTE, but a separate network - IMS is mainly concerned with signaling. • The GSM Association also specifies services beyond voice, such as video calls, instant messaging, chat, and file transfer in what is known as the Rich Communication Services (RCS). Dr. Mohammed Balfaqih CCCN 422: Wireless Communication Networks 5G Network ▪ 5G Comparing 4G Dr. Mohammed Balfaqih 5G Network ▪ 5G aims to cater for services with diverse requirements Dr. Mohammed Balfaqih CCCN 422: Wireless Communication Networks 5G Network Dr. Mohammed Balfaqih 5G Network ▪ Key enabling technologies Dr. Mohammed Balfaqih 5G Network ▪ 5G overall architecture Dr. Mohammed Balfaqih 5G Network ▪ Software Defined Network (SDN) separates the control and data planes and allows for network programmability Dr. Mohammed Balfaqih 5G Network ▪ Network Function virtualization (NFV) decouples Implementation of network functions from hardware Dr. Mohammed Balfaqih software 5G Network ▪ 5G will have several deployment scenarios Dr. Mohammed Balfaqih Thank you Dr. Mohammed Balfaqih CCCN 422: Wireless Communication Networks Review Questions 1) ____________ is used for communicating over large distances wirelessly such as cities or countries. a. Cellular network b. WiMAX network c. Wireless Local Area Network d. All the above 2) A mobile phone uses ___________ type of duplex communication. a. Half b. Full c. Zero d. Both a and b Dr. Mohammed Balfaqih CCCN 422: Wireless Communication Networks Review Questions 3) IEEE 802.11 standard is classified as a. Wireless LAN b. Wireless MAN c. Wireless WAN d. Wireless PAN 4) 4G cellular network is classified as a. Wireless LAN b. Wireless MAN c. Wireless WAN d. Wireless PAN Dr. Mohammed Balfaqih CCCN 422: Wireless Communication Networks Review Questions 5) WIMAX standard is classified as a. Wireless LAN b. Wireless MAN c. Wireless WAN d. Wireless PAN 6) In ___________, cells are divided into number of wedge-shaped sectors, each with their own set of channels a. Cell sectoring b. Cell splitting c. Frequency borrowing d. None of above Dr. Mohammed Balfaqih CCCN 422: Wireless Communication Networks Review Questions 7) In ___________, cells in areas of high usage can be split into smaller cells. a. Cell sectoring b. Cell splitting c. Frequency borrowing d. None of above 8) The step when the MTSO sends a paging message to certain BSs to find the called mobile unit is ___________. a. Mobile unit initialization b. Mobile-originated call c. Paging d. Handoff Dr. Mohammed Balfaqih CCCN 422: Wireless Communication Networks Review Questions 9) The probability of a new call being blocked, due to heavy load on the BS traffic capacity is known as __________. a. Call blocking probability b. Call dropping probability c. Call completion probability d. Handoff blocking probability 10) The probability that, due to a handoff, a call is terminated is known as ___________. a. Call blocking probability b. Call dropping probability c. Call completion probability d. Handoff blocking probability Dr. Mohammed Balfaqih CCCN 422: Wireless Communication Networks Review Questions 11) The probability that a handoff cannot be successfully completed is known as ___________. a. Call blocking probability b. Call dropping probability c. Call completion probability d. Handoff blocking probability 12) _____________ enhanced GSM by providing a datagram switching capability and allow users to open a persistent data connection a. GPRS b. EDGE c. CDMA d. None of above Dr. Mohammed Balfaqih CCCN 422: Wireless Communication Networks Review Questions 11) The probability that a handoff cannot be successfully completed is known as ___________. a. Call blocking probability b. Call dropping probability c. Call completion probability d. Handoff blocking probability 12) _____________ enhanced GSM by providing a datagram switching capability and allow users to open a persistent data connection a. GPRS b. EDGE c. CDMA d. None of above Dr. Mohammed Balfaqih CCCN 422: Wireless Communication Networks Review Questions 13)What are the classes of wireless network? 14)Explain the cellular network organization? Why hexagonal pattern is chosen for cellular networks? 15)Explain frequency reuse in your own words? 16)List with a brief description the methods to improve coverage and capacity in cellular systems. 17)What are the principal elements of a cellular system? 18)What is the handoff process? Explain any three handoff performance metrics? 19)Differentiate hard and soft handoff? 20)Compare between first and second cellular generation systems? 21)What are the most popular standards of second generation? Dr. Mohammed Balfaqih CCCN 422: Wireless Communication Networks Review Questions 22) List with a brief description the missing key functional elements of the GSM system. 23) What are the advantages of CDMA for Cellular systems? 24) What are the most prevalent standards of Third Generation (3G) mobile network? What are CDMA2000 design considerations? Dr. Mohammed Balfaqih CCCN 422: Wireless Communication Networks Review Questions 25) Compare between second and third generation cellular networks in terms of standards, frequency, bandwidth, access technique, and core network? 26) List with a brief description the missing key functional elements of LTE architecture. 27)Describe the functions of Evolved Packet System (EPS) in LTE network? 28)LTE uses bearers for quality of service (QoS) control instead of circuits. Describe the concept of bearers? What is the difference between the classes of bearers? 29)What are the key improvements of LTE-Advanced over LTE network? Give a brief description of these improvements? Dr. Mohammed Balfaqih CCCN 422: Wireless Communication Networks Review Questions 30)Compare between third and fourth generation cellular networks in terms of standards, frequency, bandwidth, access technique, and core network? 31)What are the key enabling technologies of fifth generation cellelur network? Give a brief description? 32)Name the following 5G deployment scenarios? 33)Compare between fourth and fifth generation cellular networks in terms of standards, frequency, bandwidth, access technique, and core network? Dr. Mohammed Balfaqih CCCN 422: Wireless Communication Networks