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AIRCOM LTE Webinar 4 - LTE Coverage
 

AIRCOM LTE Webinar 4 - LTE Coverage

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This webinar provides a basic overview of LTE radio coverage, focusing on early stages of LTE, types of cell and coverage dependencies.

This webinar provides a basic overview of LTE radio coverage, focusing on early stages of LTE, types of cell and coverage dependencies.

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    AIRCOM LTE Webinar 4 - LTE Coverage AIRCOM LTE Webinar 4 - LTE Coverage Presentation Transcript

    • The webinar will start shortly. AIRCOM LTE Webinar Series: Basic overview of LTE radio Coverage © 2013 AIRCOM International Ltd
    • AIRCOM LTE Webinar Series: Basic overview of LTE radio Coverage © 2013 AIRCOM International Ltd
    • About the Presenters Graham Whyley – Lead Technical Trainer  AIRCOM Technical Master Trainer since 2005  Currently responsible for all LTE training course creation and delivery  Over 20 years of training experience at companies including British Telecom and Fujitsu Adam Moore – Learning & Development Manager  With AIRCOM since 2006  Member of CIPD Contact us at training@aircominternational.com 3 © 2013 AIRCOM International Ltd
    • About AIRCOM AIRCOM is the leading provider of mobile network planning, optimisation and management software and consultancy services. Advise Manage Audit Network Optimise    4       Founded in 1995 14 offices worldwide Over 150 LTE customers Acquired Symena in 2012 Products deployed in 159 countries Comprehensive Tool and technology training portfolio Plan TEOCO offer very complimentary assurance an optimisation solutions as well as an excellent analytics portfolio. Significantly stronger combined offering for customers Find out more at www.aircominternational.com © 2013 AIRCOM International Ltd
    • LTE PORTFOLIO ACCREDITATION COURSES A202 AIRCOM Accredited LTE Planning and Optimisation Engineer (5 days inc exam) 5 © 2013 AIRCOM International Ltd
    • Agenda- Basic overview of LTE radio coverage  So you want to support VoIP What do you need?  So you want to support Circuit Switched Voice  What effects coverage 6 © 2013 AIRCOM International Ltd
    • VoIP over LTE coverage LTE network operator wants to move voice services to VoIP over IMS. What happens if we VoIP over LTE (without header compression) move into GSM/UMTS cell IP Multimedia Subsystem Packet switched Speech RTP 12 Bytes Header UDP 8 Bytes Header IPv4 20 Bytes Header PDCP 1 Byte Header RLC 100% LTE coverage 1 Byte Header MAC PSTN Gateway 1 Byte Header PSTN circuit switched 600 bits every 20 ms L1 30 kbps LTE supporting Cell This would require 100% LTE coverage from day 1 to have a competitive VoIP 7 © 2013 AIRCOM International Ltd
    • Early stages LTE In the early stages of rolling out the technology, LTE will only be available in large cities and in isolated hotspots. I am using VoIP via IMS and I am moving outside LTE coverage? GSM/UMTS I want to make circuitswitched call? LTE supporting Cell Not supporting LTE –GSM/UMTS 8 LTE is a packet-based all-IP network that cannot support circuit-switched calls. So what about coverage for circuit switched © 2013 AIRCOM International Ltd
    • Single radio voice call continuity SRVCC is an LTE functionality that allows a VoIP/IMS call in the LTE packet domain to be moved to a legacy voice domain (GSM/UMTS or CDMA) If a mobile moves outside the coverage area of LTE, then the network can use this technique to transfer the mobile from VoIP communications over the IMS, to traditional circuit switched communications over GSM, UMTS circuit switched VoIP IP Multimedia Subsystem Packet switched Packet switched PSTN Gateway PSTN circuit switched circuit switched GSM/UMTS circuit switched moves outside the coverage area of LTE 9 © 2013 AIRCOM International Ltd
    • Single radio voice call continuity If operators look to limit LTE deployments to high traffic areas and at the same time wish to transition voice service in those areas to VoIP, then SRVCC is exactly what they need. High traffic areas + Voice Services to VoIP You need SRVCC VoIP over LTE (without header compression) Speech RTP UDP 8 Bytes Header IPv4 20 Bytes Header Not supporting LTE –GSM/UMTS 10 1 Byte Header RLC LTE supporting Cell PDCP 1 Byte Header MAC 1 Byte Header 600 bits every 20 ms L1 30 kbps © 2013 AIRCOM International Ltd
    • Single radio voice call continuity Operator does NOT plan to migrate to VoIP High traffic areas NO Voice Services to VoIP LTE supporting Cell Not supporting LTE –GSM/UMTS 11 SRVCC NOT REQUIRED © 2013 AIRCOM International Ltd
    • Circuit switched fall-back Paging Response MSC/VLR Paging Paging CS Service Request extended GSM/ UMTS MME HO Command SWITCH LTE NETWORK CSFB is often seen as an interim solution for LTE operators. Voice over LTE (VoLTE) is considered to be the long-term goal for the delivery of voice services on LTE networks LTE VoIP PSTN 12 IMS © 2013 AIRCOM International Ltd
    • Circuit switched fallback UE does not support VoIP OR/AND network operator not supporting IMS circuit switched UE can only use the technique if it is simultaneously in the coverage area of LTE and a 2G or 3G cell Packet switched LTE COVERAGE UMTS/GSM COVERAGE circuit switched Circuit switched fallback inter-system handovers have traditionally been one of the least reliable aspects of a mobile telecommunication system 13 © 2013 AIRCOM International Ltd
    • Types of cell Each cell has a limited size, which is determined by the maximum range at which the receiver can successfully hear the transmitter. Ref Sens = KTB + NF + SINR + IM Ref Sens SINR QPSK 2bits/Hz 16QAM 4bits/Hz SINR SINR SINR SINR SINR 64QAM 6bits/Hz SINR SINR transmit power SINR modulation and coding scheme Macrocells -provide wide-area coverage. Evolved Node B (eNB) You may want to limit the cell size? • Does not have an upper limit for its transmit power capability • Above roof-top antenna deployment • Relatively large cell areas Microcells 14 • Can be deployed using a ‘wide area’ BTS with reduced transmit power • Below roof-top antenna deployment • Relatively small cell areas © 2013 AIRCOM International Ltd
    • Picocells Picocells are used in large indoor environments such as offices or shopping centres and are a few tens of metres across. Hotspot type deployment. PDN Gateway Evolved Packet Core Serving Gateway Macrocells MME Macrocells Internet Repeater Picocells 15 Microcells Home eNodeB © 2013 AIRCOM International Ltd
    • Closed Subscriber Group Selection Base station is associated with a closed subscriber group and a home eNB name, which it advertises in SIB 1 and SIB 9 respectively. Home eNodeB USIM contains any closed subscriber groups, SIB 1 CSG indication: To indicate whether this cell is CSG cell or not. If it is CSG cell, then CSG identity stored in the UE should match with CSG id of the cell Only those users included in the femtocell's access control list are allowed to use the femtocell resources. 16 © 2013 AIRCOM International Ltd
    • Closed Subscriber Group Selection CSG indication: To indicate whether this cell is CSG cell or not. If it is CSG cell, then CSG identity stored in the UE should match with CSG id of the cell Part of SIB 1 A femtocell can be also configured in Open Access mode, in which any user is allowed access to the femtocell 17 © 2013 AIRCOM International Ltd
    • Closed Subscriber Group Selection USIM contains any closed subscriber groups, CSG entries on the USIM consist of: • PLMN Identifier • CSG Identifier • Home eNodeB Name • CSG Type Home eNodeB SIB 9 SIB9: Home eNB name contains a home eNB name (HeNB Name) CSG Type • Closed access (residential deployment): Access is only allowed for the subscribed user. • Open access All users are allowed access to the HeNB and receive the offered services. 18 © 2013 AIRCOM International Ltd
    • Indoor coverage • Indoor coverage can be badly degraded by penetration losses through the walls of buildings. • If the base station is outdoors but the mobile is indoors, then penetration losses typically reduce the received signal power by 10 to 20 decibels, which can greatly reduce the indoor coverage area. • This is one of the motivations behind the progressive introduction of femtocells. 19 © 2013 AIRCOM International Ltd
    • Increasing coverage using Repeaters 3GPP Release 8 Introduction of LTE Repeaters Home eNode B Inter Cell Interference Coordination (ICIC) SON – Self Establishment of eNode B SON – Automatic Neighbour Releations Repeater receives • downlink signal from donor cell before amplifying and transmitting to UE • uplink signal from UE before amplifying and transmitting to donor cell • Repeaters and relays are devices that extend the coverage area of a cell. • Macrocells They can also increase the data rate at the edge of a cell, by improving the signal to interference plus noise ratio there. Repeater 20 © 2013 AIRCOM International Ltd
    • Relays-3GPP Release 10 wired backhaul MIMO-OFDM concepts to deliver high data rate over small cells Limitation of cell size is mainly because: • path loss • down-tilting angle • Other cell Interference • Parameters Limitation of LTE roll out mainly due to: • wired backhaul EPC MIMO Setting Data Efficiency (bit/s/Hz) Sectors Total Bandwidth (Mbps) LTE 1x2 5 1.7 3 25 LTE 2x2 5 3.4 3 50 LTE 2x2 10 3.4 3 102 LTE 4x4 21 Data Spectrum (MHz) 20 6.8 3 408 © 2013 AIRCOM International Ltd
    • Bandwidth REL’8 20MHz The amount of bandwidth on a wireless network is ultimately constrained by two factors: 1. amount of licensed spectrum a carrier owns. 2. the spectral efficiency of the wireless interface 15MHz 10MHz 5MHz 3MHz 1.4MHz Application overhead TCP/UDP TCP/UDP overhead Application Application Rate IP Relay IP PDCP PDCP GTP-U overhead RLC RLC UDP overhead MAC MAC IP L1 L1/L2 overhead Physical Rate L1 UE 22 AirInterface eNode B Data Rate In/out of core CORE NETWORK (EPC) L1/L2 Server © 2013 AIRCOM International Ltd
    • Relays-3GPP Release 10 •LTE relaying is different to the use of a repeater which re-broadcasts the signal. •A relay will actually receive, demodulates and decodes the data, apply any error correction, etc to it and then re-transmitting a new signal. • In this way, the signal quality is enhanced with an LTE relay, rather than suffering degradation from a reduced signal to noise ratio when using a repeater wired backhaul Relay Node (RN) Uu donor cell (eNodeB) Un EPC physical cell ID 23 © 2013 AIRCOM International Ltd
    • Coverage depends on carrier frequency Coverage depends on carrier frequency: low carrier frequencies such as 800MHz are associated with a high coverage, while at high carrier frequencies such as 2600 MHz, the coverage is less. E-UTRA Band Bandwidth UL (MHz) Bandwidth DL (MHz) Duplex Mode 1 1920-1980 2110-2170 FDD 2 1850-1910 1930-1990 FDD 3 1710-1785 1805-1880 FDD 4 1710-1755 2110-2155 FDD 5 824-849 869-894 FDD 6 830-840 875-885 FDD 7 2500-2570 2620-2690 FDD 8 880-915 925-960 FDD 9 1749.9-1784.9 1844.9-1879.9 FDD 10 1710-1770 2110-2170 FDD 11 1427.9-1452.9 1475.9-1500.9 FDD 12 698-716 728-746 FDD 13 77-787 746-756 FDD 14 788-798 758-768 FDD 24 Europe: Band 7: The 2.6 GHz auctions have been running in a few countries Band 8:is currently used mostly by GSM. The band is attractive from a coverage point of view due to the lower propagation losses. © 2013 AIRCOM International Ltd
    • Coverage depends on data rate A high data rate requires a fast modulation scheme, a high coding rate and possibly the use of spatial multiplexing, all of which increase the receiver’s susceptibility to noise and interference. Modulation and coding scheme QPSK 2bits/Hz SINR SINR SINR 16QAM 4bits/Hz SINR SINR SINR 64QAM 6bits/Hz SINR SINR SINR Relay Physical Rate 4bits/Hz Physical Rate 6bits/Hz GTP-U RLC UDP Evolved Node B IP (eNB) L1 Physical Rate 2bits/Hz PDCP MAC modulation and coding scheme L1/L2 eNode B Physical Rate 25 © 2013 AIRCOM International Ltd
    • Coverage depends SINR for Service A high data rate requires a fast modulation scheme, a high coding rate and possibly the use of spatial multiplexing, all of which increase the receiver’s susceptibility to noise and interference. Modulation and coding scheme QPSK 2bits/Hz SINR SINR SINR 16QAM 4bits/Hz SINR SINR SINR 64QAM 6bits/Hz SINR SINR SINR Relay GTP-U RLC UDP Evolved Node B IP (eNB) L1 Web browsing PDCP MAC modulation and coding scheme L1/L2 eNode B Physical Rate VoIP Service- GBR 26 © 2013 AIRCOM International Ltd
    • Improving SINR will improve coverage Evolved Node B (eNB) SINR -4 QPSK 2bits/Hz SINR -4 SINR SINR SINR 16QAM 4bits/Hz SINR SINR 64QAM 6bits/Hz SINR SINR SINR Improving SINR Relay modulation and coding scheme PDCP GTP-U RLC UDP MAC IP L1 L1/L2 eNode B SINR ave = S I+N The average interference power can be further decomposed as I = Iown + Iother , Inter Cell Interference Coordination (ICIC), Frequency Selective scheduling etc 27 © 2013 AIRCOM International Ltd
    • Poll What best describes the term Single radio voice call continuity? 1. SRVCC is a technology whereby voice and SMS services are delivered to LTE devices through the use of GSM/UMTS 2. SRVCC is needed because LTE is a packet-based all-IP network that cannot support circuit-switched calls. 3. SRVCC is often seen as an interim solution for LTE operators. 4. SRVCC is an LTE functionality that allows a VoIP/IMS call in the LTE packet domain to be moved to a (GSM/UMTS or CDMA) 28 © 2013 AIRCOM International Ltd
    • Poll- answers 1. Circuit Switched FallBack (CSFB) is a technology whereby voice and SMS services are delivered to LTE devices through the use of GSM or another circuit-switched network. 2. Circuit Switched FallBack is needed because LTE is a packet-based all-IP network that cannot support circuit-switched calls. When an LTE device is used to make or receive a voice call or SMS, the device "falls back" to the 3G or 2G network to complete the call or to deliver the SMS text message. 3. CSFB is often seen as an interim solution for LTE operators. Voice over LTE (VoLTE) is considered to be the long-term goal for the delivery of voice services on LTE networks. 4. SRVCC is an LTE functionality that allows a VoIP/IMS call in the LTE packet domain to be moved to a legacy voice domain (GSM/UMTS or CDMA) 29 © 2013 AIRCOM International Ltd
    • Coverage depends MIMO setting Spatial multiplexing is often described as the use of multiple input multiple output (MIMO) antennas. This name is derived from the inputs and outputs to the air interface, so that ‘multiple input’ refers to the transmitter and ‘multiple output’ to the receiver. 30 © 2013 AIRCOM International Ltd
    • Coverage depends MIMO setting 3GPP Release 8 4x4 MIMO in the Downlink 1x1 MIMO in the Uplink Repeaters Home eNode B The eNode B instructs the UE to use a specific antenna solution via: • RRC signalling • Downlink Control Information (DCI) on the PDCCH 3GPP Release 10 Carrier Aggregation 8x8 MIMO in the Downlink 4x4 MIMO in the Uplink Relays Relay GTP-U RLC UDP Evolved Node B MAC IP (eNB) L1 1. Single-Antenna transmission, no MIMO 2. Transmit diversity 3. Open-loop spatial multiplexing, no UE feedback required 4. Closed-loop spatial multiplexing, UE feedback required 5. Multi-user MIMO (more than one UE is assigned to the same resource block) 6. Closed-loop precoding for rank=1 (i.e. no spatial multiplexing, but precoding is used) 7. Beamforming 31 PDCP L1/L2 eNode B © 2013 AIRCOM International Ltd
    • Coverage depends MIMO setting SINR SINR Transmit Diversity Spatial Multiplexing (SM) targets increasing users’ throughput BEARER 1110 BEARER 0101 INCREASING COVERAGE Relay PDCP Adaptive Switching BEARER 1110 SAME DATA BEARER 1110-SAME DATA 32 GTP-U RLC UDP Evolved Node B MAC IP (eNB) L1 L1/L2 eNode B SU-MIMO 2x2 Doubles peak rate compared to 1x1 © 2013 AIRCOM International Ltd
    • Coverage depends MIMO setting MU_MIMO BEARER 1110 BEARER 0101 Relay PDCP GTP-U RLC UDP Evolved Node B MAC IP (eNB) L1 L1/L2 eNode B MU-MIMO 2x2 Doubles capacity compared to 1x1 33 © 2013 AIRCOM International Ltd
    • Closed Loop Transmit Diversity Here, the transmitter sends two copies of the signal in the expected way, but it also applies a phase shift to one or both signals before transmission. By doing this, it can ensure that the two signals reach the receiver in phase, without any risk of destructive interference. two signals reach the receiver in phase BEARER 1110 SAME DATA You also have Receive diversity BEARER 1110-SAME DATA Relay Closed Loop Transmit Diversity GTP-U RLC UDP Evolved Node B MAC PMI PDCP IP (eNB) L1 L1/L2 eNode B The phase shift is determined by a precoding matrix indicator (PMI), which is calculated by the receiver and fed back to the transmitter. 34 © 2013 AIRCOM International Ltd
    • SM close to the eNodeBs to increase data rates switches to Diversity Transmit Diversity increases coverage MU-MIMO for heavily loaded cells switches to Diversity 35 © 2013 AIRCOM International Ltd
    • Coverage depends 50% Loaded Network without MIMO 50% Loaded Network with SU-MIMO (Diversity and Spatial Multiplexing in Adaptive Switching Adaptive Switching 36 © 2013 AIRCOM International Ltd
    • Coverage depends Small tilt usually 5-10 degrees. This would reduce the cell radius but allow for a more uniform distribution of energy within the cell. Methods •Tilt Adjustment •Azimuth Adjustment •Power Adjustment • Antenna Height Antenna Tilt of 10 Degrees In signal from the main beam and side lobes would bounce off the ground and buildings around the cell site and spread the signal around the cell 37 © 2013 AIRCOM International Ltd
    • Coverage depends on traffic SINR Methods •Tilt Adjustment •Azimuth Adjustment •Power Adjustment • Antenna Height 38 © 2013 AIRCOM International Ltd
    • Coverage depends on link budget Ref Sens = KTB + NF + SINR + IM Path Loss = Tx – REF sens TX Power Lpmax_UL TX Power Path Loss = Tx – REF sens Ref Sens = KTB + NF + SINR + IM 39 © 2013 AIRCOM International Ltd
    • link budget Comparing systems with the same data rate, carrier frequency, then we find that the maximum ranges of LTE and 3G systems are actually very similar. 40 © 2013 AIRCOM International Ltd
    • Propagation models Propagation models relate the propagation loss to the distance between the transmitter and the receiver. Frequency Base Station Antenna height Propagation loss to Distance (Km) Relay PDCP Mobile Station Antenna height. Path Loss in dB GTP-U RLC UDP Evolved Node B MAC IP (eNB) L1 L1/L2 eNode B Several propagation models exist and vary greatly in their complexity. A simple and frequently used example is the Okumura-Hata model, which predicts the coverage of macrocells in the frequency range 150 to 1500MHz 41 © 2013 AIRCOM International Ltd
    • Propagation models-COST Hata model Coverage Frequency: 1500 MHz to 2000 MHz Mobile Station Antenna :Height: 1 up to 10m Base station Antenna Height: 30m to 200m Link Distance: 1 up to 20 km L = path loss. Unit: Decibel (dB) f = Frequency of Transmission. (MHz) C= 0dB for medium sized city and suburban areas C=3 dB for metropolitan centers hB = Base Station Antenna height. Unit: Meter (m) d = Link distance. Kilometer (km) hR = Mobile Station Antenna height. 42 This model requires that the base station antenna is higher than all adjacent rooftops © 2013 AIRCOM International Ltd
    • Coverage depends timing advance • The signals from different mobiles have to reach the base station at roughly the same time, to prevent any risk of inter-symbol interference between them. • To enforce this requirement, distant mobiles have to start transmitting slightly earlier than they otherwise would. Frequency inter-symbol interference Relay PDCP GTP-U RLC UDP Evolved Node B MAC IP (eNB) L1 L1/L2 eNode B 43 © 2013 AIRCOM International Ltd
    • Coverage depends timing advance Because the uplink transmission time is based on the downlink arrival time, the timing advance has to compensate for the round-trip travel time between the base station and the mobile: D is the distance between the mobile and the base station, and v is the speed of light. The timing advance does not have to be completely accurate, as the cyclic prefix can handle any remaining errors. LTE is required to support cell ranges up to 100 km, which translates to 667 μs two-way propagation delay = 200 Km/300000= 667uS Distance (D) Relay PDCP RLC Round trip distance 44 GTP-U UDP MAC IP L1 L1/L2 eNode B V = 300,000,000 meters per second OR 300,000 km per second © 2013 AIRCOM International Ltd
    • Coverage depends Parameters There are some parameters which also effect coverage one of these are the PRACH parameters: PRACH parameters SIB There are 5 PRACH preamble formats formats 0 to 3 applicable to FDD and TDD format 4 is only applicable to TDD (short preamble ) 45 Timing advance © 2013 AIRCOM International Ltd
    • Summary Coverage depends on: • SINR • GBR of services • MIMO setting • Parameters for cell selection • Parameters for PRACH • Timing Advance • Frequency • Base Station Antenna height • Mobile Station Antenna height • Path Loss • Environment 46 Some items for increasing coverage: • GSM refarming (lower frequency) • Adaptive Switching • Repeaters/Relays Improving SINR so increasing coverage: • Inter Cell Interference Coordination (ICIC) • Frequency Selective scheduling •Tilt Adjustment •Azimuth Adjustment •Power Adjustment © 2013 AIRCOM International Ltd
    • Next Topic Cell Selection Part2 System Information (SIB’s) Cell Selection Part1 Handover Part2 Handover Part1 Comparison between GSM, UMTS & LTE PDCCH &DCI Formats PCI Planning What effects LTE capacity Comparison of LTE Release 8, 9 &10 Increasing coverage & Capacity in LTE RRC Signalling UE measurement reports Attach Procedure NAS Signalling Resource Allocation Type LTE Protocols – UE & eNode B LTE Parameters Designing High capacity cells 47 © 2013 AIRCOM International Ltd
    • In Closing  Thank you for attending  Webinars webpage – keep up to date and register to receive email alerts on new webinars http://www.aircominternational.com/Web inars.aspx 48 © 2013 AIRCOM International Ltd