LTE Access Network
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This document provides an overview of LTE network architecture and interfaces, radio interface technologies, capacity planning considerations, and spectrum and heterogeneous network topics. The key points covered are: - The EPC core network connects to the eUTRAN access network and other networks via standardized interfaces like S1, S3, S4 and SGi. - The eUTRAN uses OFDMA in the downlink and SC-FDMA in the uplink to support flexible bandwidths, MIMO, and efficient multipath performance. - Cell capacity depends on user distribution and location within the cell, with average throughput lower than maximum potential due to modulation and coding adaptations. - Heterogeneous networks integrate macro
LTE Access Network
- 1. This document is offered compliments of BSP Media Group. www.bspmediagroup.com All rights reserved.
- 2. LTE Access Network All material is Copyright © Informa Telecoms & Media 2001-2010
- 3. LTE Network and Interfaces Internet SGi UMTS/GERAN S3,S4 EPC S2 S1 eUTRAN 2 WLAN
- 4. eUTRAN Architecture and Interfaces User Data Signalling and Control S11 MME PGW SGW S1_MME S1_U UE and eNB Signalling User Plane Data App Signalling eNB eNB X2 3
- 5. LTE Radio Interface Flexible Bandwidth Options High Order Modulation and Coding Multi-Carrier Transmission Good Multipath Performance Suited to Advanced Antenna Techniques Efficient SC-FDMA in the Uplink QPSK, 16 QAM and 64 QAM Adaptive modulation and coding Robust OFDMA in the Downlink 1.4 – 20 MHz Still good Multipath Performance Decoding complexity in the eNB More power efficient than OFDMA Advanced Antenna Support 4 MIMO, 2x2, 4x4 Beamforming
- 6. Typical Multipath Environment OFDMA – Designed to offer good performance in challenging environments 5
- 7. Shannon's Law and Capacity Low Bandwidth High Bandwidth 6 Low SNR High SNR
- 8. Capacity in LTE LTE supports Adaptive Modulation and Coding Actual Capacity will depend on users location in the cell SINR is the most important planning KPI Average cell throughput will lower than quoted maximums 5 7
- 9. The Capacity Planning Problem 100+ Mbps! Assumes good radio signal in every part of the radio cell 64QAM 8 16QAM QPSK
- 10. User Distribution in the Cell User Distribution will impact average cell throughput The resource scheduler in the eNB is very important Scheduling may be different between vendors 64QAM 16QAM ~10% of Area ~15% of Area ~75% of Area 9 QPSK
- 11. The Radio Spectrum VLF Very Low Freq 3KHz LF Low Freq 30KHz IMT Bands Shown in White MF Medium Freq 300KHz 3MHz HF High Freq VHF Very High Freq 30MHz TV 300MHz UMTS GSM 500 900 GSM 10 3GHz 300GHz 1500 1800 WiMAX WiFi 2500 MHz SHF Super High Freq DECT TV 300 UHF Ultra High Freq UHF Band is very busy Most mobile radio services operate in this band Many frequencies in UHF are designated IMT bands LTE can be deployed in any IMT Band 3000 4000 MHz
- 12. Which Radio Spectrum to Use? 11
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- 15. Carrier Aggregation Options (basic) Band A f1 a Band B f2 f3 b f4 f5 c a – intra-band, contiguous (R10 UL only) b – intra-band, non contiguous (R10 UL Only) c – inter-band 14
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- 17. Heterogeneous – Dictionary Definition heterogeneous /ˌhetərəˈjēnēəs/ - composed of parts of different kinds; having widely dissimilar elements or constituents homogeneous /ˌhōməˈjēnēəs/ - composed of similar or identical parts or elements 16
- 18. Heterogeneous Network 3G/LTE 3G/LTE 2G 3G/LTE Pico/ Enterprise Femto 3G WiFi CSG Femto 17 Large, Small and Tiny Cells Cells have different technologies with different physical characteristics Ideally all layers under the control of a single entity
- 19. Small Cell Capacity Gains 18