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www.aeroflex.com Aeroflex Company Confidential System-level Challenges in the Design of a Wideband RF Transceiver for LTE and LTE-A Senior Algorithm Engineer Aeroflex Test Solutions Stevenage, UK Dr. Jin Wang Slide 2 www.aeroflex.com Agenda 1. Design Objectives 2. Design Challenges 3. Summary 4. Q&A Slide 3 www.aeroflex.com 1.1 3GPP LTE Air Interface Overview Modulation DL: OFDM UL: DFTS-OFDM Signal Bandwidth1.4,3,5,10,15,20 MHz Signal PAPR (Crest Factor)DL: ~11 dB, UL: ~8 dB FFT Size2048 (Normal CP) Sub-Carrier Spacing15 kHz (Normal CP) DL MIMO 2x2 (Rel-8) 4x4, 4x2 (Rel-9) UL MIMO2x2 (Rel-9) Max Data RateDL: 150~300 Mbps UL: 50~100 Mbps Slide 4 www.aeroflex.com 1.2 Product Overview: TM500 Industry Standard Base Station Tester for LTE and HSPA LTE Rel-8,9,10 and beyond From RF to Protocol Layers Slide 5 www.aeroflex.com 1.3 Wideband Radio Card Operating Frequencies: 400MHz~4GHz Signal Bandwidth: up to 20 MHz Transceiver Units: 2 RX, 1 TX Form Factor: double height and double width of a uTCA slot Slide 6 www.aeroflex.com 1.4 Translate System Req. to RF Req. Receiver Sensitivity Maximum Throughput System Bandwidth MIMO Hand-over Noise Figure EVM Floor Filter Spec. LO Phase Noise LO Settling Time Product Managers/End UsersRF Engineers System Engineers Slide 7 www.aeroflex.com 2. RF Design Challenges Homodyne or Heterodyne? Whats the minimum requirement on Noise Figure? Whats the minimum requirement on EVM floor? The biggest blocker might be your own TX! Do we need to worry about IQ imbalance? What about phase noise? Further challenges in LTE-A Slide 8 www.aeroflex.com 2.1 Homodyne or Heterodyne? Homodyne (direct conversion/zero-IF) Pros: - fewer processing stages - No image frequency problem - Mainstream design in recent years Cons: - IQ imbalance - DC offset or carrier leakage Slide 9 www.aeroflex.com 2.2 Noise Figure < ? Max noise figure allowed depends on the RX sensitivity requirement, e.g. 3GPP requires that no less than 95% of maximum throughput is achieved on a reference measurement channel (BW=10MHz) when minimum input power of P REFSENS =-97dBm is applied (from 3GPP 36.101). SNR min = -1 dB (I) Slide 10 www.aeroflex.com 2.2 Noise Figure (Contd) P thermal = kTB NF P N = P thermal + NF P REFSENS SNR (II) NF = P REFSENS P thermal SNR min NF