what do higher data rates mean to cellular and connectivity testing?
Post on 17-Dec-2015
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WHAT DO HIGHER DATA RATES MEAN TO CELLULAR AND CONNECTIVITY
TESTING?
Key market drivers for the wireless industry:
Smartphone & Tablet Continuing to Grow Worldwide– Units increasing by 340M units to 2.45B annually by 2018– Handset ASP shrinking by >5% YoY– Companies releasing 2x - 3x more new designs annually
to meet both premium & basic smart phone demands
WIRELESS INDUSTRY TRENDS
Increase Demand for Higher Data Rate & Connectivity– Overall mobile data traffic is expected to grow at a 61%
CAGR to 15.9 Exabytes per month by 2018– MIMO & Carrier Aggregation requiring 2x-3x more active RX
& TX device ports– Internet-of-things driving rapid growth of MCU + RF segment
Shrinking Device Size While Increasing Complexity– Mobile IC’s moving away from conventional package to wafer-
level package technologies (Flip-chip, WLCSP, FOWLP)
– Wafer Scale Package technologies provide 50% smaller device footprint
– Shrinking geometries (65nm 45nm 28nm) enabling 2x – 3x content increases on smaller die sizes
METHODS OF INCREASING DATA RATE
3
Very High Throughput requirements are met three ways:
1) Increasing BW. • Wider Bandwidths / Aggregation
2) Increasing the number of bits/symbol. • Constellation Density• Link Adaptation & Fast Scheduling• UL / DL ratio• Forward Error Correction• Cyclic Prefix reduction
3) Increasing the number of Spatial Streams.• Diversity• Beam forming• MIMO• MU-MIMO
256 QAM64 QAM
Multi-User MIMO
Spatial Multiplexing
• Early Communications
TWO STANDARDS – W-CDMA AND OFDM
4
(-2000G - BPSK)
-1000G – Coded Message
-500G – First Cell
• Problems with using Smoke to send messages - WIND
TWO STANDARDS – W-CDMA AND OFDM
5
W-CDMARaised Root Cosine Filter w/ Alpha = 0.22(HSPA+)
WCDMA – Has similar traits to smoke, in that its noisy and is required to be filtered to stay with in its allocated frequency. This hinders WCDMA from making the best use of its bandwidth.
-500G -400G
3G
• Early Communications
TWO STANDARDS – W-CDMA AND OFDM
6
3G
-2200G -150G – Coded MessageFrequency and SpatialSeparation combined
OFDM(802.11a,g,n,ac & LTE)
OFDM used for LTE and WLAN – Has similar traits to light, in that if the frequencies have a minimal separation – they tend not to interfere with each other. This allows OFDM to make good use of its spectrum.
-240G – Coded MessageSpatial Separation Would have helped
METHODS OF INCREASING DATA RATE
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Very High Throughput requirements are met three ways:
1) Increasing BW. (LTE 100M Aggregation, 802.11ac 160M)• Wider Bandwidths / Aggregation
2) Increasing the number of bits/symbol. . (LTE 64 QAM , 802.11ac 256 QAM)• Constellation Density• Link Adaptation & Fast Scheduling• UL / DL ratio• Forward Error Correction• Cyclic Prefix reduction
3) Increasing the number of Spatial Streams. (802.11ac supports up to 8x8 MIMO)• MIMO
CELLULAR EVOLUTION
802.11a/b 802.11g 802.11n 802.11ac 802.11ad
• LTE Supports many different types of bandwidth configurations. 1.4,3,5,10,20M and any combo up to 100M
• TEST – support required bandwidth
WIDER BANDWIDTH & AGGREGATION – HIGHER DATA RATES
10
LTE-Advanced Maximum Bandwidth
5 x 20MHz20MHz
20MHz
20MHz
20MHz
20MHz
• 802.11acSupports many different types of bandwidth configurations. 20,40,80,160M
• Note that there is also an aggregation mode for 802.11ac – that’s called 80+80.
WIDER BANDWIDTH & AGGREGATION – HIGHER DATA RATES
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• High frequency modulation signal• Sourcing a wider bandwidth signal requires much better baseband
instruments than narrow band signals. Skew is one of the biggest concerns. The UltraWave 12G, UltraWave 24, and the UltraPAC80 have skew accuracy and repeatability performance to test wide bandwidth waveforms.
WIDER BANDWIDTH & AGGREGATION – TEST
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0 50 100
150
200
250
300
350
400
450
500
0
1
2
3
4
5
6
7 I and Q Timing Skew effects on EVM
802.11ac 160M 256QAM
LTE-Adv 100M 64 QAM
802.11ac 80M 256QAM
802.11ac 80M QPSK
802.11ac 40M 256QAM
LTE 20M 64QAM
% E
VM
802.11ac 160MEVM Limit = 2.51%
METHODS OF INCREASING DATA RATE
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Very High Throughput requirements are met three ways:
1) Increasing BW. (LTE 100M Aggregation, 802.11ac 160M)• Wider Bandwidths / Aggregation
2) Increasing the number of bits/symbol. . (LTE 64 QAM , 802.11ac 256 QAM)
• Constellation Density• Link Adaptation & Fast Scheduling• UL / DL ratio• Forward Error Correction• Cyclic Prefix reduction
3) Increasing the number of Spatial Streams. (802.11ac supports up to 8x8 MIMO)
• MIMO
• 16 QAM = 4 Bits per symbol• 64 QAM = 6 Bits per symbol• 256 QAM = 8 Bits per symbol
• Constellation Density is determined by quality of the signal at the RX. If poor signal / bits dropped – Then the TX reduces the density.
CONSTELLATION DENSITY – HIGHER DATA RATE
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Ideal Signal
Measured Signal
Test Limit
LTE Base Station = 13.5%LTE User Equip 12.5%
802.11ac = 11.22%LTE Base Station = 9.0%
802.11ac = 3.98% 802.11ac = 2.51%
16-QAM802.11a/g, LTE
64-QAM802.11a/g/n; LTE-A
256-QAM802.11 ac
- Device Spec Limit
• In order to achieve higher data rates – some methods require an understanding of the channel.
• This channel information is communicated to the base station (BS) by the user equipment (UE) or its signal.
– FDD vs. TDD - TDD can be have more up to date information, because UL shares the same channel as DL
WHAT IS KNOWN ABOUT THE CHANNEL?
15
?UL
DL
• Link Adaptation - Data Rates are varied based of information about the channel at a given time. TDD is often more up to date.
– Used with - 802.11ac & HSPA + & LTE
• Fast Scheduling – When users data is sent the data rate can vary to take advantage of better channel conditions – Resulting in higher data rate = less on time = better battery life.
– Used with - HSPA+ & LTE
• TEST
– Data Rate normally does not change during test
– However VSA can handle it.
LINK ADAPTATION & FAST SCHEDULING
16
LTE Example - Resource Blocks Data Rate vs Channel
• In order to be flexible with users needs for more UL or more DL a scheduling plan was created. Below is an example for LTE TDD
– HSPA+• HSDPA was designed to favor DL and HSUPA for UL. HSPA+ was
designed to be more flexible with DL and UL scheduling.
• TEST – Normally this does not change during test
UL / DL RATIO – HIGHER DATA RATE
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LTE - TDD
• Forward Error correction (FEC)
OTHERS
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Data Rate (Mbps)
Modulation Type (OFDM)
Punctured Coding
48 64-QAM 2/3
54 64-QAM 3/4
802.11a/g
• Cyclic Prefix reduction – Higher Data rate
Figure 1 Figure 2
FFT Window
METHODS OF INCREASING DATA RATE
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Very High Throughput requirements are met three ways:
1) Increasing BW. (LTE 100M Aggregation, 802.11ac 160M)• Wider Bandwidths / Aggregation
2) Increasing the number of bits/symbol. . (LTE 64 QAM , 802.11ac 256 QAM)
• Constellation Density• Link Adaptation & Fast Scheduling• UL / DL ratio• Forward Error Correction• Cyclic Prefix reduction
3) Increasing the number of Spatial Streams. (802.11ac supports up to 8x8 MIMO)
• MIMO
• MIMO - Multiple Input into the channel and Multiple Outputs from the channel.
• MIMO utilizes the multi-path environment so that signals are different. • MIMO uses two or more antennas to transmits different information on each
antenna. For each antenna added the data rate is increased by the multiple of the number of antennas over the SISO rate.
• Each MIMO stream contains not only the data, but information that will assist the receiver in demodulating the signal. This advancement in MIMO technology is primary due to higher end processor that are able to do the math to pull the data apart.
• TEST • Each path should be active and can be tested as MIMO or Signal Channel.• Cross talk between streams can be tested with ESA – however seldom is
MIMO – HIGHER DATA RATES
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1. Provide full test coverage to guarantee device quality
• RF Source Accuracy• EVM test capability• ACLR performance for out of band
service providers compliance
Source: www.qualcomm.com
2. Provide economical solution for high volume production
LTE-Advanced requires up to 5x modulated data compared to 3G.
LTE Commercial Release Timeline
TESTING CHALLENGES
Teradyne Confidential
UltraFLEX RF Specifiers:
UltraFLEX RF Test Partners:
Lowest cost of test Fastest time to market Highest performance instruments Easiest to use software
Teradyne: #1 ranked RF ATE company since 2008(source: Gartner, April 2014)
ULTRAFLEX RF:#1 PRODUCTION SOLUTION FOR WIRELESS
Based on 2013 Reported Revenue (Gartner, April 2014)
>515 UltraFLEX RF systems installed since 4Q-
2007
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