Ls Telcom Ag · XETR:LSX
Ls Telcom — Norkring AS — LS telcom Summit 2013
47 slides from Ls Telcom's conference presentation, Jul 3, 2013
Slide 1: DVB-T2 MISO versus SISO Field Test
DVB-T2 (T2) MISO versus SISO Field Test Author: Bjørn Skog, M.Sc. E-mail: [email protected] Company: Telenor Broadcast, Norkring AS, Norway www.norkring.no July 3rd 2013 @ LS telcom Summit 2013 V.2 2.7.13
Slide 2: The Case
The Case • To investigate what coverage improvement (MISO gain) could be obtained in a SFN network using the Distributed Alamouti Scheme or Space-Time Block Coding – MISO = Multiple Input, Single Output – SISO = Single Input, Single Output www.norkring.no
Slide 3: MISO Figures 1 & 2
MISO Figures 1 & 2 Figures from page 5 of www.norkring.no http://www.lstelcom.com/fileadmin/content/marketing/flyer/general/white_paper_DVB-T2_planning.pdf
Slide 4: MISO Background / advantages
MISO Background / advantages • To avoid the zero dB echo problem or increase in required C/N for decoding and to fully utilize the single frequency network (SFN) gain: • a cost effective coverage improvement technique in DVB-T2 is the option of using multiple-input single-output (MISO) mode, using t
Slide 5: MISO details
MISO details 1 • The T2 receiver uses only one receiving antenna, while the Alamouti scheme allows coverage improvements equivalent to that obtained from a two antenna receiver diversity system and a maximal ratio combining scheme. • One transmitter (group 1) transmits an un-modified version of ever
Slide 6: MISO details
MISO details 2 • The transmitter (group 2) transmits a slightly modified version of each constellation pair, and in reverse frequency order. Group 2 transmits -C1* and C0* where * denotes the complex conjugation operation. In practice co-located MISO SFN transmissions are too expensive for most comm
Slide 7: MIMO Multiple Input Multiple Output
MIMO Multiple Input Multiple Output • Figures explaining MIMO, MISO and SISO – Distributed MIMO (network cost effective: no new transmitting antennas or additional transmitters are required) www.norkring.no
Slide 8: MIMO advantages
MIMO advantages • The more complex and advanced diversity technique called MIMO (multiple-input multiple-output), is mainly developed and used to overcome the limitations of the SISO (and MISO) Shannon capacity limit. • In wireless communication systems, the path towards high spectral efficiency tra
Slide 9: MIMO disadvantages
MIMO disadvantages • This means in practice that there is no network cost advantage using MIMO for broadcasting there. • Using MIMO 2x2, for the transmitter antennas this means new cross polarized antennas and 2 transmitters per site (double power) and for the receiving antennas, this means new cros
Slide 10: Future use of MIMO for BC
Future use of MIMO for BC 1 • Considering the DVB.org Technical Module: • TM-MIMO Study Mission report to the 94th TM meeting @ EBU, Geneva, 4th and 5th June 2013: • The possible lowered field strength requirement for a new DVB-Tx variant currently considered, simulated and possibly later developed
Slide 11: Future use of MIMO for BC
Future use of MIMO for BC 2 • This interesting work within DVB.org Technical Module can potentially give 100% to 200% more capacity per RF (8 MHz) channel or a significant reduction in the required field strength, and this work might end up with two terrestrial system descriptions: • A simpler varia
Slide 12: MIMO directional receiving antennas
MIMO directional receiving antennas High gain UHF receiving antennas for MIMO is less practical www.norkring.no
Slide 13: Practical consequences for DVB-T2 network operators and end-users
Practical consequences for DVB-T2 network operators and end-users • This is the focus in this presentation and the work behind, network coverage and cost is especially relevant for countries with wast areas to be covered and relatively low population density. • The need for a high percentage populat
Slide 14: Test objectives
Test objectives • Norkring as a terrestrial broadcasting network operator, wanted to better utilize the benefits of the T2 technology presently available, during T2 network planning of new or converted (from DVB-T) networks • To investigate if using MISO versus SISO gave any coverage advantages or a
Slide 15: Investigative method
Investigative method • Investigative method was changing only one parameter (from SISO to MISO) and measure the required field strength for coverage or decoding of the video, in a real SFN environment with complex transfer channels between transmitters and receiver • This change was executed at ever
Slide 16: Statement of the problem
Statement of the problem • MISO removes the RF spectrum ripples and notches that occur in a standard (SISO) SFN channel. This degrades the system’s signal quality (Modulation Error Ratio, MER) and do not occur in a MISO SFN because the two transmitted signals are no longer identical, so destructive
Slide 17: Measurement RF spectrum curves for MISO and SISO with zero dB echo
Measurement RF spectrum curves for MISO and SISO with zero dB echo: Here the delay spread is “nearly minimum” (less than 1 µs), this gives a serious degradation of the SISO RF Spectrum (picture to the right) and none in the MISO RF Spectrum (picture to the left) At page 45 in this presentation, it i
Slide 18: Why field test MISO?
Why field test MISO? • The testing of MISO versus SISO, was selected because this was the last unknown possible advantage with the current T2 equipment implementation. I write possible because there are two diverging conclusions concerning this, based on field measurements. • This field test results
Slide 19: Results MISO Gain
Results MISO Gain 1 • For high capacity T2 modes, approximately 3 dB gain or 3 dB lowered field strength requirement for zero dB echo receiving conditions was found. MISO can already be used with commercial T2 transmitters and receivers and has no additional network or equipment cost implications. •
Slide 20: MISO test details
MISO test details • T2 Norway Mjøsa area SFN field test autumn 2012 test results (all modes used 32K number of (rotated) carriers) • Conclusions from this report on the gain in using MISO vs. SISO for zero echo dB receiving conditions between two “neighboring” T2 transmitters (received with equal am
Slide 21: Statistical summary results for code rates and QAM levels
Table: Statistical summary results for different code rates and QAM constellation levels • Code Rate: 3/4 Constellation: 256 QAM Guard Interval: 1/16 Pilot Pattern 2 MISO versus SISO gain = 4,1 dB • Code Rate: 2/3 Constellation: 256 QAM Guard Interval: 1/16 Pilot Pattern 2 MISO versus SISO gain = 3,
Slide 22: MISO Conclusion
MISO Conclusion • The MISO gain is significant and the only practical reason not using MISO in a SFN is because the modulation parameters wanted (for either having very large SFN or because of maximum bitrate capacity considerations) is not allowed to be used in combination with MISO. • This may qui
Slide 23: Required RF input signal level using Sony Bravia TV
Figure 1: Required RF Input signal MISO (average 26,5 dBµV) and SISO (30,1 dBµV) CR for 2/3 256QAM, Sony Bravia TV Zero dB echo receiving DVB-T2 mode: Code Rate=2/3 256QAM Gl=1/16 PP2 32 Required RF input signal level in dBµV using Sony Bravia TV 31 30 29 28 27 26 25 24 1 2 3 4 5 6 7 8 9 10 11 Numbe
Slide 24: MISO vs. SISO gain for CR 2/3 256QAM
Figure 2: MISO vs. SISO gain for CR 2/3 256QAM. Average gain = 3,5 dB Zero dB echo receiving DVB-T2 mode: Code Rate=2/3 256QAM Gl=1/16 PP2 6,0 Gain in dB lower required input signal by using MISO instead of SISO, for the Sony Bravia TV 5,0 4,0 3,0 2,0 1,0 0,0 1 2 3 4 5 6 7 8 9 10 11 Number of measur
Slide 25: MISO vs. SISO gain for CR 3/5 256QAM
Figure 3: MISO vs. SISO gain CR 3/5 256QAM. Average gain = 2,1 dB: Lower gain due to better error protection, which allows for correcting errors due to faded carriers in SISO Zero dB echo receiving DVB-T2 mode: Code Rate=3/5 256QAM Gl=1/16 PP2. 4,0 Gain in dB lower required input signal by using MIS
Slide 26: MISO vs. SISO gain for CR 3/4 256QAM
Figure 4: MISO vs. SISO gain for CR 3/4 256QAM. Average gain = 4,1 dB Zero dB echo receiving DVB-T2 mode: Code Rate=3/4 256QAM Gl=1/16 PP2. 8,0 7,0 Gain in dB lower required input signal by using MISO instead of SISO, for the Sony Bravia TV 6,0 5,0 4,0 3,0 2,0 1,0 0,0 1 2 3 4 5 6 7 Number of measure
Slide 27: MISO vs. SISO gain for CR 3/4 64QAM
Figure 5: MISO vs. SISO gain for CR 3/4 64 QAM. Average gain = 2,4 dB Zero dB echo receiving DVB-T2 mode: Code Rate=3/4 64QAM Gl=1/16 PP2. 4,0 Gain in dB lower required input signal by using MISO instead of SISO, for the Sony Bravia TV 3,0 2,0 1,0 0,0 1 2 3 4 5 6 7 Number of measurement locations Ga
Slide 28: MISO vs. SISO gain for CR 3/4 16QAM
Figure 6: MISO vs. SISO gain for CR 3/4 16 QAM. Average gain = 2,2 dB Zero dB echo receiving DVB-T2 mode: Code Rate=3/4 16QAM Gl=1/16 PP2. 4,0 Gain in dB lower required input signal by using MISO instead of SISO, for the Sony Bravia TV 3,0 2,0 1,0 0,0 1 2 3 4 5 6 7 Number of measurement locations Ga
Slide 29: Discussion of MISO gain
Discussion of MISO gain 1 • The gain is much higher for Code Rate 3/4 than for 3/5, because the more robust mode (3/5), means bit errors caused by selective fading is less harmful, popularly this can be described as: “many carriers can be lost in noise” and still the signal be decoded. www.norkring.
Slide 30: Discussion of MISO gain
Discussion of MISO gain 2 • The “MISO gain” was achieved due to the physical condition that the RF spectrum is flatter and that the MER for each RF carrier received in the “zero dB transfer channel” is of better quality. • This physical phenomenon occurs due to the fact that for SISO a zero dB echo,
Slide 31: Details about MISO and measurements
Details about MISO and measurements 1 • For visually most impressing demonstrating the MISO gain fast and effectively, I recommend using low delay spread between the transmitters and code rate ¾. • The average or median MER value per carrier may not often be so much higher, But you avoid low MER val
Slide 32: Details about MISO and measurements
Details about MISO and measurements 2 • Both short and long echo delays (delays spread between the two transmitters relative the Guard Interval) were used and both gave good MISO gain. • Concerning coverage, the MISO gain was always positive, meaning no negative coverage results were measured for MI
Slide 33: Details about MISO and measurements
Details about MISO and measurements 2 • The transfer channel from each of the two transmitters was possible for the T2 receiver Sony Bravia to estimate, because each transmitter (MISO Group 1 and 2) has its own pilot pattern, generally the pilots are inverted in transmitter group 2. • This enables c
Slide 34: DD2 1st
DD2 1st • DD2 implies only 224 MHz bandwidth will be available for terrestrial TV 470 to 694 MHz (down from 320 MHz today in use in Norway). WRC-15 cannot dictate the use of this band to ensure more effective use of it, meaning much larger SFN size, in practice requiring T2, EU can decide in a new f
Slide 35: DD2 2nd
DD2 2nd • - the possible benefits and limitations for using MISO versus SISO in T2 for surviving such a RF channel / bandwidth constraint • - compared with the possible network and end-user cost increase (drawback) and possible benefits (larger capacity per MUX and RF channel used), when alternative
Slide 36: DD2 3rd
DD2 3rd • Selecting the most appropriate mode for T2 involves optimizing multiple parameters that affect coverage, network cost and network capacity • This task is much more complicated and involves advanced analysis for T2 relative for T1, due to the large number of transmission mode parameters pos
Slide 37: DD2 4th
DD2 4th • The most cost effective strategy for DVB-Tx (T1 or T2) in Norway surviving DD2, depends partly on frequency coordination with neighboring countries, for Norway most importantly Sweden, for creating larger DVB-Tx SFN areas. • Nationwide or large SFNs are the most capacity maximizing strateg
Slide 38: DD2 5th
DD2 5th • If not nationwide SFN areas is decided because of regionalized content or other constraints/considerations, then probably the SFN size will be compatible with T2 guard intervals that is supported by MISO. www.norkring.no
Slide 39: DD2 6th
DD2 6th • A UHF frequency conference for European countries for re planning all TV channels at UHF frequencies between 470 to 694 MHz, without DD1 and DD2 frequencies, would be the best solution for optimizing net capacity by using large SFN areas. • The UHF frequency use currently in Norway is sub-
Slide 40: DD2 7th
DD2 7th • For surviving DD2, the most important tools are in this order: • re-planning of SFN areas to better suit T2 and DD2, • Use MISO when SFN areas are of appropriate size to get ca 3 dB better zero dB echo performance for high capacity modes “for free” (no network cost) and • use H.265 video c
Slide 41: DD2 8th
DD2 8th • The best strategy for surviving a post DD2 regulated environment, proposal for this strategy in more detail: • If we after DD2, in a most cost effective way, shall maximize the terrestrial TV network capacity and coverage, I think that the first and most important step would be, to have a
Slide 42: DD2 9th
DD2 9th • Having many multiplexes available will enable a robust modulation per multiplex, giving cost effective coverage (low power consumption, lower frequency re-use distance). • One cost challenge for terrestrial TV network operators, is that all DVB-T transmitters and all combiners must be repl
Slide 43: DD2 10th
DD2 10th • Example for 7 MUX: • Sweden gets RF UHF channels 30, 31, 32, 33, 34, 35, 36 and 37 • Norway gets RF UHF channels 38, 39, 40, 41, 42, 43, 45 and 46 etc. • If one MUX shall be regionalized, to save frequencies it could be required that it uses more robust modulation, alternatively also gets
Slide 44: DD2 11th
DD2 11th • I have talked to one DVB-T2 transmitter manufacturer, and the only way to save the antenna combiner cost, is to make “multi-MUX”-modulators. Trying to do this using today’s modulators with one MUX per modulator and combining them before the amplification, Only leads to large intermodulati
Slide 45: The End
The End • Q&A • The report with details about the measurements is saved in the icon to the right: DVB-T2_Norkring_MISO_SISO_test_autumn2012_VersionJune26_2013.doc • This report’s author can be contacted like this: [email protected] Mobile Phone: +47 9006 1049 www.norkring.no
Slide 46: norkrin
“ft. y norkrin
Slide 47: norkring
wy, norkring BROADCASTING EASY