Mobile Digital TV Technology for the Terminal Dave Evans, Sri Andari Husen, Hans Brekelmans, Peter Massey Philips Research Laboratories Philips first with a mobile phone demonstration. 3GSM, February 2005

Philips Research Laboratories2 Technology for the Terminal Technical challenge RF Tuner Antenna TV coexistence in the phone Channel decoding – dealing with Doppler What next? Conclusion

Philips Research Laboratories3 Technical Challenge Reception in all situations Good picture quality Limited impact on phone battery life Global usage Mobile TV is now addressing the issues that are familiar in the design of mobile terminals –Size –Performance –Reception on the move –Low power –Multi-standard

Philips Research Laboratories4 TV in the phone – Generalised architecture Additional elements for broadcast TV reception TV tuner Channel decoder Media processor Display Cellular transceiver Baseband controller + interface Coexistence + Software Philips supplies complete system solutions for the mobile terminal

Philips Research Laboratories5 RF Tuner Major challenge was power consumption –Starting point ~ 500mW Now >100mW (>5% with DVB-H time slicing) Low/zero IF design Minimal off-chip components 470 to 860 MHz operation –Separate on chip LNA for 1452 to 1675 MHz operation On-going work to improve performance

Philips Research Laboratories6 Mobile DTV Antenna Two issues: –Close proximity between mobile DTV and GSM antennas –Common ground plane Coupling between them disturbs the GSM antenna and affects its performance Co-design of the GSM and Mobile DTV antennas is essential Signal coupling from GSM to mobile DTV antenna is high –Need to incorporate GSM signal blocking Ideally continuous operation from 470 to above 700 MHz –Limited to ~700 MHz to assist GSM coexistence

Philips Research Laboratories7 Interaction between GSM & DVB-H Strong coupling, poor isolation Reflection phase matters! GSMDVB-H TV filter must be reflective at GSM GSM feed DVB-H port

Philips Research Laboratories8 Interaction between GSM & DVB-H open circuit at DVB-H monopole short circuit at DVB-H monopole GSM S 11 GSM seriously effected by impedance of DVB-H circuit. Co- design is necessary. GSM feed DVB-H port

Philips Research Laboratories9 Antenna + RF Tuner Compact PIFA 470 to 700 MHz continuous operation Antenna includes a GSM trap Antenna & RF tuner Feed tab Integrated GSM filter

Philips Research Laboratories10 TV Coexistence in the Phone Interference from GSM900 transmissions due to very close co-location –DTV receiver blocking –58 dB isolation between GSM TX and mobile DTV receiver is required Potential solutions –Isolation between antennas – limited to between 6 to 10 dB –Can be improved by use of GSM trap within mobile DTV antenna, ~ 20 dB –Managing GSM transmission at the terminal – limited scope –Managing DVB-H transmissions – not possible –Power cancellation – not very promising –Receiver filter, good solution but requires frequency separation – restricts channel usage. TV channel 50 ( ~ 700 MHz) OK, extending this to 54/55 desired Coexistence best achieved by filter before TV RX + antenna with GSM trap Out-of-band noise – high pass filter at GSM TX output

Philips Research Laboratories11 Broadband matching + filtering, PIFA to LNA NF 17dB, 470 to 710 MHz 50dB attenuation above 877MHz

Philips Research Laboratories12 Channel Decoding Key issue for mobile TV –Reception at high vehicle speed Problem –Impact of Doppler effects on OFDM –Channel changes during symbol period –Inter carrier interference (ICI) 150 kph equates to typically 100 Hz Doppler 8k DVB-T mode has 1.1 kHz subcarrier spacing Solution –Channel estimation and Doppler compensation –ICI cancellation

Philips Research Laboratories13 The faster the vehicle, the more severe the ICI, the poorer the reception. Challenge: DVB-T/H 8K mode (f s = 1.12 kHz) reliable high throughput reception under high Doppler frequency (  10% f s ) with low complexity. Mobile multipath channel

Philips Research Laboratories14 Channel Estimation The received signal in frequency domain is approximated as follows: where: H is the complex channel transfer function vector for all the subcarriers H’ is the the temporal derivative of H (proportional to vehicle speed) Ξ is the fixed Inter-Carrier Interference spreading matrix a is the transmitted data vector n is a complex circular white Gaussian noise vector Wanted received signal Inter-Carrier Interference Noise

Philips Research Laboratories15 Channel Estimation Estimation of H: rather than time interpolation, frequency interpolation Estimation of H’: calculated from H estimation of past and future symbols OFDM symbol frequency time pilots empty carriers data carriers

Philips Research Laboratories16 Inter-carrier Interference ICI level is not constant but varies over frequency ICI level per sub-carrier can be estimated from H’ Soft demapper takes into account ICI level per sub- carrier, rather than average ICI power

Philips Research Laboratories17 Basic Channel Decoding Scheme channel estimation Soft demapper Data Estimation Log likelihood ratio per bit To de-interleaver & Viterbi decoder

Philips Research Laboratories18 Overall Scheme channel estimation Soft QAM demapper Data Estimation To de-interleaver & Viterbi decoder ICI cancellation (Using regenerated ICI) Log likelihood ratio per bit

Philips Research Laboratories19 Performance after Viterbi decoder when H is known

Philips Research Laboratories20 Final points on channel decoding Channel model –MBRAI specification defines the use of COST 207 TU6 profile –Modeling of the Doppler spectrum is not defined System performance is very sensitive to model parameters –No conformance tests are defined in for the complete channel model –Caution needs when comparing performance

Philips Research Laboratories21 What next? On-going work to improve performance –Further reductions in power consumption –Move to a CMOS architecture Single chip solution that includes channel decoder –Emerging RF filter technologies including MEMS –Antenna diversity, extra dBs are very useful – gain of a few dBs? Technology will evolve to meet that in the terminal, convergence! Multi-standard solutions –Needed now to support multi-standard multi-band cellular requirements –Also required for WLAN/BT, mobile DTV and GPS –Reconfigurable, highly digitised radios Coexistence in the phone –Exploitation of multiple radios to assist mobile DTV reception - diversity

Philips Research Laboratories22 Conclusion Keys issues and challenges are understood Solutions are available now On-going process of performance improvement Continuing to maintain the leading position of Philips Complete systems solution shown at IFA, Berlin, September 2005