Mobile Broadcast and Spectrum Issues (DVB-T) Workshop April 2003 TECHNICAL ASPECTS IN SPECTRUM ALLOCATION FOR DVB-UMTS CONVERGENCE TERMINALS DVB-UMTS & EICTA MBRAI Mobile Broadcast and Spectrum Issues (DVB-T) Workshop April 2003 Pekka Talmola

DVB-UMTS Group and EICTA DVB ad hoc Group UMTS work items Co-operative services by joint utilisation of DVB and UMTS technologies Concepts for terminals in co-operative networks, especially: Convergence terminals using both DVB-T and cellular radio services such as GSM, GPRS and UMTS. Further work have been done and will be done in EICTA MBRAI Mobile and Portable DVB-T Radio Access Interface Specification. Deals also with interoperability issues between cellular and DVB-T.

Targets Tight integration of the radio systems within the terminal unit. Practical limitations to the terminal design and operating frequency allocations. This document reviews the technical merits from the terminal point of view of various frequency bands that could be reserved for use by convergence terminals. DTV DVB - T BCP Mux DVB - T transmitter broadcast network operator Mobile terminal DVB - UMTS IP data WCP p - t - p core RAN network UMTS / UTRA GPRS / GERAN mobile operator Scenario 2: IP services co-ordinated on UMTS and DVB networks

Problem Areas RF Immunity for DVB-T reception from the Cellular transmitter Out of band spurios products Blocking Transmitter wideband PA-noise Internal unwanted coupling Power consumption of the DVB-UMTS terminal Battery operated terminal Very high linearity requirements in RF due to the high power level differences Antenna efficiency Small integrated antennas Very wide frequency range to support in the worst case

Design Aspects 1: Antenna Efficiency The antenna size will be small probably less than /10 ->Real part of the antenna impedance will be small, most of the radiation comes from the ground plane. Wide frequency range (UHF) means that resonant designs are impossible ->Tuneable matching circuit has to be designed Matching small resistive part of the antenna to receiver input with tuneable circuit will be lossy. ->Antenna gain will be very low, in the order of -5dBi to –10 dBi Combining VHF III to this kind of antenna would mean extremely low antenna gain, much less than –10 dBi. ->VHF III is unpractical Being able to narrow the band to about 80 MHz (10 channels) would enable resonant designs (point frequency) and higher antenna gains from –3 to 0dBi range. High UHF-frequencies have slight advantage over the lower ones

Design Aspects 2: Doppler Shift Often misunderstood as the decisive factor for mobile reception, but is still important. In UHF low frequencies will give 1.5 times advantage over the high UHF Current demodulators give rather good performance > 100 km/h with 8k 16QAM ½ @ 500-600 MHz VHF III will give >2 advantage over low UHF This is, however, needed only in very special cases like high speed trains. Low or mid UHF is sufficient for most applications.

Design Aspects 3: Cellular Interoperability Spurious carrier like emissions in UHF are not a major problem Blocking of the DVB-T receiver can be problem Can be handled by DVB-T pre-filtering GSM Tx +33 dB at 880 MHz Max allowed at the DVB-T input is –35 dBm 68 dB total filtering requirement 10 dB from antenna isolation 58 dB filter requires at least 100 MHz transition band Tx-noise Wideband noise from the Tx PA G=20 dB, NF=15 -> Pn= -70 dBm 20 dB more than 16QAM sensitivity! PA gain drops at lower frequencies HP Filter at Tx output would be easier to implement for low DVB-T Rx freq. Going below 600 MHz would probably be a useful solution. 880 MHz 960 MHz 858 MHz GSM Tx +33 dBm

Design Aspects 4: Propagation & Interference Lower frequencies in UHF or VHF III give advantages in propagation. In principle better coverage. In practise this advantage will be balanced out by the worse antenna efficiency at these frequencies. Impulse interference will be a problem for portable devices At low frequencies, especially VHF III interference level is considerably higher.

Design Aspects 5: Harmonisation A harmonised approach to the frequency range would be highly desirable enabling economics of scale to be used. VHF III would clearly not allow this and any terminal having VHF III would also have to support UHF

Conclusion Giving marks for various design aspects from --- to +++ will result the following conclusion: The conclusion is that when simultaneous use of cellular 900 MHz radios is required low UHF-band should be used. Band IV (474MHz to 602 MHz) could be suitable compromise, having 17 channels.