SatSig topic:

TV Distribution over 802.11 a/b/g/n, 802.16e

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Nov 17^th, 2008 at 11:42pm

Hi gents,
I'm aware of MMDS TV Broadcasting and IPTV systems for distributing TV programs wirelessly.

However, does anybody know if it is possible to distribute TV programs over a wireless 802.11 xxxx network. I'm not talking about distributing locally as in a house, (this can be done), but commercially over the airwaves (2.4Ghz/5.8Ghz using 802.1x) akin to a commercial wireless broadband network setup?

Any Ideas

Thanks

Nov 18^th, 2008 at 12:50am

I'm not a video engineer, but on the surface the difficulty would appear to be one of RF bandwidth. I understand an uncompressed digital broadcast channel to be about 6MHz. I also understand the 802.1xx RF bandwidth to be in the neighborhood of 10 to 12MHz. That alone suggests the number of uncompressed TV channels that could be handled by current 802.1xx hardware - would be severely limited.

Compression seems an obvious near-term solution to a video neophyte like myself. But I wouldn't know how to achieve that, without adding additional hardware on either side of the 802.1xx segment.

//greg//

Nov 18^th, 2008 at 1:11pm

We have looked at the distribution of low bit rate IP-TV over wired and wireless LAN systems using IP-TV broadcast packet mode transmissions. The idea is to send TV from the teleport to a number of VSAT sites (or receive only sites using DVB-S2 receivers) that would each then broadcast the data packets into their local LANs using a broadcast IP address. The end user can use either a PC to see a PC screen version of the programme or use a tiny Amino set top box to convert ethernet to RGB/HDMI/S-Video type connection direct to large TV screen.

At the teleport hub you need to receive the TV off-air and convert to IP packet for transmission via a DVB-S2 encapsulator.

Note that you need a licence from the original programme maker.

Regarding 802.11 you will find range and interference problems. The range is limited unless the wireless hub uses a high gain toroidal beam and the remotes use high gain directional antennas. Capacity depends on the bit rate you choose for the video. As Greg points out, high bit rates may give rise to congestion. Using broadcast IP addressed packets is critical. What will you do if multiple TV channels are wanted ? If the service is to be paid for consider exactly how you will prevent free unauthorised reception. Cost of delivery over the satellite is approx $4-$7 per kbit/s per month.

Best regards, Eric.

Nov 19^th, 2008 at 1:42am

Eric, USN, thanks for that.

I hear ye on the 802.XX side. Capacity, compression, bandwidth etc major problem.

We've tested a system that works well through Cat5e. How it works: Receive TV signal through Dish, link to IPTV server (does all mod/demod, channel splitting, coding/encoding, live streaming etc), distribute through Cat 5e to IPTV Set Top Box, linked to TV.

IT works well, but only for hotels, apartment blocks etc. Your idea Eric is as close as it gets, I think. IPTV Server system is very expensive and not cost effective V standard TV Coax distribution systems. Why use IPTV when the latter is perfectly sound?

IPTV can be, if required, distributed wirelessly but only to c30feet with absolute clear LOS.

IT seems we'll have to wait for 802.xx to catch up although I've been told that 802.11n looks promising because of large data throughput potential.

Would be interesting to hear any other ideas or open other threads on this topic.

Regards