Welcome to EDAboard.com

Welcome to our site! EDAboard.com is an international Electronic Discussion Forum focused on EDA software, circuits, schematics, books, theory, papers, asic, pld, 8051, DSP, Network, RF, Analog Design, PCB, Service Manuals... and a whole lot more! To participate you need to register. Registration is free. Click here to register now.

Register Log in

Why do we use the 60 GHz band?

Status
Not open for further replies.

Pushhead

Full Member level 4
Joined
Jan 19, 2005
Messages
199
Helped
20
Reputation
40
Reaction score
10
Trophy points
1,298
Activity points
1,870
Hi All,

I'd like your good answers about this topic.
In fact, i'm not asking only about the 60 GHz band, but generally the "tens of gigahertz" bands.
1. I know that cellular service providers use microwave links @ ~30 GHz to transmit data with high capacity. Why can't they use their own GSM/WCDMA/etc. frequency bands for the same purpose?

2. Given that they have a physically larger bandwidth at those microwave bands, what is their transmission modulation? Is it different than the one they use for regular broadcast?

Thanks and have a good week,
P.
 

radiohead

Advanced Member level 1
Joined
May 13, 2004
Messages
447
Helped
65
Reputation
126
Reaction score
29
Trophy points
1,308
Location
Heart of Europe
Activity points
3,562
1. This is because you need much more bandwidth. It's a historical thing: The mobile phone antenna towers needed to be deployed very fast at the most exotic places and the operators required a high-bandwidth (aggregated from all GSM traffic) backhaul network for interconnecting all towers. Optical fiber would have been an option but deployment time would have been much longer. Hence the microwave links.

2. Deeper modulation requires good phase noise and frequency stability of the LO. Also reaching linearity in the PA is much more difficult at these multidecade GHz bands. This is why it is doubtful whether OFDM is possible at 60GHz (ie at an affordable price) and things like CPM and GMSK are considered. So yes you have more bandwidth but you cannot increase modulation depth a lot when having a good link budget.
 

    Pushhead

    points: 2
    Helpful Answer Positive Rating

Pushhead

Full Member level 4
Joined
Jan 19, 2005
Messages
199
Helped
20
Reputation
40
Reaction score
10
Trophy points
1,298
Activity points
1,870
Thanks guys.
What i'm actually trying to understand is how those backhaul RF front-ends actually process a large bandwidth signal, when it is down converted back to their "regular" network processors with the slower clock rates?
Is it uncompressed data that is compressed later, is it being multiplexed?

Thanks again,
P.
 

wanghaonan

Newbie level 3
Joined
Nov 6, 2009
Messages
3
Helped
0
Reputation
0
Reaction score
0
Trophy points
1,281
Activity points
1,294
Although the carrier frequency is up to 60Ghz, the signal it carrys is much lower than that, may be low enough for the "regular" network processors.
 

amir88

Advanced Member level 4
Joined
Nov 4, 2009
Messages
118
Helped
13
Reputation
26
Reaction score
8
Trophy points
1,298
Location
bandarabbas
Activity points
1,926
Another important note is that in high frquency we've got greater B.W.,for example at 6GHz the B.W. is ~60MHz
 

polo536

Newbie level 4
Joined
Feb 1, 2009
Messages
5
Helped
1
Reputation
2
Reaction score
0
Trophy points
1,281
Activity points
1,300
i have a short pdf can be useful for u
 

Status
Not open for further replies.
Toggle Sidebar

Part and Inventory Search

Welcome to EDABoard.com

Sponsor

Top