RE: Satellite Bandwidth Questions
"Ahmed, Masuma" <masuma.ahmed@lmco.com> Mon, 04 January 1999 18:53 UTC
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Date: Mon, 04 Jan 1999 10:53:28 -0800
From: "Ahmed, Masuma" <masuma.ahmed@lmco.com>
Subject: RE: Satellite Bandwidth Questions
To: tcpsat@lerc.nasa.gov, 'Chris Metz' <chmetz@cisco.com>
Cc: "Ahmed, Masuma" <masuma.ahmed@lmco.com>
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Chris, The conversion between MHz/GHz and bps depends on the modulation scheme used for a specific RF channel. For example, the spectral efficiency is usually about 1.6 if using QPSK and about 6 b/Hz/s for 64QAM. The C/Ku/Ka bands mentioned in your email are the frequencies these bands are in and they are not the channel bandwidth that your questions referred to. For example, the RF channel bandwidth could be 100 to 500 MHz within a specific band. Therefore, when making conversion to bps you need to multiply the spectral efficiency (for the specific modulation scheme that is used) with the RF channel bandwidth. Hope this helps. Masuma Ahmed ---------------------------------------------------------------------------- ------------------- Dr. Masuma Ahmed Director, Global Broadband Services Astrolink International Limited A Lockheed Martin Global Telecommunications Venture 1272 Borregas Avenue Sunnyvale, CA 94089, USA Tel: (408)543-3623 Fax: (408) 543-3104 Email: masuma.ahmed@lmco.com <mailto:masuma.ahmed@lmco.com> , masuma@aya.yale.edu ---------- From: Chris Metz [SMTP:chmetz@cisco.com] Sent: Tuesday, December 29, 1998 8:49 AM To: tcpsat@lerc.nasa.gov Subject: Satellite Bandwidth Questions Hi- I am studying TCP over Satellite considerations and have reviewed draft-ietf-tcpsat-stand-mech-06.txt. I live in a "bits per second" world in terms of bandwidth I would like to understand how bps relates to the terms used to describe satellite bandwidth. So is there a reference somewhere or good book on satellite basics that can fill in the following terms: Band Uplink (GHZ) Downlink (GHz) Uplink (bps) Downlink (bps) C 6 4 ?? ?? Ku 14 12 ?? ?? Ka 30 20 ?? ?? I suppose I am asking how does one convert MHz and GHz into conventional bandwidth (bps) terminology. This for clearing this up for me and my apologies for the "simpleton" question. Chris Metz Consulting Systems Engineer Cisco Systems email: chmetz@cisco.com phone: 212-714-4207 pager: 800-365-4578
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- RE: Satellite Bandwidth Questions Ahmed, Masuma