[Cialug] Mediacom Business Cable

[Zachary Kotlarek]

On Dec 10, 2010, at 11:37 AM, Nathan C. Smith wrote:

> I was wondering if the technology was somehow similar to DSL or what caused the asymmetrical requirement.  Is this true of all Cable-Internet technologies?  The price looks good until you uncover the bandwidth issue.


There are two main reasons:

1.  Cable connections are frequency-division duplex (like DSL) and most configurations allocate more bandwidth to downlinks than uplinks. This is a policy decision by the provider, and could be changed if they were so inclined. Presumably the selected the ratio to meet their marketing goals and customer usage patterns.

2. DOCSIS says downlinks use QAM-64 or QAM-256, while uplinks can use anything from QPSK to QAM-32 (or to QAM-128 in DOCSIS 3). So assuming no interference and the same bandwidth allocation for up and down links, downlinks can transmit more data. This is a policy decision by DOCSIS that is I suspect is backed by actual technological limitations in consumer equipment --- lower power, higher noise, etc. --- that prevent reliable transmission denser encodings.

	Zach

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