CDMA/TDMA Cellular Antennae Sharing And Power

3 comments

Rate

Shandy Active Contributor Join Date: Aug 2006 Posts: 17	CDMA/TDMA Cellular Antennae Sharing And Power 03/05/2008 7:48 PM
	Not so hypothetical situation: A cellular operator is running a site(s) with paralleled CDMA and TDMA systems sharing two antennae, one for TX and RX0 and the other RX1 (diversity). The CDMA is hitting the final output around 20 W and the TDMA combined power closer to 50 W. Question: Is it probable that the CDMA carrier could end up realizing increased performance (e.g. notably better than expected ERP of a similar system not sharing) because it is combined with the higher powered TDMA?
	Register to Reply
	Pathfinder Tags: TDMA CDMA antenna sharing

Interested in this topic? By joining CR4 you can "subscribe" to
this discussion and receive notification when new comments are added.

These comments received enough positive votes to make them "good answers".

Gavilan Guru Join Date: Sep 2007 Location: East Texas Posts: 1439 Good Answers: 31	#1 Re: CDMA/TDMA Cellular Antennae Sharing And Power 03/05/2008 10:03 PM
	Look at the harmonics. If the interference is constructive then why not? But, what does that do to the ERP of the CDMA. The conservation of energy must factor in there somewhere. Gavilan __________________ "The greater danger for most of us lies not in setting our aim too high and falling short; but in setting our aim too low, and achieving our mark." -- Michelangelo
	Register to Reply

Hottech Power-User Join Date: Nov 2006 Location: Canada Posts: 336 Good Answers: 5	#2 Re: CDMA/TDMA Cellular Antennae Sharing And Power 03/07/2008 9:48 AM
	No way. Any antenna sharing pose interference problems and require HQ filters. The two systems are radically different in spectrum management. Your proposition would imply to use wider bandwidth antennae that have lower gain. The product gain X bandwidth is a constant. The effective radiant power is the product of power and gain on a specified direction. Additionally, splitters, circulators and other required components (more connectors and feeders) are a complication that adversely effect the overall gain of a transmission link through their attenuation. In the end of the day, you have to multiply all the gains and attenuations of the components of a transmission link! Sharing a site for different systems is a common practice for land taxes, effective hight (propagation), power and other reasons. Overall, installation, operation and maintenance costs are shared, even between competitors. But technically, the only acceptable solution is to have a dedicated radiant setup for each system (separate antennae mounted at different heights on the same telecommunication tower.
	Register to Reply Good Answer (Score 2)

ethobil Power-User Join Date: Aug 2007 Location: Port Harcourt Nigeria Posts: 206 Good Answers: 3	#3 In reply to #2 Re: CDMA/TDMA Cellular Antennae Sharing And Power 03/08/2008 7:10 AM
	Good answer. In addition, the poser is equivalent to comparism between point-to-point and point-to-multipoint radio linkage, though the two set ups are not the same; the poser is primarily two distinct equipment connected to one antenna while point-to-multipoint entails one equipment connected to two or more antennae. The effective radiated power will be adversely affected, with limited coverage area for the CDMA/TDMA using one antenna as obtains in point-to-multipoint system with respect to point-to-point system. Cheers, ethobil __________________ Join us to make the world a better place: Propergate peace.
	Register to Reply

These comments received enough positive votes to make them "good answers".

Copy to Clipboard

ethobil (1); Gavilan (1); Hottech (1)

	Got Something to Say?
	Ask a Question Start a Discussion

	Search this Forum
	Communications & Electronics: Go

	Aerospace
	BioMech & BioMed
	Chemical & Material Science
	Civil Engineering
	Communications & Electronics
	Education and Engineering Careers
	Electrical Engineering
	General Discussion
	Instrumentation
	Manufacturing
	Mechanical Engineering
	New Technologies & Research
	Software & Programming
	Sustainable Engineering
	Transportation

	Site Directories
	Forum Directory Blog Directory User Group Directory RSS Feeds CR4 Rules of Conduct CR4 FAQ Site Glossary Who's Online (78 right now) Show Members