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Half or Full Duplex?


(Time Division Multiplex)
(Frequency Division Multiplex)


A decade ago, full duplex ultra highspeed point-to-point technologies only existed in Free Space Optics hardware.  The alternatives were limited to lease line, buried fiber, licensed microwave, or else just settling for a low end 802.11b (2.4GHz) “consumer grade” low speed link.

It made the choices pretty straight forward. When timing, budget, and true performance requirements were assessed; one of the above popped up to the top of the list pretty quickly.

But not now.  The alternatives are abundant.  And Siklu is at the forefront in developing fixed wireless solutions at both a street-level (single base to multiple end locations) and rooftop (now 10 Gbps full-duplex, AES encrypted).   Selecting the optimal solution is key in achieving the highest levels of reliability possible.

What is Half-Duplex (Time Division Multiplex)?
Although duplex systems involve two devices that can both send and receive communications, they can’t always do so at the same time. A half-duplex system means that a device cannot send and receive information simultaneously. Hence, when a device is transmitting, it cannot receive, and vice versa.  Walkie-talkies are a good example of this. When you press the button to speak, you can only transmit. Therefore, you can’t receive a transmission until you complete your own transmission and push the release the button. WiFi, Sub6 and Microwave RF communications often run at half-duplex systems. From a practical perspective, this means that communications and data transmissions take twice as long.

What is Full-Duplex (Frequency Division Multiplex)?
Full-duplex communication systems use multiple frequency ‘bands” which allow transmission and reception to occur simultaneously. Telephones fit this category because you can both speak and hear the person on the other end of the line at the same time.
Full-duplex systems are superior to half-duplex because they are able to cut down data-transfer time.  Further, only full-duplex can support today’s VOIP calling systems.  

In a nutshell, here is a brief “high-altitude” technology comparison that may be helpful:





Sub-6 RF Time Division Multiplexed RF Lowest cost / longest distance Lower throughputs (<100 Mbps, latency) Sub-6 frequencies face major interference in urban areas
Microwave RF Time Division Multiplexed RF 100-500 Mbps, less crowded freq. Freq. 6-38 GHz
Large Dishes, require FCC approved fully licensed path planning
Millimeter Wave RF Frequency Division Multiplexed RF True 1.0 to 10.0 GigE full duplex, lowest cost per databit Shorter distance, only a ‘lite’ FCC license required


So, which should you select? It really gets down to how you will use the link, which likely drives your priorities:

-Security policy
-Availability requirement (9’s)

And in addition to the above, your particular physical environment (geographic location, mounting, link distance) also impact both optimal technology selection, as well as make/model alternatives.

Wouldn’t a field experienced recommendation come in handy?

That’s why Siklu Direct is here.  To serve you when you need us.

Get a QuickQuote now.