Alpha Omega Wireless Blog

Is Wireless True Ethernet Throughput? - The 5 Misconceptions - Part 5

Posted by Joe Wargo on Sat, Mar 20, 2010 @ 04:03 PM

After a decade of designing, selling, and installing outdoor wireless bridge systems I consistently come across five reoccurring questions that all clients ask and their misconceptions. Each week I'll present one of the five questions and answer them in plain English and put the misconceptions rest.

Question 5: Is Wireless True Ethernet Throughput?

Answer: Yes!

Wireless point to point bridge networks can provide true usable Ethernet throughput from T1 speeds to over GigE Full Duplex (gigabit wireless). Wireless Point to Multipoint networks can provide T1 speeds up to 170Mbps+ aggregate throughput. Wireless mesh Networks can provide up to 25Mbps+ aggregate throughput. These are true usable throughputs.

Note: When evaluating wireless backhaul systems it is important to cut through all the marketing and look at the actual specifications of a chosen system. Many times we see the product marketing rounding up actual values or using the data burst rates of a radio system, rather than the actual usable data throughput.

Outdoor wireless backhaul networks can provide true low latency, high speed native  Ethernet connectivity. Think of wireless connectivity just as invisible copper or fiber. The value of wireless networks is that they can provide a more direct path of connectivity. This is true when looking at point to point wireless bridges. In the case of leased line connectivity, a clients network path may go through multiple CO's (central offices) or multiple switching locations in order to create a land line point to point network. 

A great example of this happens when some one sets up a Spanning Tree Network using wireless backhaul as a redundancy solution. Many times in this environment the network wants to converge over the outdoor wireless brdige network because it provides a more direct path (hence a lower cost average). As they say the most direct path between two points is a straight line. Also, wireless backhaul networks can have <1ms of latency, even over long distances (up to 50 miles). In most STP networks the wireless bridge network needs to be given a higher cost value in order to keep the network from automatically converging over it. Another value is that wireless point to point and point to multipoint wireless networks can provide connectivity where traditional copper or fiber cannot be installed. 

Many of the "Value Line" outdoor wireless bridge systems (e.g. the lower cost unlicensed wireless systems that use Wi-Fi chip sets) do have a distinction between the radio's data rates and the usable throughput. These radios, common among wireless mesh and point to multipoint wireless backhaul systems, do add packet headers to the IP packets that get passed across the wireless link. Commonly we see manufactures state a radio is 54Mbps, when in reality the true usable throughput is typically under 27Mbps aggregate. This is for several reasons: the radios operate in TDD (Time Division Duplexing) and they are using Wi-Fi radios that add overhead to the packet stream by encapsulating the IP packets and by sending out beacon requests.

Traditional microwave outdoor wireless backhaul systems, such as licensed microwave links, can offer true carrier grade Full Duplex (simultaneous up-link and down-link) Ethernet connectivity and can even offer traditional wayside TDM circuits. Often referred to as Carrier Grade systems, these radio systems do not carry the same overhead as Wi-Fi based radios systems. So these radio systems provide true usable Ethernet and TDM throughput. These systems can provide traditional native 100Mbps Full Duplex Ethernet connectivity or even expand up to over true GigE (Gbps) Full Duplex just like fiber.

Outdoor wireless backhaul can also provide scalable throughputs in between 10Mbps and GigE (gigabit wireless). For example, 200Mbps Full Duplex on a particular network segment which can then be spit into two 100Mbps Full Duplex segments. Wireless backhaul systems can also provide inherent security and added encryption, Layer 2 connectivity, QOS, VLAN tagging, etc.

Tags: General, Wireless 101, Licensed wireless, Un-lincesed Wireless