Orhan Ergun 2 Comments

Microwave or Fiber which one is faster ? I will explain  the faster connectivity option and some of the use cases for each, deployment considerations a bit in this post. Why latency is important for some special businesses  ? Have you heard about HFT (High Frequency Trading) ? If you like the discussion points, after reading the post, share your comment, let me know it so I can write more on this subject.

 

Microwave which is also known as Radio links have been used by many companies for decades. Most of the Mobile (Cellular) networks use microwave to connect their cell towers to their backhaul networks.

 

For mobile operators, a reason using microwave is not the speed which microwave provides.  It is used to connect their remote sites (Rural areas) , because microwave is a faster and cheaper deployment option compare to fiber. (Reliability and security is a different aspect which we will not discuss in this post).

 

When more capacity (bandwidth) is required, fiber becomes more economical. Actual cost of fiber deployments is laboring cost. Digging a trench and laying the fiber , getting the required permissions from the land owners and from the municipalities.

 

You have to dig a trench that’s hundreds (or thousands) of kilometers long, or lease access to ducts that have already been laid by infrastructure companies.

 

Geography of the land is very important for the fiber deployments. For example,  when faced with a mountain or river, do you go straight across at great expense, or do you make a diversion to the nearest bridge or tunnel?

 

Combine all of these factors and you’ll understand why most of the world’s terrestrial fibre networks are deployed alongside existing roads and railways. Make sense ?

 

 

Let’s go back to our initial question. Microwave or Fiber , which one is faster ?

 

 

 

microwave tower

Figure – Microwave Tower with a lot of radios

 

In other words , which one has lower latency. (More bandwidth means more people can send a data at the same but faster means lower latency)

 

A radio signal travelling through air at just under the speed of light (299,700km per second). Through a glass or plastic fibre, where light has to bounce along the refractive index rather than travel in a straight line, the speed of light is reduced to around 200,000km/s.

 

This fact is known by transport network engineers but not by the most of the network engineers.

 

Why this is important ?

 

Let’s say we have two building which have a 200km distance between.

 

With microwave (radio signal through air) latency between the two buildings would be 1,064 millisecond or 1064microsecond

 

With fiber, a latency between the buildings would be 1.594 millisecond or 1594microsecond.

 

Yes, microwave is 50% faster than fiber.

 

But really, is 500 microsecond difference is required ?

 

Yes, in fact for some business it is a lot.

 

Have you ever heard HFT (High Frequency Trading) ?

 

I will not explain the details of HFT networks in this post but I promise I will do that too, you can remind me if I don’t 🙂 But let me tell you a bit why even 500 microsecond would be very important for them.

 

In HFT business end to end latency is called tick-to-trade latency.

 

Tick is market data and trade is a buy/sell or any other type of order (Tick data flows from the stock exchanges to the HFT company , trade data flows from the HFT to stock exchanges)

 

And whole business rely on having a faster network than any other company in the market. Having an information from the exchanges, carrying it through the network to your servers , processing it and taking an action based on algo (Algorithm but in HFT environment there are tons of jargon) all happen under less than a 100microsends.

 

In fact some HFT vendors claim that they provide tick-to-trade latency as less than 50microseconds.

 

Transport medium such as microwave and fiber contributes to the propagation and serialization delays.

 

Propagation delay is what I explained above, how long it would take to carry data between point A and B. Microwave is winner in our comparison.

 

Serialization delay means, how long it would take to place a data into a wire from the networking device.

 

It is known fact 10G fiber has much lower serialization delay than 1G fiber.

 

To be more precise, for 128- byte data 1G (Gigabit Ethernet) serialization delay is 1 microsecond, 10G serialization delay is 0.1 microsecond. It seems that this is not a large difference but you should consider that the delay would be accumulated at every port. In general, companies that desire to deploy low-latency infrastructures would implement 10 Gigabit Ethernet wherever possible. Especially in the HFT (High Frequency Trading) business.

 

 

 

 

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