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Deputy Mayor / Adjoint au Maire

Re: Network sharing basics



WPS is strictly for 2G networks. This is mentioned in your link:

Handsets must have access to your service provider's 2G network. At this time, 3G networks do not support WPS.

Deputy Mayor / Adjoint au Maire

Re: Network sharing basics

Thank you @sheytoon forbreaking down network sharing for those of us who didn't study in your field.


Would it be fair to compare the diagram you presented to a home network accessing internet where the router is the RAN, but the actual access to internet is controlled offsite from the ISP? I realize there are several variables as well for accessing internet, but that seems similar as there are multiple layers of control, each must be functioning for the end user to receive the service.


Re: Network sharing basics

@Jeremy_M Please consider this for the knowledge base. Assuming there are no egregious errors of course!

Great Citizen / Super Citoyen

Re: Network sharing basics

Thanks for sharing and explaining.

That was a good sunday morning coffee read :-)


Is the high cost of cellular in Canada partly due to its size (loooong cables required for the transport network between the various RAN and core and the large number of towers (eNodeB, might as well try to learn the terms) required to service all Canadian, esp in rural areas?

Mayor / Maire

Re: Network sharing basics

@sheytoon how does carrier aggregation factor into the picture?

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Deputy Mayor / Adjoint au Maire

Re: Network sharing basics


Wireline networks are quite different from wireless, but as a very high level analogy, it is similar to what you described. Though I would say the cable/DSL modem would be the "access" part of the network, not the router.


Certainly the CMTS/DSLAM and customer modem must both be working in order to get service.

Model Citizen / Citoyen Modèle

Re: Network sharing basics

Same question! So the speed different between Bell and Telus/PM is mainly because the carrier aggregation (bandwidth) and their backbone network?


I heard Telus is investing in GTA ( Is this going to significantly improve Telus network performance vs Bell.


Thank you so much for sharing!

Deputy Mayor / Adjoint au Maire

Re: Network sharing basics


Not sure exactly what the high cost is due to. I don't work on the business side, just engineering.


To recap: backhaul is the connection from the eNodeB's baseband unit (BBU) to the core network. There's 2 main types of backhaul connections for modern networks: fiber and microwave.


Bell and Telus have invested heavily in fiber, and most of their sites, especially in urban and suburban areas use fiber directly to eNodeB locations. Rural sites use microwave, and extreme rural sites use satellite backhaul, but that introduces massive latency (delay).


Rogers has fiber as well, but more microwave than Bell or Telus. Part of the reason for this is RAN sharing allows Bell/Telus to focus on building half the country with the same amount of money, so they can deploy fiber more quickly and easily.


Wind Mobile has a lot of microwave due to being a new player. Microwave is much easier and cheaper to deploy, but it doesn't provide the same capacity or reliability as fiber.


A microwave antenna looks like this. You can spot one easily on a site:

 Class 4 antenna.jpg

As we start to see massive throughput increases with LTE-Advanced and 5G, we will start to see limitations in microwave backhaul and companies like Rogers and Wind will need to catch up.

Deputy Mayor / Adjoint au Maire

Re: Network sharing basics


I'll provide a bit of background before I answer your question.


Wireless networks use spectrum that each operator has licensed from the government to broadcast.


LTE specifications allow flexible channel sizes to be deployed with the following bandwidths: 1.4, 3, 5, 10, 15, or 20 MHz. Wider channels provide faster speeds. The spectrum itself is not related to speeds. For example, 20 MHz of 700 MHz spectrum (Band 12 or 17) would be faster than 10 MHz of 2600 MHz spectrum (Band 7). But nobody owns 20 MHz of 700 MHz, so they usually own wider bandwidths at higher frequencies. That's why people generally say higher frequency spectrum is for capacity, while lower frequency spectrum is for coverage.


A company like Freedom Mobile might have 10 MHz of spectrum in Band 4, so they can deploy a single 10 MHz LTE channel or 2 separate 5 MHz channels (1 for 3G and 1 for LTE). Generally, everyone deploys the widest bandwidth possible at all times.


Example, for Band 4 in Toronto, Bell owns 10 MHz of block F and Telus owns the adjacent 5 MHz of block E.

B4 Block F owners:

B4 block E owners:


Since these blocks are contiguous (there is no gap between them), if someone owned both blocks E and F, they would own 15 MHz, which they could deploy as a single 15 MHz LTE channel, even though it's technically 2 blocks of government licensed spectrum. Bell and Telus were given permission by Industry Canada to use each other's Band 4 spectrum, so they own 15 MHz of Band 4 in most of the country, but not everywhere. That's why you don't see a 15 MHz channel for Band 4 in Halifax (Mainland Nova Scotia spectrum tier) on Bell / Telus.


As LTE traffic increases, congestion occurs and more capacity is needed to serve customer demand. There are load-balancing techniques that can be used, but another option is Carrier Aggregation (CA). This allows an operator like Bell or Telus to combine multiple channels into one logical channel.


The specifications allow up to 5 channels to be combined, and as mentioned, each channel can be up to 20 MHz wide. In an ideal scenario, this means someone can deploy 100 MHz CA with 5 carriers.



As of 3GPP Release-13, up to 32 carriers can be aggregated for a total of 640 MHz of spectrum:



In reality, operators don't own so much spectrum, so they still want to combine what they have into CA combinations. For Bell, a good example in Toronto is Band 2 (20 MHz) + Band 4 (15 MHz) + Band 29 (10 MHz). This is 3-CA or 3-carrier CA or tri-band CA, using 45 MHz of aggregated spectrum, resulting in peak download speeds of 335 Mbps.


In technical terms, the main band is called the Primary Component Carrier (PCC), and the additional bands are added as Secondary Component Carriers (SCC). You can have 1 PCC and up to 4 SCCs at one time being used. For Samsung phones, dial *#0011# and you can see the status of CA during a download session. Here you can see B2 PCC and B4 SCC1 and B29 SCC2. Channel sizes are shown as well. In this example, B2 is 15 MHz because this is in Calgary, not Toronto.



One thing to keep in mind is that the total aggregated bandwidth is very important. A single 20 MHz LTE channel (non-CA) will be faster than 3-CA of 5 MHz each (total aggregated bandwidth = 15 MHz).


The eNodeB can configure many different CA combinations very easily, and Bell or Telus can configure 5-CA today if they wanted to, but the problem is that phones are built with very specific CA combinations. Just because a phone supports B2 and B4 in non-CA (regular) mode, it doesn't mean it supports B2 + B4 CA with those specific channel bandwidths. So, you can appreciate why this is a very difficult task for operators. They need to work with phone manufacturers to build devices with very specific CA combinations. This is difficult for Canadian operators, because they are small on the global stage. Samsung and Apple are not going to build customized phones with certain CA capabilities just for Bell or Telus or Rogers. This is one of the reasons why you always see Industry Canada (IC or ISED) follow the USA spectrum regulations (FCC). This gives us a better chance to use phones designed for the USA market, which has a stronger "ecosystem".


To answer your question, CA is entirely a RAN feature, and as long as certain bands are shared by both Bell and Telus (which they are, except B30), then they can all use CA the same way.


Update: Bell / Telus now has quad-band or 4-CA with B2 (20 MHz) + B4 (15 MHz) + B7 (20 MHz) + B7 (20 MHz), for a total of 75 MHz aggregated bandwidth. They have also enabled higher-order modulation, called 256 QAM, which enables total peak download speeds close to 750 Mbps.

Deputy Mayor / Adjoint au Maire

Re: Network sharing basics


CA shouldn't be the cause of speed difference. I'm skeptical of that reasoning. Both Bell and Telus subscribers should be able to use all CA combinations today. Both operators usually have excellent backhaul and core networks, but since the experience is different between Bell and PM, I'm suspecting it might be due to the core.


The Telus press release is a bit confusing with regards to Toronto. Telus doesn't really own any RAN in the GTA, but they do own many sites in Windsor and Ottawa, which might be part of the Ontario wireless upgrades they mentioned.