3G/4G modems - Alternatives?


I will search through what I’ve already been past. I didn’t give it much of a look because it wasn’t M.2. There are plenty of chips that use LCC that can be socket mounted or surface mounted.

MobileTek L620


This package is smaller. Definitely smaller than M.2.
Digi Xbee LTE-M

Sorry. I forgot the link.

The standard for cellular M.2 is to use the back plate for heat dissipation so the heat management for M.2 is already designed in the card. Unless Purism isn’t using an industry standard/best practice/accepted industry procedure we can use any M.2 module that is compatible with the main board.

Again though, after talking with manufacturers, M.2 isn’t being adopted in the industry.


The Quectel BC66 (17.7×15.8×2.0 mm) is only designed for surface mounting, but you have more cooling options on a motherboard and you can make the chip package smaller. If you could cool that same chip properly on a plugin card, Quectel would offer it on a half-sized mPCIe card (30x26.8 mm), but no manufacturer does, whereas many manufacturers offer Wi-Fi/Bluetooth on half-sized mPCIe cards.

Laptop manufacturers have every reason to want to solve this problem. They want to make one laptop model and change the cellular modem for every region/provider, but they have all stuck with the larger 3042 M.2 and full-sized mPCIe cards for a reason. Laptop makers could save a ton of money by designing a surface mounted socket for the cellular baseband, but none have done it, and I have to assume that figuring out how to cool a socketed chip has been the problem. You need to clamp down a graphite sheet, a copper sheet or a heat pipe on top to pull away the heat. Huawei reports that 5G uses 2.5 times more energy than 4G, so this is going to be an even greater problem in the future.


Cooling is a problem. Even Samsung and Apple haven’t been able to get it right with all their money that’s put into R&D.


A problem yes. One that we don’t need and shouldn’t create for ourselves.

3 seconds to download a 2 hour movie. Great if we are downloading a ton of movies to watch offline. Although I’m sure it takes longer then 3 seconds to pick witch movie to watch. If you’re streaming that speed is wasted.

I know movies isn’t the only thing 5g is for but for most users it is probably the task that uses the most bandwidth. I’ll be forced to use 5g one-day because 4g will be switch switched off to free up frequencies for sub6. The high speed mmWave can remain exclusively for smart cars and cities.


I totally agree. At this point, S. Korea, Singapore, Netherlands and Norway have 4G download speeds that average around 50 MBit/s. Implementing 4G around the world is a much better goal than 5G, which will only work in the center of cities anyway and will probably cause health problems for the millions of people who have to live next door to the 5G microstations.

Frankly, 5G is mostly marketing BS, so that the smartphone industry can have the next big thing to jump start a stagnant smartphone market that is no longer growing. It is all about convincing people that they need something new and that their existing phone isn’t good enough.


This is a LTE-M Module.
There’s a significant difference between LTE Cat-M and the LTE you expect to use in a mobile device.

LTE-M is a separate Standard for low-powered sensor-type devices and only supports low-power ultra-low-datarate applications.
No web-browsing, calling, chatting, … over LTE-M, it doesn’t deliver the datarate.

This is also reflected in the hardware, a design goal of LTE-M was to significantly reduce the required hardware, and thus LTE-M hardware is much smaller, much cheaper, uses less power - but just doesn’t have the required features to be used in phone-type hardware.

Just to make this clear: while LTE-M could support up to 1 Mbps, in practice this will never be reached.
We’re talking average data rates of about 100 kbps.


The BC66 is a NB-IoT module, which while based on LTE, is a significantly different technology.
NB-IoT devices are not capable of being a phone modem.
They can’t do voice calls, they can’t even do TCP transmissions.
NB-IoT is a standard for sensor-type devices and can deliver about 10-20 Kilobits per second.
You can send sensor data multiple times a day, but you couldn’t open a webpage, send a matrix message or do anything you expect to do with a phone.


5G is a real thing, but people are generally misinformed about what it actually is, largely due to poor reporting and marketing gone out of hand.

5G is a capacity layer. Most of the worlds 4G networks are run at capacity, and people need more. Significantly more.
That’s what 5G is here for; bringing larger bandwidth, especially for densely populated areas where LTE can barely cope anymore.

Fundamentally 5G is so similar to LTE that it’s barely new technology, especially the early deployments.
It it breaks some assumptions you could make for LTE, and requires support for significantly broader channels, more different frequencies and a lot more compute power.
That’s why new hardware is inevitable, the current LTE hardware just doesn’t have the capacity.

That said, right now LTE is fine, 5G is there to take the load off. The handset-manufactures will of course be happy to be able to sell you a new device. While most people will not need a 5G handset in a while, there are 2 significant reasons why it’s a good thing:

  1. The heavy users can shell out the big bucks for the newest tech and get what they want, while also taking load of LTE for the other users to enjoy.
  2. 5G will be widely deployed in the future and the early adopters help financing this - and all future users will profit; even those that can now rightly say: LTE is enough. It was the same with LTE; at some point 3G was enough.


LTE-M is capable of handling VoLTE and SMS. Data rates are low but we can’t have everything.


I should have noticed that it isn’t a standard LTE chip. That explains why the chip package is smaller than all the others that we looked at.

Granted that we should probably be arguing about specific aspects of 5G, rather than just saying “5G,” because it is big standard that involves many things.

Here are the problems as I see it:

  1. mmWave should not be permitted. The US government should free up frequencies in the below 6 GHz space like every other country is doing if it wants 5G. If the US government wants to use mmWave, we should demand health studies to prove that it is safe. Anything can block the mmWave signal and you have to put mmWave antennas on all four edges of the phone, and then you have to put microstations every 250 meters just to implement it. This is insane and we have no idea what will be the health effects. mmWave will have a very limited range and by very costly compared to using the below 6 GHz frequencies.
  2. We have a little better idea what happens to people living next to sub-6GHz cell towers, and we know that some people have real problems. Shenzhen is supposedly the model for 5G implementation, and they are planning 24,000 macro-stations and 21,000 micro-stations, so everyone in the city will be within 200 meters of a station. Do you want to live next to a 5G stations? I know that I don’t.
  3. Huawei says that its 5G cellular baseband chip uses 2.5 times more energy than its 4G chip, and its 5G phone uses 2 times more energy than its 4G model. If all 3 billion smartphones in the world double their energy consumption by moving to 5G, think about the amount of GHG emissions and the amount of extra fossil fuel extraction that will cause. Huawei had to use an expensive 0.4mm copper sheet for heat dissipation, rather than a cheap graphite sheet or heat pipes. Multiply 2 grams of copper by 3 billion phones and you start to see the problem. Extracting a kg of virgin copper emits 25 kg of GHGs. We only have 60 years of copper left (at current extraction rates with today’s reserves at current prices). As the price of copper goes up, more reserves will be economically viable to extract, but we will be using low-grade laterite ores which have a much greater environmental impact to extract per kg of copper than today’s ores.
  4. 5G will make billions of people junk their current phones and buy new models. A Greenpeace study calculates that the manufacturing of smartphones and tablets in 2014 consumed 9.4% of the world’s primary production of cobalt in 2014, and cobalt is essential for making the transition to 100% renewable energy because it is used in electric car and grid batteries. Mobile device production in 2014 used 1.8% of the world’s silver, 1.6% of gold, 8.9% of palladium, 1.4% of indium, 1.1% of magnesium, 2.7% of tantalum, 0.78% of tin. Each of these metals are very important. For example Indium is essential for making CIGS thin-film solar cells. Why are we wasting the world’s resources to make devices that we don’t need?
  5. 5G will increase the growing gap between the rich and the poor and the gap between the urban and rural regions. The rich who can afford expensive cellular plans in the cities will have 5G, while everyone else is left in the slow lane. We already have enough social division as it is, which is leading to the rise of dangerous right-wing populists with Fascist tendencies like Trump, Duterte, Putin, Erdogan, etc. who feed on the resentments of people who feel like they have been left behind. In place of China spending $411 billion to implement 5G, it should be spending that money to provide better 4G coverage to the entire country, so it can reduce the gap between the rich and the poor and the urban and the rural, and every country should be doing the same to reduce the social divisions.
  6. We desperately need to move to a mobile device industry which is not based on planned obsolescence, but 5G is being used by the mobile device industry and the cellular providers to promote another cycle of planned obsolescence and greater sales. Smartphone sales have finally peaked in recent years and there is some evidence that people are starting to use their phones longer before junking them. 5G is going to reverse that recent trend.
  7. 5G is creating all sorts of geopolitical tensions, since 3 of the 6 companies that make 5G equipment are Chinese and the US is using very questionable methods (like the Huawei ban) to try to hinder Chinese economic domination, especially in developing countries.
  8. 5G is creating another division between countries, and every country feels compelled to invest billions in the new technology to keep up with its neighbors. The world is going to waste trillions of dollars implementing 5G when that money could be much better spent in 4G and other infrastructure projects. Countries like the US need to be spending their resources on a Green New Deal, not 5G.

The parts of the 5G standard to make it more flexible and more efficient in the use of frequency bands are good, but there are serious environmental, social and health concerns with the other parts of 5G. Part of the reason why I helped crowdfund the Librem 5 is because it is one of the only phones on the market (besides the Fairphone) which is NOT based on planned obsolescence, so it makes me very mad that the cellular industry is promoting new standards that will make the Librem 5 obsolete in a couple years time.

The mobile industry could have implemented an evolutionary path with 4G that would have gotten faster speeds for a broader swath of the population (not just the urban rich) and wouldn’t make today’s 3 billion smartphones obsolete. At any rate, the average download speeds in the best countries (like S. Korea) is only 50 MBit/s, and the 4G standard supports up to 100 MBit/s and that could have been extended to 150 MBit/s, so you have to ask if 5G was really necessary, since we have an evolutionary path with 4G.

  1. who is John Galt ?


Fair enough.
LTE-M does indeed, in contrast to NB-IoT (Cat NB) allow VoLTE and related IMS services.
It is much closer to full LTE using a 1,4 MHz block from LTE spectrum and is essentially the lowest speed LTE variant + a few powersaving extras.

That said, while LTE-M allows this, the currently available LTE-M devices don’t, and specifically the U-Blox R410 used in the XBee module I was replying to, doesn’t.

Also, future LTE-M specific modules, even if they will support VoLTE, will likely be unusable for phone-type applications, because the power saving modes effectively mean, that you can’t be reached.
It’s fine for outgoing emergency calls though (if supported).


This forum software really doesn’t make it easy to reply to such long posts.
So I go number by number:

  1. There’s currently no reason to suspect that mmWaves in the sub 60 GHz range are a health risk, besides thermal effects. Further study is always useful, but I don’t see a reason to simply forbid it for unspecified concern.

  2. Actually we don’t know that people have problems. People claim to have problems, which is an entirely different thing. I’ve had my fair share of experiences with people who claim health effects from still unpowered radio transmitters, and there have been plenty of studies on the subject which never found actual problems, but many found psychosomatic reactions based on assumption that a radio source is active.

  3. True, 5G chips use more power - but that power is used for higher data rates. If you don’t use the higher data rate, the power doesn’t go up. This has of course also been true for LTE and UMTS at some point. GSM would be the outlier, because it was the first digital standard and very specifically designed for powersaving over performance.

  4. Billions of people junk their phones every year anyway, I don’t see 5G changing that. Nobody will replace their phones in the coming years just for 5G, that wouldn’t have replaced it anyway. When the new iPhone comes, iPhone users will buy it, no matter if it has 5G or not. And Android phones for non-experts are obsolete in 2 years time in most of the cases, and will have to be replaced rather sooner than later.

  5. 5G is a capacity layer. It’s not a service for the rich (even though in the early years it will be more expensive). The rural population will not get the same 5G capacity as the city population, but cities are just more densely populated. Build up is always done in densely populated areas first, be it streets, cable internet, mobile networks, or McDonalds franchises.
    That said, nobody in rural areas is really missing out if they just have LTE.

  6. Technology moves forward. Always has always will. While it would be nice if we didn’t have to replace our devices as often, most people don’t have to: they want to! Having new things is nice and people enjoy that.
    Omitting 5G doesn’t change that, won’t happen and wouldn’t magically change humanity.
    I don’t know if planned obsolescence is a thing or not, but real obsolescence sadly is. 5G is not the issue here. 5G has explicitly specified LTE interoperability, which means, that any future 5G site can do LTE simultaneously with no impact for LTE users, which will mean, that LTE devices will continue to be supported for at least a decade.

  7. 5G hasn’t changed anything in geopolitics. This has been going on for a long time. The US hasn’t had a equipment manufacturer for radio base stations for years, Huawei has been dominant for years (due to a huge local market, strictly protectionist government policies and an enormous R&D budget), and the trade war between the US and China has nothing to do with 5G or Huawei.
    It’s a battle for world domination and the US are (rightly) very concerned to lose theirs. 5G is an open standard, very international, and in contrast to IEEE US-Standards like WiFi and Ethernet, is not dominated by one country or even one manufacturer.

  8. International tensions due to technology are nothing new either and 5G has changed nothing.
    In the past, there have been competitions who has the largest steel industry, the largest merchant fleets, the most colonies, and generally (true even today) the most influence.
    Battling over who has the best infrastructure seems rather innocent in comparison.

In conclusion, 5G is heavily misunderstood.
It’s simply an extension of LTE and most things new in 5G were planned for LTE anyway and have been in the LTE standards for years. It’s just the consequential improvement in technology we get all the time, built to accommodate the new usage patterns that have been emerging for years.
Most of what 5G brings has been true for LTE for a while:

  • Higher Frequencies
  • Larger Bandwidths
  • Smaller Cells (and more of them)
  • Generally more radio transmissions


I also thought about that. And as I don’t really care for speeds above 50MBit/s I was wondering whether one day we might have modems with heat-throttling, or as a workaround, a daemon that throttles network throughput based on the input of a thermal sensor (effectively the same, just implemented outside the modem), to make it possible to upgrade the modem while avoiding heat problems.

A thing that is also generally misunderstood is that the needed energy (and thus the theoretical impact on humans) goes down if there are more cell towers.
I mean, isn’t it funny that people worry about the cell towers they see, but not so much about the wireless hotspots they don’t see? :wink:

Now, I was just wondering if high frequencies, as they are short-range, eat up that effect completely.
The only overview I could find quickly was here for Germany (Wikipedia), and for mobile it seems to even indicate that newer technology (LTE) uses less energy. Just the wireless 5GHz puzzled me a bit, so I don’t know what that means for 5G (*). Does somebody know about a more comprehensive table like this?

(*) Related question: does the 5G chip (modem) itself need a lot of power, or is it the transmitting unit? Actually, if it gets hot by merely receiving / processing data, that would hint it is not the transmitting part. I’m just curious. :thinking:


I’m honestly not sure if 5G chipset makers worry that much about thermal dissipation.
Throttling ist not really a thing here, because what it’s all about is short, fast, bursts. Nobody does 5 minute long transmissions at 1 Gigabit per second on a handset.
You get a short, typically few millisecond long burst, and then a long pause afterwards, which gives the chip plenty of time to cool down.
That said, I haven’t seen what the handset manufacturers actually will build.
The huge heatsink clearly is there for the CPU mainly, because that one will see sustained load.

Generally, the newer standards have much lower maximum output power.
The actual exposition is less related to output power and more to output duration. The largest power goes to sustained high speed downloads.
It is also generally true, that total exposition goes down the closer you are to the base station, because your handset will be the relevant factor, not the basestations. So smaller cells generally mean less overall power use, and less radiated power.
The larger correlation, especially nowadays would however again be the sustained rates.
If all users permanently cause high load, the overall exposition will be higher, because the base stations send a lot more, and the handsets send a lot more.

This is actually more complex. There are 2 factors: 5G requires multiple transmitters, each of them at a much lower power than typical transmitters used today, since they do beamforming.
The total output power of all transmitters combined might still be higher, since they need to achieve a high enough concentrated signal to achieve their required download speeds.
On average, 5G transmitters will use less power for the same datarate than LTE transmitters (which use less than 3G, which uses less than 2G).

Then there is the baseband, the part that does the calculations (digital signal generation), not amplification or transmission.
Here is why 5G can use a lot more power, because the baseband has a LOT of work to do, since it has to do the beamforming calculations.
It also has to calculate a lot faster to achieve the higher channel bandwidths (a 100 MHz 5G carrier requires 5 times the compute power than an otherwise identical 20 MHz LTE carrier), since a 5 times increase in bandwidth means that calculations have to be done 5 times faster. It also increases the performance by a factor of 5 (or even slightly more, wider channels are more efficient).

So yes, right now, due to limited compute performance, 5G modems will use more power, comparable to your computer which will also use more power if you have to run it at a higher clock to do fast enough calculations.


… and i’m still on edge most of the time … pun intended


This has been interesting discussing the merits of 5g and package sizes but it is a little off topic.

Purism has decided on M.2. That is what we have to work with.

Unless the chosen module is customised in some way preventing us from using modules from other vendors we have a few options available.


Accordingly, anytime soon it would be great (in-house support is preferred for myself) to find out how it looks like with the production of Gemalto Cinterion PLPS9-W (LGA chip) and if it would be possible to replace Gemalto Cinterion PLS8-E (or PLS8-US) with it eventually by using the same M.2 card (M.2 connector plate compatible with Gemalto 156 pad LGA mount). Again, I am not expert but some further forum opinions and enlightening on the possible alternative supporting Band 28 is welcome.
IMO, for you in Asia-Pacific region showing some kind of additional positive intention to support the required LTE B28 ( 700 APT) frequency band was due to yesterday and while for us in Europe such requirement is something that is definitely coming.


New certified one (04-Jul-2019) having name Gemalto Cinterion ALAS5-W is bringing additional UTRA FDD IX (Japanese version of 3G UMTS1700) with it but otherwise supporting the same frequencies like Gemalto Cinterion PLPS9-W.