Huawei BBU (Baseband Unit) for LTE/UMTS/GSM also known as the BTS 3900 / BBU 3900

My used Huawei BTS3900 LTE RAN Adventure – The Impulse Purchase

Meta: The Australian government made up it’s mind some time ago that Huawei would be blacklisted from providing equipment for 5G networks.
Several other countries have adopted the same policy in regards, and as such, deployed Huawei tech is being replaced, and some of it filters down to online auction sites…

So I kind of purchased an item described as “Huawei BBU3900” with a handful of unknown cards and 2 LRFU units, for just over $100.

My current lab setup is a single commercial picocell and a draw of SDR hardware that works with mixed results, so the idea of having a commercial macro cell to play with seemed like a great idea, I put lowball offer in and the seller accepted.

Now would be a good time to point out I don’t know much about RAN and it’s been a long time since I’ve been working on power systems, so this is shaping up to be a fun project.

I did a Huawei RAN course years ago and remembered the rough ingredients required for LTE:

  1. You needed either RRUs (Remote Radio Units) or RFUs (Radio Frequency Units) to handle the RF side of things.
    RRUs are designed for outdoor use (such as mounting on the tower) and RFUs are designed for indoor use, like mounting in a cabinet.
    I’ve ended up with two LRFUe units, which I can join together for 2x MIMO, operate on Band 28 and can put out a whopping 80W of transmit power, yes I’m going to need some big attenuators…
  2. You need a Baseband Processor card to tell the Radio units what do do.
    The card connects the CPRIs (Typically optic fiber links) between the radio units and the baseband.
    The chassis I purchased came with a stack of WBBP (For WCDMA) cards and a single LBBP card for LTE. The LBBP card has 6 SFP ports for the CPRI interfaces, which is more than enough for my little lab. (You can also daisy-chain CPRIs so I’m not even limited to 6 Radio Units.)
  3. You need a backplane and a place for the cards to live – this is the BBU3900 chassis. It’s got basic switching to allow communication between cards, a chassis to distribute power and cooling.
    (Unlike the Ericson units there is actually a backplane for communications in the Huawei chassis – the Ericsson RBS series has is just power and cooling in the chassis)
  4. Optional – Dedicated transmission card, I’ve ended up with a Universal Transmission Processor (UTRP9) with 2x Gig Ethernet and 2x Fast Ethernet ports for transmission. This will only work for GSM and UMTS though, not LTE, so not much use for me.
  5. You need something to handle main processing (LTE / Universal Main Processing and Transmission Unit (LMPT / UMPT)).
    Unfortunately the unit I’ve ended up with only came with a WMPT (For WCDMA), so back online to find either an LMPT (LTE) or UMPT (Universal (2G/3G/4G))…
  6. You need a Universal Power and Environment Module (UPEU) to power up the chassis and handle external IO for things like temperature alarms, door sensors and fire detectors. This chassis has two for redundancy / extra IO & extra power capacity.

So in order to get this running I still need quite a few components:

  • Attenuators – I’ll be able to turn the power down, sure, but not to the levels required to be legal.
  • Antennas – These are FDD units, so I’ll need two antennas for each RFU, on Band 28
  • Feeder Cables – To connect the antennas
  • SMF cables and SFPs – I’ve got a pile in my toolbox, but I’ll need to work out what’s supported by these units
  • A big -48vDC rectifier (I got the BBU3900 unit powered up with an existing supply I had, but I’m going to need something bigger for the power hungry RFUs)
  • DC Distribution Unit – Something to split the DC between the RFUs and the BBU, and protect against overload / short
  • USB-Network adapter – For OAM access to the unit – Found these cheaply online and got one on the way
  • The LTE Main Processing & Transmission (LMPT) card – Ordered a second hand one from another seller

I powered up the BTA3900 and sniffed the traffic, and can see it trying to reach an RNC.

Unfortunately with no open source RNC options I won’t be posting much on the topic of UMTS or getting the UMTS/WCDMA side of things on the air anytime soon…

So that’s the start of the adventure.

I don’t know if I’ll get this all working, but I’m learning a lot in the process, and that’s all that really matters…

Note: I think this is the course I did from Huawei on the BBU3900…

9 thoughts on “My used Huawei BTS3900 LTE RAN Adventure – The Impulse Purchase

  1. I really love reading your posts Nick!

    Sounds like you are about to invest a block of time in getting to know the complexities of Huawei infrastructure…..

    If this is anything like the Nokia gear that we have invested time and resource in, the key will be accessing all of the required management elements that are required to configure and run your hardware – without this stuff the large lump of hardware you have is an exquisitely crafted doorstop!

    To find out what you need will involve a deep web search to assemble ll of the relevant documentation for your particular kit. In the past I have found sources like Scribd a useful way of locating ‘restricted’ training material and documentation that is not normally released on the public internet.

    I think that considering how much ‘surplus’ Huawei kit is going to be circulating on the second user market over the next couple of years, any effort spent getting to grips with how to ‘re-purpose’ it for private experimentation/use will be hugely useful!

    As ever – if there is anything that I can do to assist you….

  2. Hello Nick! I have the same Huawei module in University lab. I was planning to check an it’s ability to support OpenNBAP on Iu link. I already have some dummy implementation of NBAP part of RNC according 3GPP specs. I checked it with Nokia 3G and was able to observe messages exchange and NB was in onAir state. Also, I checked RF output with spectrum analyser and there was a signal. If you are interested in bring up 3G system I could share my code. It’s written on Erlang and can be simply started.

    1. Hi Ivan,
      I’d be curious to see if we can get it going with a DIY RNC – even a dummy implementation NITB style, but I believe it’d be a rather large undertaking to implement? I could be wrong, and I’d be happy to test out any code you’ve got to see if we can get it working.

      1. Hello Nick! I’m sorry for late response. I expected that your reply will be duplicated to my e-mail and did not checked replies here. Please feel free to contact me via email: bobych(at) If you have an account on I can simply grant you access to my DIY RNC implementation 🙂

      2. @Nick
        The Iu interface of UMTS is very complex,the NBAP specifiction contains thousands of pages of different procedures&messages.That’s why current there is no any open-source RNC implementation yet

  3. Some guy at osmocom tried to implemented a very limited-set of feature RNC software for WCDMA NodeBs,Accroding to the blog,It just runs through even some advance logic of making both CS&PS calls.but unfortunately he never released that toy yet.But it at least seems like possible to handcraft some specific procedures of NBAP and make the cells alive?I guess that guy did the same way in those days.

  4. Hi Nick , how do you source your lmpt boards since there is a an eol for decade old lmpt boards . Experienced all interfaces: sfp, copper going, is there a work around ?

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