Cellular Network Infrastructure » Radio Access Network » OsmoTRX

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h1. LimeSDR USB

The "LimeSDR":https://myriadrf.org/projects/limesdr/ is a low-cost SDR board featuring the Lime Microsystems LMS7002 RF chip.

!{width:700px}LimeSDR_transp_3.jpg!

Key characteristics include:

* RF Transceiver: Lime Microsystems LMS7002M MIMO FPRF

* FPGA: Altera Cyclone IV EP4CE40F23 – also compatible with EP4CE30F23

* Memory: 256 MBytes DDR2 SDRAM

* USB 3.0 controller: Cypress USB 3.0 CYUSB3014-BZXC

* Oscillator: Rakon RPT7050A @ 30.72MHz

* Continuous frequency range: 100 kHz – 3.8 GHz

* Bandwidth: 61.44 MHz

* RF connection: 10 U.FL connectors (6 RX, 4 TX)

* Power Output (CW): up to 10 dBm

* Multiplexing: 2×2 MIMO

* Power: micro USB connector or optional external power supply

* Status indicators: programmable LEDs

* Dimensions: 100 mm x 60 mm

h2. RF Output Power

* +11dB in gsm900 (arfcn 5)

* +3dB in dcs1800 (arfcn 871)

in dcs1800 a reduction in rx power improves phase noise (e.g. max_power_red 7). the resulting rf output will be around -6dB, but will meet phase noise requirements (<5°rms).

there is a graph from myriad showing the power vs frequency plot in this thread: https://discourse.myriadrf.org/t/limesdr-s-maximum-transmitting-power-at-different-frequencies/1649

h2. Clock

The on-board clock is a 250ppb VCTCXO.  GSM strictly requires 30ppb, but 250ppb _should_  be sufficient for laboratory use.

h3. Using external clock reference

using "clock-ref external" the clock-ref input can be fed with a 10MHz clock from e.g. a gpsdo.

the signal slope is not really important since there is a full pll which can handle sine as well as rectangle signals.

the internal clock reference should be fine for short testing in the lab(<30min) but is not stable enough for longterm use.

h1. LimeSDR Mini

The "LimeSDR Mini":https://myriadrf.org/projects/limesdr/ is a smaller, less expensive version of the original LimeSDR.

!{width:600px}limesdr-mini-1024x561.jpg!

Key characteristics include:

* RF Transceiver: Lime Microsystems LMS7002M FPRF

* FPGA: Altera MAX 10 (10M16SAU169C8G)

* EEPROM memory: 2 x 128 KB for RF transciever MCU firmware and data

* Flash memory: 1 x 4 MB flash memory for data

* USB 3.0 controller: FTDI FT601

* Rakon 30.72 MHz VCTCXO

* Continuous frequency range: 10 MHz – 3.5 GHz

* Bandwidth: 30.72 MHz

* RF Connection: 2 x SMA connectors (each can be switched between high and low frequency bands) + 1x U.FL REF CLK

* Power Output (CW): up to 10 dBm

* Dimensions: 69 mm x 31.4 mm

h2. RF Output Power

* +3dB in gsm900 (arfcn 5)

* -12dB in dcs1800 (arfcn 871)

h2. Clock

the internal clock is ok, but not stable enough (longterm) to run a gsm network. for short term lab use it should be ok. (few minutes).

h3. Using external clock reference

providing an external clock is tricky:

according to the spec from the clockchip used (ti LMK00105) the input signal needs to have "sharp rectangles 2V/ns or better".

this is a limitation of the LimeSDR mini due to no extra pll chip being present, in contrast to the LimeSDR-USB.

h2. Notes

due to some yet unknown issue with the usb bridge chip used on limesdr mini, some machines have issues getting a reliable usb connection and loose an extreme amount of packages.

since the extra bandwith of usb3 is not necessary for normal use of osmo-trx-lms, a simple fix is to force the device down to usb2.

this can be done easily by selecting a port which does not have a usb3 socket or use a usb2 only cable/extension to connect the device.

the board also gets quite warm and can make good use of an extra fan and/or some heatsinks.

h1. LimeNet Micro

!{width:700px}640px-LimeSDR-Micro_v2.1_board.png!

LimeNet Micro is a small all-in-one board combining the sdr, a gpsdo and some rf filters with a raspberry pi compute module3.

Due to the integrated gpsdo it should have no problems running tdma networks like gsm.

setup: install default raspbian (see getting started link below) and osmocom latest or nightly feeds.

config: use LNAL or LNAH for rx-path, BAND1 for tx

h2. RF Output Power

* +7dB in gsm900 (arfcn 5)

* -5dB in dcs1800 (arfcn 871)

in dcs1800 a reduction in rx power improves phase noise (e.g. max_power_red 5)

h2. Clock

do not select a specific clock on LimeNet Micro. (remove clock-ref line)

when this type of hardware is detected osmo-trx defaults to the gps synchronized clock from the fpga (gpsdo).

see led4/led5 for gps status https://wiki.myriadrf.org/LimeNET-Micro_v2.1_hardware_description#Indication_LEDs

the external reference clock input socket is currently not supported.

h2. further information

https://wiki.myriadrf.org/LimeNET_Micro

https://wiki.myriadrf.org/Getting_Started_with_the_LimeNET-Micro

https://wiki.myriadrf.org/LimeNET-Micro_v2.1_hardware_description

h1. LimeSDR PCIe

!{width:700px}limesdr-pcie-1-1_jpg_project-body.jpg!

TBD

h1. OsmoTRX on LimeSDR

In terms of OsmoTRX for LimeSDR, we now have @osmo-trx-lms@ which avoids the previously complex driver stack with UHD, SoapyUHD, SoapySDR, etc. All you need in terms of specific dependencies is:

* "LimeSuite":https://github.com/myriadrf/LimeSuite.git containing the actual drivers and utilities for LimeSDR (*version 17.09 or later required*, last release @18.06.0@ or @master@ really advised)

** for LimeSDR-mini, you will need 17.10 or later (last release @18.06.0@ or @master@ really advised)

If your distro doesn't ship with a LimeSuite new enough, it is advised that you install LimeSuite from osmocom repositories, see [[cellular-infrastructure:MacroBinaryPackages]].

{{graphviz_link()

digraph G{

  rankdir = LR;

  LimeSDR -> LimeSuite [label = "USB/libusb"];

  LimeSuite -> OsmoTRX [label = "osmo-trx-lms"];

}

}}

h3. Verifying the driver stack

You can ensure that LimeSuite recognizes your device using the *LimeUtil* part of LimeSuite:

<pre>

$ LimeUtil --find

  * [LimeSDR-USB, media=USB 3.0, module=STREAM, addr=1d50:6108, serial=0009060B00xxyyzz]

</pre>

h3. Running osmo-trx-lms with LimeSDR

If @rt-prio@ is set in .cfg file, running as root may be required.

A sample cfg file to run @osmo-trx-lms@ with a LimeSDR device can be found in @osmo-trx.git@ in @doc/examples/osmo-trx-lms/osmo-trx-limesdr.cfg@.

<pre>

osmo-trx-lms -C osmo-trx.git/doc/examples/osmo-trx-lms/osmo-trx-limesdr.cfg

</pre>

h2. Other LimeSDR related information

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