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Re: [Discuss-gnuradio] openLTE annoucement

From: Jiao Xianjun
Subject: Re: [Discuss-gnuradio] openLTE annoucement
Date: Wed, 13 Aug 2014 08:08:04 +0000 (UTC)
User-agent: Loom/3.14 (http://gmane.org/)

Ben Wojtowicz <bwojtowi <at> gmail.com> writes:

> I am pleased to announce version 00.05 of openLTE, an open source LTE
> project (sourceforge.net/projects/openlte).  This version includes a
> gnuradio application that reads recorded I/Q downlink LTE data from a
> file, decodes MIB and SIB1, and displays the decoded information.
> This information includes:
> - Measured frequency offset
> - System Frame Number
> - Physical Cell ID
> - Number of transmit antennas
> - Bandwidth
> - PHICH format
> - PLMN Identity
> - Tracking Area Code
> - Cell ID
> - Cell Barred information
> - Reselection information
> - Frequency band
> - System Info scheduling
> - Duplexing mode
> This version requires input data to be interleaved 8-bit I and Q (I
> first) recorded at 30.72MSPS centered on an LTE channel.  Please see
> the README file for installation and usage.
> There are limitations with this version that will be addressed in the
> future.  Some of the more pertinent ones are:
> - Only handles FDD
> - Only handles normal cyclic prefix
> - Only handles DCI 1A with localized VRBs on the PDCCH
> - Only handles normal PHICH duration
> Enjoy,
> Ben


One more information I can offer is that actually we don't need 30.72Msps as
it in 3GPP spec. I have developed an LTE Downlink Receiver which works on
19.2Msps for 100RB LTE system and it decodes actual 4G/LTE (both TDD and
FDD) signal in field Beijing successfully (SIB information is parsed finally).

Why 19.2Msps is important? I think some cheap SDR front-ends will benefit
from that, such as hackRF which only support ~20Msps and 20MHz bandwidth.

The method is simple: 19.2*8/5 = 30.72, which is a general fractional
sampling rate conversion method in Digital Signal Processing.

See the project here: github.com/JiaoXianjun    LTE-Cell-Scanner project.

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