From 267214a06db4f64149f8b5343c49ea2d4bd12138 Mon Sep 17 00:00:00 2001 From: rpp Date: Wed, 10 Jun 2015 11:49:55 +0200 Subject: [PATCH] Implemented channel hopping for CX channels --- grc/receiver/gsm_cx_channel_hopper.xml | 3 +- include/grgsm/receiver/cx_channel_hopper.h | 3 +- lib/receiver/cx_channel_hopper_impl.cc | 96 +++++++++++++++++++--- lib/receiver/cx_channel_hopper_impl.h | 12 ++- 4 files changed, 96 insertions(+), 18 deletions(-) diff --git a/grc/receiver/gsm_cx_channel_hopper.xml b/grc/receiver/gsm_cx_channel_hopper.xml index 77936f1..903c1a0 100644 --- a/grc/receiver/gsm_cx_channel_hopper.xml +++ b/grc/receiver/gsm_cx_channel_hopper.xml @@ -7,7 +7,8 @@ MA ma - int + [] + int_vector diff --git a/include/grgsm/receiver/cx_channel_hopper.h b/include/grgsm/receiver/cx_channel_hopper.h index 7c0750c..c8c2787 100644 --- a/include/grgsm/receiver/cx_channel_hopper.h +++ b/include/grgsm/receiver/cx_channel_hopper.h @@ -26,6 +26,7 @@ #include #include +#include namespace gr { namespace gsm { @@ -48,7 +49,7 @@ namespace gr { * class. gsm::cx_channel_hopper::make is the public interface for * creating new instances. */ - static sptr make(int ma, int maio, int hsn); + static sptr make(const std::vector &ma, int maio, int hsn); }; } // namespace gsm diff --git a/lib/receiver/cx_channel_hopper_impl.cc b/lib/receiver/cx_channel_hopper_impl.cc index 10371ab..3e23910 100644 --- a/lib/receiver/cx_channel_hopper_impl.cc +++ b/lib/receiver/cx_channel_hopper_impl.cc @@ -25,32 +25,35 @@ #endif #include +#include #include "cx_channel_hopper_impl.h" namespace gr { namespace gsm { cx_channel_hopper::sptr - cx_channel_hopper::make(int ma, int maio, int hsn) + cx_channel_hopper::make(const std::vector &ma, int maio, int hsn) { - return gnuradio::get_initial_sptr - (new cx_channel_hopper_impl(ma, maio, hsn)); + return gnuradio::get_initial_sptr + (new cx_channel_hopper_impl(ma, maio, hsn)); } /* * The private constructor */ - cx_channel_hopper_impl::cx_channel_hopper_impl(int ma, int maio, int hsn) - : gr::block("cx_channel_hopper", - gr::io_signature::make(0, 0, 0), - gr::io_signature::make(0, 0, 0)) + cx_channel_hopper_impl::cx_channel_hopper_impl(const std::vector &ma, int maio, int hsn) + : gr::block("cx_channel_hopper", + gr::io_signature::make(0, 0, 0), + gr::io_signature::make(0, 0, 0)), + d_ma(ma), + d_maio(maio), + d_hsn(hsn) { - d_ma = ma; - d_maio = maio; - d_hsn = hsn; + d_narfcn = ma.size(); - message_port_register_in(pmt::mp("CX")); - message_port_register_out(pmt::mp("bursts")); + message_port_register_in(pmt::mp("CX")); + set_msg_handler(pmt::mp("CX"), boost::bind(&cx_channel_hopper_impl::assemble_bursts, this, _1)); + message_port_register_out(pmt::mp("bursts")); } /* @@ -60,6 +63,75 @@ namespace gr { { } + /** + * Random number table used for calculating the + * hopping sequence. Defined in GSM 05.02. + */ + unsigned char RNTABLE[114] = { + 48, 98, 63, 1, 36, 95, 78, 102, 94, 73, \ + 0, 64, 25, 81, 76, 59, 124, 23, 104, 100, \ + 101, 47, 118, 85, 18, 56, 96, 86, 54, 2, \ + 80, 34, 127, 13, 6, 89, 57, 103, 12, 74, \ + 55, 111, 75, 38, 109, 71, 112, 29, 11, 88, \ + 87, 19, 3, 68, 110, 26, 33, 31, 8, 45, \ + 82, 58, 40, 107, 32, 5, 106, 92, 62, 67, \ + 77, 108, 122, 37, 60, 66, 121, 42, 51, 126, \ + 117, 114, 4, 90, 43, 52, 53, 113, 120, 72, \ + 16, 49, 7, 79, 119, 61, 22, 84, 9, 97, \ + 91, 15, 21, 24, 46, 39, 93, 105, 65, 70, \ + 125, 99, 17, 123 \ + }; + + /* + * Slow Frequency Hopping (SFH) MAI calculation based + * on airprobe-hopping by Bogdan Diaconescu. + */ + int cx_channel_hopper_impl::calculate_ma_sfh(int maio, int hsn, int n, int fn) + { + int mai = 0; + int s = 0; + int nbin = floor(log2(n) + 1); + int t1 = fn / 1326; + int t2 = fn % 26; + int t3 = fn % 51; + + if (hsn == 0) + mai = (fn + maio) % n; + else { + int t1r = t1 % 64; + int m = t2 + RNTABLE[(hsn ^ t1r) + t3]; + int mprim = m % (1 << nbin); + int tprim = t3 % (1 << nbin); + + if (mprim < n) + s = mprim; + else + s = (mprim + tprim) % n; + + mai = (s + maio) % n; + } + + return (mai); + } + + /** + * Given MA, MAIO, HSN, and FN, decide which frames + * to forward to the demapper. + */ + void cx_channel_hopper_impl::assemble_bursts(pmt::pmt_t msg) + { + pmt::pmt_t header_plus_burst = pmt::cdr(msg); + gsmtap_hdr *header = (gsmtap_hdr *)pmt::blob_data(header_plus_burst); + + uint32_t frame_nr = be32toh(header->frame_number); + uint16_t frame_ca = be16toh(header->arfcn); + int mai = calculate_ma_sfh(d_maio, d_hsn, d_narfcn, frame_nr); + + if(d_ma[mai] == frame_ca) { + message_port_pub(pmt::mp("bursts"), msg); + } + } + } /* namespace gsm */ } /* namespace gr */ diff --git a/lib/receiver/cx_channel_hopper_impl.h b/lib/receiver/cx_channel_hopper_impl.h index 439c7bd..7a52b05 100644 --- a/lib/receiver/cx_channel_hopper_impl.h +++ b/lib/receiver/cx_channel_hopper_impl.h @@ -31,12 +31,16 @@ namespace gr { class cx_channel_hopper_impl : public cx_channel_hopper { private: - int d_ma; - int d_maio; - int d_hsn; + std::vector d_ma; // Mobile Allocation list. Contains all channels that are used while channel hopping + int d_maio; // Mobile Allocation Index Offset + int d_hsn; // Hopping Sequence Number + int d_narfcn; // Length of d_ma + + int calculate_ma_sfh(int maio, int hsn, int n, int fn); + void assemble_bursts(pmt::pmt_t msg); public: - cx_channel_hopper_impl(int ma, int maio, int hsn); + cx_channel_hopper_impl(const std::vector &ma, int maio, int hsn); ~cx_channel_hopper_impl(); };