Implemented channel hopping for CX channels
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4f0f3b5fbf
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@ -7,7 +7,8 @@
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<param>
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<name>MA</name>
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<key>ma</key>
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<type>int</type>
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<value>[]</value>
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<type>int_vector</type>
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</param>
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<param>
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@ -26,6 +26,7 @@
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#include <grgsm/api.h>
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#include <gnuradio/block.h>
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#include <vector>
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namespace gr {
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namespace gsm {
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@ -48,7 +49,7 @@ namespace gr {
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* class. gsm::cx_channel_hopper::make is the public interface for
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* creating new instances.
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*/
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static sptr make(int ma, int maio, int hsn);
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static sptr make(const std::vector<int> &ma, int maio, int hsn);
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};
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} // namespace gsm
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@ -25,32 +25,35 @@
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#endif
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#include <gnuradio/io_signature.h>
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#include <grgsm/gsmtap.h>
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#include "cx_channel_hopper_impl.h"
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namespace gr {
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namespace gsm {
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cx_channel_hopper::sptr
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cx_channel_hopper::make(int ma, int maio, int hsn)
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cx_channel_hopper::make(const std::vector<int> &ma, int maio, int hsn)
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{
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return gnuradio::get_initial_sptr
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(new cx_channel_hopper_impl(ma, maio, hsn));
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return gnuradio::get_initial_sptr
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(new cx_channel_hopper_impl(ma, maio, hsn));
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}
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/*
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* The private constructor
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*/
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cx_channel_hopper_impl::cx_channel_hopper_impl(int ma, int maio, int hsn)
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: gr::block("cx_channel_hopper",
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gr::io_signature::make(0, 0, 0),
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gr::io_signature::make(0, 0, 0))
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cx_channel_hopper_impl::cx_channel_hopper_impl(const std::vector<int> &ma, int maio, int hsn)
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: gr::block("cx_channel_hopper",
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gr::io_signature::make(0, 0, 0),
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gr::io_signature::make(0, 0, 0)),
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d_ma(ma),
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d_maio(maio),
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d_hsn(hsn)
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{
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d_ma = ma;
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d_maio = maio;
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d_hsn = hsn;
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d_narfcn = ma.size();
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message_port_register_in(pmt::mp("CX"));
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message_port_register_out(pmt::mp("bursts"));
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message_port_register_in(pmt::mp("CX"));
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set_msg_handler(pmt::mp("CX"), boost::bind(&cx_channel_hopper_impl::assemble_bursts, this, _1));
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message_port_register_out(pmt::mp("bursts"));
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}
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/*
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@ -60,6 +63,75 @@ namespace gr {
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{
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}
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/**
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* Random number table used for calculating the
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* hopping sequence. Defined in GSM 05.02.
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*/
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unsigned char RNTABLE[114] = {
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48, 98, 63, 1, 36, 95, 78, 102, 94, 73, \
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0, 64, 25, 81, 76, 59, 124, 23, 104, 100, \
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101, 47, 118, 85, 18, 56, 96, 86, 54, 2, \
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80, 34, 127, 13, 6, 89, 57, 103, 12, 74, \
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55, 111, 75, 38, 109, 71, 112, 29, 11, 88, \
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87, 19, 3, 68, 110, 26, 33, 31, 8, 45, \
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82, 58, 40, 107, 32, 5, 106, 92, 62, 67, \
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77, 108, 122, 37, 60, 66, 121, 42, 51, 126, \
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117, 114, 4, 90, 43, 52, 53, 113, 120, 72, \
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16, 49, 7, 79, 119, 61, 22, 84, 9, 97, \
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91, 15, 21, 24, 46, 39, 93, 105, 65, 70, \
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125, 99, 17, 123 \
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};
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/*
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* Slow Frequency Hopping (SFH) MAI calculation based
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* on airprobe-hopping by Bogdan Diaconescu.
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*/
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int cx_channel_hopper_impl::calculate_ma_sfh(int maio, int hsn, int n, int fn)
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{
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int mai = 0;
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int s = 0;
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int nbin = floor(log2(n) + 1);
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int t1 = fn / 1326;
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int t2 = fn % 26;
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int t3 = fn % 51;
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if (hsn == 0)
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mai = (fn + maio) % n;
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else {
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int t1r = t1 % 64;
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int m = t2 + RNTABLE[(hsn ^ t1r) + t3];
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int mprim = m % (1 << nbin);
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int tprim = t3 % (1 << nbin);
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if (mprim < n)
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s = mprim;
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else
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s = (mprim + tprim) % n;
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mai = (s + maio) % n;
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}
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return (mai);
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}
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/**
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* Given MA, MAIO, HSN, and FN, decide which frames
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* to forward to the demapper.
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*/
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void cx_channel_hopper_impl::assemble_bursts(pmt::pmt_t msg)
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{
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pmt::pmt_t header_plus_burst = pmt::cdr(msg);
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gsmtap_hdr *header = (gsmtap_hdr *)pmt::blob_data(header_plus_burst);
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uint32_t frame_nr = be32toh(header->frame_number);
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uint16_t frame_ca = be16toh(header->arfcn);
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int mai = calculate_ma_sfh(d_maio, d_hsn, d_narfcn, frame_nr);
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if(d_ma[mai] == frame_ca) {
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message_port_pub(pmt::mp("bursts"), msg);
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}
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}
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} /* namespace gsm */
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} /* namespace gr */
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@ -31,12 +31,16 @@ namespace gr {
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class cx_channel_hopper_impl : public cx_channel_hopper
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{
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private:
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int d_ma;
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int d_maio;
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int d_hsn;
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std::vector<int> d_ma; // Mobile Allocation list. Contains all channels that are used while channel hopping
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int d_maio; // Mobile Allocation Index Offset
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int d_hsn; // Hopping Sequence Number
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int d_narfcn; // Length of d_ma
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int calculate_ma_sfh(int maio, int hsn, int n, int fn);
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void assemble_bursts(pmt::pmt_t msg);
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public:
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cx_channel_hopper_impl(int ma, int maio, int hsn);
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cx_channel_hopper_impl(const std::vector<int> &ma, int maio, int hsn);
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~cx_channel_hopper_impl();
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};
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