From fc85f44f49859f56666358efbe1a5d09c86f88f8 Mon Sep 17 00:00:00 2001
From: Florian Kaltenberger <florian.kaltenberger@eurecom.fr>
Date: Tue, 30 Aug 2016 15:26:28 +0200
Subject: [PATCH] fixed a bug in Alamouti coding (introduced in
7bc37c5696f31f093e9346dbb46586c652c2c45c)
---
openair1/PHY/LTE_TRANSPORT/dlsch_modulation.c | 18 ++++++++----------
1 file changed, 8 insertions(+), 10 deletions(-)
diff --git a/openair1/PHY/LTE_TRANSPORT/dlsch_modulation.c b/openair1/PHY/LTE_TRANSPORT/dlsch_modulation.c
index c3ffe90513..0641d69de2 100644
--- a/openair1/PHY/LTE_TRANSPORT/dlsch_modulation.c
+++ b/openair1/PHY/LTE_TRANSPORT/dlsch_modulation.c
@@ -361,8 +361,6 @@ int allocate_REs_in_RB(LTE_DL_FRAME_PARMS *frame_parms,
else if (mimo_mode == ALAMOUTI) {
*re_allocated = *re_allocated + 1;
- // normalization for 2 tx antennas
- amp = (int16_t)(((int32_t)tmp_amp*ONE_OVER_SQRT2_Q15)>>15);
switch (mod_order0) {
case 2: //QPSK
@@ -419,8 +417,8 @@ int allocate_REs_in_RB(LTE_DL_FRAME_PARMS *frame_parms,
//((int16_t *)&txdataF[0][tti_offset])[0]+=(int16_t)(((int32_t)amp*qam16_table[qam16_table_offset_re])>>15);
//((int16_t *)&txdataF[0][tti_offset])[1]+=(int16_t)(((int32_t)amp*qam16_table[qam16_table_offset_im])>>15);
- ((int16_t *)&txdataF[0][tti_offset])[0]+=qam_table_s0[qam16_table_offset_re];
- ((int16_t *)&txdataF[0][tti_offset])[1]+=qam_table_s0[qam16_table_offset_im];
+ ((int16_t *)&txdataF[0][tti_offset])[0]+=(qam_table_s0[qam16_table_offset_re]*ONE_OVER_SQRT2_Q15)>>15;
+ ((int16_t *)&txdataF[0][tti_offset])[1]+=(qam_table_s0[qam16_table_offset_im]*ONE_OVER_SQRT2_Q15)>>15;
// Antenna 1 position n Real part -> -x1*
@@ -450,8 +448,8 @@ int allocate_REs_in_RB(LTE_DL_FRAME_PARMS *frame_parms,
//((int16_t *)&txdataF[1][tti_offset])[0]+=-(int16_t)(((int32_t)amp*qam16_table[qam16_table_offset_re])>>15);
//((int16_t *)&txdataF[1][tti_offset])[1]+=(int16_t)(((int32_t)amp*qam16_table[qam16_table_offset_im])>>15);
- ((int16_t *)&txdataF[1][tti_offset])[0]+=-qam_table_s0[qam16_table_offset_re];
- ((int16_t *)&txdataF[1][tti_offset])[1]+=qam_table_s0[qam16_table_offset_im];
+ ((int16_t *)&txdataF[1][tti_offset])[0]+=-(qam_table_s0[qam16_table_offset_re]*ONE_OVER_SQRT2_Q15)>>15;
+ ((int16_t *)&txdataF[1][tti_offset])[1]+=(qam_table_s0[qam16_table_offset_im]*ONE_OVER_SQRT2_Q15)>>15;
break;
@@ -494,8 +492,8 @@ int allocate_REs_in_RB(LTE_DL_FRAME_PARMS *frame_parms,
//((int16_t *)&txdataF[0][tti_offset])[0]+=(int16_t)(((int32_t)amp*qam64_table[qam64_table_offset_re])>>15);
//((int16_t *)&txdataF[0][tti_offset])[1]+=(int16_t)(((int32_t)amp*qam64_table[qam64_table_offset_im])>>15);
- ((int16_t *)&txdataF[0][tti_offset])[0]+=qam_table_s0[qam64_table_offset_re];
- ((int16_t *)&txdataF[0][tti_offset])[1]+=qam_table_s0[qam64_table_offset_im];
+ ((int16_t *)&txdataF[0][tti_offset])[0]+=(qam_table_s0[qam64_table_offset_re]*ONE_OVER_SQRT2_Q15)>>15;
+ ((int16_t *)&txdataF[0][tti_offset])[1]+=(qam_table_s0[qam64_table_offset_im]*ONE_OVER_SQRT2_Q15)>>15;
// Antenna 1 => -x1*
@@ -534,8 +532,8 @@ int allocate_REs_in_RB(LTE_DL_FRAME_PARMS *frame_parms,
//((int16_t *)&txdataF[1][tti_offset])[0]+=-(int16_t)(((int32_t)amp*qam64_table[qam64_table_offset_re])>>15);
//((int16_t *)&txdataF[1][tti_offset])[1]+=(int16_t)(((int32_t)amp*qam64_table[qam64_table_offset_im])>>15);
- ((int16_t *)&txdataF[1][tti_offset])[0]+=-qam_table_s0[qam64_table_offset_re];
- ((int16_t *)&txdataF[1][tti_offset])[1]+=qam_table_s0[qam64_table_offset_im];
+ ((int16_t *)&txdataF[1][tti_offset])[0]+=-(qam_table_s0[qam64_table_offset_re]*ONE_OVER_SQRT2_Q15)>>15;
+ ((int16_t *)&txdataF[1][tti_offset])[1]+=(qam_table_s0[qam64_table_offset_im]*ONE_OVER_SQRT2_Q15)>>15;
break;
--
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