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Transceiver52M: Reduce RACH and TSC correlation windows

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Start the correlation search window at 4 symbols before
the expected correlation peak. End the search at 10
symbols and 4 + maximum expected delay for RACH and TSC
bursts respectively.

This change lowers receive side cpu utilization while
maintaining reasonable timing jitter and accuracy tolerance.

Signed-off-by: Thomas Tsou <tom@tsou.cc>

git-svn-id: http://wush.net/svn/range/software/public/openbts/trunk@6743 19bc5d8c-e614-43d4-8b26-e1612bc8e597
This commit is contained in:
Thomas Tsou
2013-10-17 06:18:49 +00:00
parent 4bd5f6e64a
commit 914fe4e164
1 changed files with 8 additions and 8 deletions
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16
Transceiver52M/sigProcLib.cpp
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@@ -1213,8 +1213,8 @@ static int detectBurst(signalVector &burst,
*
* Correlation window parameters:
* target: Tail bits + RACH length (reduced from 41 to a multiple of 4)
* head: Search 8 symbols before target
* tail: Search 8 symbols after target
* head: Search 4 symbols before target
* tail: Search 10 symbols after target
*/
int detectRACHBurst(signalVector &rxBurst,
float thresh,
@@ -1232,8 +1232,8 @@ int detectRACHBurst(signalVector &rxBurst,
return -1;
target = 8 + 40;
head = 8;
tail = head;
head = 4;
tail = 10;
start = (target - head) * sps - 1;
len = (head + tail) * sps;
@@ -1266,8 +1266,8 @@ int detectRACHBurst(signalVector &rxBurst,
*
* Correlation window parameters:
* target: Tail + data + mid-midamble + 1/2 remaining midamblebits
* head: Search 8 symbols before target
* tail: Search 8 symbols + maximum expected delay
* head: Search 4 symbols before target
* tail: Search 4 symbols + maximum expected delay
*/
int analyzeTrafficBurst(signalVector &rxBurst, unsigned tsc, float thresh,
int sps, complex *amp, float *toa, unsigned max_toa,
@@ -1283,8 +1283,8 @@ int analyzeTrafficBurst(signalVector &rxBurst, unsigned tsc, float thresh,
return -1;
target = 3 + 58 + 16 + 5;
head = 8;
tail = head + max_toa;
head = 4;
tail = 4 + max_toa;
start = (target - head) * sps - 1;
len = (head + tail) * sps;