Changes between Version 3 and Version 4 of Internal/WinlabMadwifi/SampleRate


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Timestamp:
Nov 17, 2005, 7:00:01 PM (19 years ago)
Author:
kishore
Comment:

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  • Internal/WinlabMadwifi/SampleRate

    v3 v4  
    77 * sample.h
    88
     9This algorithm conducts a per-MAC destination rate control. For each different destination, link statistics are stored separately.
    910
    10 This algorithm conducts a per-MAC destination rate control. For each different destination, link statistics are stored separately.
     11Description of functions in sample.c:
     12
     13{{{
     14   I. static __inline int best_rate_ndx(struct sample_node *sn, int size_bin, int require_acked_before)
     15}}}
     16
     17The objective of this function is to return the bit-rate with the lowest avg. pkt. tx. time.
     18{{{
     19   Process information starting from the lowest rate:
     20   1. if ((avg. pkt. tx. time for this pkt. size and bit-rate <= 0) or
     21          ((packets have not been acked for this pkt. size and bit-rate) and
     22          (multi-rate retry is disabled)))
     23         process next higher bit-rate;
     24   2. if (processing 9Mbps)
     25         process next higher bit-rate; // 9Mbps is never better than 12Mbps
     26   3. if (successive failures at this rate > 3)
     27         process next higher bit-rate;
     28   4. if (avg. pkt. tx. time for this rate is lowest so far)
     29         set best_rate_index to that of current rate;
     30
     31   if (best rate index found)
     32      return best_rate_index;     
     33   else
     34      return -1;
     35}}}
     36
     37{{{
     38   II. static __inline int pick_sample_ndx(struct sample_node *sn, int size_bin)
     39}}}
     40
     41The objective of this function is to return the index of a "suitable" bit-rate that can be sampled.
     42{{{
     43   1. if (no packets have been sent successfully at any of the higher bit-rates)
     44         return (index of lowest bit-rate);
     45   2. current_tx_time = avg. tx. time for the bit-rate at which the card was operating in the previous interval;
     46   3. Process information starting from the index of the lowest rate (for (i = 0); i < max_rate_index; i++)):
     47      1. Choose 1 + the index of the last rate that was sampled + i;
     48      2. if (i == current_rate_index)
     49             proceed to next higher bit-rate;
     50      3. if (perfect_tx_time(rate(i)) > avg. tx. time (current rate))
     51             proceed to next higher bit-rate;
     52      4. if ((last tx. at rate(i) was less than 10 seconds ago) and
     53             (successive failures at rate(i) > 3))
     54             proceed to next higher bit-rate;
     55      5. if ((rate(i) > 11Mbps) and (rate(i) > current rate + 2))
     56             proceed to next higher bit-rate;
     57      6. if (rate(i) == 9Mbps)
     58             process next higher bit-rate; // 9Mbps is never better than 12Mbps
     59      7. if ((current rate == 11Mbps) and (rate(i) > 12Mbps))
     60             proceed to next higher bit-rate;
     61      8. return i;
     62}}}