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doc:lps:twr-tdma [2017-07-18 15:37]
arnaud [Abstract] 		doc:lps:twr-tdma [2017-07-18 15:41]
arnaud [System performance]
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 The disadvantage is that the tag has to actively send packets, it means that two tag cannot range at the same time and so some synchronization mechanism has to be put in place to allow multiple tag to use TWR measurement concurrently. The disadvantage is that the tag has to actively send packets, it means that two tag cannot range at the same time and so some synchronization mechanism has to be put in place to allow multiple tag to use TWR measurement concurrently.
  
-With TWR-TDMA we have implemented this concurrent mode using a Time Division Multiple Access algorithm. To do so, we define a time slot width and number of time slot for the system. Each tag is assigned a time slot and is only allowed to communicate in its assigned time slot. All the tags are synchronized on the Anchor 0 clock, they use it to calculate the position, in time, of the time slots.+TWR-TDMA is implementing this concurrent mode using a Time Division Multiple Access algorithm. To do so, we define a time slot width and number of time slot per frame. Each tag is assigned a time slot and is only allowed to communicate in its assigned time slot. All the tags are synchronized on the Anchor 0 clock, they use it to calculate the position, in time, of the time slots.
  
 ===== Compiling Crazyflie for TWR-TDMA ranging ===== ===== Compiling Crazyflie for TWR-TDMA ranging =====
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 ===== System performance ===== ===== System performance =====
  
-TWR-TDMA is currently implemented with time slots of 4ms. Each time slot is used by one tag to range with one anchor. This means that the ranging rate is of //1/(0.004 * (2^TDMA_NSLOTS_BITS)// and the rate of update of the full system is //1/(0.004 * (2^TDMA_NSLOTS_BITS) * nAnchors)// where nAnchors is the number of anchors in the system.+TWR-TDMA is currently implemented with time slots of 4ms. Each time slot is used by one tag to range with one anchor. This means that the ranging rate is of //1/(0.004 * 2^TDMA_NSLOTS_BITS)// and the rate of update of the full system is //1/(0.004 * 2^TDMA_NSLOTS_BITS * nAnchors)// where nAnchors is the number of anchors in the system.
  
-The more timeslots, the less often measurements can be used to estimate the tag position and so the performance of the position estimate will deteriorate. For a great number of tag the [[doc:lps:tdoa|TDoA]] mode is better suited.+The more timeslots per frame, the less often measurements can be used to estimate the tag position and so the performance of the position estimate will deteriorate. For a great number of tag the [[doc:lps:tdoa|TDoA]] mode is better suited.
doc/lps/twr-tdma.txt · Last modified: 2021-06-24 16:54 by kimberly

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