1. CX-CBP in 3.65GHz – Simulation results
Nov. 2008
CX-CBP in 3.65GHz – Simulation results
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2. 802.16h CX-CBP – Frame structure
Nov. 2008
802.16h CX-CBP – Frame structure
CX-Frame structure is shown below:
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3. CX-CBP General features
Nov. 2008
CX-CBP General features
Equal operational time assigned to each technology
10ms for each CXCBI and CXCSBI
Operation during CXCBI
Scheduled transmit opportunities
Listen-before-talk
Contention window and quiet periods
Longer slots are defined for h as compared with y
Priority is given to y
Logarithmic back-off
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4. Synchronization CX-Frame is synchronized with GPS-like time source
Nov. 2008
Synchronization
CX-Frame is synchronized with GPS-like time source
802.16h-based systems are using CXSBI in a synchronized mode
Sync of y with CXCBI is not mandated
Two operational modes
Sync. CX-CBP
The AP limits the y operation to CXCBI
See Annex in “Parameters for simulation of Wireless Coexistence in the US 3.65GHz band” document
Un-sync. CX-CBP
No limitation is imposed
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5. Nov. 2008
Parameters
Based on: IEEE /11r16, Parameters for simulation of Wireless Coexistence in the US 3.65GHz band
Scenario A “Outdoor-to-outdoor”
Offered load for each system:
In order to find the maximal capacity for each system, simulations were performed in no-interference state, and overloading each system.
The maximum throughputs derived were (for 5 MHz channel):
DL: 7.2 Mbps
UL: 4 Mbps
overall: 8 Mbps
The offered load in the interference simulation for each system was based on these relations between the maximum achievable loads, modified according to the required total load
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6. Legend Abbreviations NCX: No Coexistence Protocol
Nov. 2008
Legend Abbreviations
NCX: No Coexistence Protocol
Reference for y / h operation
SCX: Sync CX-CBP. Synchronized Coordinated Contention-Based Protocol
UCX: Unsync CX-CBP. Unsynchronized Coordinated Contention-Based Protocol
NI: No Interference
Reference for max. performance
NL: Only control elements are transmitted by the interfering system
802.16h CX-CBP: according to defined operation
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7. Nov. 2008
Cell sizes
Cell size for each system was chosen to be the minimum between its DL and UL ranges.
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8. Simulation #1 Scenario A (outdoor to outdoor) 10 users per system
Nov. 2008
Simulation #1
Scenario A (outdoor to outdoor)
10 users per system
Total offered load for both systems: 9.6 Mbps
offered load of 5.75 Mbps
375 Kbps DL per user
200 Kbps UL per user
offered load of 4 Mbps
267 Kbps DL per user
133 Kbps UL per user
5 MHz bandwidth
Retransmissions in and
The number of retransmissions is not limited
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9. Hidden Node Probability Behavior
Nov. 2008
Hidden Node Probability Behavior
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10. Hidden Node Probabilities (Mean)
Nov. 2008
Hidden Node Probabilities (Mean)
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11. Hidden Node Probabilities (10th percentile)
Nov. 2008
Hidden Node Probabilities (10th percentile)
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12. Hidden Node Probabilities (Median)
Nov. 2008
Hidden Node Probabilities (Median)
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13. Hidden Node Probabilities (90th percentile)
Nov. 2008
Hidden Node Probabilities (90th percentile)
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14. Nov. 2008
Mean Throughputs
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15. Nov. 2008
Median Throughputs
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16. Nov. 2008
Mean Latency
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17. Nov. 2008
Median Latency
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18. Nov. 2008
90th Percentile Latency
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19. Conclusions - 1 Hidden nodes Data throughput
Nov. 2008
Conclusions - 1
Hidden nodes
CX-CBP drastically improves the hidden-nodes situation for co-located and
up-link is most affected by hidden nodes
Synchronization can improve the situation
Data throughput
DL throughput is most affected by interference
CX-CBP improve the coexistence
For inter-BS distances lower than 1.5-2km, sync. CX-CBP performs better
At longer distances un-sync. CX-CBP should be preferred
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20. Conclusions - 2 Delay Downlink Up-link Nov. 2008
Both and have low latency
Up-link
– low latency
802.16
The basic latency, with no interference, is high due to limited OFDMA sub-channel capacity for each user and the very high packet size – 1500bytes
In order to increase the coverage, the up-link frame is divided equally between all the active users
The delay is maximum in case of no coexistence
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21. Simulation #2 Scenario A (outdoor to outdoor) 10 users per system
Nov. 2008
Simulation #2
Scenario A (outdoor to outdoor)
10 users per system
Total offered load for both systems: 4.8 Mbps
offered load of 2.8 Mbps
185 Kbps DL per user
98 Kbps UL per user
offered load of 2 Mbps
131 Kbps DL per user
66 Kbps UL per user
5 MHz bandwidth
Retransmissions in and
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22. Hidden Node Probabilities (Mean)
Nov. 2008
Hidden Node Probabilities (Mean)
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23. Hidden Node Probabilities (10th percentile)
Nov. 2008
Hidden Node Probabilities (10th percentile)
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24. Hidden Node Probabilities (Median)
Nov. 2008
Hidden Node Probabilities (Median)
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25. Hidden Node Probabilities (90th percentile)
Nov. 2008
Hidden Node Probabilities (90th percentile)
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26. Nov. 2008
Mean Throughputs
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27. 10th Percentile Throughputs
Nov. 2008
10th Percentile Throughputs
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28. Nov. 2008
Median Throughputs
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29. Nov. 2008
Mean Latency
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30. Nov. 2008
Median Latency
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31. Nov. 2008
90th Percentile Latency
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32. Conclusions Hidden nodes Data throughput Delay Nov. 2008
CX-CBP drastically improves the hidden-nodes situation for co-located and
up-link is most affected by hidden nodes
Synchronization can improve the situation
Data throughput
DL throughput is most affected by interference
CX-CBP improve the coexistence
When co-located, un-synch. CX-CBP improves DL by 0.5 Mbps, while degrading UL by 0.1 Mbps
Using sync. CX-CBP achieves “no-interference” throughputs for both and
Delay
Coexistence methods do not degrade the latency significantly.
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33. Simulation #3 Scenario A (outdoor to outdoor) 10 users per system
Nov. 2008
Simulation #3
Scenario A (outdoor to outdoor)
10 users per system
Total offered load for both systems: 2.4 Mbps
offered load of 1.4 Mbps
92 Kbps DL per user
50 Kbps UL per user
offered load of 1 Mbps
66 Kbps DL per user
33 Kbps UL per user
5 MHz bandwidth
Unlimited retransmissions in and
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34. Hidden Node Probabilities (Mean)
Nov. 2008
Hidden Node Probabilities (Mean)
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35. Hidden Node Probabilities (10th percentile)
Nov. 2008
Hidden Node Probabilities (10th percentile)
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36. Hidden Node Probabilities (Median)
Nov. 2008
Hidden Node Probabilities (Median)
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37. Hidden Node Probabilities (90th percentile)
Nov. 2008
Hidden Node Probabilities (90th percentile)
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38. Nov. 2008
Mean Throughputs
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39. 10th Percentile Throughputs
Nov. 2008
10th Percentile Throughputs
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40. Nov. 2008
Median Throughputs
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41. Nov. 2008
Mean Latency
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42. Nov. 2008
Median Latency
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43. Nov. 2008
90th Percentile Latency
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44. Conclusions Hidden nodes Data throughput Delay
Nov. 2008
Conclusions
Hidden nodes
CX-CBP drastically improves the hidden-nodes situation for co-located and
up-link is most affected by hidden nodes
Data throughput
Coexistence methods show no significant improvement over no-coexistence transmissions
Unsynch. CX-CBP slightly degrades the throughput without improving throughput.
Delay
Overall low latency. Coexistence methods do not degrade the latency significantly.
At low offered loads, coexistence methods are unnecessary.
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