1. CX-CBP in 3.65GHz – Simulation results for overloaded systems
March 2009
CX-CBP in 3.65GHz – Simulation results for overloaded systems
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2. 802.16h CX-CBP – Frame structure
March 2009
802.16h CX-CBP – Frame structure
CX-Frame structure is shown below:
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3. CX-CBP General features
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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
March 2009
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. March 2009
Parameters
Based on: IEEE /11r16, Parameters for simulation of Wireless Coexistence in the US 3.65GHz band
Scenario A “Outdoor-to-outdoor”
Scenario C “Outdoor-to-indoor”
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):
Scenario A
DL: 7.2 Mbps
UL: 4 Mbps
overall: 8 Mbps
Scenario C
DL: 2.4 Mbps
UL: 2.2 Mbps
overall: 3.1 Mbps
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6. March 2009
Parameters (cont.)
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
For scenario A, Simulation 1 uses 50% higher load than 9.6Mb/s in the parameters document. The load is equivalent with a spectral efficiency of 3bit/s/Hz, including the cell margin!
For scenario C, the mandatory load of 9.6 Mbps used in Simulation 2 is more than 100% of the achievable load (7.7 Mbps)
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7. Legend Abbreviations NCX: No Coexistence Protocol
March 2009
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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8. Cell sizes (Scenario A)
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Cell sizes (Scenario A)
Cell size for each system was chosen to be the minimum between its DL and UL ranges.
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9. Cell sizes (Scenario C)
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Cell sizes (Scenario C)
Cell size for each system was chosen to be the minimum between its DL and UL ranges.
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10. Simulation #1 Scenario A (outdoor to outdoor) 10 users per system
March 2009
Simulation #1
Scenario A (outdoor to outdoor)
10 users per system
Total offered load for both systems: 14.6 Mbps (stressed load)
offered load of 8.6 Mbps
570 Kbps DL per user
300 Kbps UL per user
offered load of 6 Mbps
400 Kbps DL per user
200 Kbps UL per user
5 MHz bandwidth
Unlimited retransmissions in and
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11. Hidden Node Probabilities (Mean)
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Hidden Node Probabilities (Mean)
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12. Hidden Node Probabilities (10th percentile)
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Hidden Node Probabilities (10th percentile)
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13. Hidden Node Probabilities (Median)
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Hidden Node Probabilities (Median)
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14. Hidden Node Probabilities (90th percentile)
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Hidden Node Probabilities (90th percentile)
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15. March 2009
Mean Throughputs
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16. March 2009
Median Throughputs
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17. Simulation #2 Scenario C (outdoor to indoor) 10 users per system
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Simulation #2
Scenario C (outdoor to indoor)
10 users per system
Total offered load for both systems: 9.6 Mbps (stressed load)
offered load of 5.8 Mbps
300 Kbps DL per user
280 Kbps UL per user
offered load of 3.8 Mbps
260 Kbps DL per user
120 Kbps UL per user
5 MHz bandwidth
Unlimited retransmissions in and
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18. Hidden Node Probabilities (Mean)
March 2009
Hidden Node Probabilities (Mean)
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19. Hidden Node Probabilities (10th percentile)
March 2009
Hidden Node Probabilities (10th percentile)
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20. Hidden Node Probabilities (Median)
March 2009
Hidden Node Probabilities (Median)
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21. Hidden Node Probabilities (90th percentile)
March 2009
Hidden Node Probabilities (90th percentile)
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22. March 2009
Mean Throughputs
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23. 10th Percentile Throughputs
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10th Percentile Throughputs
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24. March 2009
Conclusions
At high load, SCX allows to operate at separation distances lower than aprox. 1 km for Scenario 1 and 100m for Scenario C
Hidden Node statistics is improved by SCX for y DL and h UL, as compared with NCX
SCX and UCX significantly improve the y DL throughput, for separation distances lower than 2km in Scenario A and equivalent with the cell size in Scenario C
Both SCX and UCX improve the h UL latency, as compared with NCX
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