1. Network Entry and Initialization
2006 March
Network Entry and Initialization
IEEE P Wireless RANs Date:
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Jianwei Zhang, Huawei

2. Part 1: Network Entry And Initialization
2006 March
Part 1: Network Entry And Initialization
BS Selection When CPEs Turn on in the Overlapping Region with the Same Frequency
Jianwei Zhang, Huawei

3. Background A scenario considered:
2006 March
Background
A scenario considered:
In an overlapping area there is no active CPE. Then BSs can not communicate with each other through these CPEs. And interference maybe exist in this overlapping area
When a CPE in the overlapping area turns power on, it can not select a service BS because of interference.
For this scenario, new network entry algorithms need to be suggested.
Jianwei Zhang, Huawei

4. Different Frequency Channels Assigned in an Overlapping Area
2006 March
Different Frequency Channels Assigned in an Overlapping Area
If BS1 power > BS2 power, CPE selects BS1 as a service BS.
If BS1 power < BS2 power, CPE selects BS2 as a service BS.
If BS1 power equal to BS2 power, CPE selects a service BS through pre-determined order.
Jianwei Zhang, Huawei

5. A Frequency Assigned in an Overlapping Area
2006 March
A Frequency Assigned in an Overlapping Area
If no interference in the overlapping area :
CPE selects a service BS according to the solution introduced in the previous slide (Different frequency channels assigned in overlapping area)
If interference exists:
If interference is not serious,
The BS can utilize this CPE to communicate with each other and adjust own frequency to eliminate interference. Then CPE selects a service BS by using the solution introduced in the previous slide.
If interference in overlapping area is serious,
CPE needs to decode BS preamble signals for the following four cases:
1. Preamble signal is not coincident and PN code is different
2. Preamble signal is not coincident and PN code is same
3. Preamble signal is coincident and PN code is different
4. Preamble signal is coincident and PN code is same
Jianwei Zhang, Huawei

6. 2006 March
Simulation
Although the interference is serious in the overlapping area, CPE can decode preamble signals for the above four cases.
Jianwei Zhang, Huawei

7. A Frequency Assigned in an Overlapping Area (cont’d)
2006 March
A Frequency Assigned in an Overlapping Area (cont’d)
Interference in overlapping area is serious (cont’d):
CPE decodes the PN code, then send IE-REQ (Interference Existence-Request) to BSs to notify BSs of interference condition
BSs send ACK feedback messages to the CPE, and two BSs finish synchronization and co-existence through this CPE
BSs change own frequency to eliminate interference, then CPE select a service BS by using the solution introduced in the case that different frequency channels are assigned in the overlapping area
Jianwei Zhang, Huawei

8. 2006 March
Flow chart
Jianwei Zhang, Huawei

9. 2006 March
Conclusions
Schemes for CPE to select a service BS in various scenarios are suggested
A scheme for network entry is proposed for the case that serious interference exists in an overlapping area
Without broadcast message periods in a vacant channel, spectrum efficiency can be improved.
Jianwei Zhang, Huawei

10. Part 2: Network Entry and Initialization
2006 March
Part 2: Network Entry and Initialization
Load Balance for Different Frequencies
Jianwei Zhang, Huawei

11. 2006 March
Background
WRAN system utilizes cognitive radio technologies to identify vacant frequency bands to communicate.
Therefore when many CPEs need to make use of confined frequency resources, it makes WRAN system cell be overloaded.
To reduce this cell load, BS needs to move some CPEs in this overlapping area to another neighbor cell.
Jianwei Zhang, Huawei

12. Our Proposal 2006 March Jianwei Zhang, Huawei Cell A Cell B
CPE in cell A
CPE in cell B
Overload CPE in cell A, and be shunted to cell B
Jianwei Zhang, Huawei

13. 2006 March
Flow chart (1)
Jianwei Zhang, Huawei

14. 2006 March
Flow chart (2)
Jianwei Zhang, Huawei

15. 2006 March
Conclusions
BS can compare load status of its own cell with other cell and select flexibly target cell. While to solve overload, this proposal can achieve the purpose of utilizing frequency resource greatly.
Before shunt, BS will keep service with shunt CPEs, which will not interrupt CPEs service and can assure CPEs service continuity and QoS.
Extra cost is needed to increase and BS can directly utilize CPEs in overlapping area to finish synchronization and signalling alternation.
Jianwei Zhang, Huawei