1. [Resource Allocation for IEEE 802.22b Systems]
January 2013
doc.: IEEE b
May 2013
[Resource Allocation for IEEE b Systems]
IEEE P Wireless RANs Date:
Authors:
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Sunghyun Hwang, ETRI
Sunghyun Hwang, ETRI

2. Summary Classification Statement
January 2013
doc.: IEEE b
May 2013
Summary Classification Statement
It is a partial proposal regarding the resource allocation for b systems.
Address the issues of resource allocation
Propose the resource allocation and backup channel management on a group basis
Compare the MAP overhead for group resource allocation
Mainly consider the Smart Metering Model and Real-time/near real-time video Monitoring Model as described in the b Functional Requirements Document
Sunghyun Hwang, ETRI
Sunghyun Hwang, ETRI

3. May 2013
Technology Overview
Very large number of devices, small burst transmissions
It is a burden of MAP overhead to allocate the resources to all devices individually. It is also inefficient to use random-access fully.
The solution is Group Resource Allocation (GRA)
Allocate the resources to the Group using Bitmap format
GRA is very useful for connections with a same PHY mode and with a fixed payload size
Manage the backup channel on a Group basis
Sunghyun Hwang, ETRI

4. How to make a group? (Hub-device vs. Nano-device)
May 2013
How to make a group? (Hub-device vs. Nano-device)
Hub-device is a controller of a group consisting of many Nano-devices
Hub-device (only one): access to DB, network entry with BS, identify the Group ID(GID)
Nano-device (multiple): Sync. to Hub-device and/or BS
Hub-device is mode II or mode I device, but Nano-device is mode I device only
Nano-devices has same GID, but different Device ID(DID)
Hub-device and Nano-device are similar to H-CPE and L-CPE, respectively.
Sunghyun Hwang, ETRI

5. Type of Group Fixed Group Mobile Group
May 2013
Type of Group
Fixed Group
Hub-device is fixed (e.g., on the building, house, tower)
Fixed group consisting of fixed Nano-devices (e.g., village, wind turbines)
Fixed group consisting of nomadic Nano-devices (e.g., live stocks)
Mobile Group
Hub-device is mobile (e.g., on the vehicles)
Mobile group consisting of mobile Nano-devices (e.g., vehicles, boats)
Mobile group consisting of nomadic Nano-devices (e.g., rescue crew, firefighter)
Sunghyun Hwang, ETRI

6. Transmission Example of 802.22b Resource Allocation Message
May 2013
Transmission Example of b Resource Allocation Message BS
DS-MAP including
Legacy DS-MAP-IE
US-MAP including
Legacy US-MAP-IE
L-CPE
H-CPE
H-CPE
L-CPE
DS-MAP including
GRA DS-MAP-IE
US-MAP including
GRA US-MAP-IE
L-CPE
L-CPE
L-CPE
L-CPE
Sunghyun Hwang, ETRI

7. DS/US-MAP IE for Individual RA (Legacy)
May 2013
DS/US-MAP IE for Individual RA (Legacy)
SID: 9bits
DIUC or UIUC: 6bits
Length or Duration: 12 bits
Sunghyun Hwang, ETRI

8. DS/US-MAP IE for GRA May 2013 Parameter Size (bits) Description
Resource Allocation Bitmap
Variable
(1 bits * number of devices in the group)
Indicates whether the resources are allocated to the device in a group.
The number of devices in the group is determined by the Device Bitmap Size in GRA Configuration Message.
0: not allocated in the frame
1: allocated in the frame
Resource Starting Index 11
Indicates the starting index of resource in the unit of OFDMA slot. In the DS subframe, the index starts right after the frame preamble from 0. In the US subframe, the index 0 starts from the ranging/BW request/UCS notification contention windows (not including SCW) if it exists.
Resource Size Bitmap
(3 bits * number of devices in the group)
Indicates the resource allocation size for the device in the unit of OFDMA slot.
000: 1
001: 2
010: 4
011: 8
100: 16
101: 32
110: 64
111: 128
Sunghyun Hwang, ETRI

9. (6 bits * number of devices in the group)
May 2013
DS/US-MAP IE for GRA
Parameter
Size (bits)
Description
Group DIUC Flag 1
Indicates whether the DIUC is fixed within group.
0: not fixed within group
1: fixed within group
If(Group DIUC Flag = 0) {
Group DIUC Bitmap
Variable
(6 bits * number of devices in the group) }
Else{
DIUC 6
Sunghyun Hwang, ETRI

10. MAP Overhead as Percentage of Frame
May 2013
MAP Overhead as Percentage of Frame
Individual RA (Legacy) vs. Group RA (Proposed)
Considered Network Model
Smart Metering Model
1 BS, 25 H-CPEs, 2500 L-CPEs (100 L-CPEs per H-CPE)
Max. simultaneous communication L-CPEs: 2500 (H-CPEs: 25)
Real-time/near real-time video Monitoring Model
1 BS, 250 H-CPEs, 2500 L-CPEs (10 L-CPEs per H-CPE)
Max. simultaneous communication H-CPEs: 100
Total bits per frame: 24*1440=34,560
Assuming 6 MHz BW, ¼ CP, and QPSK-1/2
Sunghyun Hwang, ETRI

11. MAP Overhead as Percentage of Frame
May 2013
MAP Overhead as Percentage of Frame
Sunghyun Hwang, ETRI

12. Management Message for GRA Configuration: GRA-CFG
May 2013
Management Message for GRA Configuration: GRA-CFG
New Message Type 41 in IEEE Table 19 Management Message
This message is carried in the payload of a MAC PDU
This message is used for GRA configuration
Create new group
Indicate the devices that is included to a group
Define the characteristics of group
Sunghyun Hwang, ETRI

13. Management Message for GRA Configuration: GRA-CFG
May 2013
Management Message for GRA Configuration: GRA-CFG
Parameter
Size (bits)
Description
Device Bitmap Size 4
Maximum number of devices that are included to a new group.
0000: 1
0001: 2
0010: 4
0011: 8
0100: 16
0101: 32
0110: 64
0111: 128
SID Bitmap
Variable
(9 bits * number of devices)
The bitmap of station ID that is included to a new group.
GID 12
Group ID to which the device is included to a group.
Group Type 1
0: Fixed Group
1: Mobile Group
Group Location 48
Latitude and longitude of a new group
Sunghyun Hwang, ETRI

14. Management Message for GRA Update: GRA-UPD
May 2013
Management Message for GRA Update: GRA-UPD
New Message Type 42 in IEEE Table 19 Management Message
This message is carried in the payload of a MAC PDU
This message is used to update the GRA configuration
The device can be added to or deleted from a group
Sunghyun Hwang, ETRI

15. Management Message for GRA Update: GRA-UPD
May 2013
Management Message for GRA Update: GRA-UPD
Parameter
Size (bits)
Description
Deletion Flag 1
Flag to indicate whether the device is added to or deleted from a group.
0: Added to a group
1: Deleted from a group
SID 9
Station ID that is added to or deleted from a group.
GID 12
Group ID to which the device is added to or deleted from a group.
If(Deletion Flag = 0) {
Device Bitmap Index 7
Indicates the index of the device in a group’s device bitmap. }
Sunghyun Hwang, ETRI

16. How to Manage the Backup Channel of Group?
January 2013
doc.: IEEE b
May 2013
How to Manage the Backup Channel of Group?
All devices within group share the same backup channel information.
Control all devices with one message simultaneously
Type of group is determined according to the mobility of Hub-device.
Using the location information from the Hub-device, the BS can identify whether the group could overlap with other group.
Sunghyun Hwang, ETRI
Sunghyun Hwang, ETRI

17. How to Manage the Backup Channel?
May 2013
How to Manage the Backup Channel?
Fixed vs. Fixed
In principle, allocate same backup channel to each group (e.g., farmhouse vs. wind turbine)
But, if they could overlap, the allocated backup channel shall be different to avoid interference among groups (e.g., farmhouse vs. village).
Fixed vs. Mobile or Mobile vs. Mobile
In principle, allocate different backup channel to each group (e.g., wind turbines vs. vehicles)
But, if they could not overlap, the allocated backup channel could be same for frequency reuse (village vs. vehicles)
Periodic monitoring to check whether groups could overlap each other
The backup channel of each group shall be updated according to the monitoring result
Sunghyun Hwang, ETRI

18. Example of Backup Channel Management
May 2013
Example of Backup Channel Management
Sunghyun Hwang, ETRI

19. Backup Channel Decision Process (@BS)
May 2013
Backup Channel Decision Process
Start
Is there any white spaces which are not being allocated to other groups?
Is there any backup channels which are being allocated to mobile groups? No
Yes
⑤ Allocate some of backup channels which are being allocated to BS
① Allocate the white spaces to target group No
Yes
Is there any backup channels which are being allocated to fixed groups?
Do they overlap each other? No No
Yes
Yes
③ Allocate some of backup channels which are being allocated to mobile groups
Do they overlap each other?
④ Allocate some of backup channels which are being allocated to fixed and/or mobile groups No
② Allocate some of backup channels which are being allocated to fixed groups
Yes
End
Slide 19
Sunghyun Hwang, ETRI
Sunghyun Hwang, ETRI

20. Management Message for Backup Channel
May 2013
Management Message for Backup Channel
Modified Backup and Candidate Channel List (Table 22 of Standard)
Syntax
Size
Notes
Backup_and_candidate_channel_list_IE_Format() {
Element ID = 10
8 bits
Length
Number of Channels in the list
For (i=0; i < Number of Channels in the list; i++) {
List of backup channels in order of priority to be used by CPEs in case of loss of communication with the BS due to incumbents. This list may also include candidate channels, in which case they will follow the backup channels in the list, and will also be included in order of priority. The number of backup channels in the list is indicated in DCD Element ID 9 (see Table 21). The list shall be a disjoint set with the current operating channel.
Channel Number [i]
GID [i]
12 bits }
Sunghyun Hwang, ETRI

21. May 2013
Conclusions
Reduction of the MAP overhead using group resource allocation: MAP overhead assuming 1000 devices
Individual RA( ): 78% of frame
GRA (Resource size=12bits, Individual DIUC/UIUC): 55% of frame
GRA (Resource size=3bits, Group DIUC/UIUC): 11% of frame
As new group or new incumbent user appears, or mobile group moves into other group, we can avoid frequent channel switching
Reduce the signaling overhead
Prevent QoS degradation due to frequent channel switching
Sunghyun Hwang, ETRI