1. IEEE 802.21 MEDIA INDEPENDENT HANDOVER
Title: Multi-Radio Power Management
Date Submitted: July 15, 2008
Presented at IEEE session #27 in Denver
Authors or Source(s): Behcet Sarikaya (Huawei), Dennis Edwards (CoCo), Anthony Chan (Huawei), James Han (Motorola), Michael Williams (Nokia), Scott Henderson (RIM), Farrokh Khatibi (Qualcom)
Abstract: MRPM Tutorial

2. IEEE 802.21 presentation release statements
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The contributor is familiar with IEEE patent policy, as outlined in Section 6.3 of the IEEE-SA Standards Board Operations Manual < and in Understanding Patent Issues During IEEE Standards Development

3. Problem Statement Multi-mode terminals are becoming popular
Multi-mode terminals consume more power
Each interface power is managed independently of the other radios
Integrated radio management is needed
The most power savings can be obtained by powering off not needed radios
Possibly keep one active and power off others
Connection managers being used in terminals
They are proprietary
They don’t make use of any network signaling

4. Battery life for multiple interfaces without MPRM
Active
Standby
Normal sleep
Deep sleep
Off
Battery life (approximate only)
Remarks
1 interface A
X hrs
Reference
Y hrs
2 interfaces
A,B
W < Y hrs
Lose Y-W hrs of standby mode battery life
3 interfaces
A,B,C
T < W hrs
Lose Y-T hrs of standby mode battery life
Z hours
U < Z hours
Lose Z-U days of sleep mode battery life
V < U hours
Lose Z-V days of sleep mode battery life
>> Z hours

5. Battery life for multiple interfaces with MRPM
Active
Standby
Normal sleep
Deep sleep
Off
Battery life (approximate only)
Remarks A
X hr
Reference (single interface)
Active/On B
Y > X hrs
Z > X hrs
W > X hrs
X hrs
U hrs
standby
T > U
2 interfaces
B,C
R > T
3 interfaces
S > R
Q hr
sleep
P > Q
M > P Q

6. What MRPM Can Do to Help? Powering off interfaces
Develop power saving enablers that operators can use
Amend to support power management of the multi-radio mobile node interfaces.
Define media-independent primitives and signaling for power management.
The signaling will be exchanged in the network among multiple radio networks including IEEE 802
Establish synergy between and MRPM

7. Powering Off Interfaces
Maximum power savings are obtained by powering off interfaces because in all other states interfaces consume power
A powered off interface can be activated again by certain means such as signaling on the system bus
Powering off interfaces is not a new idea, it’s been around since ten years or so
MRPM has to proxy the powered off interface
In cellular interfaces powered off interface should appear as “idle”
MRPM has to proxy idle mode operations
Such as idle mode entry and location update signaling

8. Multi-Radio Power Management
The purpose of MRPM is to manage multiple MN radios in a way that increases MN operating time. This goal is complementary to, but distinct from, other operating and handoff criteria
MRPM provides a mechanism for controlling the operating mode of a wireless network interface. MRPM provides a set of power management abstractions that allow tailoring each wireless technology’s operating modes to match network availability and the communication requirements of the MN user.

9. Multi-Radio Power Management
MRPM is an information source, providing link energy efficiency input to network selection decisions. The MRPM inputs may be augmented by location services to facilitate radio scheduling by the MIH Network Selection Entity (NSE), the architectural component responsible for handoff policy enforcement.

10. Scenarios Extending 802.21 CS/ES Abstract Radio Power Modes
Energy Consumption Metrics
Utilizing Location Services
Network Radio Proxy scenarios

11. Scenario-Turning off Radios for Undetected Networks
Get out of the airplane
Power on all interfaces
Connect to the first discovered network
Download neighborhood network info from MIH IS
Turn off all other radios because the detected network turned to be the only one available
Save power by using MIH IS

12. Scenarios- Energy Efficient Inputs for Network Selection
Dual radio MN
MN is currently connected to a network
2nd radio is in low power scanning mode.
When 2nd radio network is discovered which is with a different technology, hand off to it to extend battery life
determine that handing off to 2nd network will save power while satisfying current network demand.
For two networks with the same technology then parameters of both networks are consulted to find that throughput is higher on 2nd network so energy cost will be less
MN will handoff to the lowest cost for bit network
MN will power off all other radios

13. Energy Consumption Metrics‏ technical detail
IS metrics for network and link power consumption will be proposed
IE_NET_DATA_POWER_LOAD value is likely to be a fixed optimal value
LINK_PARAM_GEN values are measured quantities that reflect recent network conditions.
bit energy cost = mW * J/Ws * us/b = W*10-3 * J/Ws * s/b*10-6 = J/b*10-9 = nJ/b
DATA_POWER_LOAD
UNSIGNED_INT(2)
The type used with the IE_NET_DATA_POWER_LOAD, expressing power consumed, in mW, at the network IE_NET_DATA_RATE
Data Power Load
A new value, 5, needs to be added to the list LINK_PARAM_GEN options that specifies the power consumed, in mW, at the LINK_PARAM_GEN option 0, Data Rate
Energy Consumption
UNSIGNED_INT(4)
A new value, 6, needs to be added to the list LINK_PARAM_GEN options that specifies the energy consumed, in nJ, during the interval used to determine the value of LINK_PARAM_GEN option 3, Throughput

14. Scenario: Sparse coverage problem
Save battery life by not scanning for networks that don’t exist.
MN is in a rural area with not many networks.
MN is connected to some network queries MIH IS for a list of all networks in a relatively large geographic area.
MN knows that when it leaves current coverage area that it won’t find another network for a long time.
MN can determine its own location and uses coverage map obtained by MRPM enhanced MIH IS to know when it is approaching a new network coverage area. At that time it turns radio on and puts it in a low power scanning state. When radio detects the network it is set to the active state and connects to the network.

15. Utilizing Location Services
Use nested circular coverage models to extend the IE_POA_LOCATION element with TX_RANGE information.
MN must be able to tell its location relative to, and independently of, any network POA
GPS, gyros, ...
May be augmented by network beacons, buoys, ....
Coverage map from MIH IS and MN location combine to avoid scanning in out of coverage areas and to facilitate radio scheduling and advanced proxy services.
TX_RANGE
SEQUENCE(
UNSIGNED_INT(2),
UNSIGNED_INT(2) )
A type that contains two numbers. The first unsigned integer is the distance, R2, from a PoA where complete network coverage is available. The second unsigned integer is the maximum distance R1 to which network coverage may extend. Both values are in meters

16. Scenario: Emulate presence of a radio
Dual-mode MN
Radio A is connected to the current network A
MN wants to receive calls coming towards its radio B on network B
MRPM has to emulate MN’s presence in network B
MRPM needs to have the presence emulated using “Network Radio Proxy”

17. MRPM Architecture MN NSE 21-08-0214-01-0000 Current Network MRPM NRP
Candidate
PoA & NRPA
Current
Enabled
MIH IS
Current Network
Proxied Network
Multi-Radio Power Management Service Flow

18. Network Radio Proxy
An MRPM Network Radio Proxy (NRP) is a new entity that MRPM will define.
An NRP must be accessible to an MN over the MIH protocol via a current network PoA. The NRP makes it appear that a powered down radio on the MN has actually joined the candidate network. An NRP thus maximizes the candidate network availability while minimizing MN battery drain.
The emulation of certain functions (e.g., MN location updates) are technology specific operations and may require an NRP Agent (NRPA) to exist on the PoA of such networks.

19. Emulation Scenario: Location Update Using Active Interface
MN is moving
MN’s location is known in Network A at cell level
MN’s location in Network B needs to known at the tracking area level
This requires location updates
MRPM NRP should enable this technology dependent signaling
Signaling is done using Radio A

20. Emulation Scenario: Location Update Using Active Interface
While a proxy session is active, the MN may move from the coverage area of one PoA to another on the same network. When such a situation is identified, the NSE sends a PROXY_UPDATE to the NRP. The NRP would then change the NRPA that represents the MN on the network.
Should mobility cause the MN to switch to a third network then the NSE will send a PROXY_MOVE message to the NRP, notifying it of the network change.
Should the MN leave the coverage area of the proxy network then it will send a PROXY_LEAVE message to the NRP.

21. Network Radio Proxy Details
NRP Service descriptions will need to be added to the MIH _NET_CAPABILITIES.
The MIH NSE communicates with the NRP using the following message types:
PROXY_REPLACE,
PROXY_JOIN,
PROXY_LEAVE,
PROXY_UPDATE,
PROXY_MOVE,
PROXY_FILTER,
PROXY_TRAFFIC_PENDING, PROXY_FORWARD and
PROXY_WAKING_UP

22. Conclusions
MRPM (Officially Multi-radio Power Conservation Management) will extend
Base protocol IS
Base protocol CS & ES
MRPM will not change air interfaces in 3GPP/2 or 802 technologies
MRPM will propose new entities, e.g. NRP
MRPM will propose protocol between NRP and existing entities, e.g. NSE
More importantly MRPM will lead to power conservation for multi-radio terminals

23. Q & A?

24. BACKUP SLIDES

25. Power Management in Existing Technologies
After investigating the power management in existing technologies, one can see that the power consumptions (of Baseband Processors) are quite different from technology to technology.
The main factors impacts power consumptions and response times are
TX/RX times
Registration
Control signaling
Bearer traffics

26. Power Management in Existing Technologies

27. TR Scenario 6.1: Waking a Radio Over the Current Interface
MIH _NET_CAPABILITIES identifies candidate networks supporting NRP services for a turned off radio on the MN.
NSE uses its awareness of its own location to determine it is in range of the candidate networks.
NSE could join network or send a PROXY_JOIN request to NRP on candidate network via MIH protocol over PoA of current network. In the latter case the NRP coordinates with MN to emulate the presence of the MN on the candidate network and so initiate an NRP session.
Data destined for the turned off radio on the MN arrives at the NRP on the candidate network. The NRP intercepts the traffic and sends a PROXY_TRAFFIC_PENDING message to NSE. If the data is of interest then the NSE may decide to accept the traffic over the current interface by sending a PROXY_FORWARD message to the NRP.

28. NRP Scenarios- IP level issues
NAT boxes/firewalls in 802 networks operate in a way to consume more power on the radio, e.g. radio can not go to idle mode, has to stay active and thus consume more power
NRPA being placed before the NAT box should enable better radio operation