Proposed Text of Device Collaboration Mode for M2M Application IEEE Presentation Submission Template (Rev. 9) Document Number: IEEE C802.16p-11/0048 Date Submitted: Source: Jinsoo Choi, Kyujin Park, HanGyu Cho, Kiseon Ryu, Jin Sam Kwak LG Electronics Re:Comment on IEEE p PWR RG document C802.16p-rg-11/0002 Abstract: This contribution provides the proposed text of device collaboration mode for M2M application to be included in IEEE p amendment document. Purpose: To be discussed and adopted in the IEEE p amendment document. Notice: This document does not represent the agreed views of the IEEE Working Group or any of its subgroups. It represents only the views of the participants listed in the “Source(s)” field above. It is offered as a basis for discussion. It is not binding on the contributor(s), who reserve(s) the right to add, amend or withdraw material contained herein. Release: The contributor grants a free, irrevocable license to the IEEE to incorporate material contained in this contribution, and any modifications thereof, in the creation of an IEEE Standards publication; to copyright in the IEEE’s name any IEEE Standards publication even though it may include portions of this contribution; and at the IEEE’s sole discretion to permit others to reproduce in whole or in part the resulting IEEE Standards publication. The contributor also acknowledges and accepts that this contribution may be made public by IEEE Patent Policy: The contributor is familiar with the IEEE-SA Patent Policy and Procedures: and. Further information is located at and. 1

Introduction  IEEE p PAR scope This amendment specifies IEEE Std medium access control (MAC) enhancements and minimal orthogonal frequency division multiple access (OFDMA) Physical Layer (PHY) modifications in licensed bands to support lower power consumption at the device, support by the base station of significantly, efficient support for small burst transmissions, and improved device authentication.  For the requirements above, device cooperation is promising for M2M from the perspective of M2M requirements Low power consumption at the device Cost-effective M2M device M2M features Low or no mobility Time tolerant data transmission Infrequent small data transmission M2M applications Smart Grid Sensors (e.g. disaster, climate, flood, trash can, etc.)  In this proposal, focusing on the first requirement about lower power consumption, Device collaboration scheme is suggested for only fixed M2M devices (i.e. M2M devices with no mobility). The application scenario of device cooperation is mainly focused on UL case to reduce M2M device transmit power consumption. The necessity of device cooperation for DL case is FFS. 2

Motivation on M2M device cooperation 3  To increase network lifetime by resolving unbalanced power consumption among fixed M2M devices For fixed M2M devices, the energy consumption and relevant battery lifetime of each M2M device will be different depending on the geometry of the devices even if the M2M devices are same type of devices (with same battery equipped) which are deployed by a same user(or service provider). In the case of the battery of cell-edge M2M devices, it is needed to replace the battery much frequently comparing with the near-cell M2M devices which is undesirable for M2M users (services providers). Device cooperation can be a candidate solution for this power unbalancing among fixed M2M devices deployed by a same user(service provider) through pathloss reduction gain. IEEE p BS Near-cell M2M device Cell-edge M2M device L1 L2 L3 L1, L3 << L2 L1 : pathloss between near-cell M2M device and BS L2: pathloss between cell-edge M2M device and BS L3: pathloss between near-cell and cell-edge M2M devices Target source device who requires low power consumption Cooperative device Figure1: Cooperative transmission with reduced pathloss

Motivation on M2M device cooperation (cont’d) 4 IEEE p BS  Battery lifetime extension for battery-limited M2M devices Device cooperation can be also useful for battery lifetime extension for battery limited M2M devices. A nearby M2M device with power source can relay the UL transmission of battery-limited M2M devices which result in path-loss gain and reduced power consumption for UL transmission of the battery-limited M2M devices. A group anchor device which may have a power source can also gather the data traffics of nearby battery limited M2M devices and forward them to the BS. In aspect of power management by the operator in fixed scenario as well as enabling efficient group control of multiple M2M devices, this concept could be more feasible to utilize device cooperation mode in M2M application. Figure2: Cooperative transmission through anchor type of device Anchor device M2M device with power source X

Scenarios for anchor type of cooperative transmission IEEE p BS Dual mode anchor source IEEE p BS Single mode anchor source link link 5 Case-1Case-2 Technology Dual-mode equipment - Source-anchor link is out of scope in p Single-mode equipment - Low cost - Power-efficient protocol used in source- anchor link - Coverage of anchor Scenario Where short range network such as link is well equipped (e.g. urban area) Where new network link is required to be settled in wide-range (e.g. rural area or rarely short range network existed) Case-1: Cooperative transmission using dual-mode anchor device Case-2: Cooperative transmission using single-mode anchor device

Design on the device cooperation in p  Main design criteria The design should be considered based on p PAR scope and SRD. The proposed scheme should not change and modify the existing operation/rule. Based on existing frame structure, resource allocation, control signaling, etc Maintaining the existing HARQ timing rule/equation There will be no critical performance impact on the other AMSs’ operation. No critical performance degradation on other AMSs who are not operated by device cooperation Require transparent operation with other AMSs’ operation  Proposed device cooperation method First define related terminologies Source M2M device Cooperative M2M device Consider required capability, especially for cooperative M2M device Listen to data/control from source M2M device Send data & control of the source M2M device to the 16p BS Design operations for cooperation mode The cooperative M2M device shall stop UL transmission during the interval when listening to the UL signal from the source M2M device. The halt interval in the cooperative M2M device may be configured based on the subframe level or radio frame level. The possible PHY impact on subframe level configuration (e.g. unnecessary symbol puncturing, long TTI usage restriction, etc), the frame level configuration is recommended. Focusing the usage of device cooperation mode on M2M devices who really require low power consumption rather than delay sensitive transmission, possible delay problem would not be critical issue. 6

Proposed mode switching for cooperative transmission  On state mode In aspect of source device Receive the DL data and control from the BS directly in DL subframes, and transmit UL data and control to the cooperative device in UL subframes. In aspect of cooperative device Receive DL data and control for itself from the BS in DL subframes, and transmit its own UL data and control to the BS in UL subframes. Additionally, it shall relay the UL data and control of the source device, received in the D2D listening interval of the previous ‘off-state’ interval, to the BS.  Off state mode In aspect of source device Conduct as power saving mode. In aspect of cooperative device Shall receive UL data and control from the source device through the UL subframe(s) (i.e. D2D listening interval). It can be also operated as power saving mode if needed. 7 Figure3: Example of frame based on/off-state switching

8 Consideration on system impact with the proposed scheme  Frame structure and resource allocation Existing frame structure can be used for both TDD and FDD cases. Based on frame-level mode switching, no new subframe type or symbol puncturing is required. No separated region to operate device collaboration mode with existing AMSs is needed.  HARQ timing rule Existing HARQ timing rule based on aligned position of assignment, data burst transmission and HARQ feedback can be applied. For M2M devices who are operated in device collaboration mode, frame level latency can occur according to defined HARQ process and error handling (b/w source and cooperative or b/w cooperative and BS) method. But, because device collaboration mode will be applied in the scenario which requires low power consumption rather than delay sensitive transmission, this impact would not be critical.  Scheduling Basically it is assumed that both source device and cooperative device receive the assignment information in their on-duration based on existing assignment method. In off duration, the cooperative device can receive the assignment information of the source device or maintain the off-state for power saving.  Grouping b/w source and cooperative device Considering fixed M2M devices within a same user (service provider), grouping b/w source and cooperative device can be set as the predefined way to avoid unnecessary signaling and scheduling overhead.

9 Conclusion  To support the requirement of low power consumption of M2M devices, Device cooperation scheme can be a good candidate solution in M2M power-limited environment. Considering efficient power management by the operator in fixed scenario as well as enabling efficient group control of multiple M2M devices, the anchor type of cooperative transmission could be more feasible way to utilize device cooperation mode in M2M application. While maintaining existing frame structure/HARQ timing/resource allocation/scheduling, we can design the operation of device cooperation mode.  To mature the design based on the proposed high-level concept, following consideration can be further studied. The detail DL/UL signal path and device operation during HARQ retransmission procedure Proper duration and its periodicity of switching mode for cooperative Tx. Control signaling Etc.

10 Proposed text Adopt the proposed text in “3. Definitions” and “ Device collaboration” sections in p PWR RG document C802.16p-rg-11/0002 as following. 3. Definition 3.x Source M2M device: The end device whom the data traffic to the BS is generated from or the data traffic generated from the BS is targeting for 3.x Cooperative M2M device: The device who helps the source M2M device(s) in UL by relaying or co- transmitting data and control information Device collaboration for M2M application Device collaboration is a technique where a certain device helps the other device’s transmission. Especially, the device collaboration is supported for lower power consumption of a specific M2M source device by reducing the UL pathloss and relevant Tx power of the source M2M device. For supporting device collaboration, the cooperative M2M device shall stop UL transmission during the interval when listening to the UL signal from the source M2M device Device collaboration mode The Device Collaboration mode is configured to support the cooperative M2M device receiving the UL data & control of the source M2M device and relaying them to the BS. Once the device collaboration is triggered, the Device Collaboration mode is configured to both of the source and cooperative M2M devices Start of the text

11 Proposed text (cont’d) Frame based on-off switching During the device collaboration mode, both of the source and cooperative devices operate with switched manner of two different device states; On-state and off-state. The interval of the ‘on-state’ and ‘off-state’ is identically equal to a frame interval (i.e. 5ms) respectively. The device state of the source device shall be cross-paired with the device state of the cooperative device, i.e. the ‘on-state’ of the source device shall be overlapped with the ‘off-state’ of the cooperative device and vice versa. Fig. x shows the example of the frame based on-off switched operation of the source and cooperative devices in device collaboration mode On-state During the ‘on-state’ interval, the source device shall receive the DL data and control from the BS directly in DL subframes, and transmit UL data and control to the cooperative device in UL subframes. The cooperative device shall also receive DL data and control for itself from the BS in DL subframes, and transmit its own UL data and control to the BS in UL subframes. And additionally, it shall relay the UL data and control of the source device, received in the D2D listening interval of the previous ‘off- state’ interval, to the BS Off-state During the ‘off-state’ interval, the source device may conduct as power saving mode. It may not receive any DL signal from the BS and transmit any UL signal. The cooperative device shall receive UL data and control from the source device through the UL subframe(s) (i.e. D2D listening interval) in ‘off-state’ interval.

12 Proposed text (cont’d) Figure x – Example of source and cooperative device operation during device collaboration mode End of the text