1. Submission May 2013 BUPT Slide 1 Potential Solutions to D2D Assisted WLAN Date: May 16, 2013 Authors:

2. Submission May 2013 BUPT Slide 2 Abstract The existed WLAN can not meet the increasing data requirements. Several problems are caused for WLAN, such as low accessibility, traffic unbalance, co-channel interference, coverage hole, etc. We propose new solutions by introducing WLAN D2D

3. Submission May 2013 BUPT Slide 3 Background User Requirements: −Hundreds of Gbps rate −Seamless coverage Operator Challenge: −High OPEX for operation and upgrade to support increasing demands In the past 802.11 WNG meetings, several prospects were proposed for next generation WLAN The existed WLAN can not meet the user requirements

4. Submission May 2013 BUPT Slide 4 Current Issues of WLAN

5. Submission May 2013 BUPT WLAN D2D Wi-Fi Direct -Wi-Fi Direct is proposed to provide high rate transmission by making use of point to point communication. It holds the advantage of mobility and portability and has a safe connection

6. Submission May 2013 BUPT WLAN D2D Aspects that can be enhanced by introducing D2D -Transmission rate improvement is realized by increasing the spectrum utilization -Wi-Fi Direct occurs only on three social channel (channel 1,6,11 in 2.4GHz band); -D2D can be used to reuse the other WLAN channels by proper intererence control -Real-time traffic -Wi-Fi Direct needs to constantly scan for available device, the device discovery and group formation is a complex process -D2D discovery and communication is under control of AP or self-management in real time traffic which costs less delay

7. Submission May 2013 BUPT D2D Management AP control -Resource dispatch through AP is complex. Besides, it can not be realized when D2D users are located outside the AP coverage Distributed D2D management -Neighbor users detection and discovery based on benchmarks -Choose the benchmarks according to the geographical position -Benchmarks sends out detecting signal -Users get the idea of relative position according to the signal recieved -D2D users sense the less used spectrum to reuse which will bring less interference

8. Submission May 2013 BUPT Slide 8 Offloading Traffic Reduce the load of AP -Users that have similar interests form a cluster. The cluster head gets access to AP instead of all the cluster members and then disseminates information in interest-based cluster by cellular D2D communication Balance the load of AP -If the cluster locates at the overlap of multi-APs coverage, the cluster head chooses to ask information from a leisure AP, in order to balance the traffic of different APs.

9. Submission May 2013 BUPT Interference Coordination Single/Multi-operator APs are close to each other ‒ It is labor costly to identify the interference by checking all APs one by one Slide 9 AP-AP information exchange via cellular D2D ‒ Coordination is slow and has higher latency via wired backhaul, especially for these APs belong to different operators ‒ UE identifies interference, then exchange information via D2D ‒ UEs feedback information to its served AP, respectively ‒ Interference management scheduling can be used in AP

10. Submission May 2013 BUPT Slide 10 Extended Coverage The conventional methods ‒ Increasing transmitting power, using directional antenna or smart antenna We suggest to study more on coverage area extension method, three stages: ‒ AP broadcasts information, users near AP have more probability to correctly receive information ‒ According to CSI, the edge users select at least one user which correctly receive information at the first stage; ‒ The selected user relays information to the edge user, and the edge user combines the received information

11. Submission May 2013 BUPT Slide 11 Technology Requirements for UE and AP Introducing WLAN D2D requires new technology UE should be able to ‒ Discoverother UEs UE needs to know whether a certain UE is in its proximity, and has the same interesting. ‒ Measure the channels from APs and other UEs The measure results need be reported to other UEs ‒ Maintain two different links Both links with AP and D2D UEs are coexistence AP should be able to ‒ Interference coordination Adjust the power or frequency according measure results from UE

12. Submission May 2013 BUPT Slide 12 Summary WLAN D2D is introduced to compensate the defects of WLAN ‒ Problem of device management can be solved by benchmark detection and spectrum sensing ‒ Problem of low accessibility and traffic unbalance can be solved by identifying clusters of users with similar interests ‒ Problem of co-channel interference between APs can be solved by coordination via WLAN D2D ‒ Problem of coverage hole can be solved by WLAN D2D relay Technologies for UE and AP should be studied