Li-Fi Research and Development Centre University of Edinburgh 2nd ACM Workshop on Visible Light Communication Systems (VLCS 2015) September 11, 2015, Paris, France On Limited feedback Resource Allocation for Visible Light Communication Networks Li-Fi Research and Development Centre University of Edinburgh Mohammad Dehghani Soltani, Xiping Wu, Majid Safari, Harald Haas 2nd ACM Workshop on Visible Light Communication Systems (VLCS 2015)

Agenda Importance of feedback (Throughput & Fairness) Type of feedbacks Optimizing Feedback (Maximize the overall throughput) Proposed Limited Feedback Scheme Some simulations Conclusions 2nd ACM Workshop on Visible Light Communication Systems (VLCS 2015)

Importance of Feedback The aim is to allocate resources elastically in time, spectrum and space, in order to accommodate a large range of traffic profiles and granularities in an efficient way. Resources should be specified and this resources should be fedback to the access points to core network 2nd ACM Workshop on Visible Light Communication Systems (VLCS 2015)

Limited Feedback Scheme Types of feedback Full Feedback Scheme Users send the SINR of all subcarriers at the beginning of each frame Limited Feedback Scheme Each user sends the SINR of all of its subcarriers only once at the beginning of the first frame. For the next frames, the users only update the scheduler with their average power (i.e., the DC channel component) 2nd ACM Workshop on Visible Light Communication Systems (VLCS 2015)

𝛾 𝓁 𝑗 𝑘 = 𝛾 1 𝑗 𝑘 × 𝛾 𝓁 𝑗 0 𝛾 1 𝑗 0 Proposed Limited Feedback Scheme SINR estimation 𝛾 𝓁 𝑗 𝑘 = 𝛾 1 𝑗 𝑘 × 𝛾 𝓁 𝑗 0 𝛾 1 𝑗 0 SINR of 𝑗th user at 𝓁th frame on the 𝑘th subcarrier The frequency-selective characteristics of these devices are fairly static and in comparison to RF, they are independent of the user’s position or orientation. However, the average received power is much more dynamic and is significantly dependent on the position and the orientation of the users’ devices. Therefore, by only updating the average power, a reasonable estimate of the SINR of all the subcarriers can be obtained. 2nd ACM Workshop on Visible Light Communication Systems (VLCS 2015)

𝑅 𝑓 =𝒩 log 2 𝑀 𝑅 𝑓 =𝒩 𝒦 2 𝑙𝑜𝑔 2 𝑀 Limited Feedback Full Feedback 𝒩 : Number of user 𝑅 𝑓 =𝒩 log 2 𝑀 𝑀 : Constellation size Full Feedback 𝑅 𝑓 =𝒩 𝒦 2 𝑙𝑜𝑔 2 𝑀 𝒦: Number of subcarriers 2nd ACM Workshop on Visible Light Communication Systems (VLCS 2015)

Simulation Results Bench marks: Proportional Fair (PF) Scheduler Maximum channel quality indicator (CQI) Simulation parameters 16 Access points, 10m × 10m Room, DCO-OFDM, LOS & NLOS, FoV (90°), … Evaluation parameters Throughput User’s satisfaction 2nd ACM Workshop on Visible Light Communication Systems (VLCS 2015)

Total throughput for different resource allocation schemes with full and limited-feedback (average request data rate: 40Mbps and 80Mbps) 2nd ACM Workshop on Visible Light Communication Systems (VLCS 2015)

Average number of users who achieve at least 95% of their desired rate for different resource allocation schemes with full and limited-feedback (average request data rate: 40Mbps and 80Mbps) 2nd ACM Workshop on Visible Light Communication Systems (VLCS 2015)

Comparing CDF of user throughput for full and limited feedback approaches with 60 users (average request data rate: 40Mbps and 80Mbps) 2nd ACM Workshop on Visible Light Communication Systems (VLCS 2015)

Comparing CDF of user satisfaction level for full and limited feedback approaches with 60 users (average request data rate: 40Mbps and 80Mbps) 2nd ACM Workshop on Visible Light Communication Systems (VLCS 2015)

Future works CONCLUSION Limited Feedback has a close performance to FF in Li-Fi network Limited Feedback generates much lower feedback overhead Future works A heterogeneous network will be considered Feedback update in technology specific network SDN for intelligence resource assignment 2nd ACM Workshop on Visible Light Communication Systems (VLCS 2015)

Thank you for your consideration! 2nd ACM Workshop on Visible Light Communication Systems (VLCS 2015)