A New Metric for Evaluating the Throughput Performance of HEW Date: 2014-03-20 Authors: Yunzhou Li, Tsinghua Univ.
Abstract • This presentation suggests to add a new metric for evaluating the throughput performance of HEW and explains some reasons. • The new metric is called throughput with learned knowledge, which may include large-scale channel state information, directions/positions of STAs and neighbour APs, statistics characteristic of some important applications, etc. • The presentation proposes to add the new metric as one of evaluation metrics besides the traditional per-BSS throughput and per-STA throughput. Yunzhou Li, Tsinghua Univ.
Background • At present, the per-BSS throughput and per-STA throughput are calculated according to system-level simulation assumed that all the APs don’t utilize prior knowledge about the applications, channel state information, the positions of distributed STAs. • However, there are many results showed that these knowledge can help HEW to adjust the transmission policies and improve the efficiency of spectrum usage. • APs have capability to learn of these knowledge by measurement and refine the precise of these knowledge. Yunzhou Li, Tsinghua Univ.
The knowledge of direction and position is helpful to improve efficiency • The knowledge of direction and position is helpful to enhance multiple simultaneous communications in both the spatial and frequency domains, in both the UL and DL. • Due to up to 8/16 antennas mounted in one AP, it is feasible to acquire the knowledge of direction and position of each STA w.r.t the AP. Yunzhou Li, Tsinghua Univ.
The Large-scale CSI can be utilized to improve performance • Although there is a performance loss of the coordinated transmission with large-scale CSIT compared to that with full CSIT, the scheme with LsCSIT provides a noticeable performance gain over the equal power allocation scheme. Virtual MIMO in Multi-Cell Distributed Antenna Systems: Coordinated Transmissions with Large-Scale CSIT, JSAC 2013 Yunzhou Li, Tsinghua Univ.
Throughput with learned knowledge • In recent years, there are a lot of efforts being done to optimize the system performance (known as “smart AP”) based on learned knowledge on the statistical characteristics of some important applications, such as WiFox, StreamBoost. • Furthermore, some measurement procedures should be designed to facilitate the acquisition of learned knowledge and make HEW-AP smarter.  WiFox: Scaling WiFi Performance for Large Audience Environments , Proceeding of CoNEXT '12  http://www.qualcomm.com/media/releases/2013/01/04/qualcomm-introduces-streamboost-technology-optimize-performance-and Yunzhou Li, Tsinghua Univ.
Proposal • We suggest that a procedure of acquisition of learned knowledge should be added as a possible option in the step of initialization in document of HEW Evaluation Methodology. • In addition, the “HEW Evaluation Methodology” should be keep open to be amended for new technology. Yunzhou Li, Tsinghua Univ.
Summary • In this presentation, we don’t want to argue which technique is good and how much gain can be achieved by certain technique. • We present some knowledge, such as directional information, may be useful to exploit the efficiency of HEW. On the other hand, these knowledge can be learned by APs after working a period. In addition, some measurement procedure may facilitate the acquisition of these knowledge. • If the difference between the throughput without any prior knowledge and the one with learned knowledge may be noticeable, the schemes with learned knowledge should be paid attention. • Finally, a procedure of acquisition of learned knowledge is suggested to add as a possible option in the step of initialization of Evaluation Methodology. Yunzhou Li, Tsinghua Univ.