Thursday, August 15, 2013

SIGCOMM2013: BigStation: Enable Scalable Real-time Signal Processing in Large MU-MIMO Systems

Presenter: Qing Yang
Co-authors: Xiaoxiao Li, Kun Tan, Hongyi Yao, Fang Ji, Wenjun Hu, Jiansong Zhang, and Yongguang Zhang

Today we see more demand for wireless capacity. We would like to engineer the next wireless network to match the capacity of existing wired networks. However, we can only increase the spectrum so much and reusing the spectrum increases complexity.

This work significantly increases wireless capacity using spatial multiplexing with many antennas. To handle so many antennas, computation is parallelized with many simple processing units. This work establishes a distributed processing pipeline, which exploits data parallelism across servers at each processing stage.

This work was prototyped using a Sora MIMO Kit. They found that with overprovisioned AP antennas, the peak transmission rate scales linearly with the number of antennas, with 9 antennas demonstrating a scaling of 6.8x over a single antenna.

Q: If you had to guess what the scaling limitation is, what do you think the fundamental boundary is? Is it infinitely scalable?
A: My estimation is that we can probably handle about 100 antennas.

Q: Do you think we can continue such an improvement up to 40 antennas in production?
A: There are still critical challenges that we haven't solved yet. These challenges will need to be worked out before this will be suitable for industry.

Q: You talk about the long tail of processing, is there packet loss?
A: Yes, when there is a high data rate, we do see packet loss, but I think it could be reduced.

Q: For production, you really need to design the interconnect to be synchronous, instead of using ethernet.
A: I don't know if this would actually work - we need to investigate more.