Stateful InterPacket Signal Processing for Wireless Networking Shangqing

Stateful Inter-Packet Signal Processing for Wireless Networking Shangqing Zhao �, Zhengping Luo �, Zhuo Lu �, Xiang Lu ǂ, Yao Liu � � University ǂ of South Florida Chinese Academy of Sciences (CAS), and University of CAS

Outline • Background • Motivation • STAPLE − Architecture − State configuration • Implementation and experiments − Experimental setups − Evaluation results • Summary

Modern Wireless Communication Pad AP Laptop Smart Phone

Modern Wireless Communication Preamble Header Packet Data

Modern Wireless Communication Preamble Header Data − Known to the public (training sequence) − Used for energy detection, timing/frequency synchronization, channel estimation…

Modern Wireless Communication Preamble Header Data − Specify the packet information for different layers Ø PHY: packet length, data rete … Ø MAC: frame type, source and destination address …

Modern Wireless Communication Preamble Header Data − User’s actual data

Modern Wireless Communication Wireless Receiver

Modern Wireless Communication Wireless Receiver Signal processing Preamble • Synchronization • Channel estimation • Equalization Signal decoding

Modern Wireless Communication Wireless Receiver Signal processing Signal decoding Header Demodulating Decoding -

Modern Wireless Communication Wireless Receiver 101101… Signal processing Signal decoding

Modern Wireless Communication Wireless Receiver Packet 12 Signal processing Signal decoding Fact: wireless channel isleverage random, and frequency Independent each packet arrival Rethink this process andfor common information offset and CSI are time-varying across packets to improve signal processing

Motivation v Examples: Case 1: a station (STA) only receives data from a certain access point (AP) common information: Ø Source address Ø Destination address AP STA

Motivation v Examples: Case 2: use cellphone to watch a movie online common information: Ø Packet length Ø Data rate

Motivation v Question: Does the common information (e. g. packet length, data rate, Address) universally exist in the normal scenario? 0. 8 SIGCOMM 04 Packet SIGCOMM 08 Trace SIGCOMM 08 0. 1 0 STAPLEn 0 500 1000 Packet length (byte) STAPLEac SIGCOMM 04 SIGCOMM 08 Yes ! 802. 11 b SIGCOMM 04 0. 2 Standard 0. 6 Probability distribution 0. 3 1500 0. 4 802. 11 a/g 0. 2 0 802. 11 n 0 20 Data rate (Mbps) 802. 11 ac Not evenly distributed 40 60

Motivation v Question: How to harness such common information to improve the signal processing ?

Motivation State Table Data 1001 decoding 10101 Packet 1 Longer Preamble 1001 10101 **** Preamble Signal processing Receiver Header 1001 10101 1001 **** decoding 1111 Data 10101 ****CRC Common information State (in header)

Motivation State Table 10101 Recovered state Packet 2 1001 10101 **** Signal processing Receiver Header 1001 10001 decoding Data 1001 decoding 10101 1111 Longer Preamble 1001 10101 **** CRC

STAPLE v Framework: Traditional • We propose a STAteful inter-Packet signa. L proc. Essing (STAPLE) framework. − It is a generic design for various wireless standards. STAPLE

STAPLE v Framework: the state Refine the Channel. Recover estimation

State Configuration v Question: Which fields can constitute the state ?

State Configuration v State for 802. 11 b: State Entropy

State Configuration 802. 11 a/g 802. 11 ac 802. 11 n 802. 15. 4

Implementation 802. 11 b 802. 11 a 802. 11 g 802. 11 n 802. 11 ac 802. 15. 4

Implementation v Platform: ‒ USRP X 300 s with CBX daughterboards. ‒ Use Octo. Clock-G to synchronize multiple USRPs performing MIMO experiments. 2 -antenna TX 8 -antenna RX

Implementation v Indoor environment: v Metrics: 1. Packet delivery ratio (PDR) 2. Performance gain ratio

Single-Link Performance (ac) v Varying locations: ‒ Place AP at location 1, and station at location 0, 3, 4, 5. Wood door Location 0 AP Location 4 ‒ STAPLE is more effective in a severe environment.

Single-Link Performance (ac) v Varying modulation scheme: ‒ Place AP at location 1, and station at location 7. ‒ 2 * 8 MIMO link Location 7 AP ‒ 16 QAM has a large improvement.

Network Performance(ac) v Uplink and downlink: ‒ Place AP at location 0, and stations at locations 1~6. Stations AP ‒ Nodes 4~6 have the larger improvement.

Network Performance v Different standards: (Uplink) ‒ Benefits exist in many standards. (Downlink)

Summary v STAPLE can improve the packet delivery ratio by up to 20% under various conditions. v STAPLE is a generic design which can benefit a wide range of wireless networks.

Q&A Thank you !