Lu, Haoyang
(2019)
Designing Wireless Networks for Delay-Sensitive Internet of Things.
Doctoral Dissertation, University of Pittsburgh.
(Unpublished)
Abstract
Internet of Things (IoT) applications have stringent requirements on the wireless network delay, but have to share and compete for the limited bandwidth with other wireless traffic. Traditional schemes adopt various QoS-aware traffic scheduling techniques, but fail when the amount of network traffic further increases. In addition, CSMA with collision avoidance (CSMA/CA) mechanism enables the coexistence of multiple wireless links but avoids concurrent transmissions, yielding severe channel access delay on the delay-sensitive traffic when the channel is busy.
To address the aforementioned limitations, we present two novel designs of wireless side channel, which operate concurrently with the existing wireless network channel without occupying extra spectrum, but dedicates to real-time traffic. Our key insight of realizing such side channel is to exploit the excessive SNR margin in the wireless network by encoding data as patterned interference. First, we design such patterned interference in form of energy erasure over specific subcarriers in OFDM systems. Delay-sensitive messages can be delivered simultaneously along with other traffic from the same transmitter, which reduces the network queuing delay. Furthermore, we propose EasyPass, another side channel design that encodes data in the same OFDM scheme as being used by the main channel, but using weaker power and narrower frequency bands. By adapting the side channel's transmit power under the main channel's SNR margin, the simultaneous main channel transmission would suffer little degradation. EasyPass reduces the channel access delay by providing extra transmission opportunities when the channel is occupied by other links. Last, we present a novel modulation design that transforms the choices of link rate adaptation from discrete to continuous. With minimum extra overhead, it improves the network throughput and therefore reduces the network delay.
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Details
| Item Type: |
University of Pittsburgh ETD
|
| Status: |
Unpublished |
| Creators/Authors: |
|
| ETD Committee: |
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| Date: |
24 January 2019 |
| Date Type: |
Publication |
| Defense Date: |
24 September 2018 |
| Approval Date: |
24 January 2019 |
| Submission Date: |
24 September 2018 |
| Access Restriction: |
2 year -- Restrict access to University of Pittsburgh for a period of 2 years. |
| Number of Pages: |
128 |
| Institution: |
University of Pittsburgh |
| Schools and Programs: |
Swanson School of Engineering > Electrical Engineering |
| Degree: |
PhD - Doctor of Philosophy |
| Thesis Type: |
Doctoral Dissertation |
| Refereed: |
Yes |
| Uncontrolled Keywords: |
wireless networks; wireless side channel |
| Date Deposited: |
24 Jan 2019 16:17 |
| Last Modified: |
24 Jan 2021 06:15 |
| URI: |
http://d-scholarship.pitt.edu/id/eprint/35351 |
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