Shaping Spectral Leakage for IEEE 802.11p Vehicular Communications

Pham, Thinh Hung; McLoughlin, Ian; Fahmy, Suhaib A.

doi:10.1109/vtcspring.2014.7023089

Cited by 8 publications

(12 citation statements)

References 14 publications

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“…Thus, addressing the challenge of meeting SEM requirements through baseband processing in CR systems is both sensible and practical. As an example, we recently demonstrated the first baseband digital filtering method capable of meeting the 802.11p Class D SEM [11].…”

Section: Methodsmentioning

confidence: 99%

“…The latter techniques are dominated by shaping methods [21,22], which apply a time domain window to the OFDM symbol to modify its response in the frequency domain prior to up-conversion. This was the approach taken in [11].…”

Section: Methodsmentioning

confidence: 99%

“…In fact, there has been much debate regarding whether and when chip makers will be able to meet such challenging requirements [4]. To the best of the authors' knowledge, no implementations or testbeds for 802.11p have been published that are able to meet the class D specification, prior to our own very recently published technique in [11]. …”

Section: 11p Physical Layermentioning

confidence: 99%

“…The first is to define a CR signal processing architecture for SDR that performs a flexible degree of spectral shaping, at an adaptable rate, in the digital baseband. This adopts the novel baseband filtering technique proposed in [11], extended to support not only channel and time agility, but also to reduce the degree of shaping for conditions where transmission power is reduced. The second contribution is to evaluate the technique for both 802.11p and 802.11af spectral shaping.…”

Section: Contributionmentioning

confidence: 99%

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Spectrally efficient emission mask shaping for OFDM cognitive radios

Pham

Fahmy

McLoughlin

2016

Digital Signal Processing

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Orthogonal Frequency Division Multiplexing has been widely adopted in recent years due to its inherent spectral efficiency and robustness to impulsive noise and fading. For cognitive radio applications in particular, it can enable flexible and agile spectrum allocation, yet suffers from spectral leakage in the form of large side lobes, leading to inter-channel interference, unless mitigated carefully. Hence, recent OFDM-based standards such as 802.11p for vehicular communication and 802.11af for TV whitespace impose strict spectrum emission mask limits to combat adjacent channel interference. Stricter masks allow channels to operate closer together, improving spectral efficiency at the cost of implementation difficulty. Meeting the strict limits is a significant challenge for implementing both 802.11p and 802.11af, yet remains an important requirement for enabling cost-effective systems. This paper proposes a novel method that embeds baseband filtering within a cognitive radio architecture to meet the specification for the most stringent 802.11p and 802.11af masks, while allowing ten 802.11af sub-carriers to occupy a single basic channel without violating SEM specifications. The proposed method, performed at baseband, relaxes otherwise strict RF filter requirements, allowing the RF subsystem to be implemented using much less stringent 802.11a designs, allowing cost reductions.

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Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: 11p Physical Layermentioning

confidence: 99%

Section: Contributionmentioning

confidence: 99%

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Spectrally efficient emission mask shaping for OFDM cognitive radios

Pham

Fahmy

McLoughlin

2016

Digital Signal Processing

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“…Since the two standards are largely similar, we run the entire baseband design at half the clock frequency (10MHz) to achieve compatibility with the 802.11p standard. It is worth noting that for actual 802.11p deployment, more stringent output spectrum shaping is required than for 802.11a [11]. The Android handset can access two functions in the FPGA hardware: the packet generator and the gain control module.…”

Section: Fpga Subsystemmentioning

confidence: 99%

A case for leveraging 802.11p for direct phone-to-phone communications

Choi

Gao

Ramanathan

et al. 2014

Proceedings of the 2014 International Symposium on Low Power Electronics and Design

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WiFi cannot effectively handle the demands of device-to-device communication between phones, due to insufficient range and poor reliability. We make the case for using IEEE 802.11p DSRC instead, which has been adopted for vehicle-to-vehicle communications, providing lower latency and longer range. We demonstrate a prototype motivated by a novel fabrication process that deposits both III-V and CMOS devices on the same die. In our system prototype, the designed RF front-end is interfaced with a baseband processor on an FPGA, connected to Android phones. It consumes 0.02uJ/bit across 100m assuming free space. Application-level power control dramatically reduces power consumption by 47-56%.

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