Adjacent channel interference in 802.11a is harmful: Testbed validation of a simple quantification model

As a key component of urban rail transit systems, communications-based train control (CBTC) is an automated train control system using train-ground communications to ensure efficient operation of rail vehicles. In addition to CBTC systems, passenger information systems (PISs) are adopted in urban rail transit systems to improve quality of service (QoS) offered to customers. The interference between CBTC systems and PISs is an important factor impacting QoS of both CBTC systems and PISs. With recent advances in cognitive dynamic systems, in this paper, we take a cognitive control approach to interference mitigation considering the co-existence of CBTC systems and PISs. In our cognitive control approach, the notion of information gap is adopted to quantitatively describe effects of interference on CBTC. The wireless channel is modeled as a finite-state Markov chain with multiple state transition probability matrices, which are derived from real field measurements. Simulation results show that the proposed cognitive control approach can significantly improve performance of CBTC train-ground communications under interference from co-existing PISs.

Section: The Interference From the Pis Working At The Adjacent Channelmentioning

confidence: 99%

A cognitive control approach to interference mitigation in communications-based train control (CBTC) co-existing with passenger information systems (PISs)

Wang

Hua-shen

2017

“…We assume that five nonoverlapping channels are available in the wireless network. Note that, typically, three channels can be used without interference among a total of 13 channels of IEEE 802.11a WLAN standards [4,28]. For IEEE 802.11n, four orthogonal channels of 20 MHz are allowed, and for IEEE 802.11g, three channels of 22 MHz are available.…”

Section: Convergence Propertymentioning

confidence: 99%

Fair rate control for cognitive multi-channel wireless ad hoc networks

Yoon

Kim

2014

Multi-channel wireless ad hoc networks enhance network capacity with the use of available channels in parallel but should strike a balance between maintaining network connectivity and maximizing utilization of different channels. Also, a promising wireless multi-channel ad hoc network should be cognitive to interference from various wireless devices operating on industrial, scientific, and medical bands effectively by scavenging less loaded channels dynamically using periodic spectrum sensing and distributed channel selection algorithm. In this paper, we study cross-layer fair rate control problems for hybrid channel assignment-based multi-channel ad hoc networks in the cognitive context. We first identify two inherent constraints which are specific to multi-channel multi-radio wireless ad hoc networks and primary user interference. We then formulate a fair rate control problem by exploiting the network utility maximization framework and propose a price-based distributed solution. We investigate in detail the convergence property of the distributed solution via simulation on a grid topology. We also show its convergence in adaptation to the change in primary user interference in the cognitive context. We present a performance comparison study with a generic class of existing works in the literature.

“…However, no more than five interfaces are required because as our experiments (and the related literature) have shown that energy emitted using a channel 60 MHz or more far from the main channel does not have any impact on network's performance. According to [29] the leakage of the immediately adjacent channels (IACs) to the main channel is X 1 = 22.04 dB, while for the next adjacent channels (NACs) is X 2 = 39.67 dB. Based on these values, we assume that the interference generated by a signal of S dBm in the IACs is S -X 1 dB, while for the NACs is S -X 2 dB.…”

Section: Error-cmm Network Modulementioning

confidence: 99%

Design and performance evaluation of a lightweight wireless early warning intrusion detection prototype

Fragkiadakis

Τράγος

Tryfonas

et al. 2012

The proliferation of wireless networks has been remarkable during the last decade. The license-free nature of the ISM band along with the rapid proliferation of the Wi-Fi-enabled devices, especially the smart phones, has substantially increased the demand for broadband wireless access. However, due to their open nature, wireless networks are susceptible to a number of attacks. In this work, we present anomaly-based intrusion detection algorithms for the detection of three types of attacks: (i) attacks performed on the same channel legitimate clients use for communication, (ii) attacks on neighbouring channels, and (iii) severe attacks that completely block network's operation. Our detection algorithms are based on the cumulative sum change-point technique and they execute on a real lightweight prototype based on a limited resource mini-ITX node. The performance evaluation shows that even with limited hardware resources, the prototype can detect attacks with high detection rates and a few false alarms.