CSMA/CN: Carrier Sense Multiple Access With Collision Notification

Sen, Souvik; Choudhury, Romit Roy; Nelakuditi, Srihari

doi:10.1109/tnet.2011.2174461

Cited by 172 publications

(138 citation statements)

References 22 publications

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“…[14] and [28] use multiple radios in mobile scenarios for hiding handoff latency for real-time applications. Earlier works have also used multiple software-defined radios for collision detection [29], [30] and full duplex connectivity [31], [32]. However, the focus of this work is the use of off-the-shelf radios and the design of a software architecture for managing these devices to achieve different user-defined policies.…”

Section: Combining Fragmented Channelsmentioning

confidence: 99%

MulWiFi: Flexible Policy Enforcement in Multi-Radio High-Speed WiFi Networks

Nishat¹,

Uzmi²,

Qazi³

2017

ijacsa

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Abstract-As data rates in 802.11 Wireless LANs (WLANs) scale to Gbps, it becomes increasingly challenging for a single radio resource to meet the goals of high MAC efficiency, service differentiation, and adaptability to diverse network scenarios. We present MulWiFi, a system that uses a centralized controller to manage multiple off-the-shelf radios in a single device for addressing challenges in high-speed WLANs. MulWiFi allows flexible policy enforcement based on application requirements and channel state information at each radio. MulWiFi offers the ability to 1) customize the MAC based on application requirements and network scenarios; 2) assign different roles to radios; 3) improve MAC throughput efficiency at high data rates; and 4) combine fragmented channels. We demonstrate the early promise of MulWiFi through three case studies and discuss future opportunities and challenges.

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Section: Combining Fragmented Channelsmentioning

confidence: 99%

MulWiFi: Flexible Policy Enforcement in Multi-Radio High-Speed WiFi Networks

Nishat¹,

Uzmi²,

Qazi³

2017

ijacsa

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“…In the second method, an approximate CSMA/CD for WLANs is realized using a scheme called CSMA/collision notification (CN) [12]. In CSMA/CN, a receiver detects the interfering signal while receiving a packet and immediately notifies the transmitter, which utilizes two antennas: one for normal transmission and the other dedicated to listening for notifications.…”

Section: Introductionmentioning

confidence: 99%

“…In CSMA/CN, a receiver detects the interfering signal while receiving a packet and immediately notifies the transmitter, which utilizes two antennas: one for normal transmission and the other dedicated to listening for notifications. Upon detection of a notification signal, the transmitter aborts its transmission, freeing up the channel for other transmitters in the vicinity [12].…”

Section: Introductionmentioning

confidence: 99%

“…When the notification signal arrives during the transmission of the own transmit signal, another antenna judges whether collision is detected, because the correlation value between the received signal (ideally only notification signal plus the noise) and the known training signal becomes high after canceling the own transmit signal [12].…”

Section: Introductionmentioning

confidence: 99%

“…Firstly, it is difficult to detect collision in a real propagation environment using only the correlation value, because the correlation value with limited number of samples is actually very small as the power level of the notification signal is much lower than that of the own transmit signal at another antenna on the transmitter. Secondly, since the power of the own transmit signal is much higher than that of the notification signal from the receiver, the received power becomes saturated at the amplifier and it causes the noise power to increase; [12] provided there is no concrete countermeasure for this effect. In addition to these problems, feedback delay may still occur even if the receiver immediately notifies the transmitter of a collision.…”

Section: Introductionmentioning

confidence: 99%

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Collision Detection Method Using Self Interference Cancelation for Random Access Multiuser MIMO

et al. 2017

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This paper proposes an interference detection method for multiuser-multiple input multiple output (MU-MIMO) transmission, which utilizes periodical preamble signals in the frequency domain and the concept of full-duplex transmission when assuming idle antennas at the access point (AP) in MU-MIMO. In the propose method, collision detection (CD) of MU-MIMO is achieved by utilizing asynchronous MU-MIMO called random access MU-MIMO. In random access MU-MIMO, several antennas that are not used for the transmission exist, due to asynchronous MU-MIMO. Hence, idle antennas at the AP can receive preamble signals while the transmit antennas at the AP transmit the preamble signals: this procedure is regarded as full-duplex transmission, which cancels the self-interference between AP antennas. The interference can be detected by subtracting the short preamble signal, which is multiplied by the estimated channel response using the received signal after the FFT processing. Moreover, we utilize dual polarization to reduce the mutual coupling between transmit and receive antennas at the AP. Through a computer simulation, it is shown that the proposed method can successfully detect collision from other user terminals (UTs) with OFDM signals when the interfering power from the interfering user terminal (IT) is greater than the noise power. In addition, the interfering power from IT at the AP and the desired user terminal (DT) is measured in an actual indoor environment, and the possibility of using the proposed method at the AP is discussed by using the measurement results.

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