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IEEE 802.11ax partitions a regular 20MHz channel into smaller sub-channels called resource units to support simultaneous multiuser operation using orthogonal frequency division multiple access (OFDMA). Uplink OFDMA random access (UORA) in IEEE 802.11ax allows stations to transmit via a scheduled random access mechanism. UORA is initiated via a trigger frame which aside from serving as a synchronization mechanism, also informs stations which resource units are allowed for random access. Using the trigger frame information, the stations engage in an OFDMA backoff process to win access to a resource unit. Similar to slotted ALOHA, the maximum normalized throughput of UORA is only 37 percent due to high probability of collisions at high loads. To reduce collisions, we equip UORA with carrier sensing capability resulting in a new uplink hybrid UORA (H-UORA) OFDMA access mechanism. Unlike other multi-carrier CSMA methods previously proposed in literature, H-UORA is an easily implementable modification to current 802.11ax WLANs. We show that H-UORA can achieve a normalized throughput of at least 80 percent (which increases further depending on the buffering capabilities of the access point) using various numerical analysis and simulations.

Channel bonding in IEEE 802.11 wireless LANs is a technique whereby adjacent 20MHz channels are ‘bonded’ to create a wider bandwidth channel that supports higher data rate transmissions. Although rate improvements due to channel bonding has been shown in sparse wireless LAN environments, its effectiveness in dense scenarios requires further exploration due to increased sensitivity to interference from overlapping co-channel basic service sets. With the newly finalized 802.11ax standard supporting enhanced spatial reuse feature, its impact on the expected gains from channel bonding needs careful analysis. In this work, we propose a new analytical framework that accurately models the performance of channel bonding as a function of both PHY and MAC parameters for a dense network scenario. A new channel bonding algorithm that is robust to overlapped co-channel interference is described, i.e. it preserves channel bonding gains by intelligently choosing the channel bonding bandwidth based on network conditions and parameters that are readily available to all stations, critically the modulation scheme chosen for packet transmission. The predicted gains of the proposed algorithm are verified via comprehensive simulations conducted with the open source network simulator ns-3.

In this paper, we propose an Interleave-Division Multiple Access (IDMA) based uplink multi-user system fornext generation WLAN. By minimizing the latency throughaccurate detection per iteration, we were able to design a receiver architecture that meets the latency demands of current IEEE802.11 WLAN. To do this, the proposed system utilizes a novel algorithm for simplified LLR calculation of the soft input soft output demapper needed in the IDMA first stage detection.The proposed system has a maximum of 34.8 bits/s/Hz spectral efficiency for a single spatial stream and can support up to 8 users in a single 20MHz channel. We compare the proposed system to a reference OFDMA system and show its advantages in terms of diversity, flexibility and BER performance. Keywords: 802.11ax; IDMA; uplink multi-user access

Packet collisions due to overlapping Basic Service Set (BSS) interference can result in decreased network efficiency. To overcome this problem, 802.11 stations need to confirm the channel availability through the Clear Channel Assessment (CCA) mechanism. Besides energy detection, which has low sensitivity, packet detection in Wi-Fi also utilizes a more sensitive preamble correlation method to check for a valid data symbol within 4µs. Hence, a successful CCA is only possible if the received signal exceeds a certain power level or the contending station could receive the signal preamble. In this paper, we demonstrate how a deep learning-based method like Convolutional Neural Network (CNN) can be used to supplement Wi-Fi’s CCA capability to increase its sensitivity without requiring the reception of the signal preamble. We also elaborate on the role of filter size and max-pooling in signal processing points of view. Our simulations show that the proposed CNN model can classify different packet formats and their modulation types, even when different symbol timing offsets occur. Based on the ns-3 simulation, we demonstrate that the proposed approach leads to better channel utilization and enhanced throughput in a multiple BSS network by prioritizing high throughput transmissions.

In this paper, we propose self-interference (SI) cancellation in cooperative multiple-input multiple-output (Co-MIMO) for full-duplex (FD) wireless communication systems. This proposal solves SI by applying the block diagonalization used in multi-user MIMO. Therefore, there is no need for a radio frequency (RF) canceller, which has a large hardware (HW) size and is difficult to extend to MIMO. Furthermore, we can achieve higher throughput by applying Co-MIMO, in which multiple access points (APs) work together to communicate. The proposed method's implementation uses field-programmable gate array (FPGA) and software-defined radio (SDR). In the experiment, a total of 33 [dB] SI can cancel with two cooperative APs and two antennas per AP in the IEEE 802.11 system.

We demonstrate a self-interference (SI) cancellation in cooperative multiple-input multiple-output (Co-MIMO) for full-duplex (FD) wireless communication systems by applying the block diagonalization used in multi-user MIMO. The proposed method's implementation uses a field-programmable gate array (FPGA) and software-defined radio (SDR). In the experiment, a total of 33 [dB] SI can cancel with two cooperative APs and two antennas per AP in the IEEE 802.11 system.

This paper proposes a full-duplex wireless communication system applying cooperative multiple-input multiple-output (Co-MIMO). This proposal solves self-interference (SI) in full-duplex wireless communication systems by applying the block diagonalization used in multi-user MIMO (MU-MIMO). Therefore, there is no need for a radio frequency (RF) canceller, which has a large hardware size and is difficult to extend to MIMO. Furthermore, higher throughput can be achieved by applying Co-MIMO, in which multiple access points work together to communicate. We also introduce the implementation of the proposed method using a field-programmable gate array (FPGA) and software-defined radio (SDR) in this paper. It shows that SI cancellation can be realized by using them. The proposed method is implemented based on the IEEE 802.11n frame format as an example. In the experiment, a total of 30 [dB] SI cancellation is confirmed with a transmission power of -12 [dBm]. The SI cancellation amount can be further increased by increasing the transmission power.