This paper analyzes the performance of IEEE 2024 802.11be (Wi-Fi 7) and 2028 802.11bn (Wi-Fi 8) amendments with modulation and code schemes (MCS) that use 4K and 16K quadrature amplitude modulation (QAM) schemes with low-density parity check codes when the physical layer implements transmit beamforming (TxBF) transceivers impaired with phase noise (PN) and carrier frequency offset (CFO). We have concluded that scheduling MCS with 4K-QAM signaling is feasible with TxBF transceivers jointly impaired with PN and CFO. On the other hand, scheduling MCS with 16K-QAM signaling demands a robust hardware, quantified in this paper within the scope of 802.11be/bn amendments, to avoid significant power losses in the link budget due to PN and CFO.

The IEEE 802.11ax amendment (Wi-Fi 6) has defined modulation code schemes that implement uniform Gray mapping rectangular 1024-QAM constellation. In this paper, we derive approximate log-likelihood ratio (LLR) metrics for softdecoding of binary convolutional codes (BCC) using Viterbi decoding and low-density parity-check codes (LDPC) using the message-passing algorithm, implemented as the log-domain sum-product algorithm. The proposed low-complexity softdecision metrics are validated by simulating the 802.11ax physical layer that implements transmit beamforming transceivers over frequency selective channels.

This paper analyses the performance of Chase Combining Hybrid Automatic Repeat Request (CC-HARQ) protocol in the novel 2024 IEEE 802.11 be physical layer (PHY) when it is implemented Low-Density Parity-Check (LDPC) codes over Doppler channels for the following transceiver architectures: downlink transmit beamforming (DL TxBF), DL multi-user multiple-input multiple-output (DL MU-MIMO), and uplink MU-MIMO. Simulation results indicate that the performance gains due to the implementation of CC-HARQ with LDPC codes vary between 2 to 4 dB with only one retransmission, where the achievable gains depend on PHY layer set-up and channel modelling. We also have observed that the performance of DL MU-MUMO transceivers presents a great sensibility with the decrease of precoding accuracy due to the joint effects of Doppler spread and channel state information feedback delay. Finally, we have concluded that the implementation of 802.11be PHY with 4096-QAM is possible with practical signal-to-noise ratio (SNR) when it is implemented TxBF transceivers even without implementing HARQ protocols. In this set-up, the implementation of CC-HARQ scheme with only one retransmission allows power gains between 3 to 4 dB, increasing the usage of 4096-QAM.

The IEEE 802.11be Task Group (TG) was created in May 2019 to develop the Extremely High-Throughput (EHT) 802.11be amendment for Wireless Local Area Networks (WLANs). This paper analyses the throughput, capacity and reliability improvements due to two candidate technologies forecasted in the Project Authorization Request (PAR): the increase of maximum number of spatial streams from 8 to 16 and introduction of Hybrid Automatic Repeat Request (HARQ) retransmission protocols [1]. The simulation results, validated using a first-order approach, for single-user multiple-input multiple output (SU-MIMO) with transmit beamforming (TxBF), downlink (DL) and uplink (UL) multi-user MIMO (MU-MIMO) technologies show expressive gains on the throughput and reliability due to the implementation of Chase combining HARQ in systems with 16 antenna ports in the 802.11ax/be physical layer (PHY).

This industry-oriented paper analyzes the implementation of the channel sounding compression schemes specified in the novel IEEE 802.11ax wireless local area network (WLAN) amendment, as known as Wi-Fi6, assuming orthogonal frequency division multiplexing (ODFM) downlink (DL) and uplink (UL) multi-user multiple-input multiple-output (MUMIMO) technologies. It is shown results with the following hardware impairments: phase noise (PN), in-phase and quadrature (IQ) imbalance and carrier frequency offset (CFO). Based on an extensive set of simulation results, which are validated using a first-order approach, we have concluded that the implementation of channel sounding compression schemes can even improve substantially the system performance. This counterintuitive statement can be explained as follows: power increase on the transmitted pilots when the 802.11ax compression channel schemes are implemented allows, depending on the 802.11ax physical layer (PHY) configuration, a better estimation of the channel state information (CSI) even with the implementation of a linear interpolation procedure used to estimate the frequency response for the tones where pilots are not transmitted due to the channel sounding compression mechanism.

The IEEE 802.11ax amendment has defined compression schemes to transmit orthogonal pilots in order to reduce the overhead to acquire the channel state information (CSI) necessary to the operation of multiple-input multiple-output (MIMO) transceivers. This paper analyzes the effects of high-efficiency long training fields (HE-LTF) transmission modes on the performance of 802.11ax MIMO transceivers impaired with hardware impairments (carrier frequency offset, in-phase and quadrature imbalance and phase noise). We have concluded that it is necessary to develop smart algorithms to define on-flight the optimal HE-LTF transmission mode since the use of compression techniques, besides reducing the training overhead, it can also improve the system performance in some configurations due to denoising effects of the linear interpolation procedure.

The proof-of-concept research on orthogonal frequency division multiplexing uplink multi-user multiple-input multiple-output (OFDM UL MU-MIMO) technology has been complemented by the industry and academia with additional research activities on the consequences of non-ideal impairments in the system performance. In this paper, we analyze and design algorithms to mitigate the joint effects of carrier frequency offset, in-phase and quadrature imbalance, differences on the receive power and time-of-arrival on the performance of OFDM UL MU-MIMO, one of the main novel technologies in the physical layer portfolio of the sixth-generation wireless local area networks under developing in the IEEE Task Group 802.11ax.

The 802.11ax Specification Framework delivered by the IEEE High Efficiency WLANs (HEW) Task Group (TG) in early 2016 has specified the uplink multi-user multiple-input multiple-output (UL MU-MIMO) as a key medium access control (MAC) and physical layer (PHY) technique to improve the uplink network throughout in ultra-dense networks loaded with small form factor devices. In this paper, we first show that the phase noise (PN) hardware impairment does not degrade the 802.11ax UL MU-MIMO PHY performance even with differences on the received power among the clients. In the following, we show that the effects of in-phase and quadrature (IQ) imbalance on the UL MU-MIMO PHY performance can be catastrophic, especially when it is used high-cardinality modulation schemes without uplink power control. Finally, we show that a joint implementation of an uplink power control scheme and a time-domain IQ mitigation algorithm can mitigate the dramatic effects on the 802.11ax UL MU-MIMO PHY performance due to IQ imbalance and phase noise hardware impairments in channels where the average power received per client at the access point presents a significant standard deviation.

In this paper we present the design of CHRoME, a downlink multi-user beamforming (MUBF) protocol that addresses the inherent sensitivity of multi-stream systems to mobility, inter-stream interference, and imperfect channel state information. Our contributions are: (i) a technique for accurately selecting the downlink bit rate in the presence of inter-stream interference via a custom multi-user probe and feedback signal, immediately preceding data transmission, and (ii) a fast retransmission scheme that exploits liberated antenna resources to increase the expected per-user signal-to-interference-plus-noise ratio (SINR) and retransmit without having to re-sound the channel. We implement each mechanism and evaluate via a combination of indoor over-the-air experiments and trace-driven emulation. We demonstrate that CHRoME increases the resilience of MUBF systems to inter-stream interference and achieves multi-fold throughput gains compared to IEEE 802.11ac.

Firstly, we define a set of transmit beamforming (TxBF) transceiver architectures in the framework of IEEE 802.11n systems. In the following, assuming frequency selective spatially correlated TGn D channels, we carry out a comparative performance analysis taking into accounting the effects of realistic time synchronization and channel estimation schemes and practical feedback issues (i.e., delay, quantization and subcarrier grouping) on the throughput gains of the TxBF schemes over the Vertical Bell lab Layered Space Time (V-BLAST) spatial division multiplexing (SDM) scheme.

In this paper, we investigate the effects of transmit antenna correlation, receive antenna correlation, frequency selectivity and imperfect synchronization and channel estimation schemes on the performance of IEEE 802.11n systems with spatial expansion, receive diversity and space-time block codes. The simulations results are validated using a first order analytical modeling.

This paper investigates the legacy compatibility between IEEE 802.11n and 802.11a/g devices, focusing on the performance of legacy 802.11a/g auto-correlation and cross correlation joint time and frequency synchronization schemes operating over 802.11n networks. It is shown that synchronization schemes based on auto-correlation metric allow the backward compatibility, considering a different number of transmitting antennas operating over TGn channel models.

We develop a first order analytical medium access control (MAC) and physical (PHY) cross-layer model to estimate the saturation net throughput of IEEE 802.11e wireless local area networks (WLANs) with MAC enhancements schemes. The MAC improvements analyzed consist of minor modifications of the IEEE 802.11e enhanced distributed coordination function (EDCF) MAC protocol in order to support frame aggregation and concatenation.

We propose an analytical medium access control (MAC) and physical (PHY) cross-layer model to estimate the saturation net throughput of IEEE 802.11 wireless local area networks (WLANs) with MAC enhancements. These MAC improvements consist of modifications of the IEEE 802.11 distribution coordination function (DCF) MAC protocol in order to support concatenation and multiframe transmission techniques.

In this paper, we develop a theoretical medium access control (MAC) and physical (PHY) cross-layer model in order to estimate the energy consumption in IEEE 802.11e wireless local area networks (WLANs) operating under the enhanced distribution coordination function (EDCF) request-to-send/clear-to-send (RTS/CTS) scheme. A comparison between numerical and simulation results is carried out assuming the IEEE 802.11a PHY layer operating under saturated traffic conditions over uncorrelated flat fading Rayleigh channel.

A theoretical cross-layer model that allows assessing the goodput and delay of the IEEE 802.11a local area networks (WLANs) operating under saturated traffic conditions over block fading channels is developed. This model takes into account the distributed coordination function (DCF) request-to-send/clear-to- send (RTS/CTS) medium access control (MAC) protocol, the physical (PHY) layer and an adaptive link level scheme.

An analytical cross-layer model for the saturation goodput and delay of IEEE 802.lie wireless local area networks (WLANs) operating simultaneously under the enhanced distributed coordination function (EDCF) basic access (BA) and request-to-send/clear-to-send (RTS/CTS) medium access control (MAC) protocols is derived. A comparison between numerical and simulation results is carried out assuming the IEEE 802.11a physical (PHY) layer.

In this paper we show that dynamic time slot scheduling algorithms can improve significantly the performance of time division duplexing (TDD) direct sequence code division multiple access (DS-CDMA) systems with bi-dimensional (2D) RAKE receivers.

In this paper, we investigate the impact of 2D RAKE receiver on the performance of time division code division multiple access/packet reservation multiple access (TD-CDMA/PRMA) and slotted TD-CDMA/ALOHA uplink medium access control protocols for packet voice transmission in single and multi-cell networks. Simulation results show that the dependence of 2D RAKE receiver performance on the spatial-temporal channel characteristics indicates the necessity to include dynamic scheduling schemes in order to avoid designing the system considering worst case performance.