This disclosure relates to orthogonal frequency division multiple access (OFDMA) communication in wireless local area networks (WLANs). According to some embodiments, a downlink OFDMA frame may be transmitted. An uplink OFDMA frame including acknowledgements associated with the downlink OFDMA frame may be received. The uplink OFDMA frame may be processed, in some instances including determining which devices receiving the downlink OFDMA frame transmitted an acknowledgement associated with the downlink OFDMA frame in the uplink OFDMA frame.

This disclosure relates to orthogonal frequency division multiple access (OFDMA) communication in wireless local area networks (WLANs). According to some embodiments, a downlink OFDMA frame may be transmitted. An uplink OFDMA frame including acknowledgements associated with the downlink OFDMA frame may be received. The uplink OFDMA frame may be processed, in some instances including determining which devices receiving the downlink OFDMA frame transmitted an acknowledgement associated with the downlink OFDMA frame in the uplink OFDMA frame.

A client system such as a database system may be vulnerable to intrusion by an unauthorized user or system through a reverse secure shell connection that enables the intruder to execute OS-level or shell commands on the client system. A reverse shell connection may be detected by monitoring and inspecting packet data traffic between the client system or internal network, and an exterior or “foreign” network. In one example of such a process, after detecting a normal shell session originating inside the internal network, a reverse shell connection exploiting the initial shell detection is detected by analyzing the transmission directions and payload sizes of a sequence of the monitored packets relative to a predetermined traffic pattern. The specific pattern may be selected for different operating systems.

A client system such as a database system may be vulnerable to intrusion by an unauthorized user or system through a reverse secure shell connection that enables the intruder to execute OS-level or shell commands on the client system. A reverse shell connection may be detected by monitoring and inspecting packet data traffic between the client system or internal network, and an exterior or “foreign” network. In one example of such a process, after detecting a normal shell session originating inside the internal network, a reverse shell connection exploiting the initial shell detection is detected by analyzing the transmission directions and payload sizes of a sequence of the monitored packets relative to a predetermined traffic pattern. The specific pattern may be selected for different operating systems.

A payment reader and a merchant device may communicate over a wireless connection. Reliable and unreliable packets may be transmitted over a single messaging path. Each of a plurality of unreliable packet may include a data payload and a packet identifier. The unreliable packets and a reliable packet may be transmitted over the single messaging path during a first connection event. A response to the reliable packet may be received during the second event and may include a received packet listing. If the received packet listing indicates that any of the unreliable packets were not received, any unreliable packet that was not received may be retransmitted.

A payment reader and a merchant device may communicate over a wireless connection. Reliable and unreliable packets may be transmitted over a single messaging path. Each of a plurality of unreliable packet may include a data payload and a packet identifier. The unreliable packets and a reliable packet may be transmitted over the single messaging path during a first connection event. A response to the reliable packet may be received during the second event and may include a received packet listing. If the received packet listing indicates that any of the unreliable packets were not received, any unreliable packet that was not received may be retransmitted.

Generally, this disclosure provides systems, devices, methods and computer readable media for patch downloading, from a host to a target, with improved acknowledge (ACK) mechanisms including combinations of out-of-sequence, single and aggregate acknowledge mechanisms. The method may include determining a packet size based on buffer capacity of the host; calculating the total number of packets (P) for transmission based on a size of the patch divided by the packet size; and calculating a packet storage capacity (N) of the target, based on buffer capacity of the target divided by the packet size. The method may also include transmitting the P packets to the target, including a sequence number and a portion of the patch, the transmission segmented into one or more cycles of up to N packets. The method may further include receiving ACKs from the target (asynchronously relative to the packet transmissions), the ACKS associated with the sequence numbers.

Generally, this disclosure provides systems, devices, methods and computer readable media for patch downloading, from a host to a target, with improved acknowledge (ACK) mechanisms including combinations of out-of-sequence, single and aggregate acknowledge mechanisms. The method may include determining a packet size based on buffer capacity of the host; calculating the total number of packets (P) for transmission based on a size of the patch divided by the packet size; and calculating a packet storage capacity (N) of the target, based on buffer capacity of the target divided by the packet size. The method may also include transmitting the P packets to the target, including a sequence number and a portion of the patch, the transmission segmented into one or more cycles of up to N packets. The method may further include receiving ACKs from the target (asynchronously relative to the packet transmissions), the ACKS associated with the sequence numbers.

The present invention addresses the problem of checking, on the wireless control device side, error occurrence states of CPRI links in detail. In order to solve the problem, this wireless device stores, in wireless link regions that can be freely used by a user, error occurrence states of wireless links, and transmits the error occurrence states to a wireless control device.

In an example of wireless communications based on orthogonal frequency-division multiple access (OFDMA), an access point may send a downlink frame to multiple stations. In response, some or all of the stations may transmit their respective uplink frames simultaneously after a predetermined time period. The uplink frames from the stations may be aggregated or multiplexed to form a final uplink frame that is received by the access point. Each of the uplink frames from the stations may include at least a legacy header and an acknowledgment frame. While a legacy header occupies the entire channel bandwidth of its uplink frame, an acknowledgment frame occupies a sub-band assigned to its station, where a sub-band is a portion of the channel bandwidth. Other methods, apparatus, and computer-readable media are also disclosed.