HP mt41 HP Velocity Technology Overview - Page 11

• Management overhead: WiFi networks carry a significant amount of management overhead. APs advertise their presence and wireless clients must regularly probe the AP to notify it that they are still there. When there are a large number of WiFi devices present in a single location, the management overhead becomes excessive and the capacity of the WiFi network is reduced. • Acknowledgments: All WiFi packets must be acknowledged by the receiver to ensure successful delivery. These acknowledgment packets are sent by a WiFi device every time it receives a packet. When combined with the overhead of protocols like TCP, this can result in 3 out of every 4 WiFi packets becoming overhead packets, with only 1 out of 4 packets containing "useful" data. • Retransmissions: Not all WiFi packets are successfully received the first time they are sent. A client might not receive a packet because of collisions or insufficient signal strength. A single bit error in a packet will result in the retransmission of the entire WiFi packet. Retransmissions might happen repeatedly for the same WiFi packet. • WiFi is half duplex: A wired Ethernet network is full duplex, meaning that a device can send and receive, or upload and download, simultaneously. WiFi is half duplex, so if a client sends data to the AP, the AP cannot send data to the same or any other client at the same time. For two-way communication, which includes most applications used over the Internet, such as video or voice chat, this essentially halves throughput when compared to a fullduplex technology, including a wired Ethernet connection. • Wireless contention: When a client wants to send data and the channel is occupied, the client must wait, otherwise collisions will occur and the data will be corrupted. Once the channel clears, the client must wait even longer before it can attempt to send. Similar to trying to cross a single-lane bridge, if there are cars wanting to cross from both directions, everyone must wait their turn and there is uncertainty about whose turn is next. If a user on a wireless network is using large amounts of bandwidth through activities such as watching a video on YouTube or downloading a file, it will be more difficult and take longer for another device to send, even if it is trying to do a task that requires very little data, such as checking email. LiveWiFi addresses these issues using WiFi prioritization and TCP over WiFi. WiFi prioritization LiveWiFi awards HP Velocity traffic a higher priority than other traffic on the network. Both endpoints mark HP Velocity traffic to prioritize packets moving in either direction. LiveWiFi leverages the WiFi Multimedia (WMM) Standard to reduce packet wait times compared to other traffic in the network. This results in lower latency, less jitter, and higher throughput. HP Velocity Technology Overview 11