vpn affect your internet speed?

The emerging IEEE 802.11e MAC, which is an amendment of the ,existing 802.11 MAC, will provide the QoS [1][7]. The ,standardization of the IEEE 802.11e is still on-going at the final ,stage [3]. In this subsection, we briefly introduce the 802.11e ,before presenting our approach. ,The current 802.11 MAC has a mandatory distributed ,coordination function (DCF), which is based on carrier sense ,multiple access with collision avoidance (CSMA/CA). While ,there is another optional coordination function, i.e., polling-based ,point coordination function (PCF), most of today's 802.11 WLAN ,devices implement the DCF only. The channel access of the DCF ,is shown in Figure 3. Basically, when a station has a frame to ,transmit, it waits until the medium becomes idle. When the ,medium becomes idle, it senses the medium for a fixed amount of ,period, called distributed inter-frame space (DIFS), which is 50 ,usec for 802.11b WLANs, followed by a random backoff period (which can range from 0 to 620 usec provided there is no frame ,transmission failure for 802.11b WLANs), during which the MAC ,continues to sense the medium. When the medium stays idle ,during the backoff period, the MAC transmits the pending frame. ,Due to the random backoff procedure before a transmission ,attempt, the collisions can be avoided mostly, but it potentially ,results in a large delay, especially, when there are collisions.  ,Busy,Medium,SIFS,DIFS,Backoff Window,Slot Time,Defer Access Select Slot and decrement backoff,as long as  medium stays idle,DIFS,Contention Window,Immediate access when,medium is idle >= DIFS,Next Frame,PIFS,Figure 3. IEEE 802.11 DCF channel access ,The emerging 802.11e MAC for QoS support defines a single ,coordination function, called hybrid coordination function (HCF). ,A key mechanism of the 802.11e is the enhanced distributed ,channel access (EDCA), which is an enhancement of the legacy ,DCF, for the prioritized QoS support.  Under the DCF, there is ,basically a single first-in first-out (FIFO) queue inside the MAC. ,However, with the 802.11e EDCA, there are basically four FIFO ,queues located in the MAC as shown in Figure 4. A frame from ,the higher layer arrives at the MAC with a priority label (from 0 ,to 7), and each frame is enqueued into one of the four queues ,according to its priority value. Each queue has a channel ,contending entity, called access category (AC), which is a virtual ,DCF. Basically, four ACs contend for the channel independently. ,When multiple ACs finish the backoff process simultaneously, the ,highest priority frame is actually transmitted into the medium. In ,order to support the differentiated channel access for different ,priority frames, the EDCA uses an enhanced CSMA/CA as shown ,in Figure 5. Basically, instead of DIFS of the DCF, an AC under ,the EDCA uses AIFS[AC], whose value differs depending on AC. ,The upper bound of the backoff period is also determined ,depending on AC. Basically, the higher the priority (of the AC), ,the larger the AIFS value, and the larger the upper bound of the ,backoff period. In this manner, we can ensure that the higher ,priority frame is transmitted into the medium faster ,probabilistically.,

vpn affect your internet speed?

The emerging IEEE 802.11e MAC, which is an amendment of the ,existing 802.11 MAC, will provide the QoS [1][7]. The ,standardization of the IEEE 802.11e is still on-going at the final ,stage [3]. In this subsection, we briefly introduce the 802.11e ,before presenting our approach. ,The current 802.11 MAC has a mandatory distributed ,coordination function (DCF), which is based on carrier sense ,multiple access with collision avoidance (CSMA/CA). While ,there is another optional coordination function, i.e., polling-based ,point coordination function (PCF), most of today's 802.11 WLAN ,devices implement the DCF only. The channel access of the DCF ,is shown in Figure 3. Basically, when a station has a frame to ,transmit, it waits until the medium becomes idle. When the ,medium becomes idle, it senses the medium for a fixed amount of ,period, called distributed inter-frame space (DIFS), which is 50 ,usec for 802.11b WLANs, followed by a random backoff period (which can range from 0 to 620 usec provided there is no frame ,transmission failure for 802.11b WLANs), during which the MAC ,continues to sense the medium. When the medium stays idle ,during the backoff period, the MAC transmits the pending frame. ,Due to the random backoff procedure before a transmission ,attempt, the collisions can be avoided mostly, but it potentially ,results in a large delay, especially, when there are collisions.  ,Busy,Medium,SIFS,DIFS,Backoff Window,Slot Time,Defer Access Select Slot and decrement backoff,as long as  medium stays idle,DIFS,Contention Window,Immediate access when,medium is idle >= DIFS,Next Frame,PIFS,Figure 3. IEEE 802.11 DCF channel access ,The emerging 802.11e MAC for QoS support defines a single ,coordination function, called hybrid coordination function (HCF). ,A key mechanism of the 802.11e is the enhanced distributed ,channel access (EDCA), which is an enhancement of the legacy ,DCF, for the prioritized QoS support.  Under the DCF, there is ,basically a single first-in first-out (FIFO) queue inside the MAC. ,However, with the 802.11e EDCA, there are basically four FIFO ,queues located in the MAC as shown in Figure 4. A frame from ,the higher layer arrives at the MAC with a priority label (from 0 ,to 7), and each frame is enqueued into one of the four queues ,according to its priority value. Each queue has a channel ,contending entity, called access category (AC), which is a virtual ,DCF. Basically, four ACs contend for the channel independently. ,When multiple ACs finish the backoff process simultaneously, the ,highest priority frame is actually transmitted into the medium. In ,order to support the differentiated channel access for different ,priority frames, the EDCA uses an enhanced CSMA/CA as shown ,in Figure 5. Basically, instead of DIFS of the DCF, an AC under ,the EDCA uses AIFS[AC], whose value differs depending on AC. ,The upper bound of the backoff period is also determined ,depending on AC. Basically, the higher the priority (of the AC), ,the larger the AIFS value, and the larger the upper bound of the ,backoff period. In this manner, we can ensure that the higher ,priority frame is transmitted into the medium faster ,probabilistically.,