Cali F, Conti M, Gregori E. IEEE 802.11 wireless LAN: capacity analysis and protocol enhancement. In Proceedings of IEEE INFOCOM'1998, March, 1998.  Home/Search   Document Not in Database   Summary   Related Articles   Check

....profiling methodology applicable to practically any wireless MAC protocol and independent of the hosts and access points. We study the performance of an 802.11b WLAN BSS (Basic Service Set) in the infrastructure mode, i.e, when a number of stations are associated with a single AP. Previous works [5], 6] 8] 11] 12] have characterized Supported in part by the UMIACS LTS contract the performance of 802.11 networks through analytical methods and simulations. Existing measurement studies [13] measure the performance of transport protocols over 2Mbps 2.4GHz FHSS pure CSMA CA WaveLAN ....

....a deviation of 0.0248 Mbps. As the number of stations increases, the throughput falls and the standard deviation increases. For example, with 5 stations, the overall throughput reduces to 5.74568 Mbps and the deviation increases to 0.540433 Mbps. Our experiments validate the results reported in [5], which analyzed IEEE 802.11 operation under various assumptions such as time independent modeling, geometrically distributed packet size, etc. Those results also showed that the IEEE 802.11 standard operates at rates lower than a theoretically possible 7.2754 Mbps. The maximum instantaneous ....

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F.Cali, M. Conti, and E. Gregori. IEEE 802.11 wireless LAN: Capacity analysis and protocol enhancement. In Proceedings of INFOCOM, 1998.

....its backoff period, and its backoff period can grow to be quite long. Sift compares favorably in this regard, because we use a fixed size backoff window. Cal, Conti, and Gregori proposed replacing the uniform distribution contention window of 802.11 with a # persistent backoff protocol [6, 7]. By estimating the population size, they chose # to maximize system throughput when all nodes always had a packet ready for transmission. They showed that 802.11 yields suboptimal throughput under this workload, and that their algorithm could approach optimal throughput under the same conditions. ....

CAL I,F.,CONTI, M., AND GREGORI, E. IEEE 802.11 Wireless LAN: Capacity Analysis and Protocol Enhancement. In Proceedings of the Conference on Computer Communications (IEEE INFOCOM) (San Francisco, CA, 1998), vol. 1, pp. 142--149.

....its backoff period, and its backoff period can grow to be quite long. Sift compares favorably in this regard, because we use a fixed size backoff window. Cal, Conti, and Gregori proposed replacing the uniform distribution contention window of 802.11 with a p persistent backoff protocol [6, 7]. By estimating the population size, they chose p to maximize system throughput when all nodes always had a packet ready for transmission. They showed that 802.11 yields suboptimal throughput under this workload, and that their algorithm could approach optimal throughput under the same conditions. ....

CAL I, F., CONTI, M., AND GREGORI, E. IEEE 802.11 Wireless LAN: Capacity Analysis and Protocol Enhancement. In Proceedings of the Conference on Computer Communications (IEEE INFOCOM) (San Francisco, CA, 1998), vol. 1, pp. 142--149.

....wireless MAC protocol and independent of the hosts and access points. We study the performance of an 802.11b WLAN BSS (Basic Service Set) in the infrastructure mode, i.e, when a number of stations are associated with a single AP. Pre Supported in part by the UMIACS LTS contract vious works [5], 6] 8] 11] 12] have characterized the performance of 802.11 networks through analytical methods and simulations. Existing measurement studies [13] measure the performance of transport protocols over 2Mbps 2.4GHz FHSS pure CSMA CA WaveLAN system, which predates 802.11b. Reference [4] ....

....a deviation of 0.0248 Mbps. As the number of stations increases, the throughput falls and the standard deviation increases. For example, with 5 stations, the overall throughput reduces to 5.74568 Mbps and the deviation increases to 0.540433 Mbps. Our experiments validate the results reported in [5], which analyzed IEEE 802.11 operation under various assumptions such as time independent modeling, geometrically distributed packet size, etc. Those results also showed that the IEEE 802.11 standard operates at rates lower than a theoretically possible 7.2754 Mbps. The maximum instantaneous ....

[Article contains additional citation context not shown here]

F.Cali, M. Conti, and E. Gregori. IEEE 802.11 wireless LAN: Capacity analysis and protocol enhancement. In Proceedings of INFOCOM, 1998.

....has the right to transmit. The PCF is not ecient, however, when facing time critical trac with di erent service requirements and when only some of the stations are active during a polling period. Much research has been devoted to IEEE 802.11 MAC protocol performance analysis and improvement [5, 6], and several standards have appeared which support mixed trac. For example, Whitecap (www.sharewave.com) uses dynamic time division multiple access (TDMA) to split the channel between nodes and within each node trac is divided into three queues of varying priority. Our proposed protocol is very ....

F. Cali, M. Conti, and E. Gregori, \IEEE 802.11 Wireless LAN: Capacity analysis and protocol enhancement," in Proc. IEEE INFOCOM'98, San Francisco, CA, USA, 1998, pp. 142-149.

....for time bounded trac. The AP sends downlink packets and polls stations for uplink packets. In the second part of the AP created superframe medium access is performed using the DCF (see Figure 1) A more detailed investigation of the access and the RTS CTS mechanism can be found in [21] 22] and [23]. 3.2 Timing Synchronization and Power Saving Within the standard, the general idea is for all stations in Power Save (PS) mode to switch o the radio part for some period. They have to be synchronized to wake up at the same time when there starts a window in which the sender announces bu ered ....

F. Cali, M.Conti, E. Gregori: \IEEE 802.11 Wireless LAN: Capacity Analysis and Protocol Enhancement", Proc. of INFOCOM

....As we explained earlier, we are motivated to develop a simpler model of channel behavior under 802.11 in order to reduce the number of events, and to increase the inherent lookahead. Our simplistic model is by no means the only attempt to model 802.11. Worthwhile analytic e orts are reported in [8, 16, 24, 121]. These models seek qualitative explanations for 802.11; our motivation is to deploy quantitative computational models. We are looking at this work though to provide ideas for our own needs. 60 0 0.02 0.04 0.06 0.08 0.1 0.12 0.14 0.16 0 0.2 0.4 0.6 0.8 1 Service Time (Seconds) ....

F. Cali, M. Conti, and E. Gregori. IEEE 802.11 wireless LAN: capacity analysis and protocol enhancement. Proceedings of IEEE INFOCOM'98 Conference on Computer Communications Seventeenth Annual Joint Conference of the IEEE Computer and Communications Societies Gateway to the 21st Century, pages 142-9 vol.1, 1999.

....the full graph of a radio network. 200 nodes, uniformly randomly placed on a 2000 x 2000 meter region, with a radio range of 250 m. Middle: the GG subset of the full graph. Bottom: the RNG subset of the full and GG graphs. 43 as the number of mutually reachable sending stations increases [1] [8]. Moreover, while any packet a node transmits monopolizes the shared channel within its radio range, MAC protocols that address the hidden terminal problem, including 802.11 [17] MACA [21] and MACAW [4] deliberately spread contention to the full radio ranges of both sender and receiver. On some ....

CALI, F., CONTI, M., AND GREGORI, E. IEEE 802.11 wireless LAN: capacity analysis and protocol enhancement. In Proceedings of IEEE INFOCOM

....to have occurred and the data packet is transmitted again after waiting another random amountoftime. If a single host transmits a data frame, the transmission time will be the following (we suppose 802.11b with the bit rate of 11 Mb s [2] and we neglect propagation times# this analysis follows [7, 20, 4]) T single = tpr t tr SIFS ACK DIFS (1) where tpr is the preamble time (144 s) t tr is the frame transmission time (size bit rate) SIFS=10s,ACK is the ACK transmission time (210 s) and DIFS=30s.Ifwe assume the frame size of 1500 bytes of data (data frame of total 1534 bytes) ....

F. Cali, M. Conti, and E. Gregori. IEEE 802.11 Wireless LAN: Capacity Analysis and Protocol Enhancement. In INFOCOM, 1998.

....The PCF is not efficient, however, when facing time critical traffic with different service requirements because only some of the stations are active during a polling period. Much research has been devoted to IEEE 802.11 medium access control (MAC) protocol performance analysis and improvement [1, 3]. However, these works do not address applications in a real time environment. In order to combine existing WLAN technology with real time requirements, we propose a new protocol Prioritized CSMA CA (P CSMA CA) which can be considered as an extension of the IEEE 802.11 WLANs standard. The new ....

F. Cali, M. Conti, and E. Gregori. IEEE 802.11 Wireless LAN: Capacity analysis and protocol enhancement. In Proc. IEEE INFOCOM'98, pages 142--149, San Francisco, CA, USA, 1998.

....subset of the full graph; and the RNG subset of the full graph. Note that the RNG and GG offer different densities of connectivity by eliminating different numbers of links. Many MAC layers exhibit drastically reduced efficiency as the number of mutually reachable sending stations increases [1] [5]. Moreover, while any packet a node transmits monopolizes the shared channel within its radio range, MAC protocols that address the hidden terminal problem, including 802.11 [11] MACA [14] and MACAW [2] deliberately spread contention to the full radio ranges of both sender and receiver. Under ....

CALI, F., CONTI, M., AND GREGORI, E. IEEE 802.11 wireless LAN: capacity analysis and protocol enhancement. In Proceedings of IEEE INFOCOM 1998 (San Francisco, California, March/April 1998), p. 142.

....[15] have provided a comparison of the IEEE 802.11 protocol with ETSI RES 10 HIPERLAN; they show that both protocols perform satisfactorily under general configurations. It is also pointed out that the protocol performance can potentially suffer in the presence of hidden terminals. Cali et al. [2] have provided a mathematical model for the capacity (the maximum throughput achievable) The focus of their work is the back off algorithm used in the MAC protocol. They suggest that the protocol capacity can be enhanced by appropriately tuning the back off algorithm. Chhaya and Gupta [4] have ....

F. Cali, M. Conti, and E. Gregori. IEEE 802.11 wireless LAN capacity analysis and protocol enhancement. In INFOCOM '98, 1998.

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Cali F, Conti M, Gregori E. IEEE 802.11 wireless LAN: capacity analysis and protocol enhancement. In Proceedings of IEEE INFOCOM'1998, March, 1998.

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F. Cali, M. Conti, and E. Gregori. IEEE 802.11 Wireless LAN: Capacity analysis and protocol enhancement. In Proc. of INFOCOM'98, San Francisco, USA, 1998.

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F. Cali, M. Conti, and E. Gregori, IEEE 802.11 Wireless LAN: Capacity Analysis and Protocol Enhancement, IEEE, 1998.

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F. Cali, M. Conti, and E. Gregori. IEEE 802.11 wireless LAN: Capacity analysis and protocol enhancement. In Proceedings of IEEE INFOCOM'98, pages 142--149, 1998.

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F. Cali, M. Conti, and E. Gregori. IEEE 802.11 Wireless LAN: Capacity Analysis and Protocol Enhancement. In Procee dings of INFOCOM , 1998.

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F. Cal, M. Conti, and E. Gregori. IEEE 802.11 wireless LAN: Capacity analysis and protocol enhancement. In INFOCOM '98, Conference on Computer Communications, pages 142--149. Institute of Electrical and Electronics Engineers, 1998.

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F. Cali, M. Conti, and E. Gregori. IEEE 802.11 Wireless LAN: Capacity Analysis and Protocol Enhancement. In INFOCOM, Mar/Apr 1998.

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F. Cali, M. Conti, and E. Gregori, IEEE 802.11 wireless LAN: capacity analysis and protocol enhancement, in Proc. of INFOCOM '98, Seventeenth Annual Joint Conference of the IEEE Computer and Communications Societies, vol. 1, 1998, pp. 142--149.

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