Báo cáo hóa học: " CSMA/CCA: A Modified CSMA/CA Protocol Mitigating the Fairness Problem for IEEE 802 11 DCF" docx

... replacing AP1 and AP2 with STA3 and STA4 and assuming that all the stations are in the same BSS but STA3 and STA4 cannot hear each other, the same problem arises. The MACAW protocol [4] fails in ... contends for links AP1-STA2 and AP1-STA3 separately. Since all the members of a WLAN share the same wireless channel, a MAC protocol is needed to coordinate their access. A...

Ngày tải lên: 22/06/2014, 22:20

... of a video stream and assigning the appro- priate MCS for each video layer to maximize the total utility is a crucial task [11- 21]. Formally, the problem can be stated as follows: consider a video ... efficiency and maximize utility is a crucial task. We formulate this MCS assignment problem as an optimization problem, called the total utility maximization problem (...

Ngày tải lên: 21/06/2014, 02:20

... information is missing and the MB types and motion vectors are available (from partition A) . 2.2. The 802. 11e WLAN standard The MAC layer of the 802. 11 standard is based on the CSMA/CA mechanism ... virtual packets at a rate equal to the average rate and at intervals equal to the inverse of frame rate. The virtual packet sizes are calculated using the bitrate and...

Ngày tải lên: 21/06/2014, 23:20

... 2010, Article ID 979120, 9 pages doi:10 .115 5/2010/979120 Research Article Modified Polar Sigma-Delta Transmitter for Multiradio Applications Martha Liliana Suarez Penaloza, 1 V ´ aclav Valenta, 1, ... standard and theoretical values for the maximum oversampling ratios for other communications standards have been calculated as well. To approach to more realistic analyses, we didn’t...

Ngày tải lên: 21/06/2014, 11:20

... method approximates the received signals as a series of linear frequency modulated signals. But, the accuracy is not high, and there are many false scatters in the image. So, a new ISAR imaging algorithm ... traditional chirplet decomposition. Now, we compare the ISAR imaging results of real data and simulated data based on the two algorithms. (1) Real data We choose a segment...

Ngày tải lên: 22/06/2014, 01:20

... and the carboxyl groups available on the surface of the support. Fourier transform infrared spectroscopy (FTIR) and Thermogravimetric analysis (TGA) unambiguously proved the existence of covalent bonds ... new peak that appeared around 1686 cm -1 is attributed to the amide carbonyl (C=O) stretch. Another new peak at 1629.87 cm -1 is attributed to secondary amide band which accompani...

Ngày tải lên: 22/06/2014, 01:20

... be- tween antennas the larger is the MIMO capacity. The spatial correlation is dictated by the angular spread of the propa- gation paths at the transmitter and the receiver. Root mean square (RMS) angular ... an- gular spread (AS), angle of departure (AoD), angle of ar- rival (AoA), and power azimuth spectrum (PAS). The ar- ray topology at the BS is, for example, a typic...

Ngày tải lên: 22/06/2014, 06:20

... beacon frame, contention-free Sanjaya Gupta et al. 5 Table 2 IEEE 802. 11b parameters Values Data rates for data packets 11 Mbps Data rates for control packets and PHY overheads 1 Mbps MAC layer ... receiver. After retrieving the VoIP payload, the DEMUX then restores the original RTP header and nec- essary destination information and assembles the data into its original form...

Ngày tải lên: 22/06/2014, 19:20

... diagrammatically A 'Health Status' visual analog scale used in the Health Assessment QuestionnaireFigure 4 A 'Health Status' visual analog scale used in the Health Assessment ... design, the appropriate application of statistical validation methods, and the suitability of the resulting measure for a particular use in clinical and population-based outcomes...

Ngày tải lên: 20/06/2014, 16:20

... every frame and thus it can take them into account calculating the actual available capacity for the nrtPS packets H i . We note that the actual uplink transmission requirements represented by the ... demonstrates the dependency of the mean overall nrtPS delay on the normalized arrival rate for different total UGS capacity values per frame. Here, the minimum and the maxim...

Ngày tải lên: 21/06/2014, 05:20