A NOVEL LINK ADAPTATION SCHEME TO ENHANCE PERFORMANCE OF IEEE 802.11G WIRELESS LAN

A novel link adaptation scheme using linear Auto Regressive （AR） model channel estimation algorithm to enhance the performance of auto rate selection mechanism in IEEE 802.11g is proposed. This scheme can overcome the low efficiency caused by time interval between the time when Received Signal Strength （RSS） is measured and the time when rate is selected. The best rate is selected based on data payload length, frame retry count and the estimated RSS, which is estimated from recorded RSSs. Simulation results show that the proposed scheme enhances mean throughput performance up to 7%, in saturation state, and up to 24% in finite load state compared with those non-estimation schemes, performance enhancements in average drop rate and average number of transmission attempts per data frame delivery also validate the effectiveness of the proposed schelne.

The optimization of FA/O barrier slurry with respect to removal rate selectivity on patterned Cu wafers

Because the polishing of different materials is required in barrier chemical mechanical planariza- tion （CMP） processes, the development of a kind of barrier slurry with improved removal rate selectivity for Cu/barrier/TEOS would reduce erosion and dishing defects on patterned Cu wafers. In this study, we developed a new benzotriazole-free barrier slurry named FA/O barrier slurry, containing 20 mL/L of the chelating agent FA/O, 5 mL/L surfactant, and a 1：5 concentration of abrasive particles. By controlling the polishing slurry ingredients, the removal rate of different materials could be controlled. For process integration considerations, the effect of the FA/O barrier slurry on the dielectric layer of the patterned Cu wafer was investigated. After CMP processing by the FA/O barrier slurry, the characteristics of the dielectric material were tested. The results showed that the dielectric characteristics met demands for industrial production. The current leakage was of pA scale. The resistance and capacitance were 2.4 k and 2.3 pF, respectively. The dishing and erosion defects were both below 30 nm in size. CMP-processed wafers using this barrier slurry could meet industrial production demands.

Design and implementation of IEEE 802.11ac MAC controller in 65 nm CMOS process

An IEEE-802.1 l ac-l＊ 1 wireless LAN system-on-a-chip （SoC） that integrates an analog front end, a digital base-band processor and a media access controller has been implemented in 65 nm CMOS technology. It can provide significantly increased throughput, high efficiency rate selection, and fully backward compatibility with the existing 802.11 a/n WLAN protocols. Especially the measured maximum throughput of UDP traffic can be up to 267 Mbps.

Effect of three kinds of guanidinium salt on the properties of a novel low-abrasive alkaline slurry for barrier CMP

The influence of three kinds of guanidinium salt on the removal rate selectivity of different materials was studied during the barrier chemical mechanical polishing （CMP） process at first. The three kinds of guanidine saltguanidine hydrochloride, guanidine nitrate and guanidine carbonate. Then we compared the effect of the three kinds of guanidine salt on the dishing, erosion and surface roughness value. In the end, the reaction mechanism was studied through electrochemical analysis. All the results indicate that there is a better performance of the slurry with guanidine hydrochloride than the slurries with the other two kinds of guanidine salt. It effectively improved the removal rate selectivity and the surface roughness under the premise of low abrasive concentration and low polishing pressure, which is good for the optimization of the alkaline slurry for the barrier CMP process.