Synchronous transmission technique for the reverse link in DS-CDMAterrestrial mobile systems

In this letter, a timing control algorithm is described, which realizes timing synchronization on the direct sequence code-division multiple-access reverse link. In addition, the uncoded bit-error probability is analytically derived. Numerical results, confirmed by simulation, show that our synchronous transmission technique can offer better performance than conventional asynchronous transmission, especially for an exponentially decaying multipath intensity profile with a large decay factor     

A 120-mm2 64-Mb NAND flash memory achieving 180 ns/Byteeffective program speed

Emerging application areas of mass storage flash memories require low cost, high density flash memories with enhanced device performance. This paper describes a 64 Mb NAND flash memory having improved read and program performances. A 40 MB/s read throughput is achieved by improving the page sensing time and employing the full-chip burst read capability. A 2-μs random access time is obtained by using a precharged capacitive decoupling sensing scheme with a staggered row decoder scheme. The full-chip burst read capability is realized by introducing a new array architecture. A narrow incremental step pulse programming scheme achieves a 5 MB/s program throughput corresponding to 180 ns/Byte effective program speed. The chip has been fabricated using a 0.4-μm single-metal CMOS process resulting in a die size of 120 mm² and an effective cell size of 1.1 μm²     

Computational analysis of convective diffusion with chemical reaction in a cavity

Unsteady convective diffusion problems involving chemical reaction in a rectangular are numerically examined. The effect of various factors affecting the removal of the contaminant in the cavity has been analyzed systematically. The vorlicity and streamfunction are used for numerical computations. For low Reynolds number cases, the rate of removal of the contaminant increases as the Grashof number becomes larger. For high Reynolds number, the secondary flow hinders the rate of removal of the contaminant as the Grashof number becomes larger.     

Channel Allocation Scheme for Handoff Control in Wireless Ad Hoc Network with Group Mobility

Because a wireless ad hoc network does not have a fixed backbone network and the mobile base station moves randomly, the conventional channel allocation scheme cannot efficiently predict group mobility and is not feasible to support a burst handoff traffic due to group mobility. In this paper, we propose an channel allocation scheme to solve this problem. Our scheme efficiently support burst handoff using guard channel and hello message in wireless ad hoc network with group mobility. We developed an analytical Markov model for the proposed scheme and evaluate our scheme in terms of new call and handoff blocking probability and channel utilization via simulation study. Simulation results show that our scheme offers better performance than the conventional schemes.     

Multicast Handoff Agent Mechanism for All-IP Mobile Network

This paper proposes a mechanism called a Multicast Handoff Agent (MHA) to reduce handoff latency for IP multicast. The MHA acts as a proxy for the Internet Group Management Protocol (IGMP) of mobile nodes and keeps information for members of multicast groups in a cell. When a mobile node moves to other cell, the MHA immediately sends unsolicited reports without waiting for the IGMP query. In addition, our mechanism may conserve battery power since it does not need to reply to a query.The mechanism is evaluated through simulation and analysis and compared with the IGMPv2 for mobility and IGMP traffic. Simulation results show that handoff latency can be largely reduced and the IGMP control traffic can be eliminated on the wireless links during the duration of membership.     

Computational simulation of melt flow in magnetic Czochralski growth process

Melt flow phenomena of magnetic Czochralski processes are simulated numerically. A model is established for the system that can grow a 5 inch diameter single crystal from the melt in a 14 inch diameter cylindrical crucible. Effective conditions to suppress convection adequately are studied by varying rotation rates of the crucible and the crystal for given magnetic fields. When the axial magnetic force is used, the method of co-rotation of the crystal and the crucible is found more effective to suppress meridional circulation than the conventional counter-rotation operation.