Hierarchical Cell Structure Research Articles

Fast cell search using I/Q multiplexed codeunder hierarchical cell structure

A novel I/Q multiplexed code assignment is proposed for asynchronous cell site operation under hierarchical cell structure, in which the I-channel code as a group code and the Q-channel code as a cell-specific code are assigned to a forward pilot channel. Simulation results show that cell search from macro to micro, or vice versa, can be accomplished in less than /spl sim/50 ms at 90% of the locations.

UMTS/IMT-2000 based on wideband CDMA

The UMTS terrestrial radio access is based on wideband 4.096 Mchip/s DS-CDMA technology. UTRA will be connected to an evolved GSM core network for both circuit and packet services. A merger between ETSI/Europe and ARIB/Japan based on W-CDMA, a GSM core network, and a common frequency allocation according to the ITU Recommendation of 2 GHz makes a global IMT-2000 standard feasible. UTRA based on W-CDMA fully supports the UMTS/IMT-2000 requirements (e.g., support of 384 kb/s for wide-area coverage and 2 Mb/s for local coverage). Furthermore, the air interface has flexible support of mixed services, variable-rate services, and an efficient packet mode. Key W-CDMA features also include improved basic capacity/coverage performance compared to second-generation systems, full support of adaptive antenna arrays, support of hierarchical cell structures with interfrequency handover, and support of asynchronous inter-base-station operation. There have been no constraints due to the strong requirements for backward compatibility with second-generation systems. This has facilitated a high degree of flexibility and a future-proof air interface. Extensive evaluations by means of simulations and field trials have been carried out by a number of companies, and full system tests are ongoing. Consequently, W-CDMA technology can now be regarded as a mature technology, ready to provide the basis for UMTS/IMT-2000.

Uplink performance of multicarrier joint detectioncode division multiple access

To comply with the requirements on future mobile communications, such as, for example, support of hierarchical cell structures, the application of multicarrier techniques is advantageous. The authors present new performance results of the multicarrier joint detection code division multiple access (MC/JD-CDMA) concept , a recent extension of the well known third generation concept JD-CDMA .

Hierarchical Layout Verification

This article presents a hierarchical cell structure that has been Used successfully to improve the performance of Intel's connectivity verifier and design rule checker. A unique algorithm for performing design rule checks efficiently in a hierarchical environment is discussed in detail. To undersize and oversize in a hierarchical environment without disrupting the cell structure, the definition of sizing must be changed so that geometries inside a cell and touching the cell boundaries do not pull away and geometries outside the cell do not extend inside. There are also a few Pathologies?caused mostly by looking at only a small portion of the layout, outside of the context where it is used. Nevertheless, careful use of hierarchical design can deliver order-of-magnitude improvements in layout checking runtime.