Drive Test Data Research Articles

Effect of Distance on the Accuracy of RSS-Based Geometric Positioning Methods

The accuracy of Received Signal Strength (RSS)-based positioning methods is highly variable due to its dependence on various varying parameters such as the wireless environment, topology of the network, propagation model utilized etc. In this paper, drive test data were analyzed to examine the effect of distances from the Mobile Station to the serving and neighbouring base stations (BSs) on the accuracy of four RSS-based geometric positioning methods. The relationship between the accuracy of these positioning methods and distances between the BSs were also considered. There is relatively varying differences that the topologies of the network have on the accuracy of the positioning algorithms. The RSS-based geometric algorithms considered include the Centre of Gravity, the Circular Trilateration, Circular Trilateration and the Least Square algorithms.

Data fusion-based interference matrix generation for cellular system frequency planning

Interference matrix (IM) has been widely used in frequency planning/optimization of cellular systems because it describes the interaction between any two cells. IM is generated from the source data gathered from the cellular system, either mobile measurement reports (MMRs) or drive test (DT) records. IM accuracy is not satisfactory since neither MMRs nor DT records contain complete information on interference and traffic distribution. In this paper, two IM generation algorithms based on source data fusion are proposed. Data fusion in one algorithm is to reinforce MMRs data, using the frequency-domain information of DT data from the same region. Data fusion in the other algorithm is to reshape DT data, using the traffic distribution information extracted from MMRs from the same region. The fused data contain more complete information so that more accurate IM can be obtained. Simulation results have validated this conclusion. Copyright © 2011 John Wiley & Sons, Ltd. (To generate interference matrix for cellular system frequency planning, two algorithms based on source data fusion are proposed. Data fusion in one algorithm is to reinforce MMRs data, using the frequency-domain information about DT data from the same region. Data fusion in the other algorithm is to reshape DT data, using the traffic distribution information extracted from MMRs from the same region. The fused data contain more complete information so that more accurate IM can be obtained.)

Mobility Tracking Based on Autoregressive Models

We propose an integrated scheme for tracking the mobility of a user based on autoregressive models that accurately capture the characteristics of realistic user movements in wireless networks. The mobility parameters are obtained from training data by computing Minimum Mean Squared Error (MMSE) estimates. Estimation of the mobility state, which incorporates the position, velocity, and acceleration of the mobile station, is accomplished via an extended Kalman filter using signal measurements from the wireless network. By combining mobility parameter and state estimation in an integrated framework, we obtain an efficient and accurate real-time mobility tracking scheme that can be applied in a variety of wireless networking applications. We consider two variants of an autoregressive mobility model in our study and validate the proposed mobility tracking scheme using mobile trajectories collected from drive test data. Our simulation results validate the accuracy of the proposed tracking scheme even when only a small number of data samples is available for initial training.

4494066 Method of electrically testing a packaging structure having N interconnected integrated circuit chips

Design rules and test structure are used to implement machine designs to thereby obviate during testing the need for mechanical probing of the chip, multichip module, card or board at a higher level of package. The design rules and test structure also provide a means of restricting the size of logic partitions on large logical structures to facilitate test pattern generation. A test mechanism is available on every chip to be packaged to drive test data on all chip outputs and observe test data on all chip inputs, independent of the logic function performed by the chip. A control mechanism is also provided to allow a chip to either perform its intended function or to act as a testing mechanism during package test. It is intended that the test mechanism built into every chip will be used in place of mechanical probes to perform a chip-in-place test and interchip wiring test of the package. The intent of the design rules is to design chips such that each chip can be "isolated" for testing purposes through the pins (or other contacts) of a higher level package containing such chips. It is also required that the "Level Sensitive Scan Design" (LSSD) discipline, or rules, be followed for each chip and for the package clock distribution network. Further, the LSSD Rules which ensures the capability of scanning data into and out of the package SRLs (shift register latches) must be satisfied for the total package.