Showing papers by "Amitava Ghosh published in 1998"
Patent•
18 Dec 1998TL;DR: In this paper, a group identification code (GIC) (305) is broadcast during a time period that the long code is masked, indicating a (spreading code) long code group to which each base station belongs.
Abstract: Base stations (101, 102) utilize a spreading code that is dependent upon whether the particular base station (101) is operating in a synchronized, or an unsynchronized mode. Unsynchronized base stations (102) within the communication system (100) utilize a long code unique to the particular base station (102), and base stations (101) operating in a synchronized mode utilize a time shifted version of the same long code. To reduce the search time for remote units (113) within the communication system (100), a group identification code (GIC) (305) is broadcast during a time period that the long code is masked. The GIC (305) indicates a (spreading code) long code group to which the long code of each base station belongs. Additionally, each base station (101, 102) within the communication system (100) determines its synchronization status and utilizes a particular GIC (305) and long code based on the base station's synchronization status.
40 citations
18 May 1998
TL;DR: In this article, the impact of using the power up function (PUF) on a DS-CDMA system was analyzed using the following custom simulation tools; (a) CDMA Link Simulator, CDMA Static System Simulator (CSSS), and CDMA Motion Simulator (CMS) based on the simulation results, it was concluded that in an infrastructure-based MS location method, PUF is essential to increase MS visibility, if the number of PUF events are managed the impact on the system performance is not catastrophic.
Abstract: The FCC has mandated that by year 2001, cellular carriers must supply Public Safety Answering Points (PSAPs) with information that locates a wireless 911 caller within a radius of 125 meters, 67 percent of the time. In order to comply with FCC requirements, one can use trilateration techniques to locate a mobile station (MS), which requires that a MS be heard at 3 or more base stations (BTS). The ability to use trilateration techniques in a DS-CDMA system is difficult since a MS close to a cell is powered down to avoid the near-far problem, which typically results in a MS not being visible at multiple BTSs. One of the ways to increase the visibility of the MS to multiple BTSs is to increase the MS power level for a brief period at a predefined instance using the power up function (PUF) command from the infrastructure equipment. This feature has already been accepted by the standards body for inclusion in IS-95B. This paper analyzes the impact of using the PUF on BTS receiver performance as well as on the whole DS-CDMA system using the following custom simulation tools; (a) CDMA Link Simulator, (b) CDMA Static System Simulator (CSSS) and CDMA Motion Simulator (CMS). Based on our simulation results it is concluded that in an infrastructure based MS location method (a) PUF is essential to increase MS visibility, (b) if the number of PUF events are managed the impact on the DS-CDMA system performance is not catastrophic and (c) in case the number of PUF events within the same cell occurs frequently a simple interference canceller at the BTS can mitigate the effect of the PUF.
24 citations
Patent•
18 Dec 1998
TL;DR: In this paper, a group identification code (GIC) (305) is broadcast during a time period that the long code is masked, indicating a (spreading code) long code group to which each base station belongs.
Abstract: Base stations (101, 102) utilize a spreading code that is dependent upon whether the particular base station (101) is operating in a synchronized, or an unsynchronized mode. Unsynchronized base stations (102) within the communication system (100) utilize a long code unique to the particular base station (102), and base stations (101) operating in a synchronized mode utilize a time shifted version of the same long code. To reduce the search time for remote units (113) within the communication system (100), a group identification code (GIC) (305) is broadcast during a time period that the long code is masked. The GIC (305) indicates a (spreading code) long code group to which the long code of each base station belongs. Additionally, each base station (101, 102) within the communication system (100) determines its synchronization status and utilizes a particular GIC (305) and long code based on the base station's synchronization status.