Showing papers on "GSM frequency bands published in 1997"
Patent•
19 Feb 1997TL;DR: In this article, a method and apparatus enables a communication device (100) to operate in multiple bands, such as GSM 900 MHz, DCS 1800 MHz, and DCS 1900 MHz bands, by eliminating the need for a mixer for each band.
Abstract: A method and apparatus enables a communication device (100) to operate in multiple bands, such as GSM 900 MHz, DCS 1800 MHz, and DCS 1900 MHz bands, by eliminating the need for a mixer for each band. In a dual band GSM/DCS 1800 radiotelephone, for example, the local oscillator (LO) injection frequencies for both GSM and DCS bands are provided to a mixer (234) through the use of combination filters (222, 246). Thus, the duplexing and matching requirements to the mixer input are simplified and the signal losses are minimized. The common output ports of the GSM RX/LO combination filter and DCS RX/LO combination filter are duplexed to the input of the mixer. Also, the input impedance matching of the mixer is designed to match the impedance for the received signals in each band, as well as provide an RF trap at the IF frequency. The match at the output of the mixer is designed to match the impedance of the IF filter and provides a low impedance to RF input frequencies. Finally, a tri-band radiotelephone is also described.
39 citations
Book•
15 Jan 1997
TL;DR: This book discusses the history and present situation of the GSM network, as well as some of the technologies used in its development, including the DECT 1800 Standard, and some of its applications.
Abstract: Cellular Concepts. The GSM Standard. GSM Network Infrastructure. The Radio Sub-System. The Network Sub-System. Network Management. Mobile Terminals. The DECT 1800 Standard. The POINTEL network (Bi-bopTM). Mobile Data Networks: MobitexTM. Satellite Radio-Paging. Glossary. Bibliography. Index.
27 citations
04 May 1997
TL;DR: Simulations have indicated that for slow moving mobiles a gain of approximately 35% is achieved by this new feature when compared with a frequency hopping network, and modifications are proposed to optimise the simulated algorithms, to improve the capacity in terms of carried traffic per cell even further.
Abstract: This paper describes a method to increase the capacity of a digital cellular network, like GSM, without having to increase the number of available frequencies or base stations. The idea is to split the frequency spectrum into two bands. One consisting of frequencies that can only be used when a high C/I ratio is ensured, the super frequencies, and the other consisting of frequencies that can be used throughout the whole cell, the regular frequencies. The minimum frequency reuse distance of the super frequencies can therefore be smaller than the reuse distance of the regular layer frequencies. By combining this reuse partitioning with frequency hopping, an increase in the network capacity in terms of carried traffic per cell is achieved. Simulations have indicated that for slow moving mobiles a gain of approximately 35% is achieved by this new feature when compared with a frequency hopping network. For faster moving mobiles the simulated gain is lower, approximately 26%. Modifications are proposed to optimise the simulated algorithms, to improve the capacity in terms of carried traffic per cell even further.
19 citations
17 Dec 1997
TL;DR: The results demonstrate a carrier to interference (C/I) improvement together with increased received signal strength indication (RSSI) in a vertically polarised multibeam antenna testbed.
Abstract: A GSM 900 MHz vertically polarised multibeam antenna testbed is presented incorporating a thin 4 beam microstrip planar antenna, a GSM mobile, a GSM base station (BS) a DSP and a personal computer (PC) to control the measurement procedure. The multibeam antenna covers 120/spl deg/ in azimuth with 4 beams offering an impedance bandwidth >10%, a minimum gain of 15.8 dBi for each beam and has dimensions of 710/spl times/800/spl times/12 mm. The static beamforming is performed at the radio frequency (RF). The results demonstrate a carrier to interference (C/I) improvement together with increased received signal strength indication (RSSI).
1 citations
Patent•
22 Dec 1997TL;DR: In this paper, a purely modulated signal for transmission of the GSM transmission band is supplied from a base band part to a mixer 610, which is mixed with a 116 MHz signal supplied to a multiplier 611 coupled with a VHF signal generator 605.
Abstract: PROBLEM TO BE SOLVED: To shorten the operation time of a radio frequency signal and to save the electric power by making the frequency resolution of a 1st analog demodulated signal wider than a channel interval and the frequency resolution of a 2nd analog demodulated signal finer than the frequency resolution of the 1st analog demodulated signal, and adjusting their frequencies according to their frequency resolution and tuning a receiver. SOLUTION: A purely modulated signal for transmission of the GSM transmission band is supplied from a base band part to a mixer 610. Then it is mixed with a 116 MHz signal supplied to a multiplier 611 coupled with a VHF signal generator 605. The intermediate-frequency signal which is generated as a result passes through a mode switch 612 at 116 MHz. The mode switch 612 is switched to a GSM terminal RF stage in GSM mode and the intermediate-frequency signal is sent to a 2nd mixer 613. Then it is mixed with a local oscillator signal having a frequency within the range of 1006 to 1031 MHz and converted to a transmission channel frequency of the GSM transmission band.
1 citations