Link and System Level Performance of Multiuser Detection CDMA Uplink

The link level performance and the cellular systemcapacity in the uplink direction of a CDMA cellularsystem utilising multiuser detection base stationreceivers is analysed by simulation. In the receiver,parallel multistage multiuser detection is employedtogether with two-antenna diversity reception and fastclosed-loop power control. A system level simulator isbuilt to utilise the link level simulation results andto show the increase in cellular capacity obtained byusing multiuser detection. The capacity is studied inurban micro and macro-cell environments utilising thechannel models developed in the European CODITproject. The modelling of the environment specific andCDMA specific features is considered in the systemsimulator. The system level simulator is calibratedwith analytical capacity calculations.     

Interference considerations for the time division duplex mode ofthe UMTS Terrestrial Radio Access

The air interface of the UMTS Terrestrial Radio Access (UTRA) covers both a frequency division duplex (FDD) part for the paired bands and a time division duplex (TDD) part for the unpaired bands of the UMTS spectrum. The Universal Mobile Telecommunication System (UMTS) is the 3rd-generation mobile communication system. This paper presents an interference evaluation of the UTRA TDD. Since both uplink and downlink share the same frequency in TDD, the signals of the two transmission directions can interfere with each other. This interference can occur between two mobile stations or between two base stations within one carrier or between two operators. The interference between uplink and downlink is evaluated by system simulations. Synchronization and coordination requirements of UTRA TDD are evaluated based on the results     

Does the triad of fungi,bacteria and exposure to moisture have an impact on chronic hyperplastic sinusitis?

Here we evaluated a possible relationship between chronic hyperplastic sinusitis (CHS) and moisture exposure and secondly a seasonal variation of fungal and bacterial findings in the healthy nose. In 28 CHS patients sinus mucus was collected during endoscopic sinus surgery. Samples from the nasal cavities of 19 healthy volunteers were collected by nasal lavage (NAL) in January and in September. Bacterial culture and fungal staining and culture were carried out. Histological samples from the sinus mucosa were obtained. Patients' medical history and environmental factors were enquired. Mold odor or moisture problems in the home or work environment were reported by 46% of the CHS patients. Patients who reported moisture exposure did not differ significantly from those who had not been exposed with regards to microbiological findings, tissue eosinophilia, and earlier operations. Cladosporium (16%) and Alternaria (11%) were found in NAL fluid collected in the autumn from the control subjects. No fungi were isolated from samples taken during the winter. An association between CHS or fungal sinusitis and moisture damage was not apparent in the present study. The fungal findings in the nasal cavity reflect the environmental exposure. This should be taken into account when NAL is used for microbiological studies. PRACTICAL IMPLICATIONS: Living in a moldy house or working in a similar environment may increase the risk of respiratory symptoms and infections. However, our results suggest that chronic hyperplastic sinusitis and fungal sinusitis are not associated with moisture exposure. The nose is a good collector of particles in the air. Especially samples taken by the nasal lavage method reflect the environmental exposure. This should be taken into account when this method is used for microbiological studies.     

Third generation WCDMA radio evolution

Third Generation Partnership Project (3GPP) produced the first full version of the WCDMA standard at the end of 1999. This release, called Release'99, contains all the necessary elements to meet the requirements for IMT‐2000 technologies, including 2 Mbps data rate with variable bit‐rate capability, support of multi‐service, QoS differentiation and efficient packet data. The Release 5 specifications were created in March 2002 and they contain downlink packet data operation enhancement, under the title high speed downlink packet access (HSDPA). HSDPA utilizes Hybrid ARQ and higher order modulation for improving data‐spectral efficiency and for pushing bit rates beyond 10 Mbps. The further 3GPP releases will study the enhancements of packet‐data performance in uplink. Other important features in future 3GPP releases include advanced antenna technologies and WCDMA standard for new spectrum allocations. The paper describes the main solutions of 3GPP WCDMA standard in more detail. Copyright © 2003 John Wiley & Sons, Ltd.