Peter Muszynski

Capacity reduction of WCDMA downlink in the presence of interference from adjacent narrow-band system

One of the main challenges when implementing the future mobile multimedia networks is the cost-effective network evolution from second- to third-generation systems. This evolution path may include the use of different technologies at the same frequency band. The performance of the wide-band code-division multiple-access (WCDMA) downlink is studied in the case when there are narrow-band (NB) interference sources at the adjacent frequencies. A simple, analytical method to calculate the downlink capacity reduction of the WCDMA macrocell in this case is presented. The analysis takes into account different downlink interference mechanisms: wide-band noise from the transmitter as well as adjacent channel interference, intermodulation, and cross-modulation originating in the mobile receiver. The effect of each interference component to the capacity of the WCDMA macrocellular network has been evaluated with numerical examples. The analysis shows that capacity per cell is sensitive to the cell size, and therefore very careful network planning is needed in order to operate the WCDMA networks efficiently. The results of this paper can be utilized when implementing the WCDMA system to the same band with existing narrow-band systems, for instance, with the PCS 1900 band in United States and GSM 1800 band in Europe.

Modeling of UE-UE interference at 2.5 GHz WCDMA

This paper presents a new modeling approach for the derivation of the capacity reduction in WCDMA downlink due to mobile-to-mobile (UE-UE) interference. The assumed frequency usage scenario is the FDD UL/DL + additional FDD DL operation at 2.5 GHz band identified by ITU-WP8F. The similar approach can be utilized also with other frequency usage scenarios and radio systems where the UE-UE interference is present. The developed downlink capacity model takes into account the average interference from closely located, spectrally adjacent mobiles. The model assumes non-uniform user distribution and the power coupling due to basestation-to-basestation (BS-BS) interference has been introduced, as well. The recognition of these interference phenomena is important since unlike the BS-UE interference between operators the DE-LE interference is difficult or even impossible to eliminate with the network planning methods. Results indicate that the effect of user distribution, adjacent network loading, UE-UE propagation, cell sizes and the BS-BS isolation have to be taken into account when comparing the performance of radio systems where the UE-LE interference is present.

WCDMA Downlink Coverage Reduction Due to Adjacent Channel Interference

This paper determines the coverage reduction of the Wideband CDMA (WCDMA) downlink in the case of interference, due to adjacent narrowband system. The coverage reduction has been evaluated in terms of blocking area around the interfering base station. The analysis takes into account different interference mechanisms and their individual effects to the coverage. The interference mechanisms which have been considered here are the out-of-band emissions of the base station transmitter, the adjacent channel interference due to non-ideal sideband filtering, the intermodulation and the crossmodulation. The coverage effects in realistic network environment have been computed by using accurate ray-tracing propagation models designed for the path loss calculation in the urban environment. In the numerical examples, the effect of GSM interference has been demonstrated, but the method can be utilized with other narrowband systems as well. The results can be utilized in radio system design, radio network planning (RNP) and the frequency allocation of the WCDMA systems.

Radio resource management solutions for WCDMA FDD systems with asymmetric UL/DL carrier allocation

This paper concerns frequency division duplex cdma systems (WCDMA FDD, cdma2000, etc.) to which extension frequency bands might be added, e.g. for capacity enhancement reasons. Such asymmetric capacity enhancements might be desirable in the future due to increased data transmission over mobile networks especially when asymmetric data is transmitted like, for example, in mobile Internet browsing. Here it is assumed that the frequencies to be added are in downlink. In such a case the one-to-one coupling of uplink (or reverse link) and downlink (or forward link) frequencies is not valid any more. This paper illustrates a new interference scenario that can occur with the new downlink extension bands, and introduces new RRM (radio resource management) solutions for this interference case. The interference mechanism is illustrated for WCDMA. The assumed frequency scenario is WCDMA/FDD uplink/downlink plus additional FDD downlink, e.g. at 2.5 GHz band identified by ITU-WP8F. The new type of interference can be detected by additional mobile station measurements that benefit in efficiency from co-siting of extension and existing frequencies. Both interference detection and avoidance being based on RRM allows flexible and efficient use of extension bands with little impact on current specifications and products.