Low end extension (LEE) for Bluetooth is a technology that enables devices very limited in power consumption, processing capabilities and memory to connect themselves to mobile terminals and other devices that currently feature a Bluetooth radio. Obviously, there are a number of small-sized devices that could add value by having wireless radio connection to mobile terminal but cannot bear the power consumption and cost associated to Bluetooth. LEE introduces minor additions to the Bluetooth chip in mobile terminals in order to allow major savings in power consumption and cost in the radios embedded into small devices such as wireless sensors and terminal enhancements. This paper presents the principles of LEE radio protocol, addresses the system capacity and elaborates the protocol implementation

The local wireless networking techniques are becoming more and more popular in mobile terminals nowadays. Even so that wireless LAN (e.g. IEEE 802.11b) and Bluetooth solutions operating at the 2.4 GHz ISM band can be found in the same device. This enables new kind of usage possibilities and applications from which the most challenging ones, from interoperability point of view, are those that require simultaneous real-time operation over these links. One good example of this kind of service is a voice over IP (VoIP) call over the WLAN to the terminal with a Bluetooth headset. In this paper problems regarding different receiver architectures are presented and solutions for optimized Bluetooth usage are considered

A multicarrier Gaussian minimum shift keying (GMSK) modulator has been developed and implemented. The design contains four GMSK modulators, which generate GMSK modulated carriers at the specified center frequencies. Utilization of the redundancy in the stored waveforms reduces the size of the GMSK trajectory look-up table to less than one-quarter of the original size in the modulator. Conventionally, the power ramping and output power level controlling are performed in the analog domain. A novel digital ramp generator and output power level controller perform both the burst ramping and the dynamic power control in the digital domain. The power control is realized by scaling the ramp curve, which follows a raised cosine/sine curve. The four GMSK modulated signals are combined together in the digital domain. The digital multicarrier GMSK modulator is designed to fulfil the spectrum and phase error specifications of the GSM 900 and DCS 1800 base stations.

A new semi-physical behavioral amplifier model to characterize the AM/AM conversion of a bipolar solid-state high power amplifier in a mobile phone is introduced. The functional model is able to copy the low-voltage features of a real amplifier causing crossover distortion. Hence it gives an improved description of the nonlinearity of Class AB amplifiers widely used in mobile phones employing a linear modulation scheme. The AM/AM conversion model is accompanied by an AM/PM conversion model function to complete the amplifier model. The model is utilized in mobile communication system studies to investigate the increase of common channel and adjacent channel interference due to the nonlinear behavior of the amplifier. The new model is compared to the existing widely used functional models, and it is found to give an excellent match to the two-tone performance of a measured amplifier.