A disclosed method tunes a signal from a channelized spectrum having a predetermined channel spacing. A signal of interest having a predetermined maximum bandwidth is mixed with a local oscillator signal, which has a frequency that is an integer multiple of the channel spacing or one-half of a channel spacing displaced from an integer multiple of the channel spacing. The local oscillator signal is selected to frequency translate the signal of interest to within a near-baseband passband whose lower edge is spaced from DC by at least about the maximum bandwidth of the signal of interest. Problems associated with 1/f noise, DC offsets, and self-mixing products are avoided or substantially diminished. Other methods and systems are also disclosed.

Simplified high frequency tuner and tuning method

In a wireless communication system, radio resources are dynamically assigned among a plurality of intercoupled base stations based upon historical loading to reduce both localized and system interference. A plurality of loading intervals are first determined that span a loading interval sequence. The loading intervals may correspond to time based periods such as fifteen-minute, thirty-minute, hour or other time intervals. The loading interval sequence may correspond to a weekday, a weekend day or such other loading period within which loading resembles a pattern. Based upon estimated loading for the loading interval, a number of channels required to service load for the loading interval are made to meet a minimal service level is determined. An initial assignment of channels among the cells/sectors of the base stations of the wireless communication system is then made to satisfy localized radio interference criteria. Such an assignment will typically be made to preclude local reuse of channels. Then, the assignments are reconsidered from the standpoint of system interference and the channels are reassigned to minimize system interference. In reassigning channels among the cells/sectors, radio propagation and, cell/sector proximity are considered so as to most accurately predict performance when the assignments are implemented. Once the channel assignments have been determined for the loading interval sequence(s), the wireless communication system is operated according to the channel assignments.

Dynamic radio resource allocation in a wireless communication system

A direct conversion tuner for tuning either analog or digital television signals includes a first and second channels, each having first and second mixers and an intervening filter stage, coupled between an RF input and an output combining unit. The first mixers receive respective first local oscillator signals which have the same frequency but a quadrature phase relationship. The frequency of the first local oscillator signals is controlled according to the selected channel so that it is located within the spectrum of the respective RF signal. The second mixers receive respective second local oscillator signals which have the same frequency but a quadrature phase relationship. The frequency of the second local oscillator signal is located above the passband of the filter stages. A digital gain and phase equalization network is included in one of the channels for adjusting the relative gain and phase shift of the two channels and is automatically controlled by a microcomputer in response to signals sampled at respective points within the first and second channels to reduce the relative gain and phase shift. As a result, near perfect cancellation of unwanted components occurs in the output combining unit.

Direct conversion tuner

An integrated low-IF (low intermediate frequency) terrestrial broadcast receiver and associated method are disclosed that provide an advantageous and cost-efficient solution. The integrated receiver includes a mixer, local oscillator generation circuitry, low-IF conversion circuitry, and DSP circuitry. And the integrated receiver is particularly suited for small, portable devices and the reception of terrestrial audio broadcasts, such as FM and AM terrestrial audio broadcast, in such portable devices.

Integrated low-if terrestrial audio broadcast receiver and associated method

A method and system (200) for dynamic rate switching via medium access channel layer signaling (208) is disclosed, wherein data rates for high data rate channels are automatically shifted up or down based on a predetermined metric. In a preferred embodiment, data rates are automatically shifted up or down based on transmit channel gain required to maintain a required signal to noise ratio.

Method of dynamic transmit scheduling using channel quality feedback

The invention concerns a process for dynamic channel allocation in mobile radio networks, wherein priorities which are increased or decreased in dependence on interference occurring in the channel concerned are established for the individual channels. When the propagation conditions are satisfactory, channels with low priority can be allocated. The mean of values dependent on the extent of interference can be formed in order to increase and decrease the priority. In addition, various priority lists can be established for various interference and/or load situations.

Process for dynamic channel allocation in mobile radio networks

A TV receiver design that uses the quadrature-receiver principle is presented. Due to a low IF (intermediate frequency) of 2.6 MHz, normal video analog-to-digital (A/D) converters are sufficient to digitize the complete modulated signal. A lot of RF processing is done within the digital domain. This processing includes fine selection, separation of picture and sound, and demodulation of picture and sound. Applying the principle of analog quadrature mixing eases the integration of most parts of a front end, coming closer to the target of a 'one-chip TV'. With a word length of 8 bit for the A/D converters, a satisfactory SNR of 42 dB of the video signal can be achieved. For the second sound signal, where the carrier is 20 dB below the picture carrier, the SNR is 34 dB. A good SNR needs a word length of 9 bit for the A/D converters. >

Digital TV receiver with a low IF

Bei einem Verfahren zur dynamischen Kanalzuteilung in Mobilfunknetzen, wobei fur die einzelnen Kanale Prioritaten festgesetzt werden, die in Abhangigkeit von in dem jeweiligen Kanal auftretenden Interferenzen erhoht oder vermindert werden, konnen bei guten Ausbreitungsbedingungen Kanale mit niedrigerer Prioritat belegt werden. Zur Erhohung und Verminderung der Prioritat kann eine Mittelwertbildung einer vom Ausmas der Interferenzen abhangigen Grose erfolgen. Auserdem konnen fur verschiedene Interferenz- und/oder Lastsituationen verschiedene Prioritatenlisten gefuhrt werden.

Verfahren zur dynamischen kanalzuteilung in mobilfunknetzen

This paper presents the novel slot assignment scheme CS+. CS+ is a full adaptive strategy based on adaptive learning of slot allocation patterns by means of a modified channel segregation approach. It was developed for future cellular systems working with PRMA++, the potential medium access control mechanism of third generation TDMA proposals like the RACE ATDMA system. The paper focuses on the performance of decentralized adaptive slot assignment strategies in microcellular environments. A major problem in such systems is that frequency preplanning, as it is common in macrocellular systems, is very difficult or can not be afforded at all in a microcell environment. Furthermore the interference situation can change very much in an unpredictable way. A slot assignment scheme has to cope with this situation to exploit the subscriber capacity improvements inherent in microcell systems. System evaluation by means of computer simulation shows that only full adaptive slot assignment strategies are really useful in the investigated scenarios. The best results both in interference reduction and I-slot access performance of PRMA++ was obtained by the self-adaptive CS+.

CS+: A novel self-adaptive slot assignment scheme for ATDMA

One of the most decisive factors for the quality of service in cellular mobile radio systems is the co-channel interference ratio (C/I), the required carrier signal power divided by the interference power from cochannels. Known methods of improving the C/I include an appropriate choice of the cluster size, directional antennas at the base station and/or steerable directional antennas at the (semi) mobile station. This paper for the first time presents a comprehensive investigation of randomly orientated, directional mobile antennas. This shows some important tradeoffs being of particular importance for the design of cellular picocell systems supporting mobiles with handhelds.

Thorsten Benkner

Papers

Process for dynamic channel allocation in mobile radio networks

Digital TV receiver with a low IF

Verfahren zur dynamischen kanalzuteilung in mobilfunknetzen

CS+: A novel self-adaptive slot assignment scheme for ATDMA

Investigation of mobile antenna diagrams on cochannel interference