Telefonaktiebolaget Lm Ericsson (Publ)

Sharp Kabushiki Kaisha Corporation

U.S. Philips Corporation

Gerd Zimmermann

Mathias Pauli

Jamshid Khun-Jush

Jan Lindskog

Peter Schramm

Wolfgang Stahl

Stefan Rommer

Peter Larsson

Hui Li

Fabian Wenger

Wolfgang Koch

Fredrik Johansson

Anders Ranheim

Lennart Gafvels

Göran Malmgren

J&ouml;rg Huschke

Karine Assmayr-Gillette

Herbert Schneider-Obermann

The invention relates to a method and a device for controlling frequency selection within a wireless communication system in response to radar-like interference signals. The method comprises continuously or quasi-continuously monitoring and assessing a plurality of frequencies with respect to a radar-like interference signal and allocating a quality parameter to each assessed frequency, the quality parameter indicating the probability that the frequency is occupied. The method further comprises selecting one or more frequencies in dependence on the allocated quality parameters and subsequent frequency monitoring.

Method and device for controlling frequency selection within a wireless communication system

Interference Measurements in a Wireless Communications SystemA method and a transmitting unit for performing an interference measurement in a multiple access wireless communications system utilizing a carrier sensing technique is described. In accordance with the carrier sensing technique, it is monitored during a sensing period (T) if a carrier is idle. A continuous or quasi-continuous interference measurement is performed on the carrier during a measurement period (T) which is typically longer than the sensing period (T). While performing the interference measurement, pulses are transmitted on the carrier such that an interval between the end of a pulse and the beginning of the next pulse is typically shorter than the sensing period (T). The interference measurements preferably relate to detection of interference from radar signals or radar like signals.

Interference measurements in a wireless communications system

In a packet transmission system, especially wireless transmission system, where data is transmitted in packets at different error protection levels and where the error protection level of one packet (=the succeeding packet) may differ from the error protection level of a preceding packet without providing code termination between the said preceding and the said succeeding packet the performance may degrade in case a different error protection level is used by the preceding packet and the succeeding packet. The invention proposes in these cases to insert a supplementary packet between the preceding and the succeeding packet whereby the error protection level of the supplementary packet is higher than the lowest error protection level that is used either by the preceding or the succeeding packet.

Unequal error protection in a packet transmission system

The invention discloses a method for use in a wireless communications system with a plurality of broadcasting nodes, comprising the step of enabling one node in the system to function as a central node in said system and letting said node enable measurements on at least one frequency in a frequency band used by the system. Said measurements are carried out to detect if said at least one frequency is being utilized by a transmitter foreign to the system. Preferably, the measurement is enabled by means of the node transmitting a message to other nodes in the system, said message being a message pre-defined within the system as a message prohibiting all nodes from transmitting during a certain interval, said message being transmitted after the system has been detected by the node to be silent during a predefined interval between frame transmissions from the nodes in the system.

Wireless communications system with detection of foreign radiation sources

A cordless telephone system is described which is arranged to determine interference strength values during a call connection for one or more channel pairs other than the channel pair momentarily carrying a call connection, such that a group of candidate channel pairs for potential channel switching is performed. Then, if a predetermined channel switching condition is met, then a switching is performed to one of the candidate channel pairs from the group.

Cordless telephone system

In two superimposing communication systems using the same frequencies, where the second communication system was not considered in the frequency planning of the first cellular communication system, frequencies are to be allocated to the second communication system in a way that they do not interfere with the first communication system. Accordingly, a medium field strength of each frequency is calculated after a time interval has expired. A number of frequencies are selected in correspondence with the value of the medium field strength. A medium value is formed with the field strengths of the selected number of frequencies. The time interval of the calculation of the medium field strength of each frequency is changed in response to the medium value.

Method and device for determining and selecting frequencies

The invention relates to a method, a communication system and a switching apparatus which perform a switching of calls to another channel (CC2) when two or more calls simultaneously attempt to use a channel (CC1). According to the invention, each channel is first set (S3, S4, S5, S8) to a first call state when first attempting to use a channel. In the first call state, first predetermined transmission conditions must be satisfied (S5) in order that the call proceeds to a second call state (S9, S10, S11, S14) in which second predetermined transmission conditions (S11) must be satisfied. Due to this progression of the call through a first, second and possibly higher order call states, it can ensured that always a new call will always accomplish a hand-over to a new channel (CC2). The invention finds particular application when a channel may be used several times by several calls in a communication network of a channel re-use type and a substantial interference of the at least two calls occur when they use the same channel in close proximity, e.g. when handing over a mobile telephone of a GSM system to a GSM-based cordless telephone system.

Method, communication system and apparatus for switching calls on a

The invention relates to a transmission system comprising a transmitter (100) which includes a coder for coding an information signal (11) into a digital signal (11, 12) constituted by the information signal (11) and a redundancy signal (12), the redundancy signal (12) being generated by way of a cyclic code from the information signal (11 ), and comprising a receiver (101) which includes a decoder with a storage unit (2) for storing the information signal (11) and with an error correction means which has an optionally feedback shift register (3) for processing the digital signal (11, 12). The transmission system is to make both the correction of burst errors as well as the correction of random errors possible in a single error correction means. There is proposed that the error correction means of the decoder comprises a burst error detection means (4) for producing a first error information signal (B) from predeterminable storage contents (S.sub.0 . . . S.sub.11) of the shift register (3) and a random error detection means (5) for producing a second error information signal (E) from the aggregate storage contents (S.sub.0 . . . S.sub.11) of the shift register (3), and that a control means (8) is provided for evaluating the first error information signal (B) and second error information signal (E) and combining means (E1) are provided for combining the storage contents (S.sub.0 . . . S.sub.17) of the shift register (3) with the storage contents of the storage unit (2). The transmission system may be used for example, in video communication systems.

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Eckental, Germany

Gerd Zimmermann