Abstract: The method involves modifying an encryption key (Kc) in accordance with a given algorithm and in dependence on the ordinal number of a time slot to obtain a modified encryption key. A modified pseudo-random sequence is formed from the resultant modified encryption key. The modification is carried out in accordance with the aid of an encryption algorithm. A logical operation is performed on the modified pseudo-random sequence and for each block of the non-encrypted information. Preferably the operation is performed on the information block that belongs to the time slot whose ordinal number has been used to form the modified encryption key. As an additional option, the frame number can also be modified in accordance with a given algorithm and in dependence on the ordinal number of the relevant time slot.

Abstract: In a method and an arrangement for establishing an encrypted connection between a mobile station and a base transceiver station in a mobile telephone system, the base transceiver station makes sure, before forwarding a cipher mode command message to the mobile station that the mobile station is in multiple-frame-mode.

Abstract: A method and device avoid repeated registration attempts to register on PLMNs which do not allow registration for a mobile terminal while permitting attempts to register on PLMNs earlier inserted in a list of a number of identities of rejected PLMNs in a storage in the terminal but which may allow registration at a later time. At least a part of the list is erasable to be erased from time to time. Surplus identities of rejected PLMNs on a non-volatile part of the list are transferred to the erasable part of the list at overflow of the non-erasable list.

Abstract: The present invention relates to the technique of handover in mobile telephony. A new Transcoder and Rate Adaptation Unit (100 FIG. 3) is introduced which provides two uplink (230, 250 respectively, FIG. 3) and two downlink (240, 260 respectively, FIG. 3) channels. The use of these two channels (230, 250 respectively, FIG. 3) on the uplink during handover provides for the use of distributed handover on the uplink. The result minimizes the audible interruption during handover by minimizing the loss of Traffic Channel frames to what is possible within the GSM standard. Additionally, interruption of the speech or background noise during these lost frames is masked by an error concealment algorithm, since the Transcoder and Rate Adaptation Unit (100 FIG. 3) still has information from the Base Transceiver Station responsible for transmission before the handover.

Abstract: In a cellular mobile telecommunication system, particularly a Global System for Mobile Communications (GSM) system, a method and apparatus determine the geographical position of a mobile station. The distance between the mobile station and a radio base station is estimated from the propagation delay. The propagation delay is determined according to the present method when the mobile station sends access bursts to the base station, which measures the access delay of the arrived bursts in the same way as an ordinary handover. However, no confirmation of received access bursts is sent from the base station to the mobile station and therefore the handover attempt is terminated. The connection between the mobile station and the previous base station is re-established. The measured access delay is proportional to the propagation delay and thereby also to the distance to the mobile station.

Abstract: The present invention relates to a method of sending to an unknown switching centre that serves a given mobile station a command concerning said mobile station. The command is sent by using a previously known short message service, e.g. SMS in the GSM-system. The command may constitute a request for the switching centre to determine the position of the mobile station and is sent from a positioning node outside the mobile communications system. The invention also relates to a method of sending data from the switching centre to the positioning node. The invention also relates to a switching centre and also to a system for carrying out the method.

Abstract: A method for establishing a new broadcast control channel carrier frequency within a cell without disturbing ongoing call traffic is disclosed. A cell having a base station transmitting broadcast control channel data over an existing BCCH carrier frequency establishes a second BCCH carrier frequency within the cell. During a first time period BCCH data is transmitted on the existing first BCCH carrier frequency. During a second time period, both the existing and new BCCH carrier frequencies carry BCCH data to enable surrounding mobile stations to detect and recognize both carriers. The transmission of the old BCCH carrier frequency is then discontinued during a third time period, such that the broadcast control channel data is only transmitted on the new BCCH carrier frequency.

Abstract: The method involves modifying an encryption key (Kc) in accordance with a given algorithm and in dependence on the ordinal number of a time slot to obtain a modified encryption key. A modified pseudo-random sequence is formed from the resultant modified encryption key. The modification is carried out in accordance with the aid of an encryption algorithm. A logical operation is performed on the modified pseudo-random sequence and for each block of the non-encrypted information. Preferably the operation is performed on the information block that belongs to the time slot whose ordinal number has been used to form the modified encryption key. As an additional option, the frame number can also be modified in accordance with a given algorithm and in dependence on the ordinal number of the relevant time slot.

Abstract: A disconnect time in accordance with the Global System for Mobile (GSM) Phase 1 standard is reduced within a particular base station controller (BSC) serving a particular mobile station. In response to a Layer 2 Disconnect message from a first mobile station and after the expiration of the reduced disconnect timer, the serving BTS releases the indicated logical channel from the first mobile station and enables the connected base station control (BSC) to more efficiently allocate the released logical channel (SDCCH or TCH) to a second mobile station. Thereafter, additional Layer 2 Disconnect messages transmitted by the first mobile station are ignored and no acknowledging Disconnect Mode (DM) message is transmitted over the indicated logical channel. Thus, collision over the same logical channel between the first and second mobile stations is avoided and the second mobile station is able to communicate over the allocated logical channel.

Abstract: The present invention relates to a method of registering a mobile station in a cellular mobile radio system in which areas, each including a plurality of cells, form registration areas. Each registration area (RA1, RA2, RA3, . . . ) has its own identity (X). According to the proposed method, individual location areas are defined whenever registering a given mobile station with the intention of avoiding an unnecessarily high number of registrations in border areas of the different registration areas. A location area may have the form of a list of registration areas (X1, X2, X3, . . . ), which is stored in a mobile station (MS), or may be stored in the system (HLR, MSC) and transmitted to the mobile station (MS) via a base station (BS) in a given registration area, in conjunction with registration of the mobile station in this area.

Abstract: An antenna configuration increases the sensitivity of a base station by providing a plurality of antennas each of which cover a disjunct or partially disjunct area of a larger cell. A receiver for each antenna receives signals transmitted from mobile stations. Equalizers are attached to each receiver for correcting the received signals. A combiner then combines the received signals from the different antennas so as to form an estimate of the transmitted signal.

Abstract: A method and system for controlling overhead information transmission in a radicommunication system is described. By desynchronizing information trasmitted in two streams on a control channel, loads on the reverse control channel are more evenly distributed to minimize overload situations. Similarly, blocked calls can be prevented by judicious transmission timing of control filler messages relative to the overhead message trains. The relative timing of various registration parameters is also described to reduce extraneous registrations.

Abstract: A method for broadcasting information in a cellular communication system comprising at least one base station with an antenna array and a plurality of mobile stations is disclosed. The common information is preprocessed to create orthogonal signals. The orthogonal signals are then beam formed so that the orthogonal signals are delivered to the different elements in the array antenna. The orthogonal signals are transmitted and then received at at least one mobile station. The signals are then processed at the mobile station to decipher the common information from the orthogonal signals.

Abstract: A method and system for performing macrodiversity or soft handover in TDMA radiocommunication systems are described. Half rate transmissions are used to provide additional diversity communication channels in systems having insufficient timeslots at full rate. The mobile station can receive the same information from and/or transmit the same information to a plurality of base stations to provide diversity combination and improve transmission quality. The mobile unit assists in making handover decisions by monitoring the signal strength of control channels transmitted by base stations in neighboring cells.

Abstract: A method in a cellular communication system provides selection of a channel for use in a pending communications operation, the selection reducing the likelihood of co-channel interference. In each co-channel cell, frequencies from the cell's frequency group are ordered in a sequence. A different frequency in each cell is designated as having a highest priority. Successively lower priorities are then assigned, in each cell, to remaining frequencies in sequence. Then, in each cell, selection is made by identifying the available frequency having the highest priority. The method may be modified to provide for even distribution of hardware use by changing the priorities in each cell periodically. The method may also be modified for use in a fully synchronized time division multiple access (TDMA) system by performing the above steps with respect to channels instead of frequencies. The method may further be modified for use in a pseudo-synchronized TDMA system (i.e.

Abstract: A method and apparatus for use in a cellular mobile radio telephone system for determining which of one of several mobile generated transmissions received in a mobile switching center, sent from the same mobile station via more than one base station, should be accepted. A determination is made based on the relative signal strengths of the signals received by the base stations and by the relative time of occurrence of the mobile generated transmissions.

Abstract: In a mobile cellular radio system, load balancing is achieved by moving dynamically the borders between any two cells such that an overloaded cell becomes smaller and the neighboring cell larger. This is achieved by lowering the entering signal strength threshold for handoff to the neighboring cell and/or increasing the entering signal strength threshold for handoff from the neighboring cell. Thresholds are unique for any two cells.