Telefonaktiebolaget Lm Ericsson (publ)

Maria Gustafsson

Erik Bengt Dahlman

Per Johan Beming

Riaz Esmailzadeh

Henrik Olofsson

Wolfgang Granzow

Georg Frank

Fredrik Bengt Ovesj&ouml;

Per Narvinger

A method for processing multiple random access requests is disclosed in which a base station transmits an acquisition indicator signal, which indicates that the base station has detected the presence of a random access transmission. The acquisition indicator can be generated based on the amount of energy received on the random access channel (e.g., as opposed to the correct/incorrect decoding of a random access message). Consequently, the delay between the beginning of the random access transmission and the beginning of the acquisition indicator transmission is significantly shorter than the delay to the beginning of an acknowledgment transmission based on the reception of a correctly decoded random access message. If a mobile station does not receive a positive acquisition indicator, it should interrupt the present transmission and start to re-transmit the random access burst in the next time slot, while modifying the transmission power level accordingly between the successive re-transmissions.

Random access in a mobile telecommunications system

An uplink common physical channel (random access channel) frame structure with a separate preamble and data portion. The preamble is used by a base station to detect that a mobile station is attempting a random access request. The data portion of the channel includes user data, and pilot symbols that provide energy for channel estimation during reception of the data portion. A guard interval is preferably inserted between the preamble and data portion of the frame, which enables data detection to occur during an idle period. As such, the frame structures for both the common physical (random access) uplink channel and dedicated physical (traffic) uplink channel are compatible.

An uplink common physical channel (random access channel) frame structure with a separate preamble and data portion. The preamble is used by a base station to detect that a mobile station is attempting a random access request. The data portion of the channel includes user data, and pilot symbols that provide energy for channel estimation during reception of the data portion. A guard interval can be generated using a &ldquo;filler&rdquo; made up of dummy chips, predetermined symbols, and/or an unmodulated carrier, and inserted between the preamble and data portion of the frame, thus enabling a mobile station to maintain its power transmission and making it easier to implement such a guard interval in a WCDMA system.

A method, system, and apparatus assigns each sector in a cell a unique preamble spreading code and a unique long-code which is concatenated with a signature-associated short code to spread the data in the data field. The period selected for the long-code can be relatively long in duration (e.g., up to hours or days in length). The widths of the transmission time slots are set equal to the length of the preambles. Subsequent to the preamble period, the matched filter is still enabled to receive the preambles of other random access requests. Therefore, the matched filter can be utilized continuously and more efficiently. Additionally, the length of the data field is not restricted. The method of concatenated spreading of the data field portion of the random access packet allows a user to generate a packet which is as long as desired. Moreover, there is very little danger that the resulting packet will collide with other random access request packets.

Each frame of a pilot channel transmission in a spread spectrum communications system is divided into a plurality of synchronization slots. Each of the synchronization slots includes a pilot code, and at least one of the synchronization slots further includes a framing synchronization code. To extract frame and slot synchronization information from the pilot channel transmission, pilot code timing is first identified by applying a matched filter or correlation to a received pilot signal, identifying peaks, and using the peaks to find a timing reference indicative of synchronization slot boundaries. Next, the set of known framing synchronization codes are correlated with the received signal over the included found synchronization slots. Given that the location within the frame of the known framing synchronization code(s) is known, once a correlation match is found at a certain slot location, the boundary of the frame (i.e., the frame synchronization) relative thereto is then also known.

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Stockholm, Sweden

Maria Gustafsson