Method for signaling a radio channel structure in a radio communication system

p0001description

p0002Method for signaling a radio channel structure m a radio communications system

p0003The invention relates to a method for signaling a radio channel structure of a radio-m Kommunikationssystern, in particular^¬ cially in a mobile radio system.

p0004In radio communications systems, information such as voice, Bildmformationen or other data, with the aid of electromagnetic waves via a radio interface between a transmitting and a receiving radio station, such as a base station or a mobile station, transmitted in the case of a mobile radio system. The electromagnetic waves takes place using carrier frequencies that the m fr are the respective system frequency band provided. In the GSM mobile communication system (Global System for Mobile Communication), the Trager- frequencies in the 900 MHz, 1800 MHz and 1900 MHz. For zukunftige mobile radio systems with CDMA and TD / CDMA transmission method via the radio interface, such as the UMTS (Universal Mobile Telecommunication System) or other 3rd generation systems are carrier frequencies in the range provided by approximately 2000 MHz. (Frequency quency Division Duplex) and TDD mode (Time Division Duplex) radio system is for the aforementioned UMTS modem between a so-called FDD mode distinguished. The TDD mode is characterized in particular by the fact that a common frequency band for both the signal transmission m the uplink (UL - Uplmk) - is used, while the FDD mode for the transmission directions uses a respective frequency band and m downlink direction (Downlmk DL). In the aforementioned GSM mobile radio system specific signals lisierungskanale m defined time slots are transmitted from the base stations and subscriber stations. These signaling channels, for example, pays the organizational sationskanal BCCH (Broadcast Control Channel), which is sent at a higher compared to normal traffic channels transmit power and information bez resembled the structure of the mobile radio system or the respective radio cell of a base station contains. This organization channel BCCH is always m the first time slot of a time frame and on a BE^¬ voted carrier frequency within a m one radio cell to grouting stationary frequency band sent. A partial neh erstation determined at an initial access to the mobile funksyste the location (frequency and time slot) of the control channel BCCH m of the radio cell, m which it is currently, and passes by the receiving and evaluating the structure of the radio interface from.

p0005In the FUTURE mobile radio system of the third generation UMTS multiple signaling channels are expected to use a common radio channel resource. In the TDD mode of the UMTS mobile radio system, for example, the control channel BCH (Beacon Channel) and FACH are (Forward Access Channel) and optionally other signaling channels such as PCH (Paging Channel) use a common radio channel resource according to a time-division multiplex. This radio channel resource is, for example, a specific spreading code m the first time slot of a time frame. In an initial access of a subscriber station is this due to the as yet un- known timing not m knowledge, which signal it seven signaling channel currently receives, so that possibly occurs a faulty synchronization or evaluation of the received signaling channel and a very long synchronization time. A solution to the problem would be for example the introduction of a special channel that this time-division plexstruktur describes or a unique label of the respective signaling channels by, for example, so-called MessageHeader m radio blocking the channels. However, both solutions have the disadvantage that they bind resource-scarce radio, no longer then for a data transmission to the AV transmission.

p0006The invention has for its object to provide a process which allows a simple signaling of the radio channel structure. This object is achieved by the method according to the features of independent claim 1 and by the base station system according to the features of the independent patent claim 10. Developments of the invention are disclosed in the dependent claims.

p0007Erfmdungsgemaß emitted from a base station at least one Si gnalisierungskanal with a channel-specific format of a radio block, and by a receiving subscriber station based on the size of the radio block a radio channel structure derived.

p0008The inventive method enables advantageous that a subscriber station can these clearly seen at a first access to a radio Kommumkationssystem based on the size of the respective function blocks of the signaling channel, without additional signaling means of a separate channel or a special Signalisierungsfel- of m radio Block must be carried out. Advantageously, the format differs also traffic channel of the format of a normal wear.

p0009According to a first embodiment of the invention use at least two signaling channels a same radio channel resource according to a time division process. In this procedure, the beneficial m the described UMTS mobile radio ste can be used, the subscriber station can uniquely identify each signaling channel, and thus drove through a fast synchronization to the radio channel structure. A radio channel resource may be from a single TDMA participants ersepaπerungsverfahren a timeslot within a frequency band or in an additional separation according to a CDMA method correspond to one or more spreading codes within a TDMA time slot.

p0010According to two alternative embodiments of the invention, the respective radio blocks of the signaling channels by an individual or a long sequence of data are distinguishable. Uses the subscriber station according to another embodiment a known error detection mechanism, it may, for example, already with reference to the length of the data drove a distinction within the radio block of the signaling channel. A too long or too short data portion is discarded in such a mechanism. Only when the length of the data coincides with the expected mechanism of the Lange, an evaluation is made, and forwarding the data to higher Protokollmstanzen. The same applies for the individual sequence of the data. Only when the received data sheet ldentifi- of the mechanism to be correct, an evaluation is made. Generally it can be formulated only if the received data correspond to the structure of this or signaling channel and signaling channels, the error detection mechanism detects this data to be correct and evaluates them.

p0011According to two other alternative embodiments of the respective format of the signaling channel m munications all radio cells of the radio-Ko is chosen equal or functional distinction zellenmdividuell. Advantageously, in a same format, the subscriber station m each radio cell the identify radio channel structure m simple manner without special training, during which at a funkzellenmdividu- ellen format an implicit signaling and thus identifying the respective radio cell by the subscriber station occurs, the subscriber station thus m is able, for example, m adjacent cells to differentiate parallel signaling channels transmitted.

p0012Particularly advantageously, the inventive method m is a radio communication system using a hybrid TD / CDMA Teilnehmersepaπerungsverfahren used.

p0013The inventive method and the cooperating components of the radio communication system are now other hand explained by illustrations in the near. show case

p00141 is a block diagram of a radio communication system, especially a mobile radio system; Figure 2 is an exemplary schematic illustration of the frame structure of the radio interface and the structure of a radio block, FIG 3 is a sequence of multiple time frames with different signaling channels, and FIG 4 radio blocks of signaling channels with different data formats.

p0015The Figure 1 shows a part emes mobile radio system as an example of the structure of a radio communication system. A mobile radio system each consist of a plurality of mobile switching centers MSC (Mobile Switchmg Center), to a switching network (Switchmg Subsystem) include and are networked together and provide access to a fixed network PSTN, and composed of one or more associated with these mobile switching centers MSC Basisstationssyste- men BSS (Base Station Subsystem). A base station system BSS again has at least one device RNC (Radio Network Controller) for assigning radio resources, and at least one each associated base station NB (Node B).

p0016A base station NB can over a radio interface to establish and maintain connections to subscriber stations UE (User Equipment). Each base station NB a radio cell Z is formed at least. The size of the radio cell Z is m usually determined by the range of a control channel BCH which is transmitted from the base stations NB with emer respectively higher and constant transmission power. In a Sektoπsierung or hierarchical cell structures, several radio cells Z can be supplied per base station NB.

p0017The example of FIG 1 shows a subscriber station UE which is located m the radio cell Z of a base station NB. The subscriber station UE has established a communication link to the base station NB, on the m uplink UL and downlink direction DL there is a signal transmission of a selected service. The communication link is separated by one or more of the subscriber station UE allocated spreading codes constructed of parallel m the radio cell Z communication links, the user station UE, for example, all the respective currently m the radio cell Z allocated spreading codes for receiving the signals of the own communication unikationsverbmdung according to the known Jo uses t Detection method.

p0018An exemplary frame structure of the radio interface, such as the TDD mode of the UMTS mobile radio system and FUTURE modified form m m m is realized the Chinese TD-SCDMA FUTURE mobile radio system is known from FIG 2 visible. According to a TDMA component, a division of a broadband frequency band, for example, the bandwidth B = 5 MHz, more time slots ts, for example, 16 time slots TSO is provided to tsl5. Each time slot TS within the frequency band B forms a frequency channel. Within a broadband frequency band B, the successive time slots ts are broken down by a frame structure. So 16 time slots TSO to be tsl5 combined into a time frame. Fr Several subsequent timeframe for result in a multi-frame.

p0019In one use of a TDD transmission method some of the time slots TSO to tsl5 uplink direction UL and part of the time slots TSO is used to tsl5 m downlink direction DL, wherein the transmission m uplink direction UL takes place for example before transmitting m downlink direction DL. In between there is a switching time SP (SP - Switchmg Point), the tragungskanalen accordance with special needs to Uber- for up and downlink direction can be flexibly sitioned po-. The variable assignment of the

p0020Timeslots ts fr up or downlink direction UL, DL can vielfaltige asymmetric resource allocations are made.

p0021Within the time slots ts information more compounds m Radio Block fb is transmitted. The data d are verbmdungsmdividuell with a fine structure, a spread code c, spread so that e pfangsseitig a number of compounds by this CDMA component (Code Division Multiple Access) are separable. From the combination of a frequency channel and a spreading code c a radio channel resource is defined, which can be used for the transmission of signaling and payload reNCy. The spreading of individual symbols of the data d causes mner- half of the symbol period T_sym Q chips of duration T_chιp transfer will. The Q chips thereby form the verbmdungsmdividuellen spread code c. In the radio Block fb a rule verb dungsmdividuelle training sequence is further arranged tseql ... which is a receiving side channel estimation. Wheat terhm a protection time gp for compensating different signal propagation tents of connections in successive time slots ts is provided within the time slot ts. For the transmission m downlink direction DL use specific signaling channels, such as the BCH and FACH, m each time frame a same radio channel resource, which, for example, always the first spreading code m corresponds to the first time slot TSO of a time frame. Fr To avoid simultaneous transmission of these channels m adjacent radio cells Z, this radio channel resource can, however, also within the time frame for "hiking^'"Ie, for example, for the assigned time slot ts m a specified time sequence other.

p0022In FIG 3, an exemplary sequence of multiple time frames is frl ... fr4 shown to describe the use of a same radio channel resource by multiple signaling channels BCH, FACH, wherein only one of the first time slot TSO of each time frame is frl ... indicated fr4. The signaling channels BCH and FACH use a time-division multiplex the common radio channel resource that is defined by the first time slot TSO and the first spread code cl.

p0023A subscriber station UE, the durchfuhrt an initial access to the wireless communication system first searches the or- ganisationskanal BCH, since this is relevant for a subsequent connection information sending. In addition, this channel can be received very well because of its higher transmission power of the subscriber station UE also near the radio cell boundaries. The subscriber station UE is per se Note that the organization channel BCH to the first radio channel resource (as described above) of a Zeitrah^¬ mens fr is sent, and is now trying to detect the control channel BCH. Because of this, as shown, not all the time frames for sending as in the known GSM mobile radio system m, the subscriber station must search UE under circumstances successively several time frames for by the organization channel BCH, until it has the information fully detected and evaluated.

p0024The control channel BCH is different from, for example, the FACH by a different data length d, as is the FIG 4 exemplified. In this case, the control channel BCH en compared to FACH shorter data field, 248 bit over 256 bit on. The error detection mechanism in the user station UE is m knowledge of these lengths of the respective data fields d. Detects this mechanism too long data field, for example, is received instead of the BCH the FACH, he discards the data field and tries again a reception. This is done until the length of the received data field is equal to the expected length. Only then is the data field with its hidden information is evaluated m higher mstanzen protocol. If, in addition, the length of data fields varies from radio cell to radio cell, then the

p0025Subscriber station UE, the knowledge of the Lange provided the signaling channels BCH, FACH of the respective radio cells differentiate and advantageous to use this knowledge for the determination of an appropriate radio cell for a connection setup.