Classifications

• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04W—WIRELESS COMMUNICATION NETWORKS
  • H04W36/00—Hand-off or reselection arrangements
  • H04W36/06—Reselecting a communication resource in the serving access point
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04W—WIRELESS COMMUNICATION NETWORKS
  • H04W36/00—Hand-off or reselection arrangements
  • H04W36/16—Performing reselection for specific purposes
  • H04W36/18—Performing reselection for specific purposes for allowing seamless reselection, e.g. soft reselection

Definitions

• the present invention relates to a method and apparatus for assigning communication channels between different radio transceiver devices in a radio communication network.
• the present invention is directed to a method and apparatus for providing a seamless recovery of a radio channel reconfiguration failure on data transmission channels between different radio transceiver devices in a cellular radio communication network.
• radio telecommunication networks for mobile communication have become very popular.
• Such radio communication networks establish mutual communication between mobile radio transceiver devices as first radio transceiver devices, hereinafter referred to as mobile station MS, of respective subscribers.
• Such cellular networks generally consist of a plurality of stationary radio transceiver devices as second radio transceiver devices, hereinafter referred to as base stations BS .
• Each base station can be assumed to be controlled by a radio network controller device RNC.
• Communication between different mobile stations MS is established via at least one intermediate base station BS .
• a respective base station BS defines a radio cell by its radio coverage area.
• a mobile station MS present within such a cell establishes a radio connection with the respective base station BS of the cell.
• the transmission principle adopted in such cellular radio networks is generally based on multiple access methods.
• plural subscribers share the same channel, for example according to a known scheme of time divisional multiple access (TDMA) or according to a scheme known as wideband code divisional multiple access ⁇ (W-CDMA) .
• TDMA time divisional multiple access
• W-CDMA wideband code divisional multiple access ⁇
• the transmission principles are for example specified in the GSM recommendations, issued by the European Telecommunication Standards Institute (ETSI).
• ETSI European Telecommunication Standards Institute
• a (physical) channel, in connection with TDMA transmission is thus divided into time slots to be assigned to respective subscribers for communication, the slots being grouped to form units of frames. While, according to W- CDMA, there are radio frames that are divided into slots, but slots are assigned to the same user.
• the multiple access is based on the code used in transmission, and not on time.
• the data transmitted in such frames comprise actual information to be transmitted between the subscribers (e.g. speech data) as well as control data used for establishing and/or maintaining a communication channel between subscribers and/or a subscriber MS and a respective base station BS.
• Data are transmitted from the respective mobile station MS to the base station BS of the cell in a so-called uplink transmission UL, and data are transmitted from the base station BS to the respective mobile station MS in a so- called downlink transmission DL.
• the respective channels for uplink and downlink transmission are physically different from each other, and each base station BS is designed so as to provide at least one channel for uplink and downlink transmission, respectively.
• a base station may be adapted to provide a plurality of different channels for each transmission direction, uplink UL or downlink DL, respectively.
• Actual transmission in radio communication networks is effected via the radio path between a subscriber MS and the base station BS of the cell.
• the radio path (air interface Urn) layer 1 (LI, physical layer) is the lowest layer of the transmission and is defined by its physical parameters ⁇ and/or other properties P, P'.
• the radio path properties having regard to physical parameters, include for example, the frequency, the signal power for transmission, and cell interference level.
• Layer 1 parameters at the radio interface include also for example forward error coding, interleaving, configuration of the layer 1 data stream multiplexing into the physical channel.
• the frequency of a physical channel may depend on the frequencies (channels) available at the base station side and/or on the traffic load within the cell, while the signal power as parameter depends on the environment of the base station (rural area with or without e.g. mountains and valleys) or densely populated city areas and/or the distance between the base station BS and a mobile station MS communicating with said base station.
• a respective set of LI parameters P, P' are supplied in the form of a data transmission (message) from the radio network controller RNC to the base station BS and to the mobile station MS. Such a message may also include the starting time, i.e. the frame number, when the parameters are rendered valid.
• the message is transmitted via (logical) signaling channels dedicated for transmission of signaling information and represents a request for changing" the set of actual parameters, e.g. from a set P to a modified set P ' .
• the mobile station even if the parameters are supplied to the mobile station MS, the mobile station, for some reasons, might not be able to apply the transmitted parameters. Then, there arises a situation that a set of new Ll parameters P' are only rendered valid on the network side, that is, used by the radio network controller RNC and the base station BS (under the assumption that the synchronization to the new set of Ll parameters is seamless), while the mobile station MS still relies on a hitherto valid set of parameters P for communication.
• a failure can be noticed at the network side, at minimum, after one period of interleaving (interleaving denoting an error control technique for ⁇ changing burst errors into random errors, as described in literature, e.g. in "Introduction To Digital Mobile Communication", by Y. Akaiwa, pp. 287 ff., John Wiley & Sons, New York, USA, 1997) .
• interleaving denoting an error control technique for ⁇ changing burst errors into random errors, as described in literature, e.g. in "Introduction To Digital Mobile Communication", by Y. Akaiwa, pp. 287 ff., John Wiley & Sons, New York, USA, 1997) .
• a plurality of interleaving periods are required to take decisions concerning channel state. Therefore, informing the radio network controller of a channel failure can only take place after detection of the failure.
• the present invention aims to provide a method and device for seamless recovery of radio channel reconfiguration failure on the network side.
• a method for assigning communication channels between a first radio transceiver device and a second radio transceiver device in a radio communication network comprising the steps of monitoring parameters of an assigned first communication channel, detecting a request for changing said monitored parameters of said first communication channel, activating, upon detection of a request for a parameter change, a second communication channel for communication between said first and said second radio transceiver devices, decoding both communication channels, judging, whether said additionally activated, second communication channel has been decoded successfully, and, upon judging that said second channel has been successfully decoded, releasing — said first communication channel and continuing communication using said second communication channel only.
• a device for assigning communication channels between a first radio transceiver device and a second radio transceiver device in a radio communication network comprising monitoring means adapted to monitor parameters of an assigned first communication channel, detection means adapted to detect a request for changing said monitored parameters of said first communication channel, activation means adapted to activate, upon detection of a request for a parameter change, a second communication channel for communication between said first and said second radio transceiver devices, decoding means adapted to decode both communication channels, judging means adapted to judge, whether said additionally activated, second communication channel has been decoded successfully, and, releasing means adapted to release said first communication channel and continuing communication using said second communication channel only, upon reception of a judgment result that said second channel has been successfully decoded.
• Radio parameters P of the physical Ll layer can securely be redefined upon occurrence of a parameter change.
• the dropped call rate i.e. the number of dropped calls, can be reduced.
• the radio network controller need not be informed about the whole reconfiguration procedure (temporary resource activation and deactivation) , which is handled by the base station. Therefore, the processing load for the radio resource management on the network controller side is reduced.
• Fig. 1 schematically shows part of a radio communication network
• Fig. 2 (consisting of Figs. 2A & 2B) represents a flowchart illustrating the method and the operation of the accordingly adapted device, according to an embodiment of the present invention.
• new hardware resources at the base station BS side are activated for a new communication channel UL2 which is characterized by a new set of parameters P', without releasing those resources allocated for the previously assigned ("old") radio communication channel UL1.
• UL uplink transmission
• there is one physical channel transmission from the mobile station MS to the base station BS but there are two receiving units R at the base station BS side which respectively operate using different layer 1 parameters for a respective mobile station MS. Then only one of these receiving units R at the base station BS may receive a signal from the mobile station MS which can provide correct decoding results.
• a radio network controller device RNC communicates with and controls a base station BS of a radio network. However it should be understood that in practice, a radio network controller device RNC controls a plurality of base stations of the network.
• the base station BS communicates with a mobile station MS present within the cell of the base station.
• data transmission in uplink direction UL from the mobile station MS to the base station BS is effected by using an uplink communication channel (UL1, ⁇ ⁇ using parameter set P, or UL2, using parameter set P').
• the used uplink communication channels UL1, UL2 differ in the respective set of layer 1 (Ll) parameters P, P'.
• Data transmission m downlink direction DL from the base station BS to the mobile station is effected by using a downlink channel DL.
• the reception of the data transmitted in uplink direction is then achieved by two activated receiving units (in Fig. 1 denoted with R) within the base station, each using a different parameter set P, P' for reception.
• Fig. 1 merely shows the minimum requirements for a base station in which the present invention may be implemented.
• the present invention merely requires that the base station has enough hardware resources for temporarily allocating additional (e.g. the double) amount of hardware resources for connection.
• additional e.g. the double
• the following description will refer to a single mobile station MS only.
• Fig. 2 represent a flowchart illustrating the method and the operation of the accordingly adapted device.
• the device (not shown in Fig. 1) forms part of the base station BS ⁇ shown in Fig. 1.
• step SI it is checked whether an uplink communication channel, e.g. ULl, between a respective mobile station MS and the base station BS is active.
• an uplink communication channel is received at one of at least two receiving units R available at the base station BS for uplink communication channels, which in the depicted example of Fig. 1 is denoted as R[UL1(P)].
• R[UL1(P)] the procedure loops until a first uplink communication channel ULl is detected as being active.
• the set of Ll parameters P of said communication channel ULl is monitored in step S3.
• step S4 there is detected whether a change in the previously monitored parameters P has meanwhile been instructed from the radio network controller RNC side to be changed. If no request / instruction for a parameter change has been detected (NO in step S4), the previously assigned/activated receiving unit R[UL1(P)] for a communication channel ULl (using layer 1 parameter set P for reception) is maintained (step S5) in uplink communication and the flow returns to step S3. If, however, a request for a change in the Ll parameter set has been detected, i.e. a new communication channel UL2 with new parameters P' is to be activated, the procedure advances to step S6.
• step S6 an additional new receiving unit R[UL2(P')] for a communication channel UL2 (using layer 1 parameter set P' for reception) in uplink communication between the mobile station MS and the base station BS is activated.
• both receiving units R of the base station BS for communication channel ULl and UL2 are simultaneously active, while there is still only one physical channel ⁇ transmission from the mobile station MS to the base station BS.
• step S7 the data transmitted on the uplink physical channel are decoded for both sets of Ll-parameters (P, P') of communication channels ULl, UL2.
• step S8 it is judged whether the decoding of the data transmitted using the additionally activated receiving unit for a communication channel UL2 was successful. If the decoding of transmitted data for a set of Ll parameters specifying communication channel UL2 failed, i.e. decoding was judged to be erroneous, (NO in step S8), the method flow branches and continues with step S9 (Fig. 2B) .
• step S9 it is determined in step S9 whether the decoding of transmitted data for a set of Ll parameters representative of communication channel ULl has still been successful. If also the decoding of transmitted data using the parameter set P defining communication channel ULl has been determined to have failed (NO in step S9) , the flow proceeds to step S10. In step S10 it is then confirmed that the communication (call) has been terminated or dropped, since no data could be decoded using either of the sets of parameters defining communication channels ULl, UL2. If, however, the decoding using the parameter set for the communication channel ULl has been successful (YES in step S9) , the flow proceeds to step Sll.
• step Sll the communication continues using the initially assigned parameters for channel ULl (with "old" parameters P) . Namely, receiving unit R[UL1(P)] is continued to be used, while receiving unit R[UL2(P')] is released to be in an idle state again. This assures, that no data will be lost due to the fact that a new communication channel UL2 having the new parameters P' could not be successfully established. Subsequently, in step S12, the radio network ⁇ controller RNC is informed of the fact that the new channel UL2 could not be established for communication between the mobile station MS and the base station BS . The radio network controller RNC may then initiate another appropriate action to establish a new communication channel with a changed parameter set.
• step S8 if the decoding of transmitted data using parameters indicating communication channel UL2 was successful, i.e. decoding was judged to be effected correctly, (YES in step S8), the method flow continues with step S13.
• step S13 the previously assigned/active receiving unit R[UL1(P)] using parameters P for communication channel ULl is released and communication between the mobile station MS and the base station BS is continued using the communication channel UL2 , i.e. the receiving unit R using the set of communication channel parameters P' for reception.
• the communication channel UL2 is the assigned communication channel and the flow returns to step S2. The processing is repeated in case a further parameter change is instructed.
• step S13 in Fig. 2A mentions to set UL2 as ULl, this is rather for explanation purposes when referring to two communication channels only."
• the properties of the communication channel UL2 are, of course, defined by its assigned set of parameters P'.
• the radio network controller RNC need not be informed about the whole procedure of temporary radio resource activation and deactivation which is handled by the base station BS, so that the processing load for the radio network controller RNC is reduced.
• the radio network controller RNC is only involved again in case establishing the new communication channel with new parameters fails while the old channel can be maintained so that no data losses will occur and the call will not be dropped. This whole procedure is transparent for the mobile station.
• step S6 there must be taken a decision as to which channel is selected for the new parameters.
• the present invention requires additional hardware resources (e.g. receiving units R in case uplink UL transmission is considered) for each communication channel the parameter set of which is instructed to be changed.
• additional hardware resources e.g. receiving units R in case uplink UL transmission is considered
• a single communication channel per base station BS to be additionally activated upon a requested change of a set of communication channel parameters might be sufficient. The reason therefore is that the probability of simultaneously instructed changes of parameter sets for communication channels at the base station BS side can be considered to be rather low.
• measures can be taken to assure that at least one communication channel of all available communication channels of a base station BS may be assigned to be used in steps S3 through S13.
• the description of the invention as given herein above has mainly be made considering the uplink transmission channels. Nevertheless, the downlink transmission resources may also be activated in a similar way as described above. This, however, requires that interference caused by the two channels is taken into account and is admissible under the radio resource scheduling requirements, since in connection with CDMA all signals are transmitted simultaneously and interfere with each other.

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• Engineering & Computer Science (AREA)
• Computer Networks & Wireless Communication (AREA)
• Signal Processing (AREA)
• Mobile Radio Communication Systems (AREA)

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• 1998
  • 1998-09-16 WO PCT/EP1998/005893 patent/WO2000016504A1/en not_active Application Discontinuation
  • 1998-09-16 JP JP2000570922A patent/JP2002525909A/ja active Pending
  • 1998-09-16 AU AU96258/98A patent/AU9625898A/en not_active Abandoned
  • 1998-09-16 CN CN98809125.9A patent/CN1270720A/zh active Pending
  • 1998-09-16 EP EP98950041A patent/EP1032992A1/de not_active Withdrawn

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