US 6,449,290 B1 · Methods and arrangements in a radio communications system

Abstract

Methods and an arrangement for synchronizing communication of framed data via asynchronous base stations (BS1, BS2) in a cellular communication system are presented. The synchronization methods are performed continuously by sending out certain system frame counter states from a central node in the system to all its connected base stations (BS1, BS2). Each base station (BS1, BS2) includes a local frame counter (LFCBS1, LFCBS2), which generates local frame counter states (t1(1)-t1(4), t2(1)-t2(4)) correlated to the system frame counter states. Transmission of information via the base stations (BS1, BS2) is synchronized by assigning each data frame (DR(1)-DR(4)) a particular frame number, which is given by the local frame counter states (t1(1)-t1(4), t2(1)-t2(4)), so that data framed (DF(1)-DF(4)) having identical numbers contain copies of a certain data packet. Correct frame numbers are derived from common downlink channel offset measurements (CCO1, CCO2) carried out in the base stations (BS1, BS2), and timing advance values (TA2) and downlink channel offsets (DCO1, DCO2) calculated in the central node.

Claims32

Dependent claims

A method in a cellular radio communications system, which is arranged for communicating information in data frames (DF) of a predetermined duration (Tf) the system comprising at least one central node (RNC1, RNC2) and at least one asynchronous base station (BS1-BS5), for synchronizing all base stations (BS1, BS2) that are connected to one (RNC1) of the at least one central node (RNC1, RNC2) independently of any global time reference for the system, the method comprising the steps of:

sending a system frame counter state (SFC) from the central node (RNC1) to all its connected base stations (BS1, BS2), the frame counter state being incremented one step for each of the data frames (DF);
and
aligning in each of the connected base stations (BS1, BS2) a state of a respective local frame counter (LFCBS1, LFCBS2) with the system frame counter state (SFC);
wherein each of the data frames (DF) is associated with a specific frame number (t1(1)-t1(4), t2(1)-t2(4)) which is derived from the respective local frame counter (LFCBS1, LFCBS2).

1 more element

A method in a cellular radio communications system comprising at least one central node (RNC1, RNC2), which is connected to at least one asynchronous base station (BS1-BS5), each of which serves at least one geographical sector (s11-s56), which in turn are each associated with a common downlink control channel (CDCH1, CDCH2),

where the base stations (BS1-BS5) communicate information with mobile stations (MS1-MS4), the information being divided into data packets (DP), which are transmitted in data frames (DF)
on downlink channels (DCH1, DCH2) via one or more sectors (s23, s24) to the mobile stations (MS1-MS4), and
on uplink channels (UCH2) from the mobile stations (MS1-MS4) via one or more sectors (s23, s24),
for establishing a connection between one of the mobile stations (MS2) and at least one base station (BS1), the method comprising the steps of:
sending a system frame counter state (SFC) from one central node (RNC1) of the at least one central node (RNC1, RNC2) to all its connected base stations (BS1, BS2), the frame counter state being incremented one step for each of the data frames (DF) and being incremented one step after each lapse of one of the data frames (DF);
aligning in each of the connected base stations (BS1, BS2) a state of a respective local frame counter (LFCBS1-LFCBS2) with the system frame counter state (SFC), each of the data frames (DF) being associated with a specific frame number (t1(1)-t1(4), t2(1)-t2(4)) which is derived from the respective local frame counter (LFCBS1-LFCBS2);
in each of the connected base stations (BS1, BS2), measuring a common downlink control channel offset value (CCO1, CCO2) between the local frame counter states (LFCBS1-LFCBS2) and a corresponding common downlink control channel (CDCH1, CDCH2), where the local frame counter state (LFCBS1-LFCBS2) is incremented at a rate correlated to the system frame counter (SFC) step rate;
reporting the common downlink control channel offset values (CCO1, CCO2) to the at least one central node (RNC1, RNC2);
defining for the mobile station (MS2) an active set (AS) in which at least one of the downlink channels (DCH1) and one of the uplink channels (UCH2) is specified;
for each of the at least one downlink channels (DCH1) in the active set (AS), setting a timing advance value (TA1), which indicates an offset between the common downlink control channel (CDCH1) and the downlink channel (DCH1);
for each of the at least one downlink channels (DCH1) in the active set (AS), calculating a downlink channel offset (DCO1) as a sum (CCO1+TA1) of a common downlink control channel offset (CCO1) and the timing advance value (TA1);
assigning a specific frame number (t1(1)-t1(4)) to each data frame (DF(1)-DF(4)) on each of the at least one downlink channels (DCH1), by giving an initial data frame (DF(1)) a first number (t1(1)) and each following data frame (DF(2)-DF(4)) an integer incrementation (t1(2), t1(3), t1(4)) of this number (t1(1)) equal to an order of each respective data frame (DF(2)-DF(4)) in relation to the initial data frame (DF(1)).

9 more elements

where the base stations (BS1-BS5) communicate information with mobile stations (MS1-MS4), the information being divided into data packets (DP), which are transmitted in data frames (DF)
on downlink channels (DCH1, DCH2) via one or more sectors (s23, s24) to the mobile stations (MS1-MS4), and
on uplink channels (UCH2) from the mobile stations (MS1-MS4) via one or more sectors (s23, s24),
for commencing communication via at least one second sector (s21) with one of the mobile stations (MS2) which is already communicating information via at least one first sector (s14) specified in an active set (AS) for the mobile station (MS2), the method comprising the steps of:
sending a system frame counter state (SFC) from one central node (RNC1) of the at least one central node (RNC1, RNC2) to all its connected base stations (BS1, BS2), the frame counter state being incremented one step for each of the data frames (DF) and being incremented one step after each lapse of one of the data frames (DF);
aligning in each of the connected base stations (BS1, BS2) a state of a respective local frame counter (LFCBS1-LFCBS2) with the system frame counter state (SFC), each of the data frames (DF) being associated with a specific frame number (t1(1)-t1(4), t2(1)-t2(4)) which is derived from the respective local frame counter (LFCBS1-LFCBS2);
in each of the connected base stations (BS1, BS2), measuring a common downlink control channel offset value (CCO1, CCO2) between the local frame counter states (LFCBS1-LFCBS2) and a corresponding common downlink control channel (CDCH1, CDCH2), where the local frame counter state (LFCBS1-LFCBS2) is incremented at a rate correlated to the system frame counter (SFC) step rate;
reporting the common downlink control channel offset values (CCO1, CCO2) to the at least one central node (RNC1, RNC2);
measuring at least one frame offset value (Of12) between a downlink channel (DCH1) in the active set (AS) and a second common downlink control channel (CDCH2), associated with the second sector (s21), not included in the active set (AS),
reporting the frame offset value (Of12) to a central node (RNC1),
updating the active set (AS) by adding thereto the second sector (s21),
calculating a timing advance value (TA2) and a downlink channel offset value (DCO2) for at least one second downlink channel (DCH2) in the second sector (s21),
setting an offset between data frames (DFs) transmitted on the at least one second downlink channel (DCH2) and the second common downlink control channel (CDCH2) equal to the timing advance value (TA2),
assigning a specific frame number (t2(1)-t2(4)) to each data frame (DF(1)-DF(4)) on the second downlink channel (DCH2), by giving an initial data frame (DF(1)) after a current local frame counter state from the second series of local frame counter states (LFCBS2(n)) a frame number (t2(1)) equal to a following local frame counter state from this series and each subsequent data frame (DF(2)-DF(4)) an integer incrementation (t2(2)-t2(4)) of this frame number (t2(1)) equal to the order of each respective data frame (DF(2)-DF(4)) in relation to the initial data frame (DF(1)).

11 more elements

An arrangement for communicating framed information in a cellular radio communications system comprising at least one central node (RNC1), which is connected to at least one asynchronous base station (BS1, BS2) through which data packets (DPs) are communicated on downlink channels (DCH1, DCH2) and uplink channels (UCH1, UCH2) with mobile stations (MS2) and where control signals are transmitted on common downlink control channels (CDCH1, CDCH2) to the mobile stations (MS2), wherein the at least one central node (RNCL ) comprises a master timing unit for generating system frame counter states (SFC) to be sent to the at least one base station (BS1, BS2), a master control unit for calculating timing advance values (TA) and downlink channel offset values (DCO1, DCO2) to be used while communicating data packets (DPs) in numbered data frames (DF) on the downlink channels (DCH1, DCH2), a diversity handover unit for executing simultaneous communication via more than one of the at least one base station (BS1, BS2) with a particular mobile station (MS2).

Dependencies are inferred from the claim text.

Methods and arrangements in a radio communications system

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Methods and arrangements in a radio communications system

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Abstract

Claims32