Patent Publication Number: US-2005143130-A1

Title: Terminal, base station and method for a cellular network

Description:
FIELD OF THE INVENTION  
      The present invention relates to a communication method of a cellular network, and to a terminal and base station for such.  
     BACKGROUND OF THE INVENTION  
      A cellular network offers large coverage areas and high terminal mobility. Thereby, even moving terminals are able to connect to the cellular network. But the data rate is limited by the usable cell size and the speed of the moving terminals. Therefore, higher data rates are only usable close to the base station with pedestrian speeds. So, in high moving vehicles it is impossible to use very high data rates.  
      To increase the data rate, an asymmetric utilization in up-link and down-link can be used. Thereby, a higher data rate for down-link can be provided, if up-link data rates are decreased accordingly. But, this asymmetric data transfer cannot increase the overall data rate.  
     SUMMARY OF THE INVENTION  
      It is therefore the object of the present invention, to increase the data rate for a selected user terminal, especially if this user is moving.  
      The object is solved by a base station according to claim  1  or  6 , by a terminal according to claim  9  or  18  and by a method according to claim  26  or  33 . Advantageous developments of the invention are mentioned in the dependent claims.  
      Throughout this application words user terminal and terminal are used for describing the terminal equipment, which may be related to a specific user. A user terminal can be in example a cellular phone, a PDA, a mobile router, or any other mobile communication apparatus capable of receiving, handling and sending data in accordance to this method and system. A terminal can be also for instance a mobile router equipment, which may or may not be associated to a specific user.  
      The terminal should be understood as any kind of terminal capable of functioning in accordance to the specified claims.  
      The apparatus and the method of the invention have the advantage that data which is intended for an specific terminal is distributed over at least two terminals so that idle terminals or terminals that do not utilizise the maximum data rate can be used as an additional passage for data packets of the data. Therefore, the overall data rate increases with the terminals concerned with the shared data transmission. Thereby, the invention makes use of a second network between the terminals to transfer the data packets to/from the specific terminal.  
      According to an advantageous development, one data packet is sent directly between the cellular network base station and the specific terminal, and the other data packets are sent over other available terminals.  
      According to another advantageous development, terminals of the cellular network which are near the terminal for which the data is intended are selected. Then, the second network can be provided as an low-range network so that high data rates can be used.  
      According to a further advantageous development, terminals of the cellular network which are moving together with the terminal for which the data is intended are selected. Then the relative speed between the terminal for which the data is intended and the other selected terminals is slow so that high data rates can be achieved. 
    
    
     BRIEF SUMMARY OF THE ACCOMPANIED DRAWINGS  
      The invention is further described in detail with relation to the accompanying drawings, in which:  
       FIG. 1  to  3  show flow charts of a method according to a first embodiment of the invention;  
       FIG. 4  to  6  show flow charts of a method according to a second embodiment of the invention;  
       FIG. 7  shows a schematic structure of base station and users according to the first embodiment of the invention;  
       FIG. 8  shows a receiving terminal of  FIG. 7  according to the first embodiment of the invention in greater detail;  
       FIG. 9  shows a sending terminal according to the second embodiment of the invention;  
       FIG. 10  shows a schematic structure of base station and user terminals according to the second embodiment of the invention; and  
       FIG. 11  shows two users according to a third embodiment of the invention. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS OF THE INVENTION  
       FIG. 1  to  3  show flow charts of a method for sending data from a base station of a cellular network to a specific user terminal (down-link).  FIG. 1  shows the steps performed on the side of the base station,  FIG. 2  shows the steps performed on the side of a user selected for forward transmission, and  FIG. 3  shows the steps performed on the side of the user for which the data is intended.  
      In step  101  the procedure performed by the base station is started, and, as shown in step  102 , input data for an user terminal U 1  is received from the cellular network. Then, in step  103  it is determined which other user terminals are connected or are able to connect to user terminal U 1  over a second network. In the first embodiment of the invention the second network is an ad-hoc network of low range so that preferably only the part of the user terminals, which is close to user terminal U 1 , are selected in the following step  104 . The number of selected other user terminals U 2  to U 4  depends also on the data rate needed between the base station and the user terminal U 1 .  
      Step  104  is followed by step  105 , in which the input data is divided in data packets DP 1  to DP 4 , whereby one data packet DP 1  is for the user terminal U 1  and the other three data packets DP 2  to DP 4  are for the selected other user terminals U 2  to U 4 .  
      The number of three user terminals selected is only intended as an exemplary example. In general, in step  104  any number of user terminals determined in step  103  can be selected. The input data is then divided in this number incremented by 1 data packets in step  105 , whereby the additional one data packet is for the user terminal U 1 .  
      Step  105  is followed by step  106 , in which a connection is established between the cellular network base station and the user terminal U 1  and the selected other user terminals U 2  to U 4 . This may be done according to any known, or future cellular network procedures. Connecting methods used in cellular network are not an essential part of this invention, and the specific methods for establishing a connection over a cellular network between the base station and the terminals are therefore omitted. The description of creating this connection is therefore simplified to the essence of that a connection is established between the base station and each terminal participating this system and method. After connecting to the user terminals U 1  to U 4 , one data packet DP 1  is sent to user terminal U 1  and the other data packets DP 2  to DP 4  are sent to the other user terminals U 2  to U 4 , as shown in step  107 . Thereafter, the procedure ends in step  108 .  
      In step  107  the data packets DP 1  to DP 4  can be sent as several subblocks. Thereby the data packets to each of the user terminals U 1  to U 4  are sent in parallel so that the effective data rate is at most the data rate for a single user terminal multiplied with the number of connected user terminals U 1  to U 4 .  
       FIG. 2  shows a flow chart of the method performed by each of the terminals of the users U 2  to U 4 .  
      The method is starting in step  201  after the connection is established between the base station and the respective user terminal. Then, a data packet DP 2 ; DP 3 ; DP 4  is received from the base station, as shown in step  202 . In step  203  it is determined, whether the data received is designated for another user terminal or for this terminal. If the data received is not designated for another user terminal, the data received is used, as shown in step  207 . If the data received is designated for another user terminal, then the user terminal U 1  for which the data received is designated is connected over a second network, whereby in this embodiment the second network is a low-range ad-hoc network (step  204 ). After connecting to user terminal U 1 , the data received in step  202  is sent to user terminal U 1  in step  205 , and the method ends in step  206 .  
      The selection of the terminals contacted to this second network can alternatively be initiated before the actual data sending procedure is started, or any data packets intended for another user terminal U 1  in the second network are received by the other user terminals U 2 -U 4 . This implicates that step  204  is performed prior to step  201 . Establishment of the connection over network  2  can take place i.e. with any suitable signalling procedure, which is not in scope of this invention.  
      If the respective data packet is sent in several subblocks, then the subblocks can either be collected in step  202 , until the whole data packet has been received, before the method proceeds with step  203 , or steps  201  to  206  can be repeated for each of the subblocks.  
       FIG. 3  shows a method performed at the terminal of the user U 1  for which the data is intended.  
      This method starts in step  301  to receive the data packet DP 1  from the base station over the cellular network in step  302 . In step  303  the data packets DP 2  to DP 4  are received from the other user terminals U 2  to U 4  over the ad-hoc network. It is also possible that steps  301  and  302  are executed in parallel or in opposite order,  302  first. Even if in steps  302  and  303  some data packets DP 1  to DP 4  are-missing, the method proceeds with step  304 . In step  304  it is probed, whether all data packets DP 1  to DP 4  have been received. If not, the method continues with step  305  and tests for a time-out. If the time-out is reached in step  305 , then the procedure performs an error procedure, as shown in step  306 .  
      The error procedure in step  306  depends on the sort of data transferred between the base station and the user terminal. In a telephone consultation some missing data packets may not be a problem. But, if computer data is transferred, then even with the use of redundancy coding the lack of information may be so heavy, that reconstruction of the data is not possible, so that a request for a (partial) resending must be sent.  
      If no time-out occurs in step  305 , then steps  302  and  303  are repeated.  
      When the data packets DP 1  to DP 4  are each sent as several subblocks, then in step  304  it is probed, if all subblocks of all data packets DP 1  to DP 4  have been received.  
      If step  304  is answered “yes”, then the data packets DP 1  to DP 4  received are combined in step  307 . Then, the data is output in step  308  and the procedure ends (step  309 ).  
       FIG. 4  to  6  show a method for sending data from a terminal to the base station of a cellular network according to a second embodiment of the invention (up-link).  FIG. 4  shows the part of the method performed on the side of the user terminal which sends the data,  FIG. 5  shows the steps on the side of a user terminal which is used as a transmission station, and  FIG. 6  shows the steps performed on the side of the base station.  
      In  FIG. 4  after the start of the method in step  401 , the input data intended for sending to the base station is input in step  402 . Then, in step  403  the terminal of the user determines which other user terminals are connected or are able to connect to the same second network, whereby in this embodiment the second network is a low-range ad-hoc network. Thereafter, as shown in step  404  all or a part of these user terminals are selected according to the data rate needed. Due to the low-range characteristic of the second network according to the second embodiment of the invention, user terminals that are close to the terminal of the user who intends to send the input data are preferably selected.  
      Step  404  is followed by step  405 , in which the input data is divided into number of selected other user terminals U 2  to U 4  plus 1 data packets DP 1  to DP 4 . Thereby, the additional data packet is intended to be sent directly from the user terminal to the base station. In another embodiment, in which the user terminal does not itself send a data packet directly to the base station, the input data is only divided into the number of data packets that corresponds to the number of other selected user terminals.  
      Then, a connecton is established between the user terminal and the cellular network base station in step  406 . After connecting to the base station, the data packet DP 1  is sent to the base station, as shown in step  407 . Thereafter, the other selected user terminals U 2  to U 4  are connected over an ad-hoc network in step  408 . Next, the other data packets DP 2  to DP 4  are sent to the selected other user terminals U 2  to U 4  in step  409 . After performing steps  406  to  409 , it is probed in step  410 , whether all data packets DP 1  to DP 4  have been sent. If not, in step  411  a possible time-out is detected which time-out results in a jump to the error procedure shown in step  412 . If no time-out occurs in step  411 , then steps  406  to  409  are repeated, until all data packets have been sent, as probed in step  410 . In this case, the procedure ends in step  413 . Alternatively, step  407  may be performed only after steps  408  and/or  409 . That is, the data packet DP 1  may be sent to the base station only after the other user terminals have been selected and or after the other data packets have been sent to the other user terminals. It&#39;s also possible that steps  407  and  409  are done in parallel, so that all data packets DP 1 , DP 2 , DP 3 , DP 4  are sent essentially in parallel.  
      The data packets DP 1  to DP 4  may also be sent as subblocks. Then, in step  410  it is determined, whether all subblocks of all data packets have been sent.  
      A time-out in step  411  may occur for several reasons. If a selected user terminal disconnects during the sending steps  406  to  409  then the respective-data packet can be sent to the base station or some other selected user terminal. Selecting a not yet selected user terminal from the users determined in step  403  is also possible. The unsent data packets can then be sent to this user terminal.  
      In  FIG. 5  the method performed by a terminal of an user selected for sharing a data packet DP 1 ; DP 2 ; DP 3  of the data according to the second embodiment of the invention is shown as a flow chart.  
      The method starts with step  501 , and receives thereafter a data packet DP 1 ; DP 2 ; DP 3  from user terminal U 1  over the ad-hoc network, as shown in step  502 . Thereafter, it is probed in step  503 , whether that data received is for transmission to the base station. If not, then the data received is for the terminal itself and used accordingly, as shown in step  504 . If the data received is for transmission to the base station, then step  505  follows, in which the connection is established between the terminal and the cellular network base station. Thereafter, as shown in step  506 , the data received is sent to the base station over the cellular network connection and the procedure ends in step  507 .  
       FIG. 6  shows the procedure performed by the base station as a part of the method according to the second embodiment of the invention as a flow chart.  
      The procedure shown in  FIG. 6  starts with step  601 . Then, the data packets DP 1  to DP 4  are received from the user terminals U 1  to U 4  via the cellular network, as shown in step  602 . In step  603  it is determined, whether all data packets DP 1  to DP 4  have been received. If not, and if a time-out occurs, as probed in step  604 , then the procedure jumps to an error routine shown in step  605 . Until the time-out, step  602  is repeated.. In the error procedure shown in step  605 , a request for resending a (specific) data packet DP 1 ; DP 2 ; DP 3 ; DP 4  can be sent to user-terminal U 1 . On the other hand, retransmission may not be necessary, for example in a telephone conversation or if that missing data can be reconstructed. The problem is the same as described with reference to step  306  in  FIG. 3 .  
      After all data packets have been received, step  606  follows, in which the data packets DP 1  to DP 4  received are combined together to the original data.  
      In step  607  this data is output, and the procedure ends in step  608 .  
       FIG. 7  shows base station and user terminals of the first embodiment of the invention.  
      The base station  1  comprises a dividing means  2 . The dividing means  2  is connected with the input line  3  to input data  4  for the user terminal U 1 . The user terminals which are connected or are able to connect to user U 1  over a second network  6  are listed in the list of user terminals  5 . List of user terminals comprise user and/or terminal information which enables contacting the specific terminals which can be used according to this invention. This may include, for example in addition to terminal and/or user identification or contact information also such additional information as terminal capabilities information and application or service useability, allowance and/or restriction information. As an example, in the first embodiment of the invention the user terminals U 2 , U 3  and U 4  are listed in the list of user terminals  5 . It should be understood, that the list of user terminals  5  may also reside outside the base station, as far as the information of the available terminals for connection is available for the base station when needed. In this exemplary embodiment, this list is provided within the base station. This information may thus also be provided from a remote list which is made available over an interface to the other related functions in the base station. The list of user terminals  5  is connected with a selecting means  7 . In this example, to transmit the data  4  in time, four times the data rate of a single base station to user terminal connection is needed. Hence, the selecting means  7  select user terminals U 2 , U 3  and U 4 . The number+1 and contact information of selected user terminals is sent from the selecting means  7  to the dividing means  2 . The selected user terminal information for U 2 , U 3  and U 4  are input from the selecting means  7  to a sending means  8 . The dividing means  2  divides the data  4  in at least two parts. The number of parts depends on the number input from the selecting means  7 . In the example the dividing means  2  divides the data  4  in four data packets DP 1  to DP 4 . The data packets DP 1  to DP 4  are sent from the dividing means  2  to the sending means  8 . The sending means  8  connects to user terminals U 1  to U 4  over the cellular network  9  and sends the data packets DP 1  to DP 4  to the respective user terminals. Thereby the data packets DP 1  to DP 4  are sent essentially in parallel.  
      Then, user terminals U 2  to U 4  connect to the user terminal U 1  over the second network  6  and send the data packets DP 2  to DP 4  to user terminal U 1 . According to another optional embodiment, the connection between terminals U 1  and other terminals U 2  to U 4  is established already at the time of sending the data packets DP 1  to DP 4 .  
       FIG. 8  shows the receiving of the data packets DP 1  to DP 4  according to the first embodiment of the invention in greater detail. In this and all other figures corresponding:parts are referred to by identical reference numbers.  
      The receiving part  15  of user terminal U 1  comprises a receiving means  16  which is adapted to receive data sent over the cellular network from base station  1 . Further, the receiving part  15  comprises a further receiving means  17  which is adapted to receive data from other user terminals via the second network  6  essentially in parallel. This kind of arrangement can be done for example in a multi-carrier system, for example OFDM, so that some number of the sub-carriers are allocated to each sending user terminal U 2 , U 3 , U 4 , and the receiving user terminal U 1  receives all sub-carriers at the same time. Or, in a time division system one time slot is allocated to each sending user terminal U 2 , U 3 , U 4 , and the receiving user terminal U 1  receives all required time slots.  
      Hence, the receiving means  16 ,  17  receive the data packets DP 1  to DP 4  at most in parallel, and forward them to a combining means  18  for combining the data packets DP 1  to DP 4  to their original data  4 .  
       FIG. 9  shows a terminal of a user sending data to the base station according to the second embodiment of the invention.  
      The sending part  20  of user terminal U 1  comprises a dividing means  21 . Data  22  is input to the dividing means  21 . In a list of user terminals  23  of the sending part  20  the user terminals are listed, which are connected or are able to connect to the same second network as user terminal U 1 . A selecting means  24  selects, as an example of this embodiment, user terminals U 2  to U 4  from the list of user terminals  23 , because the amount of data  22 , is four times the amount of data that can be sent in time through a single connection over the cellular network so that four user connections to the base station  1  are needed to achieve the preferred data rates.  
      The dividing means  21  divides the data  22  in the data packets DP 1  to DP 4  in line with the number of user terminals selected plus  1 , which is sent from the selecting means  24  to the dividing means  21 . The dividing means  21  sends one data packet DP 1  to the further sending means  25 , whereby the further sending means  25  sends the data packet DP 1  to the base station  1  over the cellular network  9 .  
      The other three data packets DP 2  to DP 4  are sent from the dividing means  21  to the sending means  26 , and the sending means  26  sends this data packets essentially in, parallel to the user terminals U 2  to U 4  over the second network  6 . This kind of arrangement can be done for example in a multi-carrier system, for example OFDM, so that some number of the sub-carriers are allocated to each sending user terminal U 2 , U 3 , U 4 , and the sending user terminal U 1  transmits data on all sub-carriers at the same time. Or, in a time division system one time slot is allocated to each receiving user terminal U 2 , U 3 , U 4 , and the sending user terminal U 1  transmits in all applicable time slots.  
      Then, user terminals U 2  to U 4  send the respective data packets DP 1  to DP 4  to the base station  1  of the cellular network  9 .  
       FIG. 10  shows the receiving of the data-by the base station  1  according to the second embodiment of the invention, whereby the base station  1  is shown in greater detail.  
      User terminal U 1  sends the data packet DP 1  directly over the cellular network  9  to the base station  1  and data packets DP 2  to DP 4  over the second network  6  to users U 2  to U 4 , and user terminals U 2  to U 4  thereafter send (forward) the data packets DP 2  to DP 4  to the base station  1  of the cellular network  9 , as described according to  FIG. 9 .  
      The base station,  1  comprises a receiving means  30  to receive the data packets DP 1  to DP 4  from user terminals U 1  to U 4 . The receiving means  30  sends those data packets DP 1  to DP 4  to a combining means  31  for combining the data packets DP 1  to DP 4  to the original data  22 , which data  22  is output at output  32 .  
       FIG. 11  shows a third embodiment of the invention.  
      In  FIG. 11 a  user is moving with his user terminal U 1 , for example in a car  40 , with velocity v. Another user is moving with his user termial U 2 , for example in another car  41 , with velocity v+δv. Both user terminals are connected to the cellular network  9 . If both user terminals U 1 , U 2  drive in the same direction on a motor highway, then the difference δv between their velocities is small. If the user terminal U 2  is idle and user terminal U 1  needs a higher data rate to the base station of the cellular network  9 , then user terminal U 1  can take advantage of the idle user terminal U 2 . User terminals U 1  and U 2  are close to each other and the relative speed δv between them is small so that spectral efficient transfer methods can be used between them by a local ad-hoc network. Hence, the data rate between user terminals U 1  and U 2  can be much higher than the data rate of a single connection between user terminal U 1  or U 2  and the base station of the cellular network  9 . Hence, the overall data rate is not limited by the transmission between user terminals U 1  and U 2  and twice the data rate of a single connection over the cellular network  9  can be provided.  
      Therefore, it is advantageous that, for example in step  104  ( FIG. 1 ) of the first embodiment of the invention and step  404  ( FIG. 4 ) of the second embodiment of the invention, user terminals with nearly the same velocity and direction of movement are selected. Other examples are user terminals moving together in a same bus or train. Although first and second embodiment of the invention have been described with four user terminals, it will be apparent that an arbitrary number of user terminals can be involved. Further, the data can be sent in several subblocks, for example if the amount of data is large. If the number of user terminals involved is increased, the portion of the connection between the user terminal which receives the data in the end and the base station is reduced. Therefore, even if the direct transmission to the receiving user terminal is omitted a large overall data rate can be achieved.  
      Further, instead that the local transfer utilizes an ad-hoc network, an other embodiment of the invention is to build a transceiver station, which station comprises many mobile terminals with wired or wireless links between them and one terminal is acting as a controller. Thereby, the links are used to transfer the data as a multipoint-to-point and/or point-to-multipoint fashion. The advantage of this control is that it enables to use the other terminals as virtual transceivers in multiple input multiple output (MIMO) systems, where there are multiple transmit antennas and multiple receive antennas.  
      In the preferred embodiments of the invention it is advantageous that the data packets are sent and/or are received essentially in parallel. In a transfer system, in which each of the terminals sends and receives in its own time slot, parallel means that the data packets are distributed to be sent and/or received nearly at the same time. Then, essentially parallel is to be understood in the way that the overall data rate is larger than the data rate available for a single connection between a cellular base station and a terminal.