Abstract:
This document proposes soft activation and inactivation of (network) repeaters that are, for example, activated on an as-needed basis. With soft activation, repeater gain ramps upward at a controlled rate, thereby avoiding rapid changes in interference caused by the repeater. Likewise, with soft inactivation, repeater gain ramps downward at a controlled rate. Soft activation/inactivation results in more gradual changes in the interference contribution of the repeater, thereby improving the performance of interference-compensating radio receivers operating in proximity to the repeater.

Description:
FIELD OF THE INVENTION 
       [0001]    The present invention generally relates to repeaters, such as used in wireless communication networks, and particularly relates to soft activation and inactivation of repeaters. 
       BACKGROUND 
       [0002]    Network repeaters play an increasingly important role in wireless communication networks. While traditional repeater installations extended general radio service into areas not well covered by a network&#39;s fixed base stations, designers now view repeaters as an effective mechanism for extending high bit rate services to cell edge users, and in other scenarios where high data rate users do not have line-of-sight (LOS) service to a controlling base station. 
         [0003]    As a non-limiting example, a controlling base station may provide sufficient signal strength in a given service area for low-rate data and control signaling, but may rely on one or more repeaters for extending high data rate services into that area. LTE Advanced, IEEE802.16j/m, and other next-generation wireless communication systems contemplate such scenarios. 
         [0004]    “Always on” repeater configurations leave a repeater&#39;s receive/transmit circuitry on continuously at an operational gain level, meaning that the repeater is always available for signal repeating, but also meaning that the repeater burns power without regard to whether any users actually need the repeater for service coverage. In such cases, the repeater&#39;s transmissions represent an unnecessary source of interference within the network, which can detract from overall uplink/downlink capacity. 
         [0005]    While the always-on configuration may make sense in installations where a repeater extends general radio service, it is much less sensible in cases where the repeater acts as a booster for high-rate services. In such cases, from power consumption and interference considerations, it is more desirable to operate the repeater on an as-needed basis. That is, the repeater is selectively activated only when needed to repeat high-rate service signals to and/or from high-rate users operating within a coverage area of the repeater. However, it is recognized herein that activating and inactivating repeaters in this manner results in potentially significant disruptions in the background interference perceived by other radio receivers operating within the wireless communication network. 
       SUMMARY 
       [0006]    This document proposes soft activation and inactivation of (network) repeaters that are, for example, activated on an as-needed basis. With soft activation, repeater gain ramps upward at a controlled rate, thereby avoiding rapid changes in interference caused by the repeater. Likewise, with soft inactivation, repeater gain ramps downward at a controlled rate. Soft activation/inactivation results in more gradual changes in the interference contribution of the repeater, thereby improving the performance of interference-compensating radio receivers operating in proximity to the repeater. 
         [0007]    In one embodiment, the repeater implements ramping control responsive to activation/inactivation signaling from a controlling base station, or responsive to detecting transmissions that are to be repeated. In another embodiment, the controlling base station implements ramping control, and the repeater ramps up or down responsive to ramp control signaling from the controlling base station. 
         [0008]    In either case, ramping preferably is based on a defined ramping profile, which can be preconfigured, or can be dynamically adapted. In its simplest implementation, the defined ramping profile includes a defined gain step and time step, such that repeater gain steps upward at a defined rate in response to activation, and steps downward at the same defined rate in response to inactivation. In another embodiment, the defined ramping profile includes an activation ramp and an inactivation ramp, i.e. different profiles for activation and inactivation. In yet another embodiment, the repeater repeats both downlink and uplink signals, and the defined ramping profile includes a downlink activation ramp, an uplink activation ramp, a downlink inactivation ramp, and an uplink inactivation ramp. The rate (slope) can be different for each such ramp, and the ramping parameters (e.g. gain/time steps) can be statically set or dynamically adapted. 
         [0009]    Notably, in one or more embodiments, a controlling base station is configured to time or otherwise schedule transmissions to repeater-supported users in consideration of the repeater&#39;s soft activation/inactivation behavior. For example, in an LTE Advanced or other high-rate wireless communication network, a given repeater may be activated as needed, to provide high bit rate service to one or more particular users, and the controlling base station may activate the repeater in advance of transmitting to the user(s), thereby allowing the repeater time to carry out soft activation before high-rate transmissions to the user(s) begins. More broadly, one or more embodiments of a controlling base station are configured to consider a repeater&#39;s soft activation/inactivation timing in user transmission scheduling (uplink and/or downlink). 
         [0010]    Of course, the present invention is not limited to the above features and advantages. Indeed, those skilled in the art will recognize additional features and advantages upon reading the following detailed description, and upon viewing the accompanying drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0011]      FIG. 1  is a block diagram of one embodiment of a wireless communication network, including a base station and a repeater, where the repeater is configured for soft activation/inactivation. 
           [0012]      FIG. 2  is a block diagram of one embodiment of a base station and a repeater, where the repeater is configured to implement transmit gain ramping responsive to a base station ramping controller. 
           [0013]      FIG. 3  is a block diagram of one embodiment of a base station and a repeater, where the repeater is configured to implement transmit gain ramping responsive to an included ramping controller. 
           [0014]      FIG. 4  is a plot of one embodiment of soft activation and inactivation of repeater transmit gain. 
           [0015]      FIGS. 5-8  are block diagrams of several embodiments of a memory or other computer-readable medium storing a defined ramping profile, for use in controlling transmit gain ramping of a repeater. 
           [0016]      FIGS. 9 and 10  are logic flow diagrams of different embodiments of repeater transmit gain control, for soft activation/inactivation. 
           [0017]      FIG. 11  is a block diagram of one embodiment of a repeater configured for soft activation/inactivation. 
           [0018]      FIG. 12  is a block diagram of another embodiment of a repeater configured for soft activation/inactivation. 
           [0019]      FIGS. 13 and 14  are logic flow diagrams of one embodiment of user scheduling at a base station, in consideration of the soft activation/inactivation timing of a repeater. 
           [0020]      FIG. 15  is a block diagram of a base station configured to carry out user scheduling in consideration of the soft activation/inactivation timing of an associated repeater. 
       
    
    
     DETAILED DESCRIPTION 
       [0021]      FIG. 1  depicts one embodiment of a wireless communication network  10 , which includes a number of base stations  12 , each providing radio service over one or more defined coverage areas  14 . For simplicity, the diagram depicts one base station  12  and one coverage area  14 , hereinafter referred to as a “cell” for convenience. The diagram additionally illustrates a repeater  16 , which enhances or otherwise extends the base station&#39;s service coverage. 
         [0022]    Correspondingly, one sees that the base station  12  directly serves one or more mobile terminals or other user equipment  18 , and indirectly serves one or more other mobile terminals  18  through the repeater  16 . In the illustration, the two mobile terminals  18  identified as “MT 1 ” and “MT 2 ” are served by the base station  12  directly, while the two mobile terminals  18  identified as “MT 3 ” and “MT 4 ” are served by the base station  12  through the repeater  16 . 
         [0023]    In fact, as those skilled in the art will appreciate, any one of the mobile terminals  18  may receive signals from both the base station  12  and the repeater  16 . However, as a general proposition, the repeater  16  extends or otherwise improves base station coverage on the downlink and/or the uplink for a given area within the cell  14 . Further, in at least one embodiment of the network  10 , the repeater  16  is used on a selective basis, such as to extend high-rate data services. For example, in one or more embodiments, the repeater  16  is configured to boost high-data rate transmissions to and/or from MT 3  and MT 4 , and operates on a selective basis where it is active when needed for such transmissions and otherwise inactive. “Active” means on and operating at a maximum or otherwise meaningful transmit gain, while inactive means off and operating at a transmit gain of zero, or otherwise operating in a standby condition where the transmit gain is at some minimum gain level. 
         [0024]    In any case, the repeater  16  uses soft activation and soft inactivation, rather than hard activation/inactivation. With hard activation/inactivation, a repeater turns on by abruptly switching its transmit gain from zero or a minimum value to a maximum or on value, and likewise abruptly drops its transmit gain when inactivated. In contrast, the repeater  16  is configured according to the present invention to use a controlled upward (downward) ramping of its transmit gain responsive to activation (inactivation). 
         [0025]      FIG. 2  illustrates one embodiment wherein the base station  12 , operating in a controlling base station role with respect to the repeater  16 , includes a ramping controller  20  that is configured to generate ramping control signals, which are transmitted via control signaling from the base station  12  to the repeater  16 . Correspondingly, the repeater  16  includes a transmit gain controller  22 , which effects activation and inactivation ramping of the repeater&#39;s transmit gain in response to ramping control signaling from the base station  12 . 
         [0026]    In another embodiment, shown in  FIG. 3 , the transmit gain controller  22  of the repeater  16  includes an embodiment of the ramping controller  20 . In such embodiments, the repeater  16  may be configured to autonomously carry out activation/inactivation ramping, although it may do so in response to activation/inactivation signaling from the base station  12 . For example, the base station  12  may include an activation controller  23 , which is configured to initiate activation/inactivation of the repeater  16 . However, in at least one embodiment, the repeater  16  activates and inactivates automatically, responsive to detecting the transmission of signals that are to be repeated. For example, the repeater  16  is configured to detect certain transmissions from the base station  12  and/or from particular ones of the mobile terminals  18 . 
         [0027]    Further, in one or more embodiments, the network  10  comprises an LTE Advanced network, the base station  12  comprises an “eNB” configured for LTE Advanced operation, the repeater  16  comprises an LTE Advance repeater, and the mobile terminals  18  comprise LTE Advanced mobile terminals. In another embodiment, all such entities are configured for IEEE802.16j/m operation. Of course, those skilled in the art will appreciate that these examples are non-limiting embodiments. More broadly, the repeater soft activation/inactivation teachings presented herein provide advantages in a number of different types of wireless communication networks, such as in any network where fast changes in the level of interference are disruptive to one or more link adaptation processes. 
         [0028]    With that broad applicability in mind,  FIG. 4  illustrates soft activation and soft inactivation for one embodiment of the repeater  16 . In the illustrated graph, the vertical axis represents the repeater&#39;s transmit gain in dB and the horizontal axis represents time. While time units are not shown, the illustrated behavior may, for example, play out over milliseconds, tens of milliseconds, or even hundreds of milliseconds. Further, the illustrated break in the horizontal axis simply suggests that the repeater  16  is active for some period of time—some activations may be longer or shorter than others—and it should be understood that the repeater  16  operates on an as-needed basis in one or more embodiments. As such, the repeater  16  is repeatedly activated and inactivated as needed, depending on the mix of mobile terminals  18  being supported by the base station  12 , their locations within the base station&#39;s cell  14 , and on the services being provided to those mobile terminals  18 . 
         [0029]    In particular, the graph can be understood as depicting an activation and a subsequent inactivation. For the activation, the repeater  16  transitions from the inactive state to the active state via a controlled upward ramping of its transmit gain. For the inactivation, the repeater  16  transitions from the active state to the inactive state via a controlled downward ramping of its transmit gain. One sees that the repeater  16  operates at a minimum starting gain value of G min  during a period of inactivity in advance of the time T 1  on the horizontal axis. (As a non-limiting example, G min , may be 0 dB.) The repeater  16  is activated at time T 1  and, according to the soft activation teachings presented herein, begins ramping its transmit gain upward from G min . At time T 2 , the repeater  16  reaches a maximum gain G max , and operates with that maximum gain while operating in the active state. As a general proposition, the repeater  16  will ramp its gain upward to G max , unless it is inactivated before reaching that value. 
         [0030]    The elapsed time between T 1  and T 2  depends on the controlled ramping rate, and the maximum transmit gain G max  reached upon ramping completion may be a fixed, absolute transmit gain value or a relative transmit gain value. For example, input/output antenna isolation, received signal power, current operating conditions, etc., all may determine the actual value of G max . Further, G max  is, in at least some embodiments, dynamically settable, and those skilled in the art will appreciate that the particular value of G max  will vary as needed or desired, over different types of repeaters and in different types of wireless networks. 
         [0031]    At a later time T 3 , the repeater  16  is inactivated and begins downward ramping of its transmit gain, according to the soft inactivation teachings presented herein. As a general proposition, the repeater  16  will ramp its transmit gain downward to G min , unless it is reactivated before G min  is reached. The graph shows that case, where the repeater  16  is activated again at T 4 , with the transmit gain at some intermediate value G x . Thus, it will be understood that in at least one embodiment activation/inactivation ramping starts at the current value of transmit gain and increments (or decrements) from that current value, subject to minimum and maximum gain constraints. 
         [0032]    In at least one embodiment, the base station  12  dynamically or semi-statically controls (via signaling) the minimum and maximum values used, in ramping control of the repeater&#39;s transmit gain. For example, in some embodiments the maximum value that upwardly bounds the repeater&#39;s transmit gain ramping is set by the hardware and/or stability limitations of the repeater  16 , while in other embodiments the base station  12  signals or otherwise indicates the maximum value to be used by the repeater. Similarly, the minimum gain can be zero or some minimal, off-state value, or the minimum can be some other targeted minimum that can be set or otherwise controlled by the base station  12 . In at least one embodiment, the controlling base station of a given repeater  16  can set (and change) the minimum and/or maximum values of transmit gain to be used by the repeater  16 , such that the repeater ramps up (or down) until such desired values are reached. 
         [0033]    Of further note, the graph shows smooth upward and downward ramping. Indeed, the repeater  16  and/or the base station  12  may implement ramping control based on smooth ramping.  FIG. 5  illustrates a memory or other computer-readable medium  30  implemented in the base station  12  or the repeater  16 , which, for example, stores a defined ramping profile  32 . In one embodiment, the defined ramping profile  32  comprises at least one ramping function that controls transmit gain ramping by the repeater, for activation and/or inactivation. While some embodiments may use the same ramp for activation and inactivation,  FIG. 5  illustrates an activation ramping function ƒ 1 (t) and an inactivation ramping function ƒ 2 (t), where t represents time. Two ramping functions provide for a different activation ramp, as compared to the inactivation ramp. For example, it may be preferable to ramp upward more aggressively upon activation and ramp downward more slowly upon inactivation. 
         [0034]      FIGS. 6-8  illustrate other non-limiting examples of the defined ramping profile  32 , which, for example, may be stored in the base station  12 , or the repeater  16 , or copied from the base station  12  to the repeater  16  via signaling. In any case, the defined ramping profile  32  in  FIG. 6  is based on a gain step G step  and a time step T step . Accordingly, activation (inactivation) ramping comprises stepwise incrementing (decrementing) the repeater&#39;s transmit gain upward (downward) according to the defined gain and time step values. As a non-limiting value, G step  equals one dB, and T step  equals one ms. 
         [0035]      FIG. 7  expands on this theme, by illustrating the defined ramping profile  32  as comprising different G step  and/or T step  values for activation and inactivation. That is, the value of G step , or T step , or both, can be different for activation versus inactivation. In one embodiment, the repeater  16  is configured to use an activation ramp that is steeper than the inactivation ramp. 
         [0036]      FIG. 8  illustrates further ramping nuances, where the defined ramping profile includes different values of G step  and/or T step  for downlink versus uplink activation, and for downlink versus uplink inactivation. That is, in one or more embodiments, the repeater  16  is configured to repeat downlink and uplink signals, and the defined ramping profile of  FIG. 8  provides one example of tailoring the soft activation behavior of the repeater  16  differently for downlink versus uplink activation, and differently for downlink versus uplink inactivation. Of course, smooth rather than stepped ramping functions can be used for the same purpose. 
         [0037]    More notably, although the ramping behavior is statically defined in one or more embodiments, other embodiments use dynamically adapted ramping behavior. For example, forward and/or reverse link loading conditions may be assessed by the base station  12 , the repeater  16 , or by another network entity, and the assessment(s) used to select a particular activation/inactivation ramp from the defined ramping profile  32 . Thus, in at least one embodiment, the defined ramping profile  32  includes a set of ramping functions or values representing different ramping rates or slopes, such that more or less aggressive ramping can be used to suit prevailing interference conditions. 
         [0038]    As a non-limiting example, more (or less) aggressive ramping is used for activation and/or inactivation if it is determined that the repeater-induced changes in cell interference are relatively less (or more) significant for currently prevailing interference conditions. Similar assessments may be made based on determining the number of mobile terminals  18  operating in proximity to the repeater  16 . Further, such determinations may consider the type(s) of service mobile terminals are engaged in. For example, one or more of the mobile terminals  18  shown in  FIG. 1  generally would be insensitive to the repeater ramping profile if they are engaged in a low-rate (“bursty”) service. 
         [0039]    Whether one ramp or multiple ramps are used, the repeater  16  implements a method of transmit gain control wherein the repeater  16  is selectively activated and inactivated within the network  10 . Broadly, the method comprises ramping a transmit gain of the repeater  16  upward according to a defined ramping profile  32 , in response to the repeater  16  being activated, and ramping the transmit gain of the repeater  16  downward according to the defined ramping profile  32 , in response to the repeater being inactivated.  FIG. 9  illustrates an embodiment of this method. 
         [0040]    According to the illustrated method, the repeater  16  is inactive (Block  100 ). While inactive, the repeater  16  waits or otherwise monitors for an indication that it should activate (Block  102 ). If the repeater  16  determines that it should activate (YES from Block  102 ), it ramps its transmit gain upward according to the defined ramping profile (Block  104 ). While active, the repeater  16  waits or otherwise monitors for an indication that it should inactivate (Block  106 ). If the repeater determines that it should inactivate (YES from Block  106 ), it ramps its transmit gain downward (Block  108 ). 
         [0041]    In one embodiment, the above method includes activating the repeater  16  based on detecting, at the repeater  16 , signal transmission activity by one or more other particular entities in the network  10 , and inactivating the repeater  16  by detecting, at the repeater  16 , cessation of the signal transmission activity. As an example, the base station  12  signals to the repeater  16  which downlink transmissions it should repeat, such as by providing Medium Access Control (MAC) identifiers for particular mobile terminals  18 , and the repeater  16  activates in response to detecting transmissions by the base station  12  to those particular mobile terminals  18 . Additionally, or alternatively, the repeater  16  monitors for uplink transmissions from particular mobile terminals  18 , and activates for uplink repeating in response to detecting such transmissions. 
         [0042]    In another embodiment, the repeater  16  activates and inactivates based on the repeater  16  receiving activation and inactivation control signaling, respectively, from the base station  12 , acting as a controlling base station. For example, the base station  12  may provide downlink and/or uplink scheduling information to the repeater  16 , or explicit activation/inactivation signaling to the repeater  16 , thereby activating and inactivating the repeater  16  at appropriate times. 
         [0043]    In the same or other embodiments, the repeater  16  at least temporarily stores the defined ramping profile  32  as one or more gain step and time step values—e.g. G step  and T step . In such embodiments, ramping the transmit gain of the repeater  16  upward or downward comprises the repeater  16  incrementing or decrementing the transmit gain according to the gain step and time step values. Further, in at least one such embodiment, the method includes receiving at the repeater  16  the one or more gain step and time step values via signaling from the base station  12 , acting as a controlling base station. 
         [0044]    In another embodiment, ramping the transmit gain of the repeater  16  upward or downward comprises the repeater  16  receiving a time sequence of relative upward or downward transmit gain adjustment commands from a controlling base station storing or otherwise having access to the defined ramping profile  32 . Referring briefly to  FIG. 10 , one sees an example of this implementation, wherein it is assumed that the repeater  16  is inactive (Block  110 ), during which time it monitors for an activation command (Block  112 ). If such a command is received, the repeater  16  monitors for transmit gain increment commands (Block  114 ), and increments its transmit gain responsive to receiving such a command (Block  116 ). 
         [0045]    Preferably, the base station  12  times the transmission of the increment commands to effect the desired ramping rate. Further, because the repeater  16  could be inactivated before reaching its maximum transmit gain, it monitors for receipt of an inactivation command (Block  118 ). If no such command is received, it remains in the gain incrementing loop. If the inactivate command is received, the repeater  16  begins monitoring for receipt of gain decrement commands (Block  120 ), and correspondingly decrements its transmit gain responsive thereto (Block  122 ). It also may continue monitoring for activate commands (Block  124 ). 
         [0046]    Returning to the method of  FIG. 9 , the repeater  16  may be advantageously activated, for example, for high-rate data transmissions on the downlink or uplink where the amount of data to be sent corresponds to a relatively long transmission time in comparison to the ramping operations. (Alternatively, the repeater  16  is ramped up, and then such transmissions are made.) However, as noted, it is possible that the repeater  16  will be inactivated while ramping toward G max , or activated while ramping toward G min . Thus, in at least one embodiment, in response to being activated while still ramping down the transmit gain from a prior inactivation, the repeater  16  ends the ramping down of the transmit gain and initiates upward ramping of the transmit gain from a current value of the transmit gain. Such operations are done in accordance with the defined ramping profile  32  and subject to a maximum value of the transmit gain. 
         [0047]    Similarly, in response to being inactivated while still ramping up the transmit gain from a prior activation, the repeater  16  ends the ramping up of the transmit gain and initiates downward ramping of the transmit gain from a current value of the transmit gain. These operations are carried out in accordance with the defined ramping profile and subject to a minimum value of the transmit gain. 
         [0048]    In particular, in one or more embodiments, the repeater  16  is configured for downlink repeater operation in which the repeater  16  is activated for downlink transmissions from a controlling base station  12  to one or more mobile terminals  18 . Here, ramping the transmit gain of the repeater  16  upward comprises starting from a minimum value or a last-set value of the transmit gain and incrementing the transmit gain for each succeeding transmit interval in which the repeater is active, subject to reaching a maximum value for the transmit gain. Similarly, ramping the transmit gain of the repeater  16  downward comprises starting from the maximum value or a last-set value of the transmit gain and decrementing the transmit gain for each succeeding transmit interval in which the repeater is inactive, subject to the reaching the minimum value. The number of transmission intervals, such as Transmit Time Intervals (TTIs), that the repeater  16  is active generally will depend on the amount of data to be transmitted/repeated on the downlink. 
         [0049]    Additionally, or alternatively, the repeater  16  is configured for uplink repeater operation in which the repeater  16  is activated for uplink transmissions from one or more mobile terminals  18  to a controlling base station  12 . Here, ramping the transmit gain of the repeater  16  upward comprises starting from a minimum value or a last-set value of the transmit gain and incrementing the transmit gain for each succeeding transmit interval in which the repeater  16  is active, subject to reaching a maximum value for the transmit gain. Likewise, ramping the transmit gain of the repeater  16  downward comprises starting from the maximum value or a last-set value of the transmit gain and decrementing the transmit gain for each succeeding transmit interval in which the repeater  16  is inactive, subject to reaching the minimum value. “Last-set” value in the above operations should be understood as the current or present value of the transmit gain at the time a downward or upward ramping is initiated. 
         [0050]    In terms of implementing the above methods, and their variations,  FIG. 11  depicts an example embodiment of the repeater  16 . The illustrated repeater  16  is configured for selective activation and inactivation within the network  10  and it comprises a transceiver  40  having a variable transmit gain for repeating received signals, a transmit gain controller  22  that is configured to ramp a transmit gain of the repeater  16  upward according to a defined ramping profile  32 , in response to the repeater  16  being activated, and ramp the transmit gain of the repeater  16  downward according to the defined ramping profile  32 , in response to the repeater  16  being inactivated. 
         [0051]    Further from the illustration, one sees that the transceiver  40  is coupled to transmit/receive antennas  42  and  44 , for receiving signals to be repeated and transmitting them. While antenna details are not shown, those skilled in the art will appreciate that appropriate antenna isolation and filtering are included, as needed, to receive signals on the downlink and/or uplink and retransmit them accordingly. Similarly, the transceiver  40  provides for downlink or uplink repeating, or both, depending upon the desired repeater configuration. 
         [0052]    The transmit gain controller  22  is, for example, implemented in one or more processing circuits  48  included in the repeater  16 . The processing circuits  48  comprise hardwired circuitry, software-based circuitry, or both, and, regardless, they are particularly configured to implement soft activation/inactivation as proposed herein. For example, in embodiments where the processing circuits  48  comprise microprocessor-based circuits, they include a memory or other computer-readable medium  50  that stores computer program instructions. Execution of the stored computer program instructions configures the processing circuits  48  for soft activation/inactivation methods as taught herein. The memory/medium  50 , which may comprise more than one device or storage medium, also may be used to store the defined ramping profile  32 , which can be provisioned in the repeater  16 , or copied over to the repeater  16  from the base station  12  via signaling. (The defined ramping profile  32  also may be dynamically updated.) 
         [0053]    With the above understanding, it will be appreciated that the processing circuits  48  can be programmed or otherwise configured to functionally implement the transmit gain controller  22 , which, as described earlier, may include an embodiment of the ramping controller  20  introduced in  FIGS. 2 and 3 . Further, in at least one embodiment, the repeater  16  includes an activation controller  52 . 
         [0054]    In one embodiment, the activation controller  52  is configured to activate the repeater  16 , where the repeater  16  is active for signal repeating, based on detecting signal transmission activity by one or more other particular entities in the network  10 . For example, the activation controller  52  is configured to detect transmissions by the controlling base station  12  and/or one or more particularly identified mobile terminals  18 . In such embodiments, the activation controller  52  is further configured to inactivate the repeater  16 , where the repeater  16  is not active for signal repeating, based on detecting cessation of the signal transmission activity. 
         [0055]    In another embodiment, the activation controller  52  is configured to activate or inactivate the repeater  16 , based on receiving activation or inactivation control signaling, respectively, from a controlling base station  12 . 
         [0056]    In the same or other embodiments, the repeater  16  at least temporarily stores the defined ramping profile  32  as one or more gain step and time step values. Correspondingly, the transmit gain controller  22  ramps the transmit gain of the repeater  16  upward or downward by incrementing or decrementing the transmit gain according to the gain step and time step values. As such, the transmit gain controller  22  can, in such embodiments, be understood as implementing a ramping controller  20 , as shown in  FIG. 3 . In at least one such embodiment, the repeater  16  is configured to receive the one or more gain step and time step values via signaling from a controlling base station  12 . 
         [0057]    In an alternative embodiment, the transmit gain controller  22  ramps the gain of the repeater  16  upward or downward responsive to the repeater  16  receiving a time sequence of upward or downward transmit gain adjustment commands from a controlling base station  12 . In such embodiments, the controlling base station  12  stores or otherwise has access to the defined ramping profile  32 . In yet another alternative, the repeater  16  stores a number of alternative ramping profiles, and activation by the base station  12  includes, for example, an indication of which of the stored ramping profiles to use. 
         [0058]    As an example, an aggressive ramping profile may be used if the base station  12  knows that there are not any other active mobile terminals in the vicinity of the repeater  16 , and a less aggressive ramping profile can be used in case nearby mobile terminals might be disturbed by a sudden change of the repeater  16 . In any case, storing different ramping profiles in the repeater  16 , which can be pre-configured in the repeater  16 , or transferred over from the base station  12 , reduces the amount of signaling needed between the base station  12  and the repeater  16 , as the base station  12  need only identify which profile to use, rather than signaling all of the parameters needed to define the profile. 
         [0059]    Further, in at least one embodiment, the repeater  16  is configured as a frequency-selective repeater, such as where it repeats signals only within a defined portion of an overall bandwidth. For example, in an LTE Advanced or other OFDM (or SC-FDMA) embodiment, the repeater  16  may be configured to repeat only selected OFDM sub-carriers, or selected subsets of such carriers. A non-limiting example of a frequency-selective embodiment of the repeater is shown in  FIG. 12 . 
         [0060]    In the illustration, the repeater  16  includes one or more filter circuits  60  configured to provide frequency-selective repeater transmission, such that the repeater  16  provides repeat transmission for certain frequencies or frequency bands according to the transmit gain. In more detail, the illustrated embodiment includes receiver (front-end) circuits  62 , which provide antenna-received signals for repeating to the filter circuits  60 . In one example, the filter circuits  60  operate at least partially in the analog domain and cooperate with the receiver circuits  62  to provide frequency-selective signal reception, such that only desired frequencies or frequency bands are passed along to transmitter circuits  64 , for repeater transmission. 
         [0061]    In one or more other embodiments, the filter circuits operate in the digital domain. However, in either case, they may operate responsive to configuration and/or control signals from one or more frequency control circuits  66 , which may be functionally implemented in or as part of the processing circuits  48  introduced in  FIG. 11 . 
         [0062]    Broadly, then, the repeater  16  is implemented as a frequency-selective repeater in one or more embodiments, such that it provides frequency selective (transmit) gain control in accordance with the soft activation/inactivation teachings presented herein. This implies e.g. that the repeater  16  only amplifies the signal on certain resources in the frequency domain. For LTE and other Orthogonal Frequency Division Multiple Access (OFDMA) systems, the filter circuits  60  can have different granularity levels measured, for example, in terms of resource blocks—where a resource block is a given time/frequency allocation. Also, as regards frequency-selective operation, the repeater  16  is configured in one or more embodiments to perform ramping independently for different frequency bands. 
         [0063]    For an LTE implementation of the network  10 , base station (eNB)  12 , and repeater  16 , the eNB sends the uplink (UL) resource allocation to a mobile terminal  18  some time in advance. To exemplify, a mobile terminal  18  (user) that is supposed to transmit on the UL data channel (referred to as the PUSCH) at subframe n receives a grant for this allocation on the Physical Downlink Control Channel (PDCCH) at subframe n−4. This implies that the repeater  16  can, by picking up the regular control signaling transmitted between eNB and user, obtain resource allocation information (time and frequency) for the user. Thus, even with a 1-2 ms interception delay in the repeater  16 , the repeater  16  can amplify the correct signal(s) and avoid amplifying and forwarding less useful information. 
         [0064]    Regarding repeater transmissions on the LTE downlink (DL), however, there are more significant challenges in the repeater determining resource allocation information for a given mobile terminal  18 . This is because of the standardized allocation of PDCCH/PDSCH (Physical Dedicated Control Channel/Physical Dedicated Shared Channel) in the OFDM grid. More specifically, scheduling assignment information is transmitted during the same sub-frame as the PDSCH allocation, which makes it challenging for the repeater  16  to receive a sub-frame and decode control channel messages on the PDCCH fast enough to enable it to provide repeater amplification of the data channel on specific resource assignments, at least within the time constraints associated with the signal&#39;s cyclic prefix timing. 
         [0065]    Even so, the eNB can instruct the repeater  16  to be turned on only for a specific region of the frequency band, and then prioritize scheduling of a mobile terminal  18  that needs the repeater&#39;s services on that particular region some number of sub-frames later. The repeater  16  could also track the PDCCH assignments and if it notes that a specific mobile terminal  18  is no longer scheduled on the particular resource region, it stops amplifying or starts to ramp down the repeater gain of that resource region. 
         [0066]    Alternatively, in a more advanced approach, one or more eNBs or other network elements exploit a known cell resource sharing scheme for the repeaters  16 . One such example of cell resource sharing scheme is termed “inter-cell-interference-coordination” (ICIC). In such cases, a given eNB—acting as a controlling base station  12  for a repeater  16 —can control cell edge resource allocations to follow the known resource reuse scheme. Thus, resource allocations can be varied for given mobile terminals  18 , in dependence on their locations within a cell, and, correspondingly, depending on whether they rely on one or more repeaters  16  for UL and/or DL transmissions. 
         [0067]    In the same or other embodiments, the base station  12 , whether functioning as an eNB in an LTE or other type of network that uses user scheduling, is configured to implement a method of transmission scheduling comprising scheduling one or both of uplink and downlink transmissions on an ongoing basis, for a plurality of mobile terminals  18  being supported by the base station, and associating one or more of the mobile terminals with a remote repeater  16  that uses soft activation and soft inactivation. As described herein, such a repeater employs a controlled upward ramping of its transmit gain when activated and employs a controlled downward ramping of its transmit gain when inactivated. 
         [0068]    In consideration of such repeater behavior, a base station method further includes activating the repeater  16 , as needed, in advance of any scheduled transmission involving one of the associated mobile terminals  18 , to accommodate the soft activation of the repeater  18 . That is, in at least one embodiment, the base station  12  considers the time needed for the repeater  16  to ramp up to a useful level of transmit gain, and it factors that timing into its user scheduling and repeater control decisions. For example, the base station  12  might defer scheduling of a user associated with a repeater  16  until such time as the repeater&#39;s gain has been ramped up, or it might otherwise schedule another user not reliant on the repeater  16 , based on its knowledge (or assumptions) of where the repeater  16  was at time-wise in terms of its controlled transmit gain ramping. 
         [0069]      FIG. 13  illustrates base station processing logic along the above lines, wherein the base station  12  associates one or more mobile terminals  18  with a given repeater  16  (Block  130 ) and then conducts ongoing scheduling operations in consideration of those associations (Block  132 ). Note that the association may be transparent to the mobile terminals  18 , and even to the repeater  16  in at least some embodiments. 
         [0070]    For example, “associate” in one embodiment simply means that the base station  12  records or otherwise identifies which mobile terminals  18  are operating within an area covered by the repeater  16  and remembers that association for purposes of scheduling and/or repeater activation timing control. In one or more other embodiments, “associate” further means that the base station  12  indicates to the repeater  16  which mobile terminals  18  it is supporting. These indications are particularly useful where, for example, the repeater  16  autonomously activates and inactivates, as needed. 
         [0071]    In any case,  FIG. 14  illustrates further details for Block  132  in  FIG. 13 , wherein conducting ongoing scheduling operations comprises determining that transmission to or from an associated user is scheduled or pending (Block  132 - 1 ). On that determination, the base station  12  activates the repeater  16  in advance of the pending transmission (Block  132 - 2 ). 
         [0072]      FIG. 15  illustrates one embodiment of a base station  12  that is configured to carry out the above method. The illustrated base station includes transceiver circuits  70  for transmitting DL signals and receiving UL signals, and includes associated control/processing circuits  72 . These circuits may comprise hardwired circuitry, software-based circuitry, or both. For example, the base station  12  may include one or more than one microprocessor-based circuit, along with supporting memory or other computer-readable medium for storing program instructions that, when executed, particularly configure the microprocessor-based circuit(s) to carry out the above method, or variations of it. 
         [0073]    As shown, the processing/control circuits  72  include a scheduler  74 , which is configured to perform user scheduling on the UL and/or the DL. In at least one embodiment, such scheduling comprises determining resource allocations—e.g. time and/or frequency allocations—at least for high-rate users. The control/processing circuits  72  also may include a gain controller  76 , which is configured to control at least some aspects of soft activation/inactivation by the repeater  16 . In any case, the scheduler  74  is configured to schedule one or both of uplink and downlink transmissions on an ongoing basis, for a plurality of mobile terminals  18  being supported by the base station  12 , and associate one or more of the mobile terminals  18  with a remote repeater  16  that uses soft activation and soft inactivation. Further, the scheduler  74  is configured to activate the repeater  16 , as needed, in advance of any scheduled transmission involving one of the associated mobile terminals  18 , to accommodate the soft activation/inactivation of the repeater  16 . 
         [0074]    As for that soft activation/inactivation, it can be broadly understood as implementing a ramping function of the (transmit) gain in the repeater  16 . The ramping function or control therefore can be implemented in the base station  12  of an associated network cell  14 , or in the repeater  16 . The gain control itself can be implemented in the analog domain, or, at least control-wise, can be implemented in the digital domain of the repeater  16 . For example, the power, biasing, and/or configuration of one or more amplifiers within the receive/transmit signal chain of the repeater can be controlled to effect the desired transmit gain ramping. 
         [0075]    As noted, the ramping function can be applied to DL gain and/or to UL gain. For the DL, the repeater  16  generally will have an established association to a controlling cell  14  and turns on or is turned on when the controlling cell  14  is transmitting on the DL. As noted, the repeater  16  turns on with a certain (low) gain and, then, for each sub-frame it is active, corresponding to when the controlling cell  14  is transmitting, the repeater  16  increases the transmit gain iteratively. The step size or ramping function used for such increasing is, in one or more embodiments, configurable. Similarly, during inactive transmission sub-frames, the repeater  16  lowers its gain according to the same or a different step size. 
         [0076]    Thus, in one or more embodiments, the gain is allowed to increase until reaching an appropriate target value, such as the maximum gain value of the repeater  16 . Another consequence is that the repeater  16  does not turn off directly after a finalized data transfer, but requires some time depending on the gain and time step sizes (or function) used to ramp the repeater&#39;s transmit gain down. Such a scheme has direct applicability to the DL, and the establishment of a repeater-to-cell connection or association can be done using signaling. 
         [0077]    Using soft activation/inactivation on DL repeater operations provides for smoother (interference) measuring operations at the mobile terminals  18 . Consequently, Channel Quality Information (CQI) reporting by the mobile terminals  18  is more stable, meaning that radio link adaptations made in consideration of those CQI reports is more stable. Further, mobility measurements are more stable, thus helping to avoid “ping-pong” handovers, etc. 
         [0078]    In the same or another embodiment, the repeater  16  is configured to apply a ramping scheme to control the uplink gain. Here, such operations may be based on the repeater  16  having an established association to a set of “active” users, such that it turns on (or is otherwise activated) only when one of these users transmits. When turned on, the repeater starts with a certain (low) gain. Then, for each sub-frame it is active, corresponding to when the “active” users are transmitting (i.e. the controlling cell  14  is receiving), the repeater  16  increases the gain with a certain (optionally configurable) step size. Further, during inactive sub-frames, the repeater  16  lowers its gain according to the same or a different step size. The gain is allowed to increase until reaching the maximum gain value of the repeater  16 , and, as on the DL repeating operation, the repeater  16  does not turn off directly after a finalized data transfer. Instead, the repeater  16  performs a controlled ramp down until the gain is back to zero or some minimum level, and the repeater is regarded as off or in standby. Such operations can be done for the LTE uplink, and the establishment of the repeater to mobile terminal relations can be done using signaling between the controlling cell  14  and the repeater  16 . 
         [0079]    Providing soft activation/inactivation on the UL provides a smoother received power level at the base station  12  and may also mitigate the risk that the received power on contiguous regions of the base station&#39;s receive bandwidth differ too much. Further, the UL power control functionality of LTE will not be disturbed by the soft activation/inactivation, as it otherwise might be with rapid activation/inactivation of repeaters. Note that the interested reader may refer to TR 36.201, “Evolved Universal Terrestrial Radio Access (E-UTRA); Long Term Evolution (LTE) physical layer” for a general description of the LTE Advanced physical layer, and to TR 36.213, “Evolved Universal Terrestrial Radio Access (E-UTRA); Physical layer procedures” for more details. 
         [0080]    Of course, the present invention is not limited to by foregoing description, or by the accompanying drawings. Indeed, the present invention is limited only by the following appended claims and their legal equivalents.