Patent Publication Number: US-10321436-B2

Title: Wireless communication system using multiple-serving nodes

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a divisional of U.S. patent application Ser. No. 12/759,383 filed Apr. 13, 2010 by Yi Yu, et al. entitled “Wireless Communication System Using Multiple-Serving Nodes” which is incorporated by reference herein as if reproduced in its entirety. 
    
    
     FIELD 
     The invention generally relates to wireless communication and in particular to a wireless communication system using multiple-serving nodes. 
     BACKGROUND 
     Wireless communication systems are widely deployed to provide, for example, a broad range of voice and data-related services. Typical wireless communication systems consist of multiple-access communication networks that allow users to share common network resources. Examples of these networks are time division multiple access (“TDMA”) systems, code division multiple access (“CDMA”) systems, single-carrier frequency division multiple access (“SC-FDMA”) systems, orthogonal frequency division multiple access (“OFDMA”) systems, or other like systems. An OFDMA system is adopted by various technology standards such as evolved universal terrestrial radio access (“E-UTRA”), Wi-Fi, worldwide interoperability for microwave access (“WiMAX”), ultra mobile broadband (“UMB”), and other similar systems. Further, the implementations of these systems are described by specifications developed by various standards bodies such as the third generation partnership project (“3GPP”) and 3GPP2. 
     As wireless communication systems evolve, more advanced network equipment is introduced that provide improved features, functionality, and performance. A representation of such advanced network equipment may also be referred to as long-term evolution (“LTE”) equipment or long-term evolution advanced (“LTE-A”) equipment. LTE is the next step in the evolution of high-speed packet access (“HSPA”) with higher average and peak data throughput rates, lower latency and a better user experience especially in high-demand urban areas. LTE accomplishes this higher performance with the use of broader spectrum bandwidth, OFDMA and SC-FDMA air interfaces, and advanced antenna methods. Uplink (“UL”) refers to communication from a wireless device to a node. Downlink (“DL”) refers to communication from a node to a wireless device. 
     For a wireless communication system using a relay node (“RN”), a wireless device may have difficulties selecting between a base station and the RN due to, for instance, UL and DL power imbalance. An RN such as an LTE Type-I RN can operate as a smaller base station. In an LTE system, a wireless device may choose a base station or RN based on the average DL signal strength, which may result in lower signal strength on the UL due to the UL/DL power imbalance. Alternatively, the wireless device may choose the base station or RN based on both DL and UL signal strengths. 
     As described in the LTE-A standard, a Type-I RN can have full radio resource control (“RRC”) functionality. Such RN can control its cell and can have its own physical cell identifier. Further, such RN can transmit its own synchronization channel and reference signal. Also, the wireless device can receive, for instance, scheduling information and hybrid automatic repeat request (“HARQ”) feedback from the RN and send control information such as a scheduling request (“SR”) signal, channel quality indicator (“CQI”) signal and HARQ feedback signal to the RN. 
     In a heterogeneous LTE-A network using a plurality of base stations and Type-I RNs, such network may have a significant difference between base station transmission power and RN transmission power. A wireless device may provide a UL transmission that is received by a base station and a RN. The received power from such transmission may be substantially dependent on the propagation path between the wireless device and the base station, RN or both. In some circumstances, the wireless device may receive a stronger DL transmission from the base station, while the RN receives a stronger UL transmission from the wireless device, leading to a UL and DL power imbalance. This disclosure describes various embodiments including for resolving such power imbalance in a multiple-serving node wireless communication system. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       To facilitate this disclosure being understood and put into practice by persons having ordinary skill in the art, reference is now made to exemplary embodiments as illustrated by reference to the accompanying figures. Like reference numbers refer to identical or functionally similar elements throughout the accompanying figures. The figures along with the detailed description are incorporated and form part of the specification and serve to further illustrate exemplary embodiments and explain various principles and advantages, in accordance with this disclosure, where: 
         FIG. 1  is a block diagram of one embodiment of a wireless communication system using multiple-serving nodes in accordance with various aspects set forth herein. 
         FIG. 2  illustrates one embodiment of a channel structure in a wireless communication system using multiple-serving nodes in accordance with various aspects set forth herein. 
         FIG. 3  illustrates another embodiment of a channel structure in a wireless communication system using multiple-serving nodes in accordance with various aspects set forth herein. 
         FIG. 4  illustrates one embodiment of an independent control channel structure in a wireless communication system using multiple-serving nodes in accordance with various aspects set forth therein. 
         FIG. 5  illustrates another embodiment of the independent control channel structure in a wireless communication system using multiple-serving nodes in accordance with various aspects set forth therein. 
         FIG. 6  illustrates another embodiment of an independent control channel structure in a wireless communication system using multiple-serving nodes in accordance with various aspects set forth therein. 
         FIG. 7  illustrates another embodiment of an independent control channel structure in a wireless communication system using multiple-serving nodes in accordance with various aspects set forth herein. 
         FIG. 8  illustrates one embodiment of a distributed control channel structure in a wireless communication system using multiple-serving nodes in accordance with various aspects set forth herein. 
         FIG. 9  illustrates another embodiment of a distributed control channel structure in a wireless communication system using multiple-serving nodes in accordance with various aspects set forth herein. 
         FIG. 10  illustrates another embodiment of a distributed control channel structure in a wireless communication system using multiple-serving nodes in accordance with various aspects set forth herein. 
         FIG. 11  is a flow chart of one embodiment of a method of providing data signals in a wireless communication system using multiple-serving nodes in accordance with various aspects set forth herein. 
         FIG. 12A  is a flow chart of one embodiment of a method of providing control signals between a first node and a wireless device in a wireless communication system using multiple-serving nodes in accordance with various aspects set forth herein. 
         FIG. 12B  is a flow chart of another embodiment of a method of providing control signals between a first node and a wireless device in a wireless communication system using multiple-serving nodes in accordance with various aspects set forth herein. 
         FIG. 13A  is a flow chart of one embodiment of a method of providing control signals between a second node and a wireless device in a wireless communication system using multiple-serving nodes in accordance with various aspects set forth herein. 
         FIG. 13B  is a flow chart of another embodiment of a method of providing control signals between a second node and a wireless device in a wireless communication system using multiple-serving nodes in accordance with various aspects set forth herein. 
     
    
    
     Skilled artisans will appreciate that elements in the accompanying figures are illustrated for clarity, simplicity and to further help improve understanding of the embodiments, and have not necessarily been drawn to scale. 
     DETAILED DESCRIPTION 
     Although the following discloses exemplary methods, devices and systems for use in wireless communication systems, it may be understood by one of ordinary skill in the art that the teachings of this disclosure are in no way limited to the examplaries shown. On the contrary, it is contemplated that the teachings of this disclosure may be implemented in alternative configurations and environments. For example, although the exemplary methods, devices and systems described herein are described in conjunction with a configuration for aforementioned wireless communication systems, the skilled artisan will readily recognize that the exemplary methods, devices and systems may be used in other systems and may be configured to correspond to such other systems as needed. Accordingly, while the following describes exemplary methods, devices and systems of use thereof, persons of ordinary skill in the art will appreciate that the disclosed examplaries are not the only way to implement such methods, devices and systems, and the drawings and descriptions should be regarded as illustrative in nature and not restrictive. 
     Various techniques described herein can be used for various wireless communication systems. The various aspects described herein are presented as methods, devices and systems that can include a number of components, elements, members, modules, nodes, peripherals, or the like. Further, these methods, devices and systems can include or not include additional components, elements, members, modules, nodes, peripherals, or the like. In addition, various aspects described herein can be implemented in hardware, firmware, software or any combination thereof. It is important to note that the terms “network” and “system” can be used interchangeably. Relational terms described herein such as “above” and “below”, “left” and “right”, “first” and “second”, and the like may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. The term “or” is intended to mean an inclusive “or” rather than an exclusive “or.” Further, the terms “a” and “an” are intended to mean one or more unless specified otherwise or clear from the context to be directed to a singular form. It is important to note that the terms “network” and “system” can be used interchangeably. 
     Wireless communication networks typically consist of a plurality of wireless devices and a plurality of nodes. A node may also be called a base station, node-B (“NodeB”), base transceiver station (“BTS”), access point (“AP”), cell, relay node (“RN”), serving node or some other equivalent terminology. Further, the term “cell” can include a specific base station, a specific sector of a base station, a specific antenna of a sector of a base station. A base station typically contains one or more radio frequency (“RF”) transmitters and receivers to communicate with wireless devices. Further, a base station is typically fixed and stationary. For LTE and LTE-A equipment, the base station is also referred to as an E-UTRAN NodeB (“eNB”). 
     A wireless device used in a wireless communication network may also be referred to as a mobile station (“MS”), a terminal, a cellular phone, a cellular handset, a personal digital assistant (“PDA”), a smartphone, a handheld computer, a desktop computer, a laptop computer, a tablet computer, a set-top box, a television, a wireless appliance, or some other equivalent terminology. A wireless device may contain one or more RF transmitters and receivers, and one or more antennas to communicate with a base station. Further, a wireless device may be fixed or mobile and may have the ability to move through a wireless communication network. For LTE and LTE-A equipment and for various industry standards, the wireless device is also referred to as user equipment (“UE”). 
       FIG. 1  is a block diagram of one embodiment of wireless communication system  100  using multiple-serving nodes in accordance with various aspects set forth herein. In  FIG. 1 , system  100  can include a wireless device  101 , a first node  121  and a second node  141 . In  FIG. 1 , wireless device  101  can include processor  102  coupled to memory  103 , input/output devices  104 , transceiver  105  or any combination thereof, which can be utilized by wireless device  101  to implement various aspects described herein. Transceiver  105  of wireless device  101  can include one or more transmitters  106  and one or more receivers  107 . Further, associated with wireless device  101 , one or more transmitters  106  and one or more receivers  107  can be connected to one or more antennas  109 . 
     In  FIG. 1 , first node  121  can include processor  122  coupled to memory  123  and transceiver  125 . Transceiver  125  of first node  121  can include one or more transmitters  126  and one or more receivers  127 . Further, associated with first node  121 , one or more transmitters  126  and one or more receivers  127  can be connected to one or more antennas  129 . 
     Similarly, second node  141  can include processor  122  coupled to memory  123  and transceiver  125 . Transceiver  125  of second node  141  includes one or more transmitters  126  and one or more receivers  127 . Further, associated with second node  141 , one or more transmitters  126  and one or more receivers  127  are connected to one or more antennas  129 . 
     In this embodiment, wireless device  101  can communicate with first node  121  using one or more antennas  109  and  129 , respectively, over first communication link  170 , and can communicate with second node  141  using one or more antennas  109  and  129 , respectively, over second communication link  180 . Further, first node  121  can communicate with second node  141  using backhaul interfaces  128  over third communication link  190 . First communication link  170  supports the communication of signals between wireless device  101  and first node  121 . Second communication link  180  supports the communication of signals between wireless device  101  and second node  141 . Third communication link  190  supports the communication of signals between first node  121  and second node  141 . First communication link  170 , second communication link  180  and third communication link  190  can support, for instance, sending a DL data signal, UL data signal, DL control signal, UL control signal, other signal or combination of signals. Further, first communication link  170 , second communication link  180  and third communication link  190  can include a physical channel, a logical channel, other channel or any combination thereof. First communication link  170  and second communication link  180  can use, for instance, any wireless communication protocol supporting technologies associated with, for instance, TDMA, CDMA, UMTS, Wi-MAX, LTE, LTE-A, Wi-Fi, Bluetooth or other similar technology. Third communication link  190  can use any wired communication protocol, wireless communication protocol or both. 
     In this embodiment, first node  121 , second node  141  or both can communicate a DL data signal, UL data signal, DL control signal, UL control signal, other signal or any combination thereof with wireless device  101 . Therefore, such embodiment can allow wireless device  101  to use, for instance, the same or different nodes  121  and  141  to communicate a DL data signal, UL data signal, DL control signal, UL control signal, other signal or any combination thereof. Determination of which node  121  and  141  to use for any such signals can be determined using, for instance, a received signal strength, data throughput rate, bit error rate (“BER”), word error rate (“WER”), other similar metric or combination of metrics. 
     For example, first node  121  can send a DL control signal to wireless device  101  using first communication link  170 . Once received, processor  102  of wireless device  101  can process the received DL control signal, can generate a response, and can provide such response to first node  121  using, for instance, a UL control signal of first communication link  170 . 
     In another example, wireless device  101  can send a UL control signal to second node  141  using second communication link  180 . Once received, processor  142  of second node  141  can forward such signal to first node  121  using third communication link  190 . 
       FIG. 2  illustrates one embodiment of channel structure  200  of system  100  in accordance with various aspects set forth herein. In this embodiment, structure  200  can allow first node  121  to provide a DL signal  210  to wireless device  101  using first communication link  170 , and can allow wireless device  101  to provide a UL signal  230  to second node  141  using second communication link  180 . A DL signal can include a DL data signal, DL control signal, other signal or any combination thereof. An UL signal can include a UL data signal, UL control signal, other signal or any combination thereof. For example, first node  121  can send a DL data signal to wireless device  101  using first communication link  170 . Further, structure  200  can allow wireless device  101  to send a UL data signal to second node  141  using second communication link  180 . Such configuration can be advantageous when wireless device  101  is in closer proximity to second node  141  than first node  121  but still receiving a strong DL signal from node  121 , allowing wireless device  101  to, for instance, operate at a lower transmit power, higher data throughput rate, other benefit or any combination thereof. 
     In another embodiment, structure  200  can allow first node  121  and second node  141  to be one and the same node. In this configuration, nodes  121  and  141  can act as, for instance, a single serving node as described in 3 rd Generation Partnership Project; Technical Specification Group Radio Access Network; Physical Channels and Modulation  ( Release  8), 3GPP, or 3GPP TS 36 series of specifications. It is important to recognize that each node  121  and  141  may send a DL signal to wireless device  101 , may receive a UL signal from wireless device  101  or both and may do the same for another wireless device. Further, this disclosure can provide the advantage of allowing full frequency re-use, frequency provisioning or both for each node  121  and  141 . 
       FIG. 3  illustrates another embodiment of channel structure  300  of system  100  in accordance with various aspects set forth herein. In  FIG. 3 , structure  300  can allow first node  121  to send a DL data signal to wireless device  101  using, for instance, a physical DL shared channel (“PDSCH”)  310  of first communication link  170 . Similarly, system  300  can allow wireless device  101  to send a UL data signal to second node  141  using, for instance, physical UL shared channel (“PUSCH”)  320  of second communication link  180 . Such configuration can be advantageous by allowing the assignment of PDSCH  310 , PUSCH  320  or both based on, for instance, the quality of the associated communication link. However, assigning the sending of a UL data signal and the sending of a DL data signal to different nodes can impact, for instance, the control channel structure of system  300 . For example, the control channel structure used in LTE Release 8 is designed for a wireless communication system using single-serving nodes and would need to be modified, as described by this disclosure, to support multiple-serving node wireless communication system  100 . For instance, first node  121  may provide a UL grant signal, DL grant signal or both to wireless device  101  using a DL control channel of first communication link  170 . Under system  100 , such grants may be provided from different nodes  121  and  141 , as opposed to the same node. Further, any timing requirements such as the UL timing alignment procedure described in LTE Release 8 may not be supported in system  100  since the transmission of DL signals, UL signals or both may be associated with different nodes. Other issues may exist, for instance, with the configuration and use of UL control channels and DL control channels, including defining the proper control channel to send an acknowledgment or no acknowledgment (“ACK/NACK”) signal, sounding reference signal (“SRS”) signal, other signal or combination of signals. 
     This disclosure includes describing two alternative control channel structures to resolve the aforementioned issues. Such alternatives are associated with an independent control channel structure and a distributed control channel structure.  FIG. 4  illustrates one embodiment of independent control channel structure  400  of system  100  in accordance with various aspects set forth therein. In  FIG. 4 , first communication link  170  can include PDSCH  310 , physical DL control channel (“PDCCH”)  430 , physical UL control channel (“PUCCH”)  450 , physical hybrid automatic repeat request indicator channel (“PHICH”)  470 , other channel or any combination thereof. Second communication link  180  can include PUSCH  320 , PDCCH  440 , PUCCH  460 , physical hybrid automatic repeat request (“HARQ”) indicator channel (“PHICH”)  480  or any combination thereof. For communication of data signals, structure  400  can allow first node  121  to provide a DL data signal to wireless device  101  using, for instance, PDSCH  310  of first communication link  170 . Further, wireless device  101  can provide a UL data signal to second node  141  using, for instance, PUSCH  320  of second communication link  180 . For communication of control signals, structure  400  can allow first node  121  and second node  141  each to have the same or different control channel structure. For example, first node  121  can provide a DL control signal to wireless device  101  using, for instance, PDCCH  430  of first communication link  170 . Wireless device  101  can provide a UL control signal to first node  121  using, for instance, PUCCH  450  of first communication link  170 . Further, second node  141  can provide a DL control signal to wireless device  101  using, for instance, PDCCH  440 , PHICH  480  or both of second communication link  180 . Further, wireless device  101  can provide a UL control signal to second node  141  using, for instance, PUCCH  460  of second communication link  180 . 
       FIG. 5  illustrates another embodiment of independent control channel structure  500  of system  100  in accordance with various aspects set forth therein. In  FIG. 5 , structure  500  can allow first node  121  to provide wireless device  101  a DL control signal using, for instance, PDCCH  430  of first communication link  170 . Similarly, structure  500  can allow second node  141  to provide wireless device  101  a DL control signal using, for instance, PDCCH  440  of second communication link  180 . It is important to recognize that the DL control signal provided by first node  121  and the DL control signal provided by second node  141  are independent of each other. First node  121  can manage, control, coordinate, schedule or any combination thereof the transmission of a DL data signal to wireless device  101  using, for instance, PDSCH  310  of first communication link  170 . Further, second node  141  can manage, control, coordinate, schedule or any combination thereof the transmission of a UL data signal from wireless device  101  using, for instance, PUSCH  320  of second communication link  180 . For example, first node  121  can provide a DL grant signal to wireless device  101  using, for instance, PDCCH  430  of first communication link  170 . Further, second node  141  can provide a UL grant signal to wireless device  101  using, for instance, PDCCH  440  of second communication link  180 . A DL grant signal can provide permission for first node  121  to send a DL data signal to wireless device  101  using, for instance, PDSCH  310  of first communication link  170 . A UL grant signal can provide permission for wireless device  101  to send a UL data signal to second node  141  using, for instance, PUSCH  320  of second communication link  180 . 
       FIG. 6  illustrates another embodiment of independent control channel structure  600  of system  100  in accordance with various aspects set forth therein. In  FIG. 6 , structure  600  can allow first communication link  170  to include PDSCH  310 , PDCCH  430 , PUCCH  450 , other channel or any combination thereof. For instance, wireless device  101  can provide a UL control signal to first node  121  using, for instance, PUCCH  450  of first communication link  170 . Such UL control signal can include, for instance, a channel quality indicator (“CQI”) signal, pre-coding matrix indicator (“PMI”) signal, rank indication (“RI”) signal, ACK/NACK signal, other signal or combination of signals. The CQI, PMI, RI and ACK/NACK signals can be used to support, for instance, the transmission from first node  121  of a DL data signal to wireless device  101  using, for instance, PDSCH  310  of first communication link  170 . Further, power control signals can be used to support, adjust, adapt, coordinate or any combination thereof the transmission of UL signals from wireless device  101  to first node  121 . First node  101  can provide a DL control signal to wireless device  101  using, for instance, PDCCH  430  of first communication link  170 , wherein the DL control signal can include a power control signal such as a transmission power control command (“TPC”) signal. 
       FIG. 7  illustrates another embodiment of independent control channel structure  700  of system  100  in accordance with various aspects set forth herein. In  FIG. 7 , structure  700  can allow second communication link  180  to include PUSCH  420 , PDCCH  440 , PUCCH  460  and PHICH  480 , other channel or any combination thereof. In  FIG. 7 , structure  700  can allow wireless device  101  to provide a UL control signal to second node  141  using, for instance, PUCCH  460  of second communication link  180 . Further, second node  141  can manage, support, coordinate or any combination thereof receiving a UL data signal from wireless device  101  using, for instance, PUSCH  320  of second communication link  180  by providing a DL control signal to wireless device  101  using, for instance, PDCCH  440 , PHICH  480  or both of second communication link  180 . For example, PHICH  480  of second communication link  180  can be used to deliver, for instance, an ACK/NACK signal from second node  141  to wireless device  101 , and PDCCH  440  can be used to deliver, for instance, a UL grant signal, ACK/NACK signal, TPC signal, timing adjustment command signal, other signal or any combination thereof from second node  141  to wireless  101 . Further, PUCCH  460  can be used to deliver, for instance, scheduling request (“SR”) signal, SRS signal, other signal or any combination thereof from wireless device  101  to second node  141 . For example, an SR signal can include the scheduling request indicator (“SRI”) signal associated with sending, for instance, a UL data signal from wireless device  101  to second node  141 . Further, wireless device  101  can send an SRS signal to second node  141  to allow for timing adjustment, UL transmission adaptation, other benefit or any combination thereof between wireless device  101  and second node  141 . It is important to recognize that the transmission of a dedicated SRS signal from wireless device  101  to first node  121  may not be required, since any timing alignment is intended for UL transmissions from wireless device  101  to second node  141 . However, the timing alignment required for first node  121  may cause interference with other wireless devices transmitting to first node  121 . Knowledge of the UL transmission timing may be useful to mitigate such interference. Therefore, such transmission timing can be estimated using, for instance, the timing of PUCCH  460  transmissions from wireless device  101  to second node  141 . 
     In another embodiment, wireless device  101  may multiplex control signals with data signals using, for instance, PUSCH  320  of second communication link  180 , PDSCH  310  of first communication link  170  or both. For example, after receiving a UL data signal and a UL control signal using PUSCH  320 , second node  141  may forward the UL control signal to first node  121  using, for instance, backhaul link  330  of third communication link  190 . If the UL control signal is an ACK/NACK signal, backhaul link  330  may increase the HARQ re-transmission delay. In order to avoid wasting DL bandwidth, the number of HARQ re-transmission procedure-related processes can be increased to accommodate longer HARQ re-transmission round trip time (“RTT”). For example, the control signals used for independent control channel structure  600  of first communication link  170  are provided in Table 1. 
     
       
         
           
               
               
               
             
               
                   
                 TABLE 1 
               
               
                   
                   
               
               
                   
                 CONTROL CHANNEL 
                 CONTROL SIGNAL 
               
               
                   
                   
               
             
            
               
                   
                 PDCCH 430 
                 DL grant signal, TPC signal 
               
               
                   
                 PUCCH 450 
                 ACK/NACK signal, CQI signal, PMI 
               
               
                   
                   
                 signal, RI signal 
               
               
                   
                 PHICH 470 
                 ACK/NACK signal 
               
               
                   
                   
               
            
           
         
       
     
     Further, control signals for independent control channel structure  700  of second communication link  180  are provided in Table 2. 
     
       
         
           
               
               
             
               
                 TABLE 2 
               
               
                   
               
               
                 CONTROL CHANNEL 
                 CONTROL SIGNAL 
               
               
                   
               
             
            
               
                 PDCCH 440 
                 UL grant signal, TPC signal, ACK/NACK 
               
               
                   
                 signal 
               
               
                 PUCCH 460 
                 SR signal, SRS signal 
               
               
                 PHICH 480 
                 ACK/NACK signal 
               
               
                   
               
            
           
         
       
     
       FIG. 8  illustrates one embodiment of distributed control channel structure  800  of system  100  in accordance with various aspects set forth herein. In this embodiment, first node  121  can schedule DL transmissions and second node  141  can schedule UL transmissions for wireless device  101 . Further, structure  800  can allow first node  121  to send a DL signal to wireless device  101  using first communication link  170 . However, wireless device  101  cannot send a UL signal to first node  121  using first communication link  170 . Instead, wireless device  101  can send a UL signal to first node  121  via second node  141  using second communication link  180  and third communication link  190 . Similarly, structure  800  can allow wireless device  101  to send a UL signal to second node  141  using second communication link  180 . However, second node  141  cannot send a DL signal to wireless device  101  using second communication link  180 . Instead, second node can send a DL signal to wireless device  101  via first node  121  using third communication link  190  and first communication link  170 . To summarize, any transmission between first node  121  and wireless device  101  using first communication link  170  may only be the transmission of a DL signal from first node  121  to wireless device  101 . Further, any transmission between second node  141  and wireless device  101  using second communication link  180  may only be the transmission of a UL signal from wireless device  101  to second node  141 . In this embodiment, wireless device  101  can be assigned first node  121 , second node  141  or both based on the quality of the corresponding communication link  170  and  180 , wherein the quality of communication link  170  and  180  can be determined using, for instance, the received signal strength, signal quality, data throughput rate, bit error rate (“BER”), word error rate (“WER”), other similar metric or any combination thereof. In some embodiments, first node  121  and second node  141  may be the same node. 
     In  FIG. 8 , structure  800  can allow wireless device  101  to send a UL control signal to first node  121  via second node  141  using second communication link  180  and third communication link  190 , wherein the UL control signal can include, for instance, an ACK/NACK signal, CQI signal, PMI signal, RI signal, other signal or any combination thereof. For example, wireless device  101  can send a UL control signal to second node  141  using, for instance, PUCCH  460  of second communication link  180 . Further, second node  141  can forward the UL control signal to first node  121  using, for instance, backhaul channel  330  of third communication link  190 . 
     In  FIG. 8 , structure  800  can allow second node  141  to send a DL control signal to wireless device  101  via first node  121  using third communication link  190  and first communication link  170 , wherein the DL control signal can include, for instance, a UL grant signal, ACK/NACK signal, TPC signal, other control signal or any combination thereof. For example, second node  141  can send a DL control signal to first node  121  using, for instance, backhaul channel  330  of third communication link  190 . Further, first node  121  can forward the DL control signal to wireless device  101  using, for instance, PDCCH  430 , PHICH  470  or both of first communication link  170 . It is important to recognize that careful coordination, management, assignment or any combination thereof of the DL and UL control signals may be required to deliver the correct control signal to the correct node. 
       FIG. 9  illustrates another embodiment of distributed control channel structure  900  of system  100  in accordance with various aspects set forth herein. In  FIG. 9 , structure  900  can allow first node  121  to schedule the transmission of a DL signal from first node  121  to wireless device  101  using first communication link  170  and can allow second node  141  to schedule the transmission of a UL signal from wireless device  101  to second node  141  using second communication link  180 . For instance, first node  121  can send a DL signal to wireless device  101  using first communication link  170 . 
     In another embodiment, second node  141  can determine the scheduling of the transmission of a UL signal by wireless device  101  to second node  141  using second communication link  180  and provide such scheduling to first node  121 , where first node  121  can provide a corresponding UL grant signal to wireless device  101  using, for instance, PDCCH  430  of first communication link  170 . It is important to recognize that the scheduling of the transmission of a UL signal from wireless device  101  to second node  141  using second communication link  180  is determined by second node  141  but sent to wireless device  101  via first node  121  using, for instance, PDCCH  430  of first communication link  170 . 
     In another embodiment, second node  141  can determine a UL power control signal associated with, for instance, PUSCH  320 , PUCCH  460 , other channel or any combination thereof transmitted by wireless device  101  to second node  141  using second communication link  180 . Further, second node  141  can provide such UL power control signal to wireless device  101  via first node  121  using, for instance, backhaul channel  330  of third communication link  190  and PDCCH  430  of first communication link  170 . 
     In another embodiment, transmission delay using backhaul channel  330  of third communication link  190  may require second node  141  to provide additional time for scheduling the transmission of a UL signal from wireless device  101  to second node  141  using second communication link  180 . For example, second node  141  can schedule the transmission of a UL signal by a predetermined amount of time after second node  141  sends, for instance, a UL grant signal to wireless device  101  via first node  121 , wherein the predetermined amount of time can correspond to, for instance, processing time, transmission delay, other delay, or any combination thereof. 
     In another embodiment, the resources associated with, for instance, an SRS signal, PUCCH  460 , other channel, or any combination thereof can be allocated by second node  141  but delivered to wireless device  101  via first node  121 . In this embodiment, wireless device  101  can provide a UL control signal to second node  141  using, for instance, PUCCH  460  of second communication link  180 , wherein the UL control signal can include, for instance, a HARQ feedback signal, CQI signal, PMI signal, RI signal, SR signal, other signal or any combination thereof. For example, second node  141  can assign an SRS signal, PUCCH  460 , other resource or any combination thereof for wireless device  101  and send such resource assignment to first node  141  using backhaul channel  330  of third communication link  190 . First node  121  can then send the configuration of the HARQ feedback signal, CQI signal, PMI signal, RI signal, SR signal, other signal or any combination thereof to wireless device  101  using, for instance, DL RRC signaling, other signaling or both. To summarize, the resources for an SRS signal, PUCCH  460 , other channel, or any combination thereof can be allocated by second node  141  and delivered to wireless device  101  via first node  121 . 
       FIG. 10  illustrates another embodiment of distributed channel structure  1000  of system  100  in accordance with various aspects set forth herein. In this embodiment, first node  121  can transmit a DL data signal to wireless device  101  using first communication link  170 . In response to such transmission, wireless device  101  can send a HARQ feedback signal to first node  121  via second node  141 . First node  121  can then determine whether to re-transmit the DL data signal to wireless device  101 . For example, first node  121  can transmit a DL data signal to wireless device  101  using, for instance, PDSCH  310  of first communication link  170 . In response to such transmission, wireless device  101  can send a HARQ feedback signal to second node  141  using, for instance, PUCCH  460  of second communication link  180 . Further, second node  141  can forward the HARQ feedback signal to first node  121  using backhaul channel  330  of third communication link  190 . First node  121  can then determine whether to re-transmit the DL data signal to wireless device  101  using, for instance, PDSCH  310  of first communication link  170 . 
     In another embodiment, transmission delay associated with forwarding a DL HARQ feedback signal such as an ACK/NAK signal from second node  121  to first node  141  using, for instance, backhaul channel  330  of third communication link  190  may require increasing the number of DL HARQ re-transmission procedure-related processes to optimize the use of available bandwidth. Further, the DL HARQ re-transmission procedure can support asynchronous re-transmission to allow, for instance, first node  121  to schedule a re-transmission of a DL signal for wireless device  101  upon receiving the forwarded DL HARQ feedback signal from second node  141 . 
     In another embodiment, instead of using PHICH  470 , a UL grant signal may be sent by first node  121  to wireless device  101  each time a re-transmission of a UL signal is required. Unlike the synchronous UL HARQ re-transmission procedure described in, for instance, LTE Release 8, wireless device  101  may not perform a re-transmission of a UL signal unless a re-transmission UL grant signal is received by wireless device  101  from first node  121 . Wireless device  101  can transmit a UL signal to second node  141  after receiving a UL grant signal from second node  141  via first node  121 . Upon receiving the UL signal, instead of sending a UL HARQ feedback signal such as an ACK/NACK signal to wireless device  101  via first node  121 , second node  141  can send a new data indicator (“NDI”) signal to wireless device  101  via first node  121  to indicate the scheduling for transmission of a new UL signal. For an unsuccessful transmission of a UL signal from wireless device  101 , second node  141  can send a new UL grant signal to wireless device  101  via first node  121  to schedule UL re-transmission for wireless device  101 . The UL grant signal can include a NDI signal, wherein the NDI signal can be used to indicate whether the UL grant signal is associated with a new transmission or a re-transmission of a UL signal. Further, a HARQ process identifier signal may be included with the UL grant signal. Such method can allow wireless device  101  to keep the UL signal in, for instance, memory  103 , so that the UL signal is available for a UL HARQ re-transmission procedure-related process. Such memory may be re-used once a UL grant signal for a new data transmission is received using, for instance, PDCCH  430  of first transmission link  170 . Further, avoiding the use of PHICH  470  via first communication link  170  can simplify the operation of first node  121  by not requiring it to configure and use PHICH  470  associated with the transmission of PUSCH  320 . 
     In another embodiment, wireless device  101  can send to first node  121  via second node  141  a PMI signal, CQI signal, RI signal, other signal or any combination thereof associated with the transmission of a DL signal from first node  121  to wireless device  101  via first communication link  170 . 
     In another embodiment, for the transmission of a UL signal by wireless device  101  using second communication link  180 , second node  141  can measure the channel quality using, for instance, the SRS signal received from wireless device  101 . A person of ordinary skill in the art will recognize that there are many methods of measuring channel quality using a received reference signal. Using such channel quality measurement, second node  141  can determine an appropriate modulation and coding scheme (“MCS”) for the transmission of a UL signal from wireless device  101 . Further, second node  141  may include additional time for scheduling the transmission of a UL signal from wireless device  101  to compensate for any delay associated with second node  141  sending the associated UL grant signal to wireless device  101  via first node  121  using, for instance, backhaul channel  330  of third communication link  190 . This may require second node  141  to perform the scheduling in advance and have a good estimation of the transmission delay on backhaul channel  330  of third communication link  190 . Similarly, a TPC signal associated with the transmission of a UL control signal from wireless device  101  to second node  121  using, for instance, PUCCH  460 , PUSCH  320  or both of second communication link  180  may be determined by second node  141  and sent to wireless device  101  via first node  121 . 
     In another embodiment, first node  121  and second node  141  may be closely coupled using, for instance, backhaul channel  330  of third communication link  190 . In such configuration, backhaul channel  330  of third communication link  190  may experience more traffic than independent control channel structure  400 ,  500 ,  600  and  700 . In distributed control channel structure  800 , a UL grant signal, TPC signal or both associated with PUSCH  320 , PUCCH  460  or both may be transferred from second node  141  to first node  121  using, for instance, backhaul channel  330  of third communication link  190 . In addition, a HARQ feedback signal, PMI signal, CQI signal, RI signal, other signal or any combination thereof may be transferred from second node  141  to first node  121  using, for instance, backhaul channel  330  of third communication link  190 . In this embodiment, time delay in sending UL signals using, for instance, backhaul channel  330  of third communication link  190  may impact system performance. However, such time delay can be mitigated by using, for instance, a fiber optic cable between backhaul interface  128  of first node  121  and second node  141 . 
     Due to separating UL and DL transmissions between first node  121  and second node  141 , time synchronization issues between wireless device  101  and nodes  121  and  141  may occur. In one embodiment, nodes  121  and  141  may be time synchronized. Such requirement may be inherent to various industry standards such as LTE-A for a Type-I relay network. For example, as described in the LTE and LTE-A standards, coordinated multi-point (“CoMP”) transmission, reception or both may require network time synchronization. CoMP transmission, reception or both can be used by LTE and LTE-A equipment to improve, for instance, data rates, cell-edge throughput, other benefit or any combination thereof. Further, such CoMP technique can be applied to multiple-serving node wireless communication system  100 , since first node  121  is on the routing path and the data information, control information or both can be transmitted to second node  141  using, for instance, backhaul channel  330  of third communication link  190 . In addition, as described in the LTE and LTE-A standards, multimedia broadcast multicast service (“MBMS”) may require network time synchronization. MBMS uses a plurality of base stations, RNs or both to broadcast the same information to a wireless device. MBMS may require a synchronized network so that a wireless device only needs to maintain time synchronization with one node. 
     In a synchronized network, wireless device  101  does not need to maintain separate time synchronization with first node  121  and second node  141 . Such requirement can simplify the design of wireless device  101 . For an unsynchronized network using independent control channel structure  400 ,  500 ,  600  and  700 , wireless device  101  may need to maintain separate time synchronization with first node  121  and second node  141 . For an unsynchronized network using distributed control channel structure  800 ,  900  and  1000 , wireless device  101  may not need to maintain time synchronization with second node  141 , since second node  141  may not transmit any DL signals to wireless device  101 . 
     In an OFDM-based wireless communication system, cyclic prefix (“CP”) may be added to an OFDM symbol to, for instance, reduce inter-symbol interference, maintain orthogonality amongst the sub-carriers or both. In an LTE system, there can be a normal CP and an extended CP, wherein the normal CP has a shorter length than the extended CP. LTE systems can use an extended CP to support, for instance, larger cell sizes, MBMS service, other benefit or any combination thereof. While the wireless propagation path between wireless device  101  and nodes  121  and  141  may comprise multiple-paths, the length of the normal CP, extended CP or both should be sufficient to support any delay between such multiple-paths, as specified for the LTE system. 
     In multiple-serving node wireless communication system  100 , wireless device  101  may receive transmissions from both first node  121  and second node  141  at the RRC-Connected state. For such case, the same CP length may be applied to both nodes  121  and  141 . Geometrically, first node  121  and second node  141  may be placed within the size of the donor cell. The multiple-path delay spread between wireless device  101  and first node  121  and wireless device  101  and second node  141  may be different but can be within the duration of the normal CP length or the extended CP length. Extended CP length can be used for nodes  121  and  141  to mitigate any concerns associated with larger multiple-path delay spread. 
     Latency in multiple-serving node wireless communication system  100  may impact quality of service (“QoS”). In system  100 , latency may increase due to, for instance, using backhaul channel  330  of third communication link  190 . In another embodiment, wireless device  101  may directly connect to first node  121  to transmit both DL and UL signals to reduce latency for a delay-sensitive network service. In this embodiment, first node  121  can be a base station and second node  141  can be an RN. 
     The control plane latency is typically determined as the transition time from idle state to active state. Even though multiple serving nodes may be used by wireless device  100 , wireless device  100  may still need to use a random access procedure to connect to first node  121 . In the case that wireless device  101  can only make channel quality measurements of DL transmissions from first node  121  during an idle state and may only try to connect to first node  121  with the strongest received power during a transition period. After the RRC connection is obtained, first node  121  may negotiate with second node  141  associated with the transmissions of a UL data signal and transition such UL transmissions to another node. Therefore, the control plane latency should not change for multiple-serving node wireless communication system  100 . 
     The user plane latency can be defined as the one-way transit time between a session data unit (“SDU”) packet being available at the internet protocol (“IP”) layer in wireless device  101  and being available at the IP layer in node  121  and  141  or being available at the IP layer in node  121  and  141  and being available at the IP layer in wireless device  101 . The user plane packet delay can include delay introduced by, for instance, associated protocols, control signaling or both. For independent control channel structure  400 ,  500 ,  600  and  700  in a multiple-serving node wireless communication system  100 , there is no additional delay for wireless device  100  compared to wireless device  101  in a single-serving node wireless communication system. As discussed previously, two independent control channel structures  400 ,  500 ,  600  and  700  are maintained for first communication link  100  and second communication link  200  and no control signals are exchanged using communication link  300 . 
     For distributed control channel structure  800 ,  900  and  1000 , additional delay may occur due to, for instance, the frequent exchange of control signals between second node  141  and first node  121  via third communication link  190 . Such delay may be caused by, for instance, sending control signals such as a HARQ feedback signal, CQI signal, PMI signal, RI signal, other control signal or any combination thereof to first node  121  or second node  141  and forwarding such signals to second node  141  or first node  121 , respectively. For example, a 4 millisecond (“msec.”) delay associated with sending a control signal from second node  141  to first node  121  and a 2 msec. delay associated with processing time at first node  121  may require increasing the packet round trip time (“RTT”) from, for instance, eight msec. as specified by “LTE Release 8” to fourteen msec. Further, the number of HARQ processes can be increased to accommodate such increase in RTT so that nodes  121  and  141  do not need to wait for the HARQ feedback signal forwarded from the other node  121  and  141  before transmitting a new packet. If the packet is not received correctly by wireless device  101 , first node  121  or second node  141 , then the re-transmission can occur six msec. later than the re-transmission in a single-serving node system. In LTE Release 8, typically up to four re-transmissions are allowed for a voice over IP (“VoIP”) service. For multiple-serving node wireless communication system  100 , two re-transmissions may be allowed within such timing constraints. To minimize reliance on the reduced number of re-transmissions, for instance, a more conservative MCS for the initial transmission by wireless device  101  can be used so that the packet can be received correctly with higher probability for the initial transmission. 
     In summary, splitting the reception of DL and UL transmissions from wireless device  101  between first node  121  and second node  141  should not incur additional control channel delay if independent control channel structure  400 ,  500 ,  600  and  700  is used. On the other hand, if distributed control channel structure  800 ,  900  and  1000  is used, the number of maximum re-transmissions allowed within a certain period can be reduced. More conservative MCS selection may be considered for the initial transmission in this case. 
     In another embodiment, wireless device  101  may be operated in conditions such that handoffs, handovers or both may affect its connection to first node  121 , second node  141  or both. For example, wireless device  101  may be required to handoff from first node  121  to another node, which would change, for instance, the source of the DL data signal from first node  121  to another node. Similarly, wireless device  101  may be required to handoff from second node  141  to another node, which would change, for instance, the source of the UL data signal from second node  141  to another node. Further, wireless device  101  may be required to handoff from first node  121  and second node  141  to different target nodes. Various handoff scenarios exist for wireless device  101  in system  100 . For instance, wireless device  101  can handoff from second node  141  to another second node, and can maintain its connection with first node  121 . Wireless device can handoff from first node  121  to another first node, and can maintain its connection with second node  141 . Wireless device  101  can handoff from second node  141  to first node  121 . Wireless device  101  can handoff from first node  121  to second node  141 . Wireless device  101  can handoff from first node  121  to another first node and can handoff from second node  141  to another second node. Wireless device  101  can handoff from first node  121  and second node  141  to the same serving node. First node  121 , second node  141  or both may need to indicate to wireless device  101  which node will be handed-off. This could be signalled via high layer signalling such as RRC signalling. Further, more coordination may be required when wireless device  101  simultaneously or contemporaneously handoffs first node  121  and second node  141 . 
       FIG. 11  is a flow chart of one embodiment of a method of providing data signals in system  100  in accordance with various aspects set forth herein. In  FIG. 11 , method  1100  can start at, for instance, block  1110 , where method  1100  can send a DL data signal from first node  121  to wireless device  101  using first communication link  170 . At block  1120 , method  1100  can send a UL data signal from wireless device  101  to second node  141  using second communication link  180 . At block  1130 , method  1100  can send the UL data signal from second node  141  to first node  121  using third communication link  190 . 
       FIG. 12A  is a flow chart of one embodiment of method  1200   a  of providing control signals between first node  121  and wireless device  101  in system  100  in accordance with various aspects set forth herein. In  FIG. 12A , method  1200   a  can start at, for instance, block  1210 , where method  1200   a  can send a DL control signal from first node  121  to wireless device  101  using first communication link  170 , wherein the DL control signal may include, for instance, a DL grant signal, other control signal or both. At block  1220 , method  1200   a  can send a UL control signal from wireless device  101  to first node  121  using first communication link  170 , wherein the UL control signal can include, for instance, an ACK/NACK signal, CQI signal, PMI signal, RI signal, other control signal or any combination thereof. 
       FIG. 12B  is a flow chart of another embodiment of method  1200   b  of providing control signals between first node  121  and wireless device  101  in system  100  in accordance with various aspects set forth herein. In  FIG. 12B , method  1200   b  can start at, for instance, block  1230 , where method  1200   b  can send a DL control signal from first node  121  to wireless device  101  using first communication link  170 , wherein the DL control signal may include, for instance, a DL grant signal, other control signal or both. At block  1240  and block  1260 , method  1200   b  can send a UL control signal from wireless device  101  to first node  121  via second node  141 , wherein the UL control signal can include, for instance, an ACK/NACK signal, CQI signal, PMI signal, RI signal, other control signal or any combination thereof. At block  1240 , method  1200   b  can send the UL control signal from wireless device  101  to second node  141  using second communication link  170 . At block  1250 , method  1200   b  can send the UL control signal from second node  141  to first node  121  using third communication link  190 . 
       FIG. 13A  is a flow chart of one embodiment of method  1300   a  of providing control signals between second node  141  and wireless device  101  in system  100  in accordance with various aspects set forth herein. In  FIG. 13A , method  1300   a  can start at, for instance, block  1310 , where method  1300   a  can send a UL control signal from wireless device  101  to second node  141  using second communication link  180 , wherein the UL control signal may include an SR signal, SRS signal, other control signal or any combination thereof. At block  1320 , method  1300   b  can send a DL control signal from second node  141  to wireless device  101  using second communication link  180 , wherein the DL control signal may include a UL grant signal, ACK/NACK signal, TPC signal, other control signal or any combination thereof. 
       FIG. 13B  is a flow chart of another embodiment of method  1300   b  of providing control signals between second node  141  and wireless device  101  in system  100  in accordance with various aspects set forth herein. In  FIG. 13B , method  1300   b  can start at, for instance, block  1330 , where method  1300   b  can send a UL control signal from wireless device  101  to second node  141  using second communication link  180 , wherein the UL control signal may include an SR signal, SRS signal, other control signal or any combination thereof. At block  1340  and block  1350 , method  1300   b  can send a DL control signal from second node  141  to wireless device  101  via first node  121 , wherein the DL control signal may include, for instance, a UL grant signal, ACK/NACK signal, TPC signal, other signal or any combination thereof. At block  1340 , method  1300   b  can send the DL control signal from second node  141  to first node  121  using third communication link  190 . At block  1350 , method  1300   b  can send the DL control signal from first node  121  to wireless device  101  using first communication link  170 . 
     Having shown and described exemplary embodiments, further adaptations of the methods, devices and systems described herein may be accomplished by appropriate modifications by one of ordinary skill in the art without departing from the scope of the present disclosure. Several of such potential modifications have been mentioned, and others may be apparent to those skilled in the art. For instance, the exemplars, embodiments, and the like discussed above are illustrative and are not necessarily required. Accordingly, the scope of the present disclosure should be considered in terms of the following claims and is understood not to be limited to the details of structure, operation and function shown and described in the specification and drawings. 
     As set forth above, the described disclosure includes the aspects set forth below.