HK1179772A - Wireless communication system using multiple-serving nodes - Google Patents

Abstract

Methods, devices and systems for a wireless communication system using multiple-serving nodes are provided. In one embodiment, a method of wireless communication comprises sending from a first node a downlink control signal to a wireless device using a first communication link; receiving by said first node an uplink control signal from said wireless device via a second node using a third communication link; and forwarding by said first node another downlink control signal from said second node to said wireless device using said third communication link and said first communication link.

Description

Wireless communication system using multiple service nodes

Technical Field

The present invention relates generally to wireless communications, and in particular to wireless communication systems using multiple serving nodes.

Background

Wireless communication systems are widely deployed to provide various voice and data related services, for example. A typical wireless communication system consists of a multiple-access communication network that allows users to share common network resources. Examples of such networks are: a time division multiple access ("TDMA") system, a code division multiple access ("CDMA") system, a single carrier frequency division multiple access ("SC-FDMA") system, an orthogonal frequency division multiple access ("OFDMA") system, or other similar system. 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, employ OFDMA systems. Further, implementations of these systems are described by specifications developed by various standards organizations, such as the third generation partnership project ("3 GPP") and 3GPP 2.

As wireless communication systems evolve, more advanced network devices are introduced that provide improved features, functionality, and performance. A representation of such an advanced network device may also be referred to as a long term evolution ("LTE") device or a long term evolution-advanced ("LTE-a") device. LTE is the next level of evolution for high speed packet access ("HSPA") with higher average and peak data throughput rates, lower latency, and better user experience, especially in high demand metropolitan areas. LTE achieves this higher performance by using wider spectral 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 wireless communication systems using relay nodes ("RNs"), wireless devices may have difficulty selecting between a base station and an RN due to, for example, UL and DL power imbalance. An RN such as an LTE type-I RN may operate as a smaller base station. In LTE systems, a wireless device may select a base station or RN based on an average DL signal strength, which may result in a lower signal strength on the UL due to UL/DL power imbalance. Alternatively, the wireless device may select a base station or RN based on both DL and UL signal strength.

As described in the LTE-a standard, a type-I RN may have full radio resource control ("RRC") functionality. Such an RN may control its cell and may have its own physical cell identifier. In addition, such an RN may transmit its own synchronization channel and reference signal. Further, the wireless device may receive, for example, scheduling information and hybrid automatic repeat request ("HARQ") feedback from the RN and transmit control information such as a scheduling request ("SR") signal, a channel quality indicator ("CQI") signal, and a HARQ feedback signal to the RN.

In heterogeneous LTE-a networks using multiple base stations and type-I RNs, such networks can have significant differences between the base station transmit power and the RN transmit power. The wireless device may provide UL transmissions that are received by the base station and RN. The power received from such a transmission may be substantially dependent on the propagation path between the wireless device and the base station, the RN, or both. In some cases, 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, resulting in an UL and DL power imbalance. The present disclosure describes various embodiments including techniques for addressing such power imbalances in a multi-service node wireless communication system.

Drawings

To facilitate an understanding of and for enabling those of ordinary skill in the art to practice the present disclosure, reference is now made to the exemplary embodiments illustrated by the drawings. Throughout the drawings, like reference numbers indicate identical or functionally similar elements. The accompanying drawings, which are incorporated in and form a part of the specification, further illustrate exemplary embodiments and explain various principles and advantages, in accordance with the present disclosure, wherein:

fig. 1 is a block diagram of one embodiment of a wireless communication system employing 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 employing 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 employing multiple serving nodes in accordance with various aspects set forth herein.

Fig. 5 illustrates another embodiment of an independent control channel structure in a wireless communication system employing multiple serving nodes in accordance with various aspects set forth herein.

Fig. 6 illustrates another embodiment of an independent control channel structure in a wireless communication system employing multiple serving nodes in accordance with various aspects set forth herein.

Fig. 7 illustrates another embodiment of an independent control channel structure in a wireless communication system employing 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 employing 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 employing 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 employing multiple serving nodes in accordance with various aspects set forth herein.

Fig. 11 illustrates a flow diagram 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 diagram of one embodiment of a method of providing a control signal between a first node and a wireless device in a wireless communication system employing a multi-service node in accordance with various aspects set forth herein.

Fig. 12B is a flow diagram of another embodiment of a method of providing a control signal between a first node and a wireless device in a wireless communication system employing multiple serving nodes in accordance with various aspects set forth herein.

Fig. 13A is a flow diagram of one embodiment of a method of providing control signals between a second node and a wireless device in a wireless communication system employing multiple serving nodes in accordance with various aspects set forth herein.

Fig. 13B is a flow diagram of another embodiment of a method of providing control signals between a second node and a wireless device in a wireless communication system employing multiple serving nodes in accordance with various aspects set forth herein.

Those skilled in the art will appreciate that: the elements of the drawings are illustrated clearly and simply to further aid in the understanding of the embodiments, and are not necessarily drawn to scale.

Detailed Description

Although the following discloses example methods, devices, and systems for use in a wireless communication system, one of ordinary skill in the art will appreciate that: the teachings of the present disclosure are not in any way limited to the examples shown. Rather, it is contemplated that the teachings of the present disclosure may be implemented in alternative configurations and environments. For example, although the example methods, apparatus and systems described herein are described in connection with the configuration of the aforementioned wireless communication system, those skilled in the art will readily recognize that: the example methods, apparatus and systems may be used in, and may be configured to correspond to, other systems as desired. Thus, while the following describes example methods, apparatus, and systems for use thereof, persons of ordinary skill in the art will appreciate that: the disclosed examples are not the only way to implement such methods, apparatus, and systems, and the drawings and description are to be regarded as illustrative in nature and not as restrictive.

The various techniques described herein may be used for various wireless communication systems. Various aspects described herein are presented as methods, devices, and systems that may include a number of components, units, members, modules, nodes, peripherals, and the like. Further, these methods, devices, and systems may or may not include additional components, units, members, modules, nodes, peripherals, and the like. Furthermore, various aspects described herein may be implemented in hardware, firmware, software, or any combination thereof. It is important to note that: the terms "network" and "system" may be used interchangeably. Relational terms such as "above" and "below," "left" and "right," "first" and "second," and the like may be used solely to distinguish one item or action from another item or action without necessarily requiring or implying any actual such relationship or order between such items or actions. The term "or" is intended to mean an inclusive "or" rather than an exclusive "or". Furthermore, the terms "a" and "an" are intended to mean one or more, unless otherwise indicated herein or otherwise clearly contradicted by context. It is important to note that: the terms "network" and "system" may be used interchangeably.

A wireless communication network is typically made up of a plurality of wireless devices and a plurality of nodes. The node may also be referred to as: a base station, node-b (nodeb), base transceiver station ("BTS"), access point ("AP"), cell, relay node ("RN"), serving node, or some other equivalent terminology. Furthermore, the term "cell" can include a particular base station, a particular sector of a base station, a particular antenna of a sector of a base station. Base stations typically include one or more radio frequency ("RF") transmitters and receivers to communicate with wireless devices. Furthermore, the base stations are typically fixed and immobile. For LTE and LTE-A equipment, the base station is also referred to as the 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 telephone, a cellular handset, a personal digital assistant ("PDA"), a smart phone, a handheld computer, a desktop computer, a laptop computer, a tablet computer, a set-top box, a television, a wireless device, or some other equivalent terminology. A wireless device may contain one or more RF transmitters and receivers and one or more antennas for communicating with base stations. Further, wireless devices may be fixed or mobile and may have the capability to move within a wireless communication network. For LTE and LTE-a devices and for various industry standards, wireless devices are also referred to as user equipment ("UE").

Fig. 1 is a block diagram of one embodiment of a wireless communication system 100 employing multiple serving nodes in accordance with various aspects set forth herein. In fig. 1, the system 100 may include: wireless device 101, first node 121, and second node 141. In fig. 1, a wireless device 101 may include a processor 102 coupled to a memory 103, an input/output device 104, a transceiver 105, or any combination thereof, and the wireless device 101 may utilize the processor 102 to implement various aspects described herein. The transceiver 105 of the wireless device 101 may include one or more transmitters 106 and one or more receivers 107. Further, one or more transmitters 106 and one or more receivers 107 associated with the wireless device 101 may be connected to one or more antennas 109.

In fig. 1, the first node 121 may include a processor 122 coupled to a memory 123 and a transceiver 125. The transceiver 125 of the first node 121 may include one or more transmitters 126 and one or more receivers 127. Further, one or more transmitters 126 and one or more receivers 127 associated with the first node 121 may be connected to one or more antennas 129.

Similarly, second node 141 may include processor 122 coupled to memory 123 and transceiver 125. The transceiver 125 of the second node 141 includes one or more transmitters 126 and one or more receivers 127. Further, associated with the 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 may communicate with first node 121 via first communication link 170 using one or more antennas 109 and 129, respectively, and wireless device 101 may communicate with second node 141 via second communication link 180 using one or more antennas 109 and 129, respectively. Further, first node 121 may communicate with second node 141 over third communication link 190 using backhaul interface 128. First communication link 170 supports communication of signals between wireless device 101 and first node 121. Second communication link 180 supports communication of signals between wireless device 101 and second node 141. Third communication link 190 supports communication of signals between first node 121 and second node 141. The first communication link 170, the second communication link 180, and the third communication link 190 may support, for example, transmitting DL data signals, UL data signals, DL control signals, UL control signals, other signals, or combinations of signals. Further, first communication link 170, second communication link 180, and third communication link 190 may include: physical channels, logical channels, other channels, or any combination thereof. First communication link 170 and second communication link 180 may use, for example, any wireless communication protocol that supports technologies associated with, for example, TDMA, CDMA, UMTS, Wi-MAX, LTE-A, Wi-Fi, Bluetooth, or other similar technologies. The third communication link 190 may use any wired communication protocol, wireless communication protocol, or both.

In this embodiment, first node 121, second node 141, or both may transmit DL data signals, UL data signals, DL control signals, UL control signals, other signals, or any combination thereof, with wireless device 101. Thus, such embodiments may allow wireless device 101 to transmit DL data signals, UL data signals, DL control signals, UL control signals, other signals, or any combination thereof using, for example, the same or different nodes 121 and 141. Which node 121 and 141 to use for any such signal may be determined using, for example, received signal strength, data throughput rate, bit error rate ("BER"), word error rate ("WER"), other similar metrics or combinations of metrics.

For example, first node 121 may transmit a DL control signal to wireless device 101 using first communication link 170. Upon receipt, processor 102 of wireless device 101 may process the received DL control signal, may generate a response, and may provide such a response to first node 121 using, for example, the UL control signal of first communication link 170.

In another example, wireless device 101 may transmit a UL control signal to second node 141 using second communication link 180. Upon receipt, processor 142 of second node 141 may forward such signals to first node 121 using third communication link 190.

Fig. 2 illustrates one embodiment of a channel structure 200 of system 100 in accordance with various aspects set forth herein. In this embodiment, structure 200 may allow first node 121 to provide DL signal 210 to wireless device 101 using first communication link 170 and may allow wireless device 101 to provide UL signal 230 to second node 141 using second communication link 180. The DL signal may include: DL data signals, DL control signals, other signals, or any combination thereof. The UL signal may include: UL data signals, UL control signals, other signals, or any combination thereof. For example, first node 121 may transmit a DL data signal to wireless device 101 using first communication link 170. Further, structure 200 may allow wireless device 101 to transmit UL data signals to second node 141 using second communication link 180. Such a configuration may be advantageous when wireless device 101 is closer to second node 141 than first node 121, but still receives a strong DL signal from node 121, allowing wireless device 101 to operate, for example, at lower transmit power, higher data throughput rates, other advantages, or any combination thereof.

In another embodiment, architecture 200 may allow first node 121 and second node 141 to be the same node. Under this configuration, nodes 121 and 141 may act as partner projects, for example, in the 3 rd generation; technical specification group radio access network; physical channel and modulation (release 8), single serving node as described in 3GPP or 3GPP TS 36 series specifications. It is important to realize that: each node 121 and 141 may transmit DL signals to wireless device 101, may receive UL signals from wireless device 101, or both, and may do the same for the other wireless device. Furthermore, the present disclosure may provide the following advantages: for each node 121 and 141, full frequency reuse, frequency provisioning (provisioning), or both are allowed.

Fig. 3 illustrates another embodiment of a channel structure 300 of system 100 in accordance with various aspects set forth herein. In fig. 3, structure 300 may allow first node 121 to transmit DL data signals to wireless device 101 using, for example, physical DL shared channel ("PDSCH") 310 of first communication link 170. Similarly, system 300 may allow wireless device 101 to transmit UL data signals to second node 141 using, for example, physical UL shared channel ("PUSCH") 320 of second communication link 180. Such a configuration may be advantageous by allowing the PDSCH310, PUSCH 320, or both to be allocated based on, for example, the quality of the associated communication link. However, allocating the transmission of the UL data signal and the transmission of the DL data signal to different nodes may affect, for example, the control channel structure of system 300. For example, the control channel structure used in LTE release 8 is designed for wireless communication systems using a single serving node and would need to be modified in the manner described in this disclosure to support multi-serving node wireless communication system 100. For example, the first node 121 may provide an UL grant signal, a DL grant signal, or both to the wireless device 101 using the DL control channel of the first communication link 170. Under system 100, such permissions may be provided from different nodes 121 and 141, as opposed to the same node. Furthermore, any timing requirements described in LTE release 8, such as the UL timing alignment procedure, may not be supported in system 100, as the transmission of DL signals, UL signals, or both may be associated with different nodes. Other problems may exist, for example: the configuration and use of the UL and DL control channels includes defining appropriate control channels for transmitting acknowledgement or negative acknowledgement ("ACK/NACK") signals, sounding reference signals ("SRS") signals, other signals, or combinations of signals.

The present disclosure includes two alternative control channel structures for addressing the above-mentioned problems. Such alternatives are associated with independent control channel structures and distributed control channel structures. Fig. 4 illustrates one embodiment of an independent control channel structure 400 of system 100 in accordance with various aspects set forth herein. In fig. 4, the first communication link 170 may include PDSCH310, physical DL control channel ("PDCCH") 430, physical UL control channel ("PUCCH") 450, physical hybrid automatic repeat request indicator channel ("PHICH") 470, other channels, or any combination thereof. The second communication link 180 may include PUSCH 320, PDCCH440, PUCCH460, physical hybrid automatic repeat request ("HARQ") indicator channel ("PHICH") 480, or any combination thereof. For communication of data signals, the structure 400 may allow the first node 121 to provide DL data signals to the wireless device 101 using, for example, the PDSCH310 of the first communication link 170. Further, wireless device 101 may provide the UL data signal to second node 141 using, for example, PUSCH 320 of second communication link 180. For communication of control signals, structure 400 may allow first node 121 and second node 141 to each have the same or different control channel structures. For example, first node 121 may provide a DL control signal to wireless device 101 using, for example, PDCCH 430 of first communication link 170. Wireless device 101 may provide a UL control signal to first node 121 using, for example, PUCCH 450 of first communication link 170. Further, second node 141 may provide a DL control signal to wireless device 101 using, for example, PDCCH440, PHICH 480, or both of second communication link 180. Further, wireless device 101 may provide a UL control signal to second node 141 using, for example, PUCCH460 of second communication link 180.

Fig. 5 illustrates another embodiment of an independent control channel structure 500 of system 100 in accordance with various aspects set forth herein. In fig. 5, structure 500 may allow first node 121 to provide a DL control signal to wireless device 101 using, for example, PDCCH 430 of first communication link 170. Similarly, structure 500 may allow second node 141 to provide a DL control signal to wireless device 101 using, for example, PDCCH440 of second communication link 180. It is important to note that: the DL control signal provided by the first node 121 and the DL control signal provided by the second node 141 are independent of each other. The first node 121 may manage, control, coordinate, schedule, or any combination thereof, the transmission of DL data signals to the wireless device 101 using the PDSCH310 of the first communication link 170. Further, the second node 141 may manage, control, coordinate, schedule, or any combination thereof, the transmission of UL data signals from the wireless device 101 using the PUSCH 320 of the second communication link 180. For example, first node 121 may provide a DL grant signal to wireless device 101 using, for example, PDCCH 430 of first communication link 170. Further, second node 141 may provide a UL grant signal to wireless device 101 using, for example, PDCCH440 of second communication link 180. The DL grant signal may provide the first node 121 with permission to transmit a DL data signal to the wireless device 101 using, for example, PDSCH310 of the first communication link 170. The UL grant signal may provide wireless device 101 with permission to transmit UL data signals to second node 141 using, for example, PUSCH 320 of second communication link 180.

Fig. 6 illustrates another embodiment of an independent control channel structure 600 of system 100 in accordance with various aspects set forth herein. In fig. 6, the structure 600 may allow the first communication link 170 to include PDSCH310, PDCCH 430, PUCCH 450, other channels, or any combination thereof. For example, wireless device 101 may provide a UL control signal to first node 121 using, for example, PUCCH 450 of first communication link 170. Such UL control signals may include, for example: a channel quality indicator ("CQI") signal, a precoding matrix indicator ("PMI") signal, a rank indicator ("RI") signal, an ACK/NACK signal, other signal, or combination of signals. The CQI, PMI, RI, and ACK/NACK signals may be used to support transmission of DL data signals from the first node 121 to the wireless device 101, for example, using the PDSCH310 of the first communication link 170. Further, the power control signal may be used to support, adjust, adapt, coordinate, or any combination thereof, the transmission of the UL signal from the wireless device 101 to the first node 121. The first node 101 may provide a DL control signal to the wireless device 101 using, for example, PDCCH 430 of the first communication link 170, where the DL control signal may comprise a power control signal, such as a transmit power control command ("TPC") signal.

Fig. 7 illustrates another embodiment of an independent control channel structure 700 of system 100 in accordance with various aspects set forth herein. In fig. 7, structure 700 may allow second communication link 180 to include PUSCH 420, PDCCH440, PUCCH460, and PHICH 480, other channels, or any combination thereof. In fig. 7, structure 700 may allow wireless device 101 to provide a UL control signal to second node 141 using, for example, PUCCH460 of second communication link 180. Further, second node 141 may manage, support, coordinate, or any combination thereof, the reception of UL data signals from wireless device 101 using, for example, PUSCH 320 of second communication link 180, by providing DL control signals to wireless device 101 using, for example, PDCCH440, PHICH 480, or both of second communication link 180. For example, PHICH 480 of second communication link 180 may be used to transmit, for example, an ACK/NACK signal from second node 141 to wireless device 101, and PDCCH440 may be used to transmit, for example, a UL grant signal, an ACK/NACK signal, a TPC signal, a timing adjustment command signal, other signals, or any combination thereof, from second node 141 to wireless 101. Further, PUCCH460 may be used to transmit, for example, a scheduling request ("SR") signal, an SRs signal, other signals, or any combination thereof, from wireless device 101 to second node 141. For example, the SR signal may include a scheduling request indicator ("SRI") signal associated with transmitting, for example, an UL data signal from wireless device 101 to second node 141. Further, wireless device 101 may transmit an SRS signal to second node 141 to allow for timing adjustments between wireless device 101 and second node 141, UL transmission adaptation, other advantages, or any combination thereof. It is important to realize that: the dedicated SRS signal may not be required to be transmitted from wireless device 101 to first node 121 because any timing alignment is expected for UL transmissions from wireless device 101 to second node 141. However, the timing alignment required by the first node 121 may cause interference to transmissions of other wireless devices to the first node 121. Knowledge of the UL transmit timing can help mitigate this interference. Accordingly, such transmission timing can be estimated using, for example, the timing of PUCCH460 transmission from wireless device 101 to second node 141.

In another embodiment, the wireless device 101 may multiplex the control signals and the data signals using, for example, the PUSCH 320 of the second communication link 180, the PDSCH310 of the first communication link 170, or both. For example, after receiving the UL data signal and the UL control signal using PUSCH 320, second node 141 may forward the UL control signal to first node 121 using backhaul link 330, e.g., third communication link 190. The backhaul link 330 may increase HARQ retransmission delay if the UL control signal is an ACK/NACK signal. To avoid wasting DL bandwidth, the number of processes associated with the HARQ retransmission process may be increased to accommodate a longer HARQ retransmission round trip time ("RTT"). For example, control signals for the independent control channel structure 600 of the first communication link 170 are provided in table 1.

TABLE 1

Further, control signals for the independent control channel structure 700 of the second communication link 180 are provided in table 2.

TABLE 2

Fig. 8 illustrates one embodiment of a distributed control channel structure 800 of the system 100 in accordance with various aspects set forth herein. In this embodiment, first node 121 may schedule DL transmissions and second node 141 may schedule UL transmissions for wireless device 101. Further, structure 800 may allow first node 121 to transmit DL signals to wireless device 101 using first communication link 170. However, wireless device 101 cannot transmit an UL signal to first node 121 using first communication link 170. Instead, wireless device 101 may transmit a UL signal to first node 121 via second node 141 using second communication link 180 and third communication link 190. Similarly, structure 800 may allow wireless device 101 to transmit an UL signal to second node 141 using second communication link 180. However, second node 141 cannot transmit a DL signal to wireless device 101 using second communication link 180. Alternatively, second node 141 may transmit the DL signal to wireless device 101 via first node 121 using third communication link 190 and first communication link 170. In summary, any transmission between first node 121 and wireless device 101 using first communication link 170 may only be a 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 a transmission of a UL signal from wireless device 101 to second node 141. In this embodiment, the first node 121, the second node 141, or both, may be assigned to the wireless device 101 based on the quality of the corresponding communication links 170 and 180, where the quality of the communication links 170 and 180 may be determined using, for example, received signal strength, signal quality, data throughput rate, bit error rate ("BER"), word error rate ("WER"), other similar metrics, or any combination thereof. In some embodiments, first node 121 and second node 141 may be the same node.

In fig. 8, structure 800 may allow wireless device 101 to transmit a UL control signal to first node 121 via second node 141 using second communication link 180 and third communication link 190, where the UL control signal may include, for example: ACK/NACK signals, CQI signals, PMI signals, RI signals, other signals, or any combination thereof. For example, wireless device 101 may transmit a UL control signal to second node 141 using, for example, PUCCH460 of second communication link 180. Further, second node 141 may forward the UL control signal to first node 121 using, for example, backhaul channel 330 of third communication link 190.

In fig. 8, structure 800 may allow second node 141 to transmit a DL control signal to wireless device 101 via first node 121 using third communication link 190 and first communication link 170, where the DL control signal may include, for example: UL grant signals, ACK/NACK signals, TPC signals, other control signals, or any combination thereof. Further, the second node 141 may transmit the DL control signal to the first node 121 using, for example, a backhaul channel 330 of the third communication link 190. Further, first node 121 may forward the DL control signal to wireless device 101 using, for example, PDCCH 430, PHICH470, or both of first communication link 170. It is important to realize that: careful coordination, management, allocation, or any combination thereof of DL and UL control signals may be required to transmit the correct control signals to the correct nodes.

Fig. 9 illustrates another embodiment of a distributed control channel structure 900 of the system 100 in accordance with various aspects set forth herein. In fig. 9, structure 900 may allow first node 121 to schedule transmission of DL signals from first node 121 to wireless device 101 using first communication link 170 and may allow second node 141 to schedule transmission of UL signals from wireless device 101 to second node 141 using second communication link 180. For example, first node 121 may transmit a DL signal to wireless device 101 using first communication link 170.

In another embodiment, second node 141 may determine a schedule for wireless device 101 to transmit UL signals to second node 141 using second communication link 180 and provide such schedule to first node 121, where first node 121 may provide a corresponding UL grant signal to wireless device 101 using, for example, PDCCH 430 of first communication link 170. It is important to realize that: the schedule for transmitting UL signals from wireless device 101 to second node 141 using second communication link 180 is determined by second node 141, but transmitted to wireless device 101 via first node 121 using, for example, PDCCH 430 of first communication link 170.

In another embodiment, second node 141 may determine the UL power control signal associated with PUSCH 320, PUCCH460, other channels, or any combination thereof that wireless device 101 transmits to second node 141 using second communication link 180. Further, second node 141 may provide such UL power control signals to wireless device 101 via first node 121 using, for example, backhaul channel 330 of third communication link 190 and PDCCH 430 of first communication link 170.

In another embodiment, a transmission delay of backhaul channel 330 using third communication link 190 may require second node 141 to provide additional time for scheduling the transmission of UL signals from wireless device 101 to second node 141 using second communication link 180. For example, second node 141 may schedule transmission of the UL signal to be a predetermined amount of time after the second node transmits, e.g., the UL grant signal to wireless device 101 via first node 121, where the predetermined amount of time may correspond to, e.g.: processing time, transmission delay, other delays, or any combination thereof.

In another embodiment, resources associated with, for example, SRS signals, PUCCH460, other channels, or any combination thereof, may be allocated by second node 141 but transmitted to wireless device 101 via first node 121. In this embodiment, wireless device 101 may provide a UL control signal to second node 141 using, for example, PUCCH460 of second communication link 180, where the UL control signal may include, for example: HARQ feedback signals, CQI signals, PMI signals, RI signals, SR signals, other signals, or any combination thereof. For example, second node 141 may allocate SRS signals, PUCCH460, other resources, or any combination thereof for wireless device 101 and transmit such resource allocation to first node 141 using backhaul channel 330 of third communication link 190. The first node 121 may then transmit a configuration of HARQ feedback signals, CQI signals, PMI signals, RI signals, SR signals, other signals, or any combination thereof, to the wireless device 101 using, for example, DL RRC signaling, other signaling, or both. In summary, resources for SRS signals, PUCCH460, other channels, or any combination thereof may be allocated by second node 141 and transmitted to wireless device 101 via first node 121.

Fig. 10 illustrates another embodiment of a distributed control channel structure 1000 of the system 100 in accordance with various aspects set forth herein. In this embodiment, first node 121 may transmit a DL data signal to wireless device 101 using first communication link 170. In response to such transmission, wireless device 101 may transmit a HARQ feedback signal to first node 121 via second node 141. The first node 121 may then determine whether to retransmit the DL data signal to the wireless device 101. For example, the first node 121 may transmit a DL data signal to the wireless device 101 using, for example, the PDSCH310 of the first communication link 170. In response to such transmission, wireless device 101 may transmit a HARQ feedback signal to second node 141 using, for example, PUCCH460 of second communication link 180. Further, the second node 141 may forward the HARQ feedback signal to the first node 121 using the backhaul channel 330 of the third communication link 190. The first node 121 may then determine whether to retransmit the DL data signal to the wireless device 101 using, for example, PDSCH310 of the first communication link 170.

In another embodiment, the transmission delay associated with forwarding a DL HARQ feedback signal (e.g., an ACK/NACK signal) from the second node 121 to the first node 141 using, for example, the third communication link 190 may require an increase in the number of processes related to the DL HARQ retransmission process to optimize the use of the available bandwidth. Further, the DL HARQ retransmission process may support asynchronous retransmissions to allow, for example, the first node 121 to schedule retransmission of DL signals for the wireless device 101 upon receiving forwarded DL HARQ feedback signals from the second node 141.

In another embodiment, instead of using PHICH470, a UL grant signal may be sent by first node 121 to wireless device 101 each time a retransmission of the UL signal is required. Unlike the asynchronous UL HARQ retransmission process described, for example, in LTE release 8, wireless device 101 may not perform retransmission of UL signals unless wireless device 101 receives a retransmission UL grant signal from first node 121. Wireless device 101 may 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 transmitting a UL HARQ feedback signal, such as an ACK/NACK signal, to wireless device 101 via first node 121, second node 141 may transmit a new data indicator ("NDI") signal to wireless device 101 via first node 121 to indicate the scheduling for the transmission of the new UL signal. For unsuccessful transmission of the UL signal by wireless device 101, second node 141 may transmit a new UL grant signal to wireless device 101 via first node 121 to schedule UL retransmission for wireless device 101. The UL grant signal may include an NDI signal, where the NDI signal may be used to indicate that the UL grant signal is associated with a new transmission or retransmission of the UL signal. Further, the HARQ process identifier signal may be included in the UL grant signal. Such an approach may allow wireless device 101 to maintain UL signals in, for example, memory 103 such that the UL signals are available for processes related to UL HARQ retransmission processes. Such memory may be reused once a UL grant signal for a new data transmission is received using, for example, PDCCH 430 of first communication link 170. Furthermore, avoiding the use of PHICH470 via the first communication link 170 may simplify the operation of the first node 121 by not requiring its configuration and use of PHICH470 in association with the transmission of PUSCH 320.

In another embodiment, wireless device 101 may transmit, to first node 121 via second node 141, a PMI signal, a CQI signal, an RI signal, other signals, or any combination thereof, associated with transmitting a DL signal from first node 121 to wireless device 101 via first communication link 170.

In another embodiment, second node 141 may measure channel quality using, for example, SRS signals received from wireless device 101 for wireless device 101 to transmit UL signals using second communication link 180. Those skilled in the art will recognize that: there are many methods of measuring channel quality using a received reference signal. Using such channel quality measurements, second node 141 may determine an appropriate modulation and coding scheme ("MCS") for transmitting the UL signal from wireless device 101. Further, second node 141 may include additional time for scheduling transmission of UL signals from wireless device 101 to compensate for any delay associated with second node 141 transmitting an associated UL grant signal to wireless device 101 via first node 121 using, for example, third communication link 190. This may require second node 141 to perform scheduling in advance and have a good estimate of the transmission delay of backhaul channel 330 of third communication link 190. Similarly, a TPC signal associated with transmitting an UL control signal from the wireless device 101 to the second node 121 using, for example, PUCCH460, PUSCH 320, or both of the second communication link 180 may be determined by the second node 141 and transmitted to the wireless device 101 via the first node 121.

In another embodiment, first node 121 and second node 141 may be tightly coupled using, for example, backhaul channel 330 of third communication link 190. In this configuration, the backhaul channel 330 of the third communication link 190 may experience more traffic than the independent control channel structures 400, 500, 600, and 700. In the distributed control channel structure 800, the UL grant signal, the TPC signal, or both, associated with PUSCH 320, PUCCH460, or both, may be transmitted from the second node 141 to the first node 121 using, for example, the backhaul channel 330 of the third communication link 190. Further, HARQ feedback signals, PMI signals, CQI signals, RI signals, other signals, or any combination thereof may be transmitted from second node 141 to first node 121 using, for example, backhaul channel 330 of third communication link 190. In this embodiment, the time delay for transmitting the UL signal using, for example, the backhaul channel 330 of the third communication link 190 may affect system performance. However, such time delays may be mitigated by, for example, using fiber optic cables between the backhaul interfaces 128 of the first node 121 and the second node 141.

A time synchronization problem between wireless device 101 and nodes 121 and 141 may occur due to the separation of UL and DL transmissions between first node 121 and second node 141. In one embodiment, nodes 121 and 141 may be time synchronized. This requirement may be inherent to various industry standards (e.g., LTE-a for type-I relay networks). For example, coordinated multipoint ("CoMP") transmission, reception, or both may require network time synchronization as described in the LTE and LTE-a standards. CoMP transmission, reception, or both may be used by LTE and LTE-a devices to improve, for example, data rates, cell-edge throughput, other advantages, or any combination thereof. Moreover, such CoMP techniques may be applied to multi-serving node wireless communication system 100 because first node 121 is on a routing path and may transmit data information, control information, or both to second node 141 using, for example, backhaul channel 330 of third communication link 190. Furthermore, as described in the LTE and LTE-a standards, multimedia broadcast multicast service ("MBMS") may require network time synchronization. MBMS uses multiple base stations, RNs, or both, to broadcast the same information to wireless devices. MBMS may require a synchronized network such that the wireless device only needs to maintain time synchronization with one node.

In a synchronized network, wireless device 101 need not maintain respective time synchronization with first node 121 and second node 141. This requirement may simplify the design of wireless device 101. For unsynchronized networks using independent control channel structures 400, 500, 600, and 700, wireless device 101 may need to maintain respective time synchronization with first node 121 and second node 141. For unsynchronized networks using distributed control channel structures 800, 900, and 1000, wireless device 101 may not need to maintain time synchronization with second node 141, as second node 141 may not transmit any DL signals to wireless device 101.

In an OFDM-based wireless communication system, a cyclic prefix ("CP") may be added to an OFDM symbol, for example, to reduce inter-symbol interference, maintain orthogonality between subcarriers, or both. In the LTE system, there may be a normal CP and an extended CP, wherein the normal CP has a shorter length than the extended CP. The LTE system may use extended CP to support, for example, larger cell sizes, MBMS services, other advantages, or any combination thereof. Although the wireless propagation paths between wireless device 101 and nodes 121 and 141 may include multiple paths, as specified for the LTE system, the length of the normal CP, extended CP, or both should be sufficient to support any delay between such multiple paths.

In multi-serving node wireless communication system 100, wireless device 101 may receive transmissions from both first node 121 and second node 141 in an RRC connected state. For this 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 in the size of a donor cell (donocell). The multipath delay spread (spread) between wireless device 101 and first node 121 and wireless device 101 and second node 141 may be different, but may be within the duration of a normal CP length or an extended CP length. An extended CP length may be used for nodes 121 and 141 to mitigate any problems associated with large multipath delay spreads.

Latency in the multi-service node wireless communication system 100 may affect quality of service ("QoS"). In the system 100, latency may increase due to, for example, the use of the backhaul channel 330 of the third communication link 190. In another embodiment, wireless device 101 may be directly connected to first node 121, transmitting both UL and DL signals to reduce latency for delay sensitive network services. In this embodiment, the first node 121 may be a base station and the second node 141 may be an RN.

The control plane latency is typically determined as the transition time from the idle state to the active state. Even though wireless device 100 may use a multi-serving node, wireless device 100 may still need to connect to first node 121 using a random access procedure. In the case where wireless device 101 can only make channel quality measurements of DL transmissions from first node 121 during the idle state and can only use the strongest received power to connect to first node 121 during the transition period. After obtaining the RRC connection, the first node 121 may negotiate with the second node associated with the transmission of the UL data signal and transfer such UL transmission to the other node. Thus, for the multi-service node wireless communication system 100, the control plane latency should not change.

The user plane latency may be defined as a one-way transmission time between session data unit ("SDU") packets available at the internet protocol ("IP") layer in wireless device 101 and session data unit ("SDU") packets available at the IP layer in nodes 121 and 141, or a one-way transmission time between session data unit ("SDU") packets available at the IP layer in nodes 121 and 141 and session data unit ("SDU") packets available at the IP layer in wireless device 101. The user plane packet delay may include delay introduced by, for example, associated protocols, control signaling, or both. For the independent control channel structures 400, 500, 600, and 700 in the multi-serving node wireless communication system 100, there is no additional delay for the wireless device 100 compared to the wireless device 101 in the single-serving node wireless communication system. As previously described, two independent control channel structures 400, 500, 600 and 700 are maintained for the first communication link 100 and the second communication link 200, and control signals are not exchanged using the communication link 300.

For distributed control channel structures 800, 900 and 1000, additional delays may occur due to frequent exchange of control signals, for example, between second node 141 and first node 121 via third communication link 190. Such a delay may be caused, for example, by transmitting a control signal (e.g., a HARQ feedback signal, a CQI signal, a PMI signal, an RI signal, other control signals, or any combination thereof) to the first node 121 or the second node 141, and forwarding such signal to the second node 141 or the 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 2msec associated with processing time from at first node 121 may require increasing the packet round trip time ("RTT") from, for example, 8msec as specified in "LTE release 8" to 14 msec. Furthermore, the number of HARQ processes may be increased to accommodate such an increase in RTT, so that nodes 121 and 141 do not need to wait for HARQ feedback signals forwarded from other nodes 121 and 141 before sending a new packet. If wireless device 101, first node 121, or second node 141 did not receive the packet correctly, the retransmission may occur 6msec later than the retransmission in the single serving node system. In LTE release 8, a maximum of 4 retransmissions are typically allowed for voice over IP ("VoIP") services. For the multi-serving node wireless communication system 100, 2 retransmissions may be allowed under this timing constraint. To minimize reliance on reducing the number of retransmissions, for example, for the initial transmission, wireless device 101 may use a more conservative MCS so that the packet may be correctly received with a higher probability for the initial transmission.

In summary, if independent control channel structures 400, 500, 600, and 700 are used, separating the reception of DL and UL transmissions from wireless device 101 between first node 121 and second node 141 should not result in additional control channel delays. On the other hand, if the distributed control channel structures 800, 900 and 1000 are used, the maximum number of retransmissions allowed in a particular period can be reduced. In this case, a more conservative MCS selection may be considered for the initial transmission.

In another embodiment, wireless device 101 may be operated under conditions such that a handover (handoff), or both may affect the connection of wireless device 101 to first node 121, second node 141, or both. For example, wireless device 101 may be required to handover from first node 121 to another node, for example, changing 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, for example, changing 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 may exist for wireless device 101 in system 100. For example, wireless device 101 may handoff from second node 141 to another second node and may determine its connection with first node 121. The wireless device may handoff from first node 121 to another first node and may maintain its connection with second node 141. Wireless device 101 may handoff from second node 141 to first node 121. Wireless device 101 may be handed off from first node 121 to second node 141. Wireless device 101 may handoff from first node 121 to another first node and may handoff from second node 141 to another second node. Wireless device 101 may 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 to switch. This may be signaled via higher layer signaling, such as RRC signaling. Further, more coordination may be needed when wireless device 101 simultaneously or contemporaneously switches first node 121 and second node 141.

Fig. 11 is a flow diagram of one embodiment of a method of providing a data signal in system 100, in accordance with various aspects set forth herein. In fig. 11, the method 1100 may begin, for example, at step 1110, where the method 1100 may transmit a DL data signal from the first node 121 to the wireless device 101 using the first communication link 170. At step 1120, method 1100 may transmit an UL data signal from wireless device 101 to second node 141 using second communication link 180. At step 1130, method 1100 may transmit an UL data signal from second node 141 to first node 121 using third communication link 190.

Fig. 12A is a flow diagram of one embodiment 1200a of a method 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 1200a may begin, for example, at step 1210, where method 1200a may transmit a DL control signal from first node 121 to wireless device 101 using first communication link 170, where the DL control signal may include, for example, a DL grant signal, other control signals, or both. At step 1220, method 1200a may transmit a UL control signal from wireless device 101 to first node 121 using first communication link 170, where the UL control signal may include, for example: ACK/NACK signals, CQI signals, PMI signals, RI signals, other control signals, or any combination thereof.

Fig. 12B is a flow diagram of another embodiment 1200B of a method of providing a control signal between first node 121 and wireless device 101 in system 100 in accordance with various aspects set forth herein. In fig. 12B, method 1200B may begin, for example, at step 1230, where method 1200B may transmit a DL control signal from first node 121 to wireless device 101 using first communication link 170, where the DL control signal may include, for example, a DL grant signal, other control signals, or both. At steps 1240 and 1260, method 1200b may transmit a UL control signal from wireless device 101 to first node 121 via second node 141, wherein the UL control signal may include, for example: ACK/NACK signals, CQI signals, PMI signals, RI signals, other control signals, or any combination thereof. At step 1240, method 1200b may transmit an UL control signal from wireless device 101 to second node 141 using second communication link 170. In step 1250, method 1200b may transmit a UL control signal from second node 141 to first node 121 using third communication link 190.

Fig. 13A is a flow diagram of one embodiment 1300a of a method 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 1300a may begin, for example, at step 1310, where method 1300a may transmit a UL control signal from wireless device 101 to second node 141 using second communication link 180, where the UL control signal may include an SR signal, an SRs signal, other control signals, or any combination thereof. At step 1320, method 1300a may transmit a DL control signal from second node 141 to wireless device 101 using second communication link 180, where the DL control signal may include, for example: UL grant signals, ACK/NACK signals, TPC signals, other control signals, or any combination thereof.

Fig. 13B is a flow diagram of another embodiment 1300B of a method 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 1300B may begin, for example, at step 1330, where method 1300B may transmit an UL control signal from wireless device 101 to second node 141 using second communication link 180, where the UL control signal may include an SR signal, an SRs signal, other control signals, or any combination thereof. At steps 1340 and 1350, method 1300b may transmit a DL control signal from second node 141 to wireless device 101 via first node 121, where the DL control signal may include, for example: UL grant signals, ACK/NACK signals, TPC signals, other control signals, or any combination thereof. At step 1340, method 1300b may transmit a DL control signal from second node 141 to first node 121 using third communication link 190. At step 1350, the method 1300b may transmit a DL control signal from the first node 121 to the wireless device 101 using the first communication link 170.

The example embodiments of the methods, devices and systems described herein, other variations, which have been shown and described, may be implemented by appropriate modifications by one of ordinary skill in the art without departing from the scope of the present disclosure. Several such possible modifications have been mentioned, and others will be apparent to those skilled in the art. For example, the above examples, embodiments, etc. are illustrative and not required. Accordingly, the scope of the present disclosure should be considered in the sense of the following claims and is not to be construed as being limited to the details of structure, operation and function shown and described in the specification and drawings.

As mentioned above, the described disclosure includes aspects set forth by the following.

Claims (20)

1. A method of wireless communication, comprising:

transmitting a downlink control signal from the first node to the wireless device using the first communication link;

the first node receiving an uplink control signal from the wireless device via a second node using a third communication link; and

the first node forwards another downlink control signal from the second node to the wireless device using the third communication link and the first communication link.

2. The method of claim 1, further comprising:

transmitting a downlink data signal from the first node to the wireless device using the first communication link; and

the first node receives an uplink data signal from the wireless device via the second node using the third communication link.

3. A method of wireless communication, comprising:

transmitting a downlink data signal from the first node to the wireless device using the first communication link;

the first node receiving an uplink data signal from the wireless device via a second node using a third communication link;

transmitting a downlink control signal from the first node to the wireless device using the first communication link; and

the first node receives an uplink control signal from the wireless device using the first communication link.

4. The method of claim 1, further comprising:

transmitting a downlink data signal from the first node to the wireless device using the first communication link; and

the first node receives an uplink data signal from the wireless device.

5. The method of claim 3, further comprising:

transmitting a downlink data signal from the first node to the wireless device using the first communication link; and

the first node receives an uplink data signal from the wireless device.

6. The method of claim 2, wherein the downlink data signal and the other downlink control signal are multiplexed on a physical downlink shared channel ("PDSCH") of the first communication link.

7. A method of wireless communication, comprising:

the second node forwards the uplink data signal from the wireless device to the first node using the second communication link and the third communication link;

transmitting a downlink control signal from the second node to the wireless device via the first node using the third communication link; and

the second node receives an uplink control signal from the wireless device using the second communication link.

8. A method of wireless communication, comprising:

the second node forwards uplink data signals from the wireless device to the first node using the second communication link and the third communication link;

transmitting a downlink control signal from the second node to the wireless device using the second communication link; and

the second node receives an uplink control signal from the wireless device using the second communication link.

9. The method of claim 7, wherein the uplink data signal and the uplink control signal are multiplexed on a physical uplink shared channel ("PUSCH") of the second communication link.

10. The method of claim 1, wherein the downlink control signal comprises at least one of: a downlink grant signal, an uplink grant signal, a timing adjustment signal, and a transmit power control ("TPC") signal; and

wherein the other downlink control signal comprises at least one of: a downlink grant signal, an uplink grant signal, a timing adjustment signal, and a transmit power control ("TPC") signal.

11. The method of claim 7, wherein the downlink control signal comprises at least one of: a downlink grant signal, an uplink grant signal, a timing adjustment signal, and a transmit power control ("TPC") signal.

12. The method of claim 1, wherein the first communication link comprises at least one of: a physical downlink shared channel ("PDSCH"), a physical downlink control channel ("PDCCH"), a physical uplink control channel ("PUCCH"), and a physical hybrid automatic repeat request indicator channel ("PHICH").

13. The method of claim 7, wherein the second communication link comprises at least one of: a physical uplink shared channel ("PUSCH"), a physical downlink control channel ("PDCCH"), a physical uplink control channel ("PUCCH"), and a physical hybrid automatic repeat request indicator channel ("PHICH").

14. The method of claim 1, wherein the first node and the second node are time synchronized.

15. A wireless communication node, comprising:

a processor coupled to a memory containing processor-executable instructions, wherein the processor is operative to:

transmitting a downlink control signal to a wireless device using a first communication link;

receiving an uplink control signal from the wireless device via another node using a third communication link; and

forwarding another downlink control signal from the other node to the wireless device using the third communication link and the first communication link.

16. The node of claim 15, wherein the processor is further operative to:

transmitting a downlink data signal to the wireless device using the first communication link; and

receiving an uplink data signal from the wireless device via the other node using the third communication link.

17. A wireless communication node, comprising:

a processor coupled to a memory containing processor-executable instructions, wherein the processor is operative to:

transmitting a downlink data signal from the first node to the wireless device using the first communication link;

the first node receiving an uplink data signal from the wireless device via a second node using a third communication link;

transmitting a downlink control signal from the first node to the wireless device using the first communication link; and

the first node receives an uplink control signal from the wireless device using the first communication link.

18. A wireless communication node, comprising:

a processor coupled to a memory containing processor-executable instructions, wherein the processor is operative to:

transmitting a downlink control signal to the wireless device via the other node using the third communication link;

receiving an uplink control signal from the wireless device using a second communication link; and

forwarding another uplink control signal from the wireless device to another node using the second communication link and the third communication link.

19. The node of claim 18, wherein the processor is further operative to:

forwarding an uplink data signal from the wireless device to the other node using the second communication link and the third communication link.

20. A wireless communication node, comprising:

a processor coupled to a memory containing processor-executable instructions, wherein the processor is operative to:

forwarding an uplink data signal from the wireless device to another node using the second communication link and the third communication link;

transmitting a downlink control signal to the wireless device using the second communication link; and

receiving an uplink control signal from the wireless device using the second communication link.