Robust relay retransmissions with dual-coding

A signal forwarding device receives a dual-encoded first set of data that is encoded according to first and second sets of encoding parameters. The signal forwarding device decodes the dual-encoded first set of data, using decoding parameters that correspond to the second set of encoding parameters, to generate a single-encoded first set of data that is encoded according to the first set of encoding parameters. The signal forwarding device transmits the single-encoded first set of data to the destination device, which decodes the single-encoded first set of data using decoding parameters that correspond to the first set of encoding parameters. If the decoding is unsuccessful, the destination device requests retransmission. The signal forwarding device decodes a stored copy of the single encoded first set of data, using decoding parameters that correspond to the first set of encoding parameters, and retransmits the first set of data to the destination device.

FIELD

This invention generally relates to wireless communications and more particularly to dual-coding transmissions to a signal forwarding device.

BACKGROUND

Some communication systems utilize a signal forwarding device, such as a repeater station, relay station or a self-backhauled station to facilitate the transfer of information between user equipment (UE) devices and a core network. The signal forwarding device is typically not connected directly to the core network but still provides service to the UE devices by forwarding information to and from the UE devices and a base station, which is connected to the core network. Where the signal forwarding device is a repeater, the repeater simply retransmits downlink signals received from another base station to the UE device and retransmits uplink signals received from the UE device to the other base station. Although the repeater may apply limited signal processing to the incoming signal such as filtering, frequency shifting, and amplification, a repeater will not decode the incoming signal that is to be forwarded. Relay stations and self-backhaul stations perform at least some signal processing before retransmitting the information. Such processing can vary from partial decoding to complete decoding of the incoming signal. For example, the incoming signal can be completely decoded and used to generate a new signal or the incoming signal may not be completely decoded but still used to transmit the forwarded outgoing signal. Some of the various levels of processing (forwarding techniques) are sometimes referred to as amplify and forward (AF), partial decoding and forward (PDF), and decode and forward (DF) schemes.

SUMMARY

A signal forwarding device receives a dual-encoded first set of data. The dual-encoded first set of data is encoded according to a first set of encoding parameters that correspond to channel conditions associated with a first communication link between the signal forwarding device and a destination device. The dual-encoded first set of data is further encoded according to a second set of encoding parameters that correspond to channel conditions associated with a second communication link between an origination device and the signal forwarding device. Upon receipt of the dual-encoded first set of data, the signal forwarding device decodes the dual-encoded first set of data, using decoding parameters that correspond to the second set of encoding parameters, to generate a single-encoded first set of data that is encoded according to the first set of encoding parameters. The signal forwarding device transmits the single-encoded first set of data to the destination device, which attempts to decode the single-encoded first set of data using decoding parameters that correspond to the first set of encoding parameters. If the decoding is successful, the destination device has successfully received the first set of data. If, however, the decoding is unsuccessful, the destination device requests retransmission from the signal forwarding device. In response to the retransmission request, the signal forwarding device retrieves a stored copy of the single encoded first set of data from a memory of the signal forwarding device. The signal forwarding device decodes the retrieved copy of the single encoded first set of data, using decoding parameters that correspond to the first set of encoding parameters, and retransmits the first set of data to the destination device.

DETAILED DESCRIPTION

As discussed above, communication systems often employ repeaters, relays and self-backhauled base stations to forward signals transmitted between base stations and the UE devices served by the base stations. Signals may be forwarded from the base station to the UE device, from the UE device to the base station, or both. In some systems, scheduling of communication resources for the communication channel between the signal forwarding device (e.g., repeater, relay, etc.) and the UE device is performed by a scheduler at the base station or a central scheduler connected to the base station. In the examples discussed herein, it is assumed that the scheduler is located at, or connected to, a base station to/from which the signal forwarding device forwards signals. However, the scheduler may not be physically located at the base station and may be located at any other suitable location (e.g., at the signal forwarding device or elsewhere in the radio access network to which the base station belongs).

In a typical relay scenario, an anchor base station would only single-encode data, which is intended for a destination device, using encoding parameters that are appropriate for the channel conditions between the base station and the relay node. Upon receipt of the transmission from the base station, the relay node would decode the data and subsequently encode the data using encoding parameters that are appropriate for the channel conditions between the relay and the destination device (e.g., UE device). One drawback of such a scenario is the additional processing delay experienced at the relay while the relay encodes the data before transmitting the data to the destination device. Another drawback of a typical relay scenario would be the delay experienced when waiting for the origination device to retransmit a data packet that was not successfully received by the destination device. However, for the examples discussed herein, various methods, devices, and systems will be described in which (1) an anchor base station transmits a dual-encoded signal that does not require any encoding by the signal forwarding device (e.g., relay) in order to send an initial transmission of data to the destination device, and (2) the relay is capable of decoding the “inner” layer of encoding of the dual-encoded signal so that the relay can retransmit a data packet that was not successfully received by the destination device, without waiting for the base station to retransmit the data packet.

Since the signal forwarding device is central to the examples, the nomenclature used throughout the description centers on the signal forwarding device. More specifically, an “origination device” is a device from which a signal is transmitted to the signal forwarding device, and the signal being received at the signal forwarding device from an origination device is referred to as a “received signal.” Similarly, a “destination device” is a device to which the signal forwarding device transmits a signal, which is referred to herein as a “forwarded signal.” Moreover, although most of the following examples refer to a base station as the “origination device” and to a UE device as the “destination device,” the examples may be modified so that the UE device is the “origination device,” and the base station is the “destination device.”

FIG. 1Ais a block diagram of an example of the circuitry utilized within a dual-encoding origination device, a signal forwarding device, and a destination device to transmit multiuser packets. For example, the various blocks shown inFIG. 1Arepresent circuitry that is configured to perform various functions and processes described herein. Although each function is shown as a separate box, the circuitry that actually performs the recited functions for each box may be configured to perform the functions for multiple boxes. For example, a controller within the origination device, the signal forwarding device, and/or the destination device may be the circuitry that is configured to perform one or more of the functions shown inFIG. 1A.

The origination device110and destination device114may be any kind of wireless communication devices and may be stationary or portable. For the examples discussed herein, the origination device110is a base station, and the destination device114is a user equipment (UE) device such as a handset. However, the devices110,114may be different types of devices in other circumstances. For example, both devices may be UE devices. In some situations, the origination device, the signal forwarding device, and the destination device are all UE devices. In still other situations, the origination device110is a UE device, and the destination device114is a base station.

In the example ofFIG. 1A, origination device110provides downlink wireless communication service to destination device114. Thus, destination device114receives downlink signals from origination device110, either directly or via signal forwarding device138. In the example ofFIG. 1A, origination device110transmits a dual-encoded data signal to signal forwarding device138, and signal forwarding device138forwards a single-encoded data signal to the destination device114.

For example, origination device110either generates the first set of user data160or receives the first set of user data160from another entity within the radio access network. In the example shown inFIG. 1A, the first set of user data160includes user data associated with one or more users. The origination device110has circuitry configured to add a first cyclic redundancy check value (CRC1)162to the first set of user data. The CRC is an error-detecting code that is used to detect if the received data at the receiver is in error or not. Although the examples shown herein utilize CRC, any suitable error-detection techniques may be used.

After adding CRC1, the first set of user data is encoded by Encoder1,164. Encoder1encodes the first set of user data according to a first set of encoding parameters corresponding to channel conditions associated with a first communication link between the signal forwarding device138and the destination device114. The first set of encoding parameters comprises a first encoding technique and/or a first encoding rate. The result of encoding the first set of user data160with Encoder1is a single-encoded first set of user data.

In the example shown inFIG. 1A, a second CRC value (CRC2)166is added to the single-encoded first set of user data. Although a CRC is used for CRC2, any suitable alternative error-detection technique may be used in place of CRC2. The single-encoded first set of user data, along with CRC2, is encoded by Encoder2,168, which, in the example shown inFIG. 1A, utilizes a non-iterative type encoding/decoding (e.g., Reed-Solomon Codes) to ensure low-latency processing at the signal forwarding device138. Encoder2encodes the single-encoded first set of user data according to a second set of encoding parameters corresponding to channel conditions associated with a second communication link between the origination device110and the signal forwarding device138. The second set of encoding parameters comprises a second encoding technique and/or a second encoding rate. The result of encoding the single-encoded first set of user data with Encoder2is a dual-encoded first set of user data.

One of the advantages of dual-encoding the data is that the encoding parameters selected for each stage of encoding can be selected based on the channel conditions for a particular communication link. For example, Encoder1may encode the first set of user data according to an encoding technique that is better suited for transmissions between a signal forwarding device and a destination device (e.g., mobile UE device). Encoder2may encode the single-encoded first set of user data according to a second encoding technique that is better suited for transmissions between an origination device (e.g., base station) and a signal forwarding device. For example, the first encoding technique may utilize a convolutional coding, which is better suited for transmissions between a signal forwarding device and a destination device, and the second encoding technique may be a turbo coding or rate-less channel coding using the Low Density Parity Codes (LDPC), which is better suited for transmissions between an origination device and a signal forwarding device. However, any of the channel coding techniques may be used for the origination device-to-signal forwarding device channel or the signal forwarding device-to-destination device channel.

Similarly, Encoder1may encode the first set of user data at a coding rate that is better suited for transmissions between a signal forwarding device and a destination device (e.g., mobile UE device), and Encoder2may encode the single-encoded first set of user data at a different coding rate that is better suited for transmissions between an origination device (e.g., base station) and a signal forwarding device. More specifically, the first set of user data may be encoded at a 1/3 coding rate to obtain the single-encoded first set of user data, and the single-encoded first set of user data may be encoded at a 2/3 coding rate to obtain the dual-encoded first set of user data, for example.

Regardless of the particular encoding parameters used, the dual-encoded first set of user data is modulated by modulator170of origination device110. In the example shown inFIG. 1A, Quadrature Amplitude Modulation (QAM) is used. However, any other suitable modulation scheme may be used. Moreover, the modulation scheme utilized by modulator170may also be selected based on the channel conditions between the origination device110and the signal forwarding device138. The modulation of the dual-encoded first set of user data yields a dual-encoded received signal136.

Origination device110utilizes transmitter122to transmit the dual-encoded received signal136to signal forwarding device138, which receives the transmission via receiver142. The demodulator172of signal forwarding device138demodulates the dual-encoded received signal136using a demodulation scheme that corresponds to the modulation scheme utilized by modulator170. The demodulation of the dual-encoded received signal136yields the dual-encoded first set of user data.

The Decoder2,174, decodes the dual-encoded first set of user data, using decoding parameters that correspond to the second set of encoding parameters, which were used by Encoder2,168, of the origination device110to encode the single-encoded first set of user data. The result of decoding the dual-encoded first set of user data with Decoder2is the single-encoded first set of user data, which is encoded according to the first set of encoding parameters.

After decoding, the second CRC value (CRC2), which was added to the single-encoded first set of user data by the origination device110, is checked by CRC2Check176, which detects whether any errors are present in the single-encoded first set of user data after decoding. If the CRC2Check176detects an error, signal forwarding device138can send a negative acknowledgment response (NACK) to the origination device110, indicating that the dual-encoded received signal136was not successfully received. If the CRC2Check176does not detect an error, signal forwarding device138can send a positive acknowledgment response (ACK) to the origination device110, indicating that the dual-encoded received signal136was successfully received. Moreover, if there are no errors, signal forwarding device138forwards the single-encoded first set of user data to the modulator178and additionally stores a copy of the single-encoded first set of user data in memory188, to potentially be used at a later time, as will be discussed more fully below.

Modulator178of signal forwarding device138modulates the single-encoded first set of user data. In the example shown inFIG. 1A, Quadrature Amplitude Modulation (QAM) is used by modulator178. However, any other suitable modulation scheme may be used. Moreover, the modulation scheme utilized by modulator178may also be selected based on the channel conditions between the signal forwarding device138and the destination device114. The modulation of the single-encoded first set of user data yields a single-encoded forwarded signal148.

Signal forwarding device138utilizes transmitter146to transmit a first single-encoded forwarded signal148to the destination device114, which receives the transmission via a receiver130. The demodulator180of the destination device114demodulates the first single-encoded forwarded signal148using a demodulation scheme that corresponds to the modulation scheme utilized by modulator178. The demodulation of the first single-encoded forwarded signal148yields the single-encoded first set of user data contained in the first single-encoded forwarded signal148.

The Decoder1,182, of the destination device114decodes the single-encoded first set of user data using decoding parameters that correspond to the first set of encoding parameters, which were used by Encoder1,164, of the origination device110to encode the first set of user data. The result of decoding the single-encoded first set of user data with Decoder1is the first set of user data. After decoding, the first CRC value (CRC1), which was added to the first set of user data by the origination device110, is checked by CRC1Check184, which detects whether any errors are present in the first set of user data after decoding.

If the CRC1Check184does not detect an error, the destination device114can send a positive acknowledgment response (ACK) to the signal forwarding device138and/or the origination device110, indicating that the first single-encoded forwarded signal148was successfully received. If the destination device114sends an ACK to the origination device110, the ACK can be sent either directly to the origination device110or to the origination device110via signal forwarding device138. If there are no errors detected by CRC1Check184, destination device114has successfully received and decoded the first set of user data (e.g., received user data186).

Thus, by dual-encoding the first set of user data at origination device110with first and second sets of encoding parameters that are selected based on the channel conditions associated with (1) the communication link between the signal forwarding device138and the destination device114, and (2) the communication link between the origination device110and the signal forwarding device138, respectively, a more robust data delivery system is created.

However, if the CRC1Check184detects an error, destination device114sends a negative acknowledgment response (NACK) to the signal forwarding device138and/or the origination device110, indicating that the first single-encoded forwarded signal148was not successfully received and/or decoded. The NACK is considered, for this example, to be a request for retransmission of the single-encoded forwarded signal, which will be transmitted by the signal forwarding device138. For example, upon receiving the NACK, the signal forwarding device138retrieves the stored copy of the single-encoded first set of user data from memory188. Decoder1,190, of signal forwarding device138decodes the retrieved single-encoded first set of user data, using decoding parameters that correspond to the first set of encoding parameters. The result of decoding the single-encoded first set of user data with Decoder1,190, is the first set of user data.

Although Decoder1,190, is shown separately from Decoder2,174, in the example ofFIG. 1A, the circuitry that performs the functionality of Decoder1,190, may be the same circuitry utilized to perform the functionality of Decoder2,174. For example, controller144ofFIG. 1Bmay be configured to perform the functionality required by Decoder2,174, and Decoder1,190. In other examples, different circuitry may be utilized to perform the functionality required by Decoder2,174, and Decoder1,190, respectively.

After decoding with Decoder1,190, the first CRC value (CRC1), which was added to the first set of user data by the origination device110, is checked by CRC1Check192, which detects whether any errors are present in the first set of user data after decoding. If the CRC1Check192does not detect an error, the signal forwarding device138can send a positive acknowledgment response (ACK) to the origination device110, indicating that the signal forwarding device138has successfully received and decoded the first set of user data (e.g., received user data186). However, if the CRC1Check192detects an error, the signal forwarding device138sends a negative acknowledgment response (NACK) to the origination device110, indicating that the first dual-encoded received signal136was not successfully received. The NACK is considered, for this example, to be a request for retransmission of the dual-encoded received signal136, which will be transmitted by the origination device110.

The signal forwarding device138has circuitry configured to add a third cyclic redundancy check value (CRC3)196to the first set of user data. The CRC is an error-detecting code that is used to detect if the received packet at the receiver is in error or not. Although the examples shown herein utilize CRC, any suitable error-detection techniques may be used. After adding CRC3, the first set of user data is encoded by Encoder3,198. Encoder3encodes the first set of user data according to a third set of encoding parameters corresponding to channel conditions associated with the communication link between the signal forwarding device138and the destination device114. The third set of encoding parameters comprises a third encoding technique and/or a third encoding rate.

In the example shown inFIG. 1A, the third set of encoding parameters may differ from the first set of encoding parameters, which were initially used by Encoder1,164, of the origination device110to encode the first set of user data. More specifically, the encoding technique and/or encoding rate of the third set of encoding parameters may differ from the first set of encoding parameters. The result of encoding the first set of user data with Encoder3is a second single-encoded first set of user data.

Modulator178of signal forwarding device138modulates the second single-encoded first set of user data. In the example shown inFIG. 1A, Quadrature Amplitude Modulation (QAM) is used by modulator178. However, any other suitable modulation scheme may be used. For example, the modulation scheme utilized by modulator178may be selected based on the channel conditions between the signal forwarding device138and the destination device114. Moreover, the modulation scheme and/or modulation order used by modulator178to modulate the second single-encoded first set of user data may differ from the modulation scheme and/or modulation order utilized to modulate the first single-encoded forwarded signal148. The modulation of the second single-encoded first set of user data yields a second single-encoded forwarded signal148.

Signal forwarding device138utilizes transmitter146to transmit the second single-encoded forwarded signal148to the destination device114. In the example shown inFIG. 1A, the transmit power used to transmit the second single-encoded forwarded signal148may differ from the transmit power used to transmit the first single-encoded forwarded signal148to the destination device114. The destination device114receives the second single-encoded forwarded signal148via receiver130. Upon receipt of the second single-encoded forwarded signal148, the demodulator180of the destination device114demodulates the second single-encoded forwarded signal148using a demodulation scheme that corresponds to the modulation scheme utilized by modulator178. The demodulation of the second single-encoded forwarded signal148yields the single-encoded first set of user data contained in the second single-encoded forwarded signal148.

The Decoder1,182, of the destination device114decodes the single-encoded first set of user data using decoding parameters that correspond to the third set of encoding parameters, which were used by Encoder3,198, of the signal forwarding device138to encode the first set of user data. The result of decoding the single-encoded first set of user data with Decoder1,182, is the first set of user data. After decoding, the third CRC value (CRC3), which was added to the first set of user data by the signal forwarding device138, is checked by CRC3Check (not shown inFIG. 1A), which detects whether any errors are present in the first set of user data after decoding.

CRC3Check is not shown inFIG. 1Asince it is presumed that the same circuitry that performs the functions of CRC1Check,184, is further configured to perform the functions of CRC3Check. For example, controller128ofFIG. 1Bmay be configured to perform the functionality required by CRC1Check,184, and CRC3Check. In other examples, different circuitry may be utilized to perform the functionality required by CRC1Check,184, and CRC3Check, respectively. Similarly, although CRC2Check,176, is shown separately from CRC1Check,192, in the example ofFIG. 1A, the circuitry that performs the functionality of CRC1Check,192, may be the same circuitry utilized to perform the functionality of CRC2Check,176. For example, controller144ofFIG. 1Bmay be configured to perform the functionality required by CRC1Check,192, and CRC2Check,176. In other examples, different circuitry may be utilized to perform the functionality required by CRC1Check,192, and CRC2Check,176, respectively.

If the CRC3Check does not detect an error, the destination device114can send a positive acknowledgment response (ACK) to the signal forwarding device138and/or the origination device110, indicating that the second single-encoded forwarded signal148was successfully received. If the destination device114sends an ACK to the origination device110, the ACK can be sent either directly to the origination device110or to the origination device110via signal forwarding device138. If there are no errors detected by CRC3Check, destination device114has successfully received and decoded the first set of user data (e.g., received user data186).

Thus, the signal forwarding device138decodes the encoding that was applied by Encoder1,164, and retransmits the first set of user data to the destination device114. In some examples, the signal forwarding device138retransmits the first set of user data, utilizing one or more different transmission, modulation, and/or encoding parameters than those used to initially transmit the first set of user data to the destination device114. The signal forwarding device138may select the one or more different transmission, modulation, and/or encoding parameters based on channel conditions associated with the communication link between the signal forwarding device138and the destination device114. Thus, this improved method and system efficiently avoids the additional latency experienced in a typical relay scenario that would require the signal forwarding device to transmit the NACK to the origination device and wait for the retransmission from the origination device before the signal forwarding device can retransmit data to the destination device that transmitted the NACK.

If CRC3Check detects an error, destination device114sends a negative acknowledgment response (NACK) to the signal forwarding device138, indicating that the second single-encoded forwarded signal148was also not successfully received and/or decoded. In response, the signal forwarding device138shown in the example ofFIG. 1Afurther modifies one or more of the transmission, modulation, and/or encoding parameters and retransmits the user data to the destination device114. In other examples, the signal forwarding device138forwards the NACK to the origination device110so that the origination device110can retransmit the first set of user data.

The preceding description of the example shown inFIG. 1Ashows that the signal forwarding device138does not use Decoder1,190, to decode the single-encoded first set of user data until a NACK is received from destination device114. However, in other examples, Decoder1,190, may be used to decode the single-encoded first set of user data, without waiting for a NACK to be received from destination device114. For example, the signal forwarding device138may automatically decode the single-encoded first set of user data, using Decoder1,190, and store a copy of the first set of user data, and if a NACK is subsequently received from the destination device114, the signal forwarding device138can efficiently retransmit the first set of user data without having to retrieve and decode the single-encoded first set of user data.

FIG. 1Bis a block diagram of an example of a wireless communication system100including an origination device, a signal forwarding device, and a destination device. Although, the system100only shows one signal forwarding device and only one destination device, the system100may include multiple signal forwarding devices that each serve one or more destination devices. The origination device110and destination device114may be any kind of wireless communication devices and may be stationary or portable. For the examples discussed herein, the origination device110is a base station, and the destination device114is a user equipment (UE) device such as a handset. However, the devices110,114may be different types of devices in other circumstances. For example, both devices may be UE devices. In some situations, the origination device, the signal forwarding device, and the destination device are all UE devices. In still other situations, the origination device110is a UE device, and the destination device114is a base station.

In the example ofFIG. 1B, origination device110provides downlink wireless communication service to destination device114. Thus, destination device114receives downlink signals (not shown) from origination device110, either directly or via signal forwarding device138. The downlink signals are received at the destination device114through antenna124and receiver130. Destination device114further comprises a controller128and a transmitter126. Origination device110transmits the downlink signals to destination device114and to signal forwarding device138via antenna116and transmitter122.

Origination device110further comprises controller120and transmitter122, as well as other electronics, hardware, and code. The origination device110is any fixed, mobile, or portable equipment that performs the functions described herein. The various functions and operations of the blocks described with reference to the origination device110may be implemented in any number of devices, circuits, or elements. Two or more of the functional blocks may be integrated in a single device, and the functions described as performed in any single device may be implemented over several devices.

For the example shown inFIG. 1B, the origination device110may be a fixed device or apparatus that is installed at a particular location at the time of system deployment. Examples of such equipment include fixed base stations or fixed transceiver stations. In some situations, the origination device110may be mobile equipment that is temporarily installed at a particular location. Some examples of such equipment include mobile transceiver stations that may include power generating equipment such as electric generators, solar panels, and/or batteries. Larger and heavier versions of such equipment may be transported by trailer. In still other situations, the origination device110may be a portable device that is not fixed to any particular location. Accordingly, the origination device110may be a portable user device such as a UE device in some circumstances.

The controller120includes any combination of hardware, software, and/or firmware for executing the functions described herein as well as facilitating the overall functionality of the origination device110. An example of a suitable controller120includes code running on a microprocessor or processor arrangement connected to memory. The transmitter122includes electronics configured to transmit wireless signals. In some situations, the transmitter122may include multiple transmitters. The receiver118includes electronics configured to receive wireless signals. In some situations, the receiver118may include multiple receivers. The receiver118and transmitter122receive and transmit signals, respectively, through an antenna116. The antenna116may include separate transmit and receive antennas. In some circumstances, the antenna116may include multiple transmit and receive antennas.

The transmitter122and receiver118in the example ofFIG. 1Bperform radio frequency (RF) processing including modulation and demodulation. The receiver118, therefore, may include components such as low noise amplifiers (LNAs) and filters. The transmitter122may include filters and amplifiers. Other components may include isolators, matching circuits, and other RF components. These components in combination or cooperation with other components perform the origination device functions. The required components may depend on the particular functionality required by the origination device.

The transmitter122includes modulator170(shown inFIG. 1A), and the receiver118includes a demodulator (not shown). The modulator170modulates the signals to be transmitted as part of the dual-encoded received signal136and can apply any one of a plurality of modulation orders. The demodulator demodulates any signals received at the origination device110in accordance with one of a plurality of modulation orders.

Scheduler132is located at origination device110in the example shown inFIG. 1B. However, the system100could be modified so that the scheduler132is located at any other suitable location. Regardless of the location of scheduler132, the system100may be configured so that multiple entities within the radio access network (e.g., different origination devices, different signal forwarding devices, and different destination devices) can access the scheduler132. For example, in an ad-hoc topology, a first origination device can access the scheduler132and transmit a dual-encoded received signal to the signal forwarding device at a given time, but a second origination device can access the scheduler132and transmit a dual-encoded received signal to the signal forwarding device at a second, different time.

The scheduler may be an application running on equipment connected directly to origination device110or connected through a backhaul or other communication link. Regardless of the location of scheduler132, channel quality information (CQI)134regarding the various communication links within the system100is provided to scheduler132, which uses the CQI134to schedule communication resources to be used by the various entities within the system100. For the example shown inFIG. 1B, the scheduler132utilizes CQI pertaining to the communication link between the origination device110and the destination device114, CQI pertaining to the communication link between the origination device110and the signal forwarding device138, and CQI pertaining to the communication link between the signal forwarding device138and the destination device114. Based on the channel quality for at least one of these three communication links, the scheduler132schedules communication resources.

As discussed above, origination device110ofFIG. 1Btransmits a dual-encoded received signal136(e.g. a downlink signal) to the signal forwarding device138, which receives the dual-encoded received signal136via antenna140and receiver142. The signal forwarding device138further comprises controller144and transmitter146, as well as other electronics, hardware, and code. The signal forwarding device138is any fixed, mobile, or portable equipment that performs the functions described herein. The various functions and operations of the blocks described with reference to the signal forwarding device138may be implemented in any number of devices, circuits, or elements. Two or more of the functional blocks may be integrated in a single device, and the functions described as performed in any single device may be implemented over several devices.

For the example shown inFIG. 1B, the signal forwarding device138may be a fixed device or apparatus that is installed at a particular location at the time of system deployment. Examples of such equipment include fixed base stations or fixed transceiver stations. In some situations, the signal forwarding device138may be mobile equipment that is temporarily installed at a particular location. Some examples of such equipment include mobile transceiver stations that may include power generating equipment such as electric generators, solar panels, and/or batteries. Larger and heavier versions of such equipment may be transported by trailer.

In still other situations, the signal forwarding device138may be a portable device that is not fixed to any particular location. Accordingly, the signal forwarding device138may be a portable user device such as a UE device in some circumstances. In some implementations, the signal forwarding device138may be a base station, eNB, or access point that performs signal forwarding functions in addition to serving UE devices. For example, a self-backhauled eNB, connected to an anchor eNB, may be configured to perform signal forwarding functions for some UE devices in addition to directly serving other UE devices utilizing the wireless backhaul to the origination device110(e.g., anchor eNB). In other implementations, the signal forwarding device138may be a drone with cellular capability. Such a drone can easily move about towards locations where the existing coverage from fixed base stations is lacking.

The controller144includes any combination of hardware, software, and/or firmware for executing the functions described herein as well as facilitating the overall functionality of the signal forwarding device138. An example of a suitable controller144includes code running on a microprocessor or processor arrangement connected to memory. The transmitter146includes electronics configured to transmit wireless signals. In some situations, the transmitter146may include multiple transmitters. The receiver142includes electronics configured to receive wireless signals. In some situations, the receiver142may include multiple receivers. The receiver142and transmitter146receive and transmit signals, respectively, through an antenna140. The antenna140may include separate transmit and receive antennas. In some circumstances, the antenna140may include multiple transmit and receive antennas.

The transmitter146and receiver142in the example ofFIG. 1Bperform radio frequency (RF) processing including modulation and demodulation. The receiver142, therefore, may include components such as low noise amplifiers (LNAs) and filters. The transmitter146may include filters and amplifiers. Other components may include isolators, matching circuits, and other RF components. These components in combination or cooperation with other components perform the signal forwarding functions. The required components may depend on the particular signal forwarding scheme that is employed.

The transmitter146includes modulator178(shown inFIG. 1A), and the receiver142includes demodulator172(shown inFIG. 1A). The modulator modulates the signals to be transmitted as part of the single-encoded forwarded signal148and can apply any one of a plurality of modulation orders. The demodulator demodulates the dual-encoded received signal136in accordance with one of a plurality of modulation orders. The modulation order for transmissions to the destination device114, however, is established by scheduler132.

As is known, the modulation order determines the number of bits used to generate the modulated symbol. There is a trade-off between modulation order, required energy, and bit-error rate (BER). As the modulation order is increased, the average energy per bit must also be increased to maintain the same BER. In the example shown inFIG. 1B, the signal forwarding device138utilizes a lower-order modulation symbol to modulate the single-encoded first set of user data before transmitting the single-encoded forwarded signal148. This scenario occurs because a typical link between the signal forwarding device138and the destination device114has a relatively lower signal-to-noise ratio (SNR) compared to the link between the origination device110and the signal forwarding device138. In some situations, for example, the origination device-to-signal forwarding device (OD-SFD) channel between the origination device110and the signal forwarding device138is typically static because both devices are fixed, whereas the signal forwarding device-to-destination device (SFD-DD) channel between the signal forwarding device138and the destination device114is generally dynamic because the destination device114is mobile. Accordingly, the origination device110may utilize a higher-order modulation order when the communication link between the origination device110and the signal forwarding device138is static, which yields a relatively higher SNR compared to the communication link between the signal forwarding device138and the destination device114.

As described above, the signal forwarding device138receives the dual-encoded received signal136with antenna140and receiver142. The signal forwarding device138demodulates the dual-encoded received signal136with demodulator172ofFIG. 1A, which yields the dual-encoded first set of user data. The dual-encoded first set of user data is decoded with Decoder2,174, ofFIG. 1A, which yields a single-encoded first set of user data.

Upon successful decoding by Decoder2, signal forwarding device138modulates the single-encoded first set of user data with modulator178ofFIG. 1A, which yields a first single-encoded forwarded signal148. The signal forwarding device138transmits the first single-encoded forwarded signal148via transmitter146and antenna140to the destination device114. For the examples discussed herein, the single-encoded forwarded signals148are transmitted within a single frequency band of the SFD-DD channel. The incoming dual-encoded received signal136is transmitted within an origination device-to-signal forwarding device channel (OD-SFD channel), which also includes a single frequency band. However, any combination of frequency bands and frequency sub-bands may be used for the OD-SFD channel and the SFD-DD channel.

In some examples, upon receiving the dual-encoded received signal136, the controller144of the signal forwarding device138is configured to measure the dual-encoded received signal136to obtain channel measurements associated with the OD-SFD channel between the origination device110and the signal forwarding device138. After measuring the dual-encoded received signal136, the transmitter146of the signal forwarding device138transmits the OD-SFD channel measurements to the origination device110. The OD-SFD channel measurements are transmitted to origination device110, as indicated by dashed signal line154inFIG. 1B. In this manner, the origination device110, using receiver118, receives channel feedback regarding the channel conditions associated with the communication link between the origination device110and the signal forwarding device138. Of course, in other examples, the origination device110can also obtain its own channel measurements regarding the channel conditions associated with the communication link between the origination device110and the signal forwarding device138by measuring incoming signals from the signal forwarding device138. After receiving the OD-SFD channel feedback, origination device110can modify one or more of the transmission, modulation, and/or encoding parameters used by transmitter122, modulator170, and Encoder2,168, respectively, based on the received channel feedback regarding the channel conditions associated with the communication link between the origination device110and the signal forwarding device138.

The destination device114receives the first single-encoded forwarded signal148via antenna124and receiver130. The destination device114further comprises controller128and transmitter126, as well as other electronics, hardware, and code. The destination device114is any fixed, mobile, or portable equipment that performs the functions described herein. The various functions and operations of the blocks described with reference to the destination device114may be implemented in any number of devices, circuits, or elements. Two or more of the functional blocks may be integrated in a single device, and the functions described as performed in any single device may be implemented over several devices.

The controller128includes any combination of hardware, software, and/or firmware for executing the functions described herein as well as facilitating the overall functionality of the destination device114. An example of a suitable controller128includes code running on a microprocessor or processor arrangement connected to memory. The transmitter126includes electronics configured to transmit wireless signals. In some situations, the transmitter126may include multiple transmitters. The receiver130includes electronics configured to receive wireless signals. In some situations, the receiver130may include multiple receivers. The receiver130and transmitter126receive and transmit signals, respectively, through an antenna124. The antenna124may include separate transmit and receive antennas. In some circumstances, the antenna124may include multiple transmit and receive antennas.

The transmitter126and receiver130in the example ofFIG. 1Bperform radio frequency (RF) processing including modulation and demodulation. The receiver130, therefore, may include components such as low noise amplifiers (LNAs) and filters. The transmitter126may include filters and amplifiers. Other components may include isolators, matching circuits, and other RF components. These components in combination or cooperation with other components perform the destination device functions. The required components may depend on the particular functionality required by the destination device.

The transmitter126includes a modulator (not shown), and the receiver130includes demodulator180(shown inFIG. 1A). The modulator modulates the signals to be transmitted as part of the channel measurement signals150,152and can apply any one of a plurality of modulation orders. The demodulator demodulates the single-encoded forwarded signals148in accordance with one of a plurality of modulation orders.

As described above, the destination device114receives the single-encoded forwarded signals148with antenna124and receiver130. The destination device114demodulates the first single-encoded forwarded signal148with demodulator180ofFIG. 1A, which yields the single-encoded first set of user data. The single-encoded first set of user data is decoded with Decoder1,182, ofFIG. 1A, which uses decoding parameters that correspond to the first set of encoding parameters utilized by Encoder1,164. The decoding with Decoder1,182, yields the first set of user data (e.g., received user data186). If the first set of user data is successfully obtained, the destination device114sends an ACK to the signal forwarding device138and/or the origination device110.

However, if Decoder1,182, does not successfully decode the single-encoded first set of user data, destination device114sends a NACK to the signal forwarding device138and/or the origination device110, indicating that the first single-encoded forwarded signal148was not successfully received and decoded. Upon receiving the NACK, the signal forwarding device138retrieves the stored copy of the single-encoded first set of user data from memory188. Decoder1,190, of signal forwarding device138decodes the retrieved single-encoded first set of user data, using decoding parameters that correspond to the first set of encoding parameters. The result of decoding the single-encoded first set of user data with Decoder1,190, is the first set of user data.

After decoding, the first set of user data is encoded by Encoder3,198. Encoder3encodes the first set of user data according to a third set of encoding parameters corresponding to channel conditions associated with the communication link between the signal forwarding device138and the destination device114. The third set of encoding parameters comprises a third encoding technique and/or a third encoding rate.

As discussed previously, the third set of encoding parameters may differ from the first set of encoding parameters, which were initially used by the origination device110to encode the first set of user data. More specifically, the encoding technique and/or encoding rate of the third set of encoding parameters may differ from the encoding technique and/or encoding rate of the first set of encoding parameters. The result of encoding the first set of user data with Encoder3is a second single-encoded first set of user data. Modulator178of signal forwarding device138modulates the second single-encoded first set of user data. The modulation scheme utilized by modulator178to modulate the second single-encoded first set of user data may be the same as, or may be different from, the modulation scheme utilized to modulate the first single-encoded first set of user data. The modulation of the second single-encoded first set of user data yields a second single-encoded forwarded signal148.

Signal forwarding device138utilizes transmitter146to transmit the second single-encoded forwarded signal148to the destination device114. In the example shown inFIG. 1B, the transmit power used to transmit the second single-encoded forwarded signal148may differ from the transmit power used to transmit the first single-encoded forwarded signal148to the destination device114. The destination device receives the second single-encoded forwarded signal148via receiver130.

Upon receipt of the second single-encoded forwarded signal148, the demodulator180of the destination device114demodulates the second single-encoded forwarded signal148using a demodulation scheme that corresponds to the modulation scheme utilized by modulator178. The demodulation of the second single-encoded forwarded signal148yields the single-encoded first set of user data contained in the second single-encoded forwarded signal148. The Decoder1,182, of the destination device114decodes the single-encoded first set of user data using decoding parameters that correspond to the third set of encoding parameters, which were used by Encoder3,198, of the signal forwarding device138to encode the first set of user data. The result of decoding the single-encoded first set of user data with Decoder1,182is the first set of user data.

In some examples, upon receiving the single-encoded forwarded signal148, the controller128of the destination device114is configured to measure the single-encoded forwarded signal148to obtain channel measurements associated with a signal forwarding device-to-destination device (SFD-DD) channel between the signal forwarding device138and the destination device114. After measuring the single-encoded forwarded signal148, the transmitter126of destination device114transmits the SFD-DD channel measurements to the origination device110. The SFD-DD channel measurements can be transmitted directly to origination device110, as indicated by dashed signal line150inFIG. 1B. Alternatively, the SFD-DD channel measurements can be initially transmitted to signal forwarding device138, as indicated by dashed signal line152, and signal forwarding device138can subsequently transmit the SFD-DD channel measurements to origination device110, as indicated by dashed signal line154.

Of course, in other examples, the signal forwarding device138can also obtain its own channel measurements regarding the channel conditions associated with the communication link between the signal forwarding device138and the destination device114by measuring incoming signals from the destination device114. The signal forwarding device138may then transmit its own channel measurements to the origination device110. Thus, there are multiple ways in which the origination device110, using receiver118, can receive channel feedback regarding the channel conditions associated with the communication link between the signal forwarding device138and the destination device114.

After receiving the SFD-DD channel feedback from the destination device114and/or the signal forwarding device138, controller120of origination device110can modify the encoding parameters used by Encoder1,164, based on the received channel feedback regarding the channel conditions associated with the communication link between the signal forwarding device138and the destination device114. Similarly, the signal forwarding device138may utilize the SFD-DD channel measurements, regardless of whether the measurements are received from the destination device114or are obtained by the signal forwarding device138, itself. For example, the signal forwarding device138may utilize the SFD-DD channel measurements to modify the encoding, modulation, and/or transmission parameters utilized to encode, modulate, and/or transmit signals to the destination device114.

In some examples, destination device114can also transmit the SFD-DD channel measurements to origination device110, either directly or indirectly through signal forwarding device138, as part of a feedback signal. Alternatively, the SFD-DD channel measurements can be transmitted separately from the feedback signal. For example, the feedback signal can include a downlink channel feedback report comprising downlink channel measurements related to one or more downlink signals received by the destination device114. For example, the downlink channel feedback report may contain downlink channel measurements for downlink signals received from the origination device110and/or downlink channel measurements for one or more downlink signals received from one or more base stations other than origination device110. The downlink channel feedback report can additionally include the location of the resources (e.g., time slots, subcarriers, reference signal, etc.) on which the downlink channel measurements were made.

The downlink channel feedback report may also identify a carrier on which the downlink channel measurements were made, a cell identifier associated with origination device110that transmitted the downlink signals, and/or a spatial vector associated with a beamformed downlink signal. In some examples, the downlink channel feedback report may identify a cell identifier associated with a base station, other than origination device110, that transmitted the downlink signal. This scenario might occur when the downlink signal is received from a base station other than origination device110, but the destination device114needs to submit the downlink channel feedback report to the scheduler132located at the origination device110.

In yet another scenario, destination device114can receive downlink signals from a first device (e.g., origination device110), as the primary carrier of the downlink signals, and can also receive downlink signals from a second device (e.g., signal forwarding device138or a base station other than origination device110), as the secondary carrier of the downlink signals. In such a scenario, the downlink channel feedback report may (1) identify the primary carrier and/or the secondary carrier on which the downlink channel measurements were made, (2) include a cell identifier associated with the first device that transmitted the primary carrier and/or a cell identifier associated with the second device that transmitted the secondary carrier, and/or (3) include a spatial vector associated with each of one or more beamformed downlink signals, respectively.

Alternatively, the feedback signal can include an acknowledgment response, which can be either a positive acknowledgment response (ACK) or a negative acknowledgment response (NACK). The ACK message indicates that a downlink signal was successfully received by the destination device114. The NACK message indicates that the downlink signal was not successfully received by the destination device114. In some situations, the ACK/NACK message is a message that is forwarded on to the origination device110by the signal forwarding device138. In other situations, the ACK/NACK message is intended for the signal forwarding device138. In still other situations, the ACK message can be an indication to both the signal forwarding device138and the origination device110. In scenarios in which the feedback signal includes an acknowledgment response, the feedback signal may additionally identify a carrier on which the downlink signal was received, a cell identifier associated with origination device110that transmitted the downlink signal, a cell identifier associated with a base station, other than origination device110, that transmitted the downlink signal, and/or a spatial vector associated with a beamformed downlink signal. Regardless of the contents of the feedback signal, the SFD-DD channel measurements can be transmitted along with, or separate from, the feedback signal to the origination device110, either directly or through signal forwarding device138.

In this regard, if system100ofFIG. 1Butilizes a Hybrid Automatic Repeat Request (HARQ) process for error-correction and error-control, each ACK/NACK transmitted from the signal forwarding device138and the destination device114may include an identifier in order to identify the device that initially transmitted the ACK/NACK. In some cases, the HARQ Process ID may also be used. When using the HARQ mechanism, the receiver and the transmitter should know some information about the Process ID for each of the HARQ processes, so that the receiver can successfully track each of the HARQ process data without getting them mixed up. In this case, the HARQ process ID could be included along with the identifier for the identity of the device.

FIG. 2is a flowchart of an example of a method of utilizing the wireless communication system ofFIG. 1Bto transmit dual-encoded data. The method begins, at step202, with the signal forwarding device138receiving a dual-encoded received signal136from the origination device110. The dual-encoded received signal136contains a dual-encoded first set of data. In order to generate the dual-encoded first set of data, a first set of data is encoded according to a first set of encoding parameters to produce an encoded first set of data, and the encoded first set of data is further encoded according to a second set of encoding parameters. In the example shown inFIG. 2, the first set of encoding parameters corresponds to channel conditions associated with a first communication link between the signal forwarding device138and the destination device114, and the second set of encoding parameters corresponds to channel conditions associated with a second communication link between the origination device110and the signal forwarding device138.

At step204, the signal forwarding device138decodes the dual-encoded first set of data, using decoding parameters that correspond to the second set of encoding parameters, to obtain a single-encoded first set of data that is encoded according to the first set of encoding parameters. At step206, the signal forwarding device138transmits the single-encoded first set of data to a destination device114. The destination device114receives the single-encoded first set of data and attempts to decode the single-encoded first set of data using decoding parameters that correspond to the first set of encoding parameters. If the decoding procedure is successful, the destination device114will have successfully received the user data and will transmit an ACK to the signal forwarding device138and/or the origination device110.

If the decoding procedure is unsuccessful, the destination device114will transmit a retransmission request (e.g., NACK) to the signal forwarding device138and/or the origination device110. At step208, the signal forwarding device138receives the retransmission request (e.g., NACK) from the destination device114. The retransmission request can be received directly from the destination device114or via the origination device110. At step210, the signal forwarding device138decodes the single-encoded first set of data that was stored in memory188, using decoding parameters that correspond to the first set of encoding parameters, to obtain the first set of data.

At step212, the signal forwarding device138retransmits the first set of data to the destination device114. In some cases, the transmit power for the retransmitting is different than a transmit power previously used to transmit the single-encoded first set of data to the destination device114. For example, the transmit power for the retransmitting may be based, at least partially, on channel conditions associated with a first communication link between the signal forwarding device138and the destination device114.

In other examples, retransmitting the first set of data includes transmitting the first set of data using a different modulation order and/or technique than a modulation order and/or technique previously used to transmit the single-encoded first set of data to the destination device114. In still other examples, retransmitting the first set of data includes transmitting the first set of data using a different encoding rate and/or technique than an encoding rate and/or technique previously used to transmit the single-encoded first set of data to the destination device114. In still further examples, one or more of the transmit power, modulation order and/or technique, encoding rate and/or technique are modified. In these cases, a signal forwarding device138may transmit one or more control signals to the destination device114, indicating the new parameters that have been utilized to retransmit the first set of data, and in this manner, the destination device114is made aware of the modifications and can reconfigure the receiver130, the demodulator180, and/or the Decoder1,182in order to successfully detect and decode the retransmission.

Clearly, other embodiments and modifications of this invention will occur readily to those of ordinary skill in the art in view of these teachings. The above description is illustrative and not restrictive. This invention is to be limited only by the following claims, which include all such embodiments and modifications when viewed in conjunction with the above specification and accompanying drawings. The scope of the invention should, therefore, be determined not with reference to the above description, but instead should be determined with reference to the appended claims along with their full scope of equivalents.