Patent Application
20240259235
This document is directed to collaborative wireless communications amongst nodes in a wireless network.
A mobile ad-hoc network (MANET) is a decentralized type of wireless network that includes spatially distributed power-limited radio nodes with omnidirectional antennas. The performance of a MANET can be improved using beamforming techniques, which enable a signal to be directed in some privileged directions or channels and can result in an increase in the per-link capacity of the nodes of the MANET.
This document relates to methods, systems, and devices for open-loop distributed beamforming for multiple destinations. The described embodiments advantageously implement an open-loop distributed beamforming technique that requires no explicit management by the receiving side or channel state information (CSI) feedback. Compared to existing systems, the described embodiments provide, inter alia, the following advantages and benefits:
In one example aspect, a method for collaborative wireless communication is disclosed. The method includes performing a bidirectional communication with a reference node in the source cluster, receiving, from a destination cluster comprising a second plurality of nodes, a probe generated using a phase associated with the destination cluster, estimating, based on a propagation delay of the probe, a delay parameter, generating, based on the phase associated with the destination cluster and the delay parameter, a channel estimate, and transmitting, to each of the second plurality of nodes, a common message generated using a phase value and a delay value, wherein the phase value and the delay value are derived based on the channel estimate, and wherein the destination cluster is remotely located from the source cluster.
In another example aspect, a system for collaborative wireless communication is disclosed. The system includes a first plurality of nodes in a source cluster, a reference node in the source cluster, and a second plurality of nodes in a destination cluster, wherein each of the first plurality of nodes is configured to perform a bidirectional communication with the reference node, receive, from the destination cluster, a probe generated using a phase associated with the destination cluster, estimate, based on a propagation delay of the probe, a delay parameter, generate, based on the phase associated with the destination cluster and the delay parameter, a channel estimate, and transmit, to each node of the second plurality of nodes, a common message generated using a phase value and a delay value, wherein the phase value and the delay value are derived based on the channel estimate, and wherein the destination cluster is remotely located from the source cluster.
In yet another example aspect, the above-described methods are embodied in the form of processor-executable code and stored in a computer-readable program medium.
In yet another example embodiment, a device that is configured or operable to perform the above-described methods is disclosed.
The above and other aspects and their implementations are described in greater detail in the drawings, the descriptions, and the claims.
A mobile ad hoc network (MANET) is a continuously self-configuring, infrastructure-less network of mobile devices connected wirelessly. A MANET typically includes spatially distributed power-limited radio nodes with omnidirectional antennas, which may be both terrestrial and non-terrestrial. In an example, the network may be dynamic (nodes are moving) and may not be fully connected (multiple hops may be needed for full network coverage). In another example, the radios may operate in multipath fading propagation environments, and may employ constant-envelope modulations for increased power efficiency.
Distributed beamforming was originally proposed to improve the data exfiltration capability of sensor networks consisting of static low-powered nodes with narrowband (low data rate) measurements. Its benefits included increased energy efficiency, and consequently, increased operational longevity.
Embodiments of the disclosed technology leverage another facet of distributed beamforming, namely range extension, i.e., the ability to relay messages collaboratively to multiple remote (or destination) nodes that are otherwise unreachable by a single local radio or even by multiple radios transmitting simultaneously in a phase-incoherent manner. The range extension benefit can also be translated to other desired attributes such as higher rates to a destination, lower required transmit power, and the like.
In order to realize the coherence gains provided by distributed beamforming, the radio frequency (RF) phases-of-arrival of individual transmissions need to align at the intended destination. In contrast to classical beamforming that relies on collocated emitters, the RF phase of transmission is different (and typically unknown or un-estimable) for each participating emitter in distributed collaborative beamforming. Therefore, a process of phase coordination (also referred to as self-coherence) is required across the radios. This process typically compensates for phase changes due to mobility, as well as RF impairments such as oscillator frequency offsets, drifts and phase noise.
As referred to herein, “distributed beamforming” may include a cluster (or group) of handheld radio (or radio nodes) self-cohering to close a communication link between the cluster and a distant radio (or radio node) referred to as the Destination (or Dest.). In some embodiments, the handheld radio nodes may be replaced by unmanned aerial vehicles (UAVs) or vehicles with radios.
As referred to herein, “open-loop” does not mean that the destination is not involved at all, i.e., “open-loop” does not mean “destination-blind”. Rather, it means that phase-calibrating to the destination involves only one-way signaling from the destination to the local network (“downlink” only), as opposed to two-way signaling that also requires the local nodes to transmit to the destination, which is referred to as the closed-loop option.
Section headings are used in the present document to improve readability of the description and do not in any way limit the discussion or embodiments (and/or implementations) to the respective sections only.
In a subsequent slot, referred to as the 2nd Hop, each Ordinary Node transmits the same waveform to the Destination Node (the right-hand portion of
In some embodiments, the transmit phases can be determined to implement open-loop distributed beamforming (OL-DBF), as shown in
The 2nd Hop slot from
In some embodiments, the Reference Node can behave as an Ordinary Node in the Final Cal sub-slot and the Beamforming Slot, thereby participating in the Beamforming Slot and transmitting the waveform to the Destination Node.
In some embodiments, the Source Node and the Reference Node are the same node, whereas in other embodiments, the Source Node is different from the Reference Node. In yet other embodiments, the Source Node may be a backbone-type network node, a node in the network that is not part of the first cluster or the second cluster, or a node external to the network that has a dedicated communication link for the Data Sharing Slot.
In some embodiments, the slots from the 1st Hop just before a Calibration Slot to the final Beamforming Slot before the next Calibration Slot is referred to as an “epoch,” as shown in the example in
In some embodiments, a simplified version of the approach discussed above results in a distributed collaborative beamforming approach that is detailed in Section 8.
As discussed above, the Calibration Slot includes three types of sub-slots.
Herein, an Initiate Calibration sub-slot for any Ordinary Node must always precede the Respond Calibration sub-slot for that Ordinary Node.
Although only transmit slots are described in the context of
In some embodiments, the Final Calibration sub-slot can be time shifted in any sub-slot instead of the last one. For example, the Final Calibration sub-slot can be before the Initiate Calibration sub-slots or between the Initiate and Final Calibration sub-slots.
An example of the TDMA Calibration Slot for N=3 Ordinary Nodes is shown in
In some embodiments, the example embodiments described in
In some embodiments, the destination cluster also has a reference node (which is needed when considering bidirectional DBF) and reduces to the single destination probe (no extra calibration steps/slots required) when there is only one destination node (which is the reference node itself).
Embodiments that describe the distributed beamforming process between a source cluster and a destination cluster are further detailed in Section 7.
In some embodiments, each Ordinary Node tunes its carrier frequency to that of the Reference Node whose carrier frequency serves as a reference and is not adjusted, as shown in FIG. 6, where each Ordinary Node tunes its carrier frequency (denoted f1, . . . fn, . . . fN) to fR, which is the carrier frequency of the Reference Node.
The frequency offset {circumflex over (f)}FO=fR−fn between the frequency of the probe fR received from the Reference Node by the Ordinary Node in the Respond Calibration sub-slot and the frequency of the Ord Node fn can be estimated. In an example, the frequency offset can be estimated by estimating the rate of phase rotation in the received probe demodulated to baseband at the Ordinary Node n. This is followed by applying the estimate {circumflex over (f)}FO when the Ordinary Node n transmits probes to the Reference Node.
This approach is further detailed in
In some embodiments, delay estimation and transmit time adjustment can be used to ensure that the waveforms transmitted by each Ordinary Node arrive at the Destination Node at the same time.
As shown in
Implementing Tx phase calibration leads to a DBF Tx phase shaping term that each Ordinary Node (and Reference Node) applies in the Beamforming Slot to ensure that each of their waveforms arrive at the Destination Node (or more generally, at the destination cluster) phase aligned. Embodiments of the disclosed technology provide methods to perform transmit phase calibration in two cases: (1) when the transmit (Tx) phase and receive (Rx) phase at a node is identical, and (2) when the Tx Phase and Rx Phase at a node differ.
As referred to herein, the “transmit (Tx) phase” and the “receive (RX) phase” of a node correspond to the phase of the local oscillator of the node (e.g., of the transceiver of the node) when transmitting a signal and receiving a signal, respectively.
Phase Calibration when the Tx Phase and Rx Phase are Identical
In these embodiments, it is assumed frequency synchronization has been achieved between all the nodes, and that the Tx phase and Rx phase at a node are identical. Furthermore, the Reference Node is also denoted as “0” indicating the 0th node.
It is noted that the Destination Node receiving a waveform with a Rx phase that is independent of a phase term that depends on the Ordinary Node that transmitted the waveform is what enables the waveforms from Ordinary Nodes n∈[1, N] to sum constructively.
Furthermore, the measured Rx phase is the sum of three terms: the Tx phase, the channel delay induced phase and the negative of the Rx phase.
As described above, the Tx phase at a node can be either the Tx phase (e.g., the Destination Node in the Final Calibration sub-slot with Tx phase ϕD) or a modified version of it. The modified version may be the sum of the Tx phase and one phase shaping term (e.g., the Reference Node in the Respond Calibration sub-slot with modified Tx phase [ϕ0−An]) or the sum of the Tx phase and two phase shaping terms (e.g., the Ordinary Node in the Beamforming Slot with modified phase [ϕn+Bn−Cn]).
Phase Calibration when the Tx Phase and Rx Phase Differ
In this scenario, Bn−Cn is the phase shaping or phase correction term for Ordinary Node n where Bn is obtained at the end of the Respond Calibration sub-slot and Cn is obtained at the end of the Final Calibration sub-slot. It is noted, as in the previous scenario, that Destination Node receives the waveform from Ordinary Node n with a receive phase that is independent of the phase associated with Ordinary Node n (in spite of the distinct Tx and Rx phases). Thus, the waveforms received from each Ordinary Node n∈[1, N] can be received at the same phase and hence, phase-aligned, at the Destination Node.
In the absence of FO where the carrier frequency of Ordinary Node n is identical to that of the Reference Node, the phase offset ϕn(t)=ϕn is fixed with time. However, in the presence of FO where the carrier frequency of Ordinary Node n differs from that of the Reference Node, the phase offset ϕn(t) can change with time due to the FO. For example, if FO=100 Hz, this translates to one hundred (100) 360-degree rotations in one second, or equivalently, a 360-degree rotation in 10 msec and a 36-degree rotation in 1 msec. This phase rotation, if left unchecked, can significantly impair OL-DBF performance.
Embodiments of the disclosed technology provide methods to correct this type of FO-induced phase rotations, which are shown in the examples in
The disclosed embodiments can be used to generate a useable channel matrix from open-loop channel sounding probes for distributed nodes. Herein, the antennas are not co-located, the phases for each node differ in general. The case of a cluster A with N nodes transmitting to a cluster B with M nodes where each node is outfitted with an omnidirectional antenna is considered. Furthermore, the channel between node n∈[1, N] in Cluster A and node m∈[1, M] in Cluster B is examined, and it is assumed Tx and Rx phases are equal at a node that supports perfect carrier and timing synchronization. In some embodiments, the latter assumption of equal Tx and Rx phase at a node may not hold.
In some embodiments, the channel matrix in the direction of Cluster A to Cluster B in distributed MIMO consists of three parts:
Furthermore, the channel pathloss is amnBA in the direction of A to B. With channel reciprocity, amnBA=anmAB=amn, which is real-valued.
In general, each channel induced phase is a function of the carrier frequency of the node. Assuming intra-cluster frequency synchronization, each node in a cluster is assumed to have converged to a common carrier frequency for that cluster. As noted later, the common frequency in Cluster A may differ from that in Cluster B. It is also assumed that the Tx phase on ϕnA,Tx and Rx phase ϕnA,Rx at each node are equal such that ϕnA,Tx=ϕnA,Rx=ϕnA. In general, however, they may differ. It is also assumed that there is no noise.
Given the above three components, we can express the (m, n)th element in the A→B channel matrix HM,NBA for closed-loop (CL) distributed MIMO as:
Herein, the (n, m)-th element in the B→A channel matrix HN,MAB for open-loop (OL) distributed MIMO is given as:
In the above, hnmAB*≠hmnBA. The polarity of the phases associated with each node (not the channel delay induced phase) differ, which implies that the OL channel matrix differs from the CL channel matrix. Consequently, using the OL channel matrix as is in place of the CL channel matrix would not yield the desired SVD solution.
In some embodiments, the OL channel matrix can be used by transforming it to the CL matrix or a matrix with a similar form. This may be achieved by applying the conjugate of the double phase difference ej2(ϕ
Herein, there is a common phase term ϕnA with the same polarity in both the OL and CL terms, but the polarity of ϕmB differs. To this end, the double phase difference ej2(ϕ
Herein, the common phase term ϕmB has the same polarity in both the OL and CL terms. The above two versions can be combined to yield:
Thus, through OL channel sounding, node n can obtain the CL channel matrix element hmnBA scaled by a common phasor ej2(ϕ
The disclosed embodiments also provide methods for distributed MIMO in which information flows in both directions from A to B and from B to A.
In some embodiments, the following two approaches can be used to perform channel matrix estimation for both directions independently.
These approaches are summarized in Table 3 and in
In some embodiments, a single set of probes can be used for time division duplex (TDD) systems, as shown in
In some embodiments, a distributed collaborative beamforming approach is described from a set of spatially-distributed radio network nodes Ni; i=1, 2, . . . , K, towards a remote collaborating radio destination node D. In some embodiments, a method for distributed collaborative beamforming in a network comprising multiple network nodes (or nodes, or radios) comprises four stages.
In some embodiments, and for constant-envelope modulated signals, baseband phase correction can be implemented simply by an index shift into the look-up table that generates the information carrying digital phase sequence, thereby maintaining the constant envelope property for the transmitted signal.
In some embodiments, a network node may perform the four stages in an order different from that described above, as long as Stage 4 (which includes the actual beamforming operation) is performed last. For example, the network node may first receive a probe from the destination and compute the phase of the strongest tap of the channel estimation (Stage 3), then receive the common message (Stage 1), followed by participating in the self-coherence process with the other network nodes to derive its phase correction value (Stage 2), and finally perform the beamforming operation (Stage 4). For another example, the network node may first participate in the self-coherence process with the other network nodes to derive its phase correction value (Stage 2), then receive a probe from the destination and compute the phase of the strongest tap of the channel estimation (Stage 3), followed by receiving the common message (Stage 1), and finally perform the beamforming operation (Stage 4).
In some embodiments, the four-stage process described above produces a composite (co-transmitted, superimposed) signal at the destination node which has a larger signal-to-noise ratio (SNR) than what would have been received had the nodes co-transmitted in a phase-incoherent manner, thereby producing a distributed beamforming gain.
Once the matrix ΔØ has been computed fully, a selection process identifies a proper column with desirable characteristics. The column is indexed by the so-called reference node Nr, e.g., the column [δØ1r, δØ2r, . . . , δØKr] is computed and stored at each node. The values δØir, i=1, 2, . . . , K, comprise the set of required correction phases that are used in the beamforming stage (Stage 4).
In some embodiments, the matrix ΔØ is computed by electing a priori a reference node, and computing only the reference column [δØ1r, δØ2r, . . . , δØKr].
In other embodiments, the matrix ΔØ is computed by performing a round-robin computation, starting from a chosen start node and proceeding sequentially, whereby each node i in the sequence selects its paired node j on the basis of the highest SNR from all links connected to it, the same is repeated by j, provided that the next selected pair node has not already been already covered before, and so on, until all nodes are exhausted. In another example, other link metrics (e.g., the highest signal-to-interference-plus-noise ratio (SINR)) may be used to select the next paired node.
In yet other embodiments, some entries of the matrix ΔØ may be determined via the use of the identities 2Δθij=−2Δθji and 2Δθij=2Δθik+2Δθkj (the latter named the “triangle identity”). Alternatively, all entries in ΔØ are computed using the said identities plus an estimate of the quality (error variance) of the estimated value δØij.
For the computation of the matrix ΔØ in the embodiments described above, neither a fully-connected network (e.g., radio nodes in multiple hops may participate) nor a static network (e.g., dynamic phase tracking may be included in the computation) is required. In some embodiments, the value δØij can be computed in one of two ways: either via pure bidirectional exchanges of signals or via a mixture of signal exchanges and message exchanges.
Bidirectional signal exchanges. In some embodiments, a pure bidirectional exchange between nodes Ni and Nj includes the node Ni first emitting a signal, e.g., a probe akin to a tone, i.e. sipb(t)=cos(2πfct+∂i).
In complex-envelope notation, the tone sipb(t)=Re{ej∂
In this example of a purely bi-directional exchange, node Nj produces, at baseband, the negative of the total phase −θi→jtotal=−∂i−∂i→jch+∂j (referred to as “conjugation” or “phase reversal”). Upon up-conversion (which adds the phase ∂j), propagation through the reciprocal channel (which adds the phase ∂i→jch and thus cancels the term −∂i→jch) and down-conversion at node Ni (which subtracts the phase ∂i), the total phase at the radio baseband of node Ni is θi→jtotal=(−∂i−∂i→jch+∂j)+∂j+∂i→jch−∂i=2(∂j−∂i)=−δØij.
In some embodiments, node Nj can be informed of this value through the messaging protocol. In other embodiments, node Nj can initiate its own bidirectional exchange with node Nj in order to compute δØji.
Although, in principle, δØji=−δØij, in practice, such estimates may be noisy. In some embodiments, the network protocol may allow for message exchanges between nodes, and a better estimate of δØij can be made by both nodes by averaging the individual estimates.
Message and signal exchanges. In some embodiments, a mixture of signal and message exchanges includes the node Ni initiates the emission of a probe, as before, and node Nj computes θi→jtotal=∂i+∂i→jch−∂j, as described above. In this embodiment, Node Nj sends, to node Ni, an information-carrying message containing this computed value of θi→jtotal. Contemporaneously with this message, node Nj emits a probe signal, so that node Ni can in turn compute the phase θj→itotal=∂j+∂j→ich−∂i. Under the assumption of channel reciprocity, ∂i→jch=∂j→ich. Thus, node Ni possesses knowledge of θi→jtotal as well as θj→itotal and can easily infer that θi→jtotal=θj→itotal−θi→jtotal=−δØij.
In some embodiments, and as described in the context of bidirectional signal exchanges, the nodes can repeat that process by now starting from Nj, or can share the estimated value of δØij via messaging.
In some embodiments, the distributed collaborative beamforming process described in the context of
In some embodiments, all the network nodes are fully connected. The selection of a reference node, which completes Stage 2 with all nodes individually, may be performed in a sequence of its choice, since all nodes are within hearing range of the reference node. The choice of the reference node may pertain to the best average link SNR (averaged over all other nodes). More generally, any function (e.g., average, median, maximum, etc.) of a link-quality metric (e.g., SNR, SINR, etc.) may be used in the determination of the choice of the network node. It is further assumed, in this embodiment, that link-quality information is available to all nodes which share it and update it regularly.
In some embodiments, the reference node may have good access to some but not all the nodes of the network due to some low-quality links. The reference node may identify such impaired-link nodes and request, via proper messages, the help of neighboring nodes (e.g., send a request that they perform bidirectional exchanges with the impaired-link nodes in more favorable link conditions and thus assist in completing the full reference column via the said identities).
In some embodiments, there may be information on the nature of links (e.g., line-of-sight (LoS) or non-LoS (NLoS)), which may be used to determine which links are to be used by each node in its own bidirectional exchanges (e.g., only the LOS links may be used), in the process of filling out the phase matrix.
In some embodiments, an initial node may be chosen either at random, or via a quality metric (e.g., best link SNR among nodes), and is referred to as “node 1”. Node 1 completes 8012 with a second node (“node 2”), which may be the node within hearing range of node 1 with the highest link SNR of all links out of node 1. The pair (1,2) is announced via a short message, so that all nodes in the network know which pairs have been covered. Then node 2 completes 8023 with a subsequent node (“node 3”), chosen in a similar manner as before, and the pair is announced, and so on. The process ends when all nodes within hearing range (e.g., one-hop nodes) have been completed. If there are nodes within hearing range in some portion of the network (e.g., in a network of at least 2 hops), then a node from the second hop requests participation to the self-coherence process. The node(s) which hear it extend the process to that node, which then completes the process for those in the second-hop hearing range, and the process repeats until all hops have been covered. Thus, distributed collaborative beamforming can be applied to multi-hop (and not fully connected) networks, provided that the whole multi-hop network is within range of the probe of destination D for the subsequent stages.
In some embodiments, the estimate of the individual terms δØij may be accompanied by a quality metric, signifying the confidence of the estimating node on the quality of the said term (e.g., an estimated error variance). The various quality metrics may be distributed in message exchanges and used subsequently to refine estimates either via the use of identities (such as the triangle identity) when completing the matrix ΔØ, namely by incorporating weighting terms in the computation, or in refining final estimates of reciprocal links ((i→j) and (j→i)), assuming that the protocol allows computation of both. The final quality metrics for all relevant phase-difference qualities may be used for selecting the reference node, e.g., as the one whose column possesses the highest average quality metric. Links for which the quality of the estimate δØij is deemed unacceptable (too noisy) may discard the estimate and another sequence of nodes in the computation process may be selected.
In some embodiments, individual links may be subjected to significant interference (e.g., due to jamming). The elements of the matrix corresponding to such corrupted links may be eliminated from the bidirectional signal exchange (phase measurement) process. Instead, the said elements may be filled in via other measurements in related uncorrupted links and the use of the aforementioned identities (e.g., the triangle identity).
In some embodiments, the network nodes may use separate oscillator phases for the transmit and receive nodes.
In some embodiments, the terms δØij are computed not just by bidirectional signal exchanges between nodes but by a mixture of signal exchanges as well as message exchanges, whereby the messages convey the (quantized) value of the estimated baseband phase of the radio that has received a signal and has computed such a phase. The final estimate of δØij is computed by proper combination of the signal phases as well as the massage-conveyed phase values.
In some embodiments, the terms δØij are estimated via parameter-tracking methods which account for mobility and phase-noise impairments. Such phase-tracking methods can also be used to fill in (e.g., by prediction) estimated values in case the process is interrupted for a short period of time. In an example, these tracking methods can also be used to reduce the frequency for bidirectional exchanges, thus lowering the network overhead traffic necessary to support the embodiments described in the present document.
In some embodiments, a variety of methods in may be employed in choosing the strongest channel tap for computing the respective phase. In an example, the strongest channel tap is the direct largest gain value among taps. In another example, a complex channel tap is computed via interpolation methods between taps estimated using the observation samples (measurements) of the channel-estimation process.
The method 1700 includes, at operation 1720, receiving, from a destination cluster comprising a second plurality of nodes, a probe generated using a phase associated with the destination cluster.
The method 1700 includes, at operation 1730, estimating, based on a propagation delay of the probe, a delay parameter.
The method 1700 includes, at operation 1740, generating, based on the phase associated with the destination cluster and the delay parameter, a channel estimate.
The method 1700 includes, at operation 1750, transmitting, to each of the second plurality of nodes, a common message generated using a phase value and a delay value that are derived based on the channel estimate, and the destination cluster being remotely located from the source cluster.
In some embodiments, performing the bidirectional communication comprises transmitting, to the reference node, a first probe generated using a transmit phase associated with the first node, and receiving, from the reference node, a second probe generated using a transmit phase associated with the reference node, wherein the phase value is further based on the transmit phases associated with the first node and the reference node (e.g., as shown in the Initiate Calibration and Respond Calibration sub-slots in
In some embodiments, the transmit phase associated with the first node is periodically corrected to compensate for a frequency offset between the first node and the reference node (e.g., as described in Section 3).
In some embodiments, the bidirectional communication comprises a frequency offset correction corresponding to a frequency offset between the reference node and a respective node of the first plurality of nodes.
In some embodiments, the method 1700 further includes the operation of measuring the propagation delay of the probe received from the destination cluster based on a Global Positioning System (GPS) clock or a network timing reference (e.g., as described in Section 4).
In some embodiments, each of the first plurality of nodes uses a time-domain multiple access (TDMA) medium access control (MAC).
In some embodiments, the TDMA MAC comprises a first timeslot and a second timeslot used for performing the bidirectional communication, a third timeslot used for receiving the probe, and a fourth timeslot used for transmitting the common message.
In some embodiments, a length of the first timeslot is equal to a length of the second timeslot, and a length of the third timeslot is greater than the length of the first timeslot. In other embodiments, the first timeslot precedes the second timeslot. In yet other embodiments, the third timeslot precedes either the first timeslot or the second timeslot.
In some embodiments, the channel estimate comprises a predominant tap with the phase value and the delay value, and the bidirectional communication, the probe, or the common message comprises a constant envelope signal.
In some embodiments, the channel estimate comprises multiple channel taps, and each of the multiple channel taps comprises a channel tap phase and a channel tap delay.
In some embodiments, the probe received from the destination cluster is received from a node that is closest to a center of mass of the second plurality of nodes, and center of mass is determined based on position location information (PLI) or information from a Global Positioning System (GPS) signal.
Embodiments of the disclosed technology provide a system for collaborative wireless communication that includes a first plurality of nodes in a source cluster, a reference node in the source cluster, and a second plurality of nodes in a destination cluster, wherein each of the first plurality of nodes is configured to perform a bidirectional communication with the reference node (e.g., Initiate Calibration and Respond Calibration sub-slots as shown in
The described embodiments provide, inter alia, the following technical solutions:
It is intended that the specification, together with the drawings, be considered exemplary only, where exemplary means an example and, unless otherwise stated, does not imply an ideal or a preferred embodiment. As used herein, “or” is intended to include “and/or”, unless the context clearly indicates otherwise.
Some of the embodiments described herein are described in the general context of methods or processes, which may be implemented in one embodiment by a computer program product, embodied in a computer-readable medium, including computer-executable instructions, such as program code, executed by computers in networked environments. A computer-readable medium may include removable and non-removable storage devices including, but not limited to, Read Only Memory (ROM), Random Access Memory (RAM), compact discs (CDs), digital versatile discs (DVD), etc. Therefore, the computer-readable media can include a non-transitory storage media. Generally, program modules may include routines, programs, objects, components, data structures, etc. that perform particular tasks or implement particular abstract data types. Computer- or processor-executable instructions, associated data structures, and program modules represent examples of program code for executing steps of the methods disclosed herein. The particular sequence of such executable instructions or associated data structures represents examples of corresponding acts for implementing the functions described in such steps or processes.
Some of the disclosed embodiments can be implemented as devices or modules using hardware circuits, software, or combinations thereof. For example, a hardware circuit implementation can include discrete analog and/or digital components that are, for example, integrated as part of a printed circuit board. Alternatively, or additionally, the disclosed components or modules can be implemented as an Application Specific Integrated Circuit (ASIC) and/or as a Field Programmable Gate Array (FPGA) device. Some implementations may additionally or alternatively include a digital signal processor (DSP) that is a specialized microprocessor with an architecture optimized for the operational needs of digital signal processing associated with the disclosed functionalities of this application. Similarly, the various components or sub-components within each module may be implemented in software, hardware or firmware. The connectivity between the modules and/or components within the modules may be provided using any one of the connectivity methods and media that is known in the art, including, but not limited to, communications over the Internet, wired, or wireless networks using the appropriate protocols.
While this document contains many specifics, these should not be construed as limitations on the scope of an invention that is claimed or of what may be claimed, but rather as descriptions of features specific to particular embodiments. Certain features that are described in this document in the context of separate embodiments can also be implemented in combination in a single embodiment. Conversely, various features that are described in the context of a single embodiment can also be implemented in multiple embodiments separately or in any suitable sub-combination. Moreover, although features may be described above as acting in certain combinations and even initially claimed as such, one or more features from a claimed combination can in some cases be excised from the combination, and the claimed combination may be directed to a sub-combination or a variation of a sub-combination. Similarly, while operations are depicted in the drawings in a particular order, this should not be understood as requiring that such operations be performed in the particular order shown or in sequential order, or that all illustrated operations be performed, to achieve desirable results.
Only a few implementations and examples are described, and other implementations, enhancements and variations can be made based on what is described and illustrated in this disclosure.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/US2022/028180 | 5/6/2022 | WO |
| Number | Date | Country | |
|---|---|---|---|
| 63185204 | May 2021 | US |
