Patent Description:
Link dynamics in millimeter-wave (mmWave) networks have characteristics which can be compared in some respects to transmission time. That is to say, that blockage can arise frequently, in particular with indoor setups or outdoor environments in response to object and/or station mobility. In mmWave frequencies blockage can cause the received signal power of a link to drop significantly, which renders the communication link inoperative. The cost of recovering from a blocked link in multi-hop networks is significant in terms of both the time and data communications required to reestablish a connection.

Accordingly, methods are needed for recovering from blockages, or other link outages in a mesh network. The technology of this disclosure provides this functionality while overcoming the shortcomings of previous routing protocols.

Non-patent document "An Adaptive Framework for Multipath Routing via Maximally Zone-Disjoint Shortest Paths in Ad hoc Wireless Networks with Directional Antenna" (Saha et al) proposes a notion of zone-disjoint routes in a wireless medium where paths are said to be zone-disjoint when data communication over one path will not interfere with data communication in another path.

<CIT> relates to a method, apparatus, system and computer readable medium for performing beamforming.

The solution to the above problem is defined by the independent claims. Advantageous embodiments are defined in dependent claims.

Path diversity may be needed to overcome blockage for delay sensitive data content in mmWave mesh networks. However, typical wireless routing protocols discover one best route from the source station (STA) and the destination STA. These protocols are not configured to create a secondary path to cope with blockage. Hence, STAs do not transmit multiple streams to make the end-to-end transmission robust.

Routing protocols specify how different network STAs communicate with each other, disseminating information that enables them to select routes between any two STAs on a network. A method and apparatus are disclosed for creating a secondary path (via one or more of the intermediate wireless communication stations) in addition to the primary path (via a different one or more of the intermediate wireless communication stations) in order to route the same data contents simultaneously through both paths to overcome link failure problems in wireless communication networks.

Generally speaking, the disclosure teaches a new routing protocol in wireless networks in which primary and secondary path discovery is performed. The protocol utilizes antenna patterns and the beamforming (BF) training information to select the next-hop of the secondary path that is spatially uncorrelated with the primary path next-hop. A new handshaking mechanism is performed to coordinate the reception of data from the two routes at the destination station to minimize errors and delays in reception.

The specification describes the target as being mesh networking applications which can be applied to wireless LAN (WLAN), wireless personal area networks (WPAN), and outdoor wireless communications. Thus, the target applications can range from Wi-Fi like networks, internet of things (IoT) applications, backhauling of data by mesh networking, next generation cellular networks with D2D communications, IEEE802. <NUM>, IEEE802.11ad, and IEEE <NUM>. <NUM> (ZigBee), Device-to-device (D2D) communications, Peer-to-peer (P2P) communications, and the like.

A number of terms are found in the disclosure whose meanings are generally utilized as described below.

Further aspects of the technology described herein will be brought out in the following portions of the specification, wherein the detailed description is for the purpose of fully disclosing preferred embodiments of the technology without placing limitations thereon.

The technology described herein will be more fully understood by reference to the following drawings which are for illustrative purposes only:.

An apparatus and method for robust data routing to overcome the effects of blockage, by utilizing a secondary path transmission to improve robustness and reception quality. Elements of the routing protocol include selection of spatially uncorrelated primary and secondary path links. Protocol operation comprises selection of links for neighbor STAs uncorrelated with the primary path. For example applying the routing protocol on a mmWave mesh network, and having data reception from two routes at the destination STA as any of the following situations: (<NUM>) uncoordinated reception; (<NUM>) coordinated reception: combining received signal powers; or (<NUM>) coordinated reception: conditional reception from secondary route.

Robust data routing in mmWave mesh networks are described which are configured to utilize a secondary path to allow the same data packets to be transmitted through both the primary and secondary paths. The disclosure describes a set of routing protocol rules to discover the primary and secondary paths.

The disclosure also teaches a method to discover a secondary path that is not spatially correlated with the primary path so that diversity is achieved against blockage effects. The protocol takes advantage of the characteristics of communications at the mmWave networks enabling spatial re-use between primary path and secondary path communications. The disclosure additionally proposes a coordination method for data reception at the destination station from the two routes.

Ad-hoc on-demand distance vector (AODV) is a routing protocol to establish an end-to-end communication route through multiple hop relaying. With AODV, the route from source STA to destination STA will be determined by the following procedure: (<NUM>) Source STA transmits RREQ frames in multicast fashion; (<NUM>) Intermediate STAs propagate the RREQ frames in multicast fashion; (<NUM>) Destination STA replies back with RREP frame toward the source STA in unicast fashion (remembering the chain of next-hop STAs); (<NUM>) Intermediate STAs propagate the RREP toward the source STA in unicast fashion (remembering the chain of next-hop STAs); (<NUM>) Upon reception of the RREP frame, the source STA remembers the next-hop STA, and starts data communication using the route procedure by RREQ/RREP handshaking.

AODV and typical routing protocols discover one best route from the source STA to the destination STA. They do not create a secondary path to cope with blockage. Hence, STAs do not transmit multiple streams to make the end-to-end transmission robust.

<FIG> shows an example of a state-of-the-art CTS frame as described in <NUM>1ad specifications, showing the fields, with a field number above the figure and the number of octets per field shown below the frame diagram. It will be appreciated that ready-to-send (RTS), clear-to-send (CTS) are data communication procedures. The CTS frame is shown with these fields: (<NUM>) frame control, (<NUM>) duration, (<NUM>) receiver address (RA), (<NUM>) transmitter address (TA), (<NUM>) frame check sequence (FCS). In <NUM> WLAN systems, the RTS/CTS procedure is used to protect data transmission on a particular link.

For all directional Multi-gigabit (DMG) CTS frames sent in response to RTS frames, the duration value is the value obtained from the duration field of the immediately previous RTS frame, minus the time (in microseconds) required to transmit the DMG CTS frame and its short-interframe-space (SIFS) interval. Otherwise, the duration field is set to the remaining duration of the transmission slot time.

The RA field of the frame is copied from the TA field of the immediately previous RTS frame to which the DMG CTS is a response. The TA field is the MAC address of the STA transmitting the DMG CTS frame.

A mmWave mesh network is described by way of example and not limitation, as it will be appreciated that the described protocol is applicable to a number of node-to-node wireless communications situations which might not be considered a mmWave mesh network.

<FIG> is a topology diagram showing an example routing path <NUM> from source STA to destination STA, illustrating a case in which the selected path has been blocked during data transmission resulting in link failure. In the figure, STAs A, B, C, D, and E are shown by way of example in a local wireless mesh. A routing path <NUM> from source STA A through intermediate STA C to destination STA E is shown being blocked <NUM>.

Due to movement of the STAs or the surroundings, link blockage can arise. In the figure a source STA, "A" has packets intended to destination STA "E". Using an on-demand routing protocol, the path selected from source STA to destination STA is shown <NUM>. After data transmission commenced this path became blocked <NUM>. If the blockage persists for a sufficient period of time, retransmissions and feedback messaging would both fail. Detecting this blockage and employing techniques to recover from it in mmWave networks, such as performing a self-healing routing procedure, involve the consumption of significant messaging overhead and time.

<FIG> illustrates an example routing topology <NUM>', depicting the same situation as in <FIG>, but in this case the disclosed protocol is configured to route the same data through both a primary path (solid line) <NUM> and secondary path (dashed) <NUM>, from a source STA (STA A in this example) to a destination STA (STA E in this example) that processes the signals from the two paths. Despite a blocking object <NUM> arising on the primary path, a communication outage does not occur because of the transmission of the secondary path.

It should be appreciated that routing the primary and secondary data along the same path from STA A through STA C to STA E, would not overcome the blockage situation. However, with the introductions of a form of path diversity <NUM>, as seen in the figure, robustness of data routing in mmWave can be achieved. As depicted in the figure, the secondary path <NUM> allows communications to be achieved without disruption from the source STA to the destination STA. The source STA can utilize both paths to transmit the same data to the destination simultaneously.

In mmWave communications, link blockage can cause significant signal losses (e.g., most often in the range of approximately <NUM>-<NUM> dB loss) of the received signal power at the receiving STA. In view of the already tight link budget that exists in mmWave frequencies due high free space path loss (FSPL) and large O<NUM>/H<NUM>O absorption, this blockage loss could render a link inoperative.

<FIG> shows some representative comparison between the received signal strength (RSS) (assuming dBm scale) for a few cases: (a) from the primary path if unblocked, (b) from the primary path if it is blocked, (c) from both paths if unblocked, (d) from both paths with one of them blocked. In this example the primary unobstructed path, for example is a -<NUM> dBm primary path with obstruction (blockage), comprising a loss of <NUM> dB, which results in a -<NUM> dBm RSS.

RSS at the destination STA, if both primary and secondary paths are unobstructed, is -<NUM> dBm in this example for bar (c) in the figure. On a dB scale, <NUM> dB increase in signal is achieved when combining the power from both paths at the receiver, assuming equal RSS from each path.

Bar (d) in the figure shows RSS at the destination STA if only one path is obstructed. The obstructed path contributes a minor addition to the RSS on a dB scale, such that if the unobstructed path RSS is -<NUM> dBm and the obstructed path is -<NUM> dBm, the resultant RSS is -<NUM>. Comparing cases (b) and (d) from the figure shows the immense importance of having path diversity against blockage.

<FIG> illustrates an example embodiment <NUM> of a messaging flow-timeline of securing a primary and secondary path from source <NUM>, through intermediate STAs <NUM>, to a destination <NUM>, with respect to a timeline <NUM>. The disclosed protocol sets the primary path and secondary path from a source STA to a destination STA, in response to using modified RREQ and RREP information elements that are termed extended RREQ and extended RREP, respectively.

Following the flow of <FIG>, the protocol is triggered by source STA <NUM>, which is seeking to send a spatial stream <NUM> in a robust transmission through intermediate STAs to a destination STA. The routing protocol starts by broadcasting an extended RREQ <NUM> to intermediate nodes (STAs) with its route flag set to primary. The rules for the primary route at the source STA, destination STA and the intermediate STAs (possible relays) follow those of the baseline routing protocol, which by way of example and not limitation is AODV, except for path metric cost adjustment due to MIMO capability.

At block <NUM> an intermediate node, which is MIMO capable, weighs its path cost favorably, and propagates in a unicast manner the primary RREQ <NUM>, to another intermediate STA or to destination STA <NUM>. The destination station selects a primary path <NUM> and transmits an RREP back toward the source, which is picked up by intermediate STA <NUM> which propagates <NUM> the RREP to source STA <NUM>, which secures <NUM> the primary route.

When the primary route is secured source STA triggers <NUM> path discovery of a secondary route by transmitting <NUM> an extended RREQ with its route flag set to secondary. Then as seen in <FIG>, the intermediate STA runs a modified AODV <NUM> and performs cost adjustments for MIMO capability and for secondary independence, then propagates <NUM> using a unicast technique this secondary RREQ to another intermediate STA or to destination STA <NUM> which evaluates <NUM> the secondary route path cost, selects a secondary path and transmits RREP to the intermediate <NUM>. Intermediate <NUM> then propagates <NUM> this secondary RREP to source STA <NUM>, which secures <NUM> the secondary route, and transmits <NUM> the same content through both the primary and secondary routes.

According to the disclosed protocol, the intermediate STAs and the destination STA deal differently with the secondary RREQ. They employ certain rules in the disclosed protocol which encourage the following. (a) The inclusion of MIMO STAs on the primary and secondary route to be able to use advanced physical layer MIMO communications schemes, such as spatial multiplexing and MU-MIMO. (b) Discovering of an end-to-end route that is not overlapped with the primary route.

<FIG> illustrate example embodiments of an extended routing request (RREQ) information entity (IE) and an extended routing response (RREP) IE, respectively.

In <FIG> the RREQ fields are depicted as follows.

In <FIG>, fields of the routing reply (RREP) IE are as follows.

In both of these elements a new message; the route flag, is added. The route flag is one bit of information that indicates a primary or a secondary route for either the extended RREQ or RREP IE. Also, as with any information element, a distinct IE ID is used for this extended RREQ and extended RREP. This allows any STA receiving these packets to recognize them from the (regular) RREQ and RREP packets of the state-of-the-art AODV protocol.

The routing CTS frame is a modified CTS frame that is used to coordinate the transmissions of the relays on the primary and secondary paths. It also serves as a grant frame to STAs that did not solicit it with a RTS frame.

<FIG> illustrates field contents of an extended routing CTS frame, having the following fields. Comparing this with <FIG>, it is readily seen that this frame additionally includes the fields: SA, DA, lifetime, and time offset. It should be noted that in general four types of address fields are used in sending a frame over multiple hops, for instance SA, DA, TA, and RA. SA (Source Address) is an additional field that indicates who the frame is originated from. SA is unchanged throughout multiple hops when the frame travels over multiple hops. DA (Destination Address) is an additional field that indicates who the frame is destined to. DA is unchanged throughout multiple hops when the frame travels over multiple hops. TA (Transmitter Address) indicates who transmitted the frame physically. TA differs hop by hop when the frame travels over multiple hops. RA (Receiver Address) indicates who is supposed to receive the frame physically. RA differs hop-by-hop when the frame travels over multiple hops.

In this section, a method for selection of a secondary routing path that has its links spatially uncorrelated with the links of the primary path is described. One way of estimating spatial correlation in beamformed (BF) communications is to obtain the difference between the BF sectors in the angular domain.

<FIG> illustrates an example topology <NUM> showing a primary route <NUM>, and two possible secondary routes <NUM> and <NUM>. It should be appreciated that secondary route (dotted) <NUM> is spatially correlated with primary route (solid) <NUM>, as it follows a similar path, such that it may get blocked by the same blocking object <NUM> as was the primary path <NUM>. A spatially independent route (dashed) <NUM>, however, is subject to a lower probability in getting blocked by the same objects blocking the primary route. Thus, in the figure, the case is depicted in which a secondary path is selected without considering spatial correlation with the primary path. The blocking object may in this case block both the primary path and the secondary path. While another spatially independent route has a lower probability of getting blocked by the same objects blocking the primary route. A similar problem can arise when the transmitter STA or receiver STA are moving. If the secondary route is spatially correlated with primary route, both of the routes may be blocked as a result of the mobility of the STA. The information of correlation of BF patterns are obtained from the BF training data.

<FIG> illustrates an example of BF sector level sweep (SLS) training as implemented in <NUM>. In the figure, an example <NUM> is seen of BF Sector Level Sweep (SLS) <NUM> training as implemented in <NUM>. 11ad, showing transmit sector sweep <NUM> from STA <NUM> as an initiator sector sweep <NUM>, followed by a responder sector sweep <NUM> in which STA <NUM> performs a transmit sector sweep <NUM>, to which STA <NUM> generates sector sweep feedback <NUM>, to which STA <NUM> generates a sector sweep ACK <NUM>. The best Sector ID, Antenna ID, SNR and Beamformed link primary tenancy time information are fed back with the Sector Sweep (SSW) Feedback. STAs will learn directional transmission related information through the BF training process. The best sector ID information towards another STA is recorded and used in the spatial correlation computation.

<FIG> illustrate conventional data structures for controlling SSW feedback. In <FIG> is seen an SSW feedback frame depicted with the following fields.

In <FIG> are shown the subfields in the SSW feedback field.

<FIG> illustrates beam pattern lobes <NUM> of a STA in mmWave communications. Best sector information obtained through SLS BF training is utilized as a metric for correlation of secondary routes with the primary route. In the figure the best sector towards the next-hop STA in the primary path is shown, with: (<NUM>) section <NUM> having limited angular separation from another best sector, which is section (<NUM>) <NUM>, of around <NUM> degrees on the horizontal plane; while section (<NUM>) <NUM> has around <NUM> degrees separation from sector (<NUM>) <NUM>. As a result, the system is configured toward choosing a STA towards which sector (<NUM>) as the best sector for a preferred next-hop secondary path. Greater angular separation generally leads to improved node separation and thus improved independence.

<FIG> illustrates an example embodiment <NUM> of the disclosed routing protocol in which the source STA seeks to secure primary and secondary routes. It should be noted that this flow diagram only depicts operations from the standpoint of the source STA, not the activities occurring at intermediate STAs and the destination STA. The baseline routing protocol is an AODV which is tailored for directional transmissions according to the technology of this disclosure. The protocol is triggered <NUM> by the source STA, as it is an on-demand routing protocol, whereupon receiving <NUM> a packet intended for a destination which is not found in the list of its neighbors. The source STA can start the routing protocol by setting the route flag to primary (e.g., <NUM>) and creating <NUM> and sending (transmitting) <NUM> the extended RREQ to the neighbor STAs in a directional mode. The primary route rules at the source STA, destination STA and the intermediate STAs (possible relays) follow those of the baseline routing protocol. A reply is received <NUM> and processed from a neighbor STA, in which the primary path next hop is recorded <NUM>.

After the primary route is secured, the source STA triggers the path discovery of a secondary route. The secondary route is selected to be spatially uncorrelated with the primary route, this commences with selecting <NUM> links of neighbor STAs uncorrelated with the primary path. This step is depicted in greater detail in <FIG>. The path flag is set to secondary (e.g., one) and an RREQ is prepared <NUM>, and sent (transmitted) <NUM> to candidate relays from ranked neighbor nodes. In response to this, a response (RREP) is received from a neighbor node <NUM> and processed to set the secondary path. The source station transmits <NUM> data along the primary path to the next-hop station, and also transmits <NUM> data along the secondary path to the next-hop STA, after which this processing ends <NUM>.

<FIG> illustrates an example embodiment <NUM> of processing an RREQ at intermediate nodes with primary and secondary path discovery. The intermediate STAs and the destination follow different rules when receiving the secondary RREQ in order to discover an end-to-end route that is not overlapped with the primary route, as seen in the figure. Process commences <NUM> with an RREQ being received <NUM> and processed <NUM> at this intermediate node. A check is made <NUM> of SA, DA, broadcast ID and RREQ route flag to determine if these are the same as the previous RREQ. If they are the same, then the received RREQ is designated <NUM> as secondary, the RREQ is then dropped <NUM> to end <NUM> the process. Otherwise, if in block <NUM> these fields are not the same as the previous RREQ, then block <NUM> is executed to check if the RREQ flag is set to primary. If it is not set to primary, then block <NUM> performs a check if the received previous RREP has same SA, DA, and BC ID. If previous RREP had these same field values, then a jump to block <NUM> is made to drop the RREQ, and end <NUM> the process. Otherwise, if either the route flag checked in block <NUM> is primary, or the previous RREP checked in block <NUM> did not have the same values, then block <NUM> is executed to update the path cost metric, and to forward the RREQ to neighbor STAs <NUM> then end <NUM> the process.

The source STA after securing the primary path prepares the secondary RREQ to be transmitted to some selected neighbor STAs. As explained previously, BF training information is retrieved to preclude selecting a STA that has a best sector that is highly correlated with the best sector to the primary path next-hop relay.

<FIG> illustrates this process <NUM> of selecting links of neighbor STA which are uncorrelated with the primary path. The process commences <NUM> with best sector information retrieved <NUM> toward the next hop STA on the primary path. Then best sector spatial angle θ is recorded <NUM> toward next hop STA on the primary path. A spatial correlation threshold α is set (or was previously set) <NUM>, then a list of N neighbors is retrieved <NUM>, with a local list (loop counter) being initialized <NUM>. A loop check <NUM> is made (alternatively check can be at bottom of loop) if the local loop has been performed for all of the N neighbors; if yes, then block <NUM> is executed to save the updated list of K STAs, and end the process <NUM>. Otherwise, the loop is executed and best sector information is retrieved <NUM> toward the nth STA, and best sector spatial angle φ (n) towards the nth STA is recorded <NUM>. A check is then made <NUM> if the absolute value of spatial angle θ - φ (n) is less than spatial correlation threshold α. If the spatial angle is not less, then the STA is acceptable (will remain on the list) and a jump is made to block <NUM> to increment the loop counter and jump back to block <NUM> at the top of the loop. Otherwise, with a non-sufficiently diverse angle, block <NUM> is executed which drops nth STA from the reliable peer STA list, before returning to the top of the list.

<FIG> is a geometric depiction <NUM> of this route selection process, in relation to STAs A, B and C, based on the angles. It can be seen that angle α can selected based on the minimum distance d_min between two STAs that assumes blockage on one would not affect the other STA. In the figure, the value r_avg is an average distance between a transmitting STA "A" and two candidate relays "B" and "C". For example if d_min = <NUM> meters and r_avg = <NUM> meters, then from basic geometry, using the inscribed angle conjecture and Thales' Theorem: <MAT> In this example α is approximately <NUM> degrees.

This threshold α is utilized to compare the best sector horizontal angle towards the relay on the primary path, θ, with the best sector horizontal angle towards the nth candidate relay on a secondary path, φ (n), At the end of this procedure K STAs out of N reliable STAs are assumed to have spatially uncorrelated links with the link of the primary path relay.

<FIG> illustrate applying the disclosed routing protocol on an example mmWave mesh network, shown with STAs A - G. In particular, the figures depict and example of primary and secondary path discovery on the network showing bidirectional links between STAs in <FIG>. The propagation of a primary RREQ (solid) is shown in <FIG>. The primary route is selected as seen in <FIG>. Propagation of the RREQ for the secondary path (dashed) according the rules explained in the current embodiments is seen in <FIG>, with the cross sign referring to dropping of the RREQ packet at the receiving STA. In <FIG> a secondary route is seen selected.

Thus, in the above figures an example mesh network demonstrated STAs exchanging data using the disclosed routing protocol. First, an extended RREQ with primary flag is propagated (from STA A in <FIG>) to enable discovery of the primary path. After the reception of RREP at the source and securing the discovery of the primary path discovery (seen in <FIG>), the secondary path RREQ is propagated (<FIG>). In the figure, the source STA (STA A) opted not to send the secondary RREQ to STA C as the link to STA C has high spatial correlation with the link to STA D on the primary path. In addition, intermediate STAs on the primary path are configured to drop any received RREQ for the secondary path, which is depicted with the cross signs, for the secondary path RREQ arriving at STA D. Upon securing the secondary path (<FIG>) according to the invention, through the use of the proposed routing protocol, the same data content is transmitted in the two routes simultaneously.

The disclosed routing protocol is expected to increase the robustness and reliability of routing data despite link blockage, antenna misalignments, channel fading effects, and similar instances which reduce signal levels.

The simplest method for the destination STA to process the data contents from the two routes is to receive the data without any form of coordination. The higher layers of the OSI model will detect any duplication in the packets and duplicate packets can be dropped.

<FIG> depicts the data transmission by the last-hop relay on the primary path and the last-hop relay on the secondary path and the acknowledgment sent by the destination. These transmissions are uncoordinated. The packets received at the destination from the last-hop relay on the secondary path are designated duplicate and dropped, depicted by the cross sign in the figure. These packets have been correctly received by the destination STA from the primary path.

The reception of the data contents from the two routes at the destination STA can be coordinated. In at least one embodiment, the disclosure achieves coordination by enabling the combination of the received signals from the last-hop relays at the physical layer. This combination improves the overall received signal strength and thus decreases the chances of reception errors.

<FIG> depicts the coordination of these data transmissions. A RTS is sent by primary relay, to which a destination responds by a CTS frame to both relays. The CTS frame specifies the transmission time given the knowledge of the propagation time between the destination and both relays and the time consumed in the handshaking process. This handshaking process allows reception of the two signals from both relays almost at the same exact time. The messaging needed for this type of coordination is depicted in the next figure.

<FIG> illustrates messaging flow <NUM> for performing the above form of coordination between primary relay, secondary relay, and destination STA, in performing a handshaking period <NUM> and data transmission period <NUM>. During handshaking <NUM>, the primary relay transmits <NUM> a data routing directional RTS frame. The destination STA transmits <NUM> a data routing directional CTS frame to the primary relay. The destination STA transmits <NUM> a data routing directional CTS frame to secondary relay. In the data transmission period <NUM>, the primary relay transmits <NUM> data to the destination STA. The secondary relay transmits <NUM> data to the destination STA. The destination STA transmits an acknowledgement (ACK) <NUM> to the primary relay. The destination STA transmits an acknowledgement (ACK) <NUM> to the secondary relay.

<FIG> and <FIG> illustrate an example embodiment <NUM> of logic (programming) implemented at the destination STA showing simultaneous data packet reception at the destination STA from the primary and secondary relays. Execution starts <NUM> in <FIG> with an RTS received <NUM> from a primary relay, and is processed <NUM>. The destination STA then applies BF weights <NUM> toward the primary relay. A routing CTS is then transmitted <NUM> to the primary relay. Then secondary relay information is retrieved <NUM>, to which transmit BF weights are applied <NUM>, upon which the routing CTS is transmitted <NUM> to the secondary relay. Data is received and processed <NUM> from the primary and secondary relays. Then in <FIG>, a check is made <NUM> if the data was received correctly. If it was received correctly, then transmit BF weights are applied <NUM> toward the primary relay, and an ACK frame is sent <NUM> to the primary relay. Similarly, BF weights are applied <NUM> toward the secondary relay, and an ACK frame is sent <NUM> to the secondary relay, to end the process <NUM>. Returning to block <NUM>, if the data was not received correctly, then the incorrectly received packets are dropped <NUM>, and the process ends <NUM>.

<FIG> and <FIG> illustrate example embodiments <NUM>, <NUM> of transmissions by the primary relay, destination STA, and secondary path relay. In <FIG>, data is shown being received correctly by the primary path relay at the destination. In <FIG> data transmission by the secondary path relay is shown being triggered since the data reception from the primary relay was deemed a failure by the destination STA.

The above example depicts another form of coordination of the reception of the data contents from the two routes at the destination STA. If the destination STA correctly receives the data packets from the relay of the primary path, then it acknowledges this reception to the relay on the primary path. The relay on the secondary path drops the packets since it did not receive a solicitation of communications. This condition is seen in the <FIG>. On the other hand, if the data is received in error at the destination from the primary relay, then the destination STA solicits the relay on the secondary path through a CTS frame to transmit the data packets as depicted in <FIG>.

<FIG> illustrates a messaging sequence <NUM> for data transmission by the secondary path relay when the transmission by the primary path relay fails. At the top of the figure is seen the primary relay, secondary relay, and destination STA. The primary relay transmits <NUM> data to a destination STA, in response to which the destination STA transmits <NUM> a routing CTS directional frame to a secondary relay. This secondary relay transmits <NUM> data to the destination STA, which then sends an ACK back <NUM> to the secondary relay.

<FIG> and <FIG> illustrate an example embodiment <NUM> of conditional data packet reception at the destination STA from the secondary STA. Processing commences <NUM> in <FIG> with RTS received <NUM> from a primary relay, and its RTS packet contents processed <NUM>. Transmit BF weights are applied <NUM> toward the primary relay, and transmitted <NUM> to the primary relay. Data is then processed <NUM> from the primary relay. A check is made <NUM> to determine if the data was received correctly. If correctly received, then transmit BF weights are applied <NUM> toward the primary relay, and an ACK frame sent <NUM> to the primary relay before the process ends <NUM> as seen in <FIG>. Otherwise, if the data was not correctly received at block <NUM>, then secondary relay information is retrieved <NUM> in <FIG>, transmit BF weights applied <NUM> toward secondary relay, and a routing CTS frame sent <NUM> to the secondary relay. Data is received and processed <NUM> from the secondary relay, and a check is made <NUM> if the data was received correctly. If it was correctly received, then processing ends <NUM>. Otherwise, the incorrectly received packets are dropped <NUM> before ending processing <NUM>.

<FIG> illustrates an example embodiment <NUM> of a single-input-single-output (SISO) station (STA) configured for operation according to the technology of this disclosure. A data line <NUM> is seen connecting from a source/sink device through connection <NUM> to a bus <NUM> to a memory <NUM>, controller <NUM>, TX data processor <NUM>, and RX data processor <NUM>. A modulator/demodulator (mod/demod) <NUM> is shown having modulator <NUM> and demodulator <NUM>, and being coupled to the spatial processor <NUM> having antennas <NUM>. TX data processor <NUM> is coupled for output through a modulator <NUM>, while RX data processor <NUM> is coupled for input from a demodulator <NUM>.

It will be noted that the controller accesses the memory and provides control signals to the TX data processor to access the bits from the data sink and perform scrambling, coding, interleaving of raw data, and mapping to data symbols or to the RX processor to de-map the received data symbols and perform deinterleaving, decoding, and descrambling operations. The modulator processes and modulates the digital symbols to analog symbols. The demodulator receives the analog symbols and demodulates to digital symbols.

When the station operates beamforming to a transmitting signal, the beam pattern to be utilized is commanded from TX data processor <NUM> to the modulator/demodulator <NUM>. The modulator/demodulator interprets the given command and generates a command that is fed to analogue spatial processor <NUM>. As a result, analogue spatial processor <NUM> shifts phases in each of its transmitting antenna elements to form the commanded beam pattern. When the station operates beamforming to a receiving signal, the beam pattern to be used is commanded from controller <NUM> and RX data processor <NUM> to the modulator/demodulator <NUM>. Modulator/demodulator <NUM> interprets the given command and generates a command that is fed to analogue spatial processor <NUM>. As a result, analogue spatial processor <NUM> shifts phases in each of its receiving antenna elements to form the commanded beam pattern. When the station receives a signal, the received signal is fed to controller <NUM>, via analogue spatial processor <NUM>, modulator/demodulator <NUM>, and RX data processor <NUM>. The controller <NUM> determines the content of the received signal, and triggers appropriate reactions, and stores information in memory <NUM> as described above. All the management frames, exchanged packets described above are determined and generated by controller <NUM>. When a packet is to be transmitted on the air, the packet generated by the controller <NUM> is fed to analogue spatial processor <NUM> via TX data processor <NUM> and modulator/demodulator <NUM>, whereas the transmitting beam pattern is controlled as described above simultaneously.

<FIG> illustrates an example embodiment <NUM> of a multiple-input-multiple-output (MIMO) station (STA) configured for operation according to the techhology of this disclosure. It will be noted that the controller, modulators and demodulators perform the same basic functions as described for the previous embodiment. The TX spatial processor performs spatial precoding and spatial mapping of the spatial streams to match the transmit chains. The RX spatial processor performs spatial de-mapping of spatial streams received from the different receive chains and performs spatial decoding.

A data line <NUM> is seen connecting from a source/sink device through connection <NUM> to a bus <NUM> to a memory <NUM>, controller <NUM>, TX data processor <NUM>, and RX data processor <NUM>. In view of there being multiple inputs and outputs, TX data processor <NUM> couples to both the controller <NUM> and to a TX spatial processor <NUM>. Similarly, RX data processor <NUM> couples to the controller <NUM>, and receives data from a RX spatial processor <NUM>. Multiple modulator/demodulator (mod/demod) devices 550a - 550n (for example two or more) are coupled to an analogue spatial processor <NUM>, which has a plurality of antennas <NUM>. The individual modulators 552a - 552n, of mod/demod devices 550a - 550n, receive TX inputs from TX spatial processor <NUM>. In a similar manner the individual demodulators 554a - 554n, of mod/demod devices 550a - 550n, receive RX inputs from antenna <NUM> of analog spatial processor <NUM> which after demodulation are passed to RX spatial processor <NUM>.

When the station operates beamforming to a transmitting signal, the beam pattern and MIMO configuration to be used are commanded from TX data processor <NUM> to the TX spatial processor <NUM> and modulator/demodulator 550a - 550n. The modulator/demodulator 550a - 550n interprets the given command and generates commands that are fed to analogue spatial processor <NUM>. As a result, analogue spatial processor <NUM> shifts phases in each of its transmitting antenna elements <NUM> to form the commanded beam pattern and MIMO configuration. When the station operates beamforming to a receiving signal, the beam pattern for use is commanded from controller <NUM> and RX spatial processor <NUM> to the modulator/demodulator 550a - 550n. The modulator/demodulator 550a - 550n interprets the given command and generates commands that are fed to analogue spatial processor <NUM>. As a result, analogue spatial processor <NUM> shifts phases in each of its receiving antenna elements to form the commanded beam pattern with MIMO configuration. When the station receives a signal, the received signal is fed to Controller <NUM>, via analogue spatial processor <NUM>, modulator/demodulator 550a - 550n, and RX spatial processor <NUM>. The controller <NUM> determines the content of the received signal, and triggers appropriate reactions, and stores information in memory <NUM> as described above. All the management frames, exchanged packets described above are determined and generated by controller <NUM>. When a packet is to be transmitted on the air, the packet generated by the controller <NUM> is fed to analogue spatial processor <NUM> via TX data processor <NUM>, TX spatial processor <NUM>, and modulator/demodulator 550a - 550n, whereas the transmitting beam pattern are controlled as described above simultaneously.

The enhancements described in the presented technology can be readily implemented within various wireless communication devices. It should also be appreciated that wireless data communication devices are typically implemented to include one or more computer processor devices (e.g., CPU, microprocessor, microcontroller, computer enabled ASIC, etc.) and one or more associated memories storing instructions (e.g., RAM, DRAM, NVRAM, FLASH, computer readable media, etc.) whereby programming (instructions) stored in the memory are executed on the processor to perform the steps of the various process methods described herein.

It will also be appreciated that the computer readable media (memory storing instructions) in these computation systems is "non-transitory", which comprises any and all forms of computer-readable media, with the sole exception being a transitory, propagating signal. Accordingly, the disclosed technology may comprise any form of computer-readable media, including those which are random access (e.g., RAM), require periodic refreshing (e.g., DRAM), those that degrade over time (e.g., EEPROMS, disk media), or that store data for only short periods of time and/or only in the presence of power, with the only limitation being that the term "computer readable media" is not applicable to an electronic signal which is transitory.

Embodiments of the present technology may be described herein with reference to flowchart illustrations of methods and systems according to embodiments of the technology, and/or procedures, algorithms, steps, operations, formulae, or other computational depictions, which may also be implemented as computer program products. In this regard, each block or step of a flowchart, and combinations of blocks (and/or steps) in a flowchart, as well as any procedure, algorithm, step, operation, formula, or computational depiction can be implemented by various means, such as hardware, firmware, and/or software including one or more computer program instructions embodied in computer-readable program code. As will be appreciated, any such computer program instructions may be executed by one or more computer processors, including without limitation a general purpose computer or special purpose computer, or other programmable processing apparatus to produce a machine, such that the computer program instructions which execute on the computer processor(s) or other programmable processing apparatus create means for implementing the function(s) specified.

Accordingly, blocks of the flowcharts, and procedures, algorithms, steps, operations, formulae, or computational depictions described herein support combinations of means for performing the specified function(s), combinations of steps for performing the specified function(s), and computer program instructions, such as embodied in computer-readable program code logic means, for performing the specified function(s). It will also be understood that each block of the flowchart illustrations, as well as any procedures, algorithms, steps, operations, formulae, or computational depictions and combinations thereof described herein, can be implemented by special purpose hardware-based computer systems which perform the specified function(s) or step(s), or combinations of special purpose hardware and computer-readable program code.

It will further be appreciated that as used herein, that the terms processor, computer processor, central processing unit (CPU), and computer are used synonymously to denote a device capable of executing the instructions and communicating with input/output interfaces and/or peripheral devices, and that the terms processor, computer processor, CPU, and computer are intended to encompass single or multiple devices, single core and multicore devices, and variations thereof.

Although the description herein contains many details, these should not be construed as limiting the scope of the disclosure but as merely providing illustrations of some of the presently preferred embodiments. Therefore, it will be appreciated that the scope of the disclosure fully encompasses other embodiments which may become obvious to those skilled in the art.

Claim 1:
A multiple-input-multiple-output, MIMO, wireless communication apparatus (<NUM>), comprising:
(a) a wireless communication circuit configured for wirelessly communicating with other wireless communication stations;
(b) a computer processor coupled to said wireless communication circuit;
(c) a non-transitory computer-readable memory storing instructions executable by the computer processor; and
(d) wherein said instructions, when executed by the computer processor, perform steps comprising:
(i) communicating with the other wireless communication stations utilizing a routing protocol;
(ii) performing primary and secondary path discovery in establishing communications with a destination wireless communication station (<NUM>), through intermediate wireless communication stations (<NUM>);
(iii) determined (<NUM>) by the processor that intermediate station of the primary and secondary path to be selected such that the antenna pattern for the primary and secondary path are spatially uncorrelated, using BF training information toward candidate intermediate stations; and
(iv) transmitting data (<NUM>, <NUM>) simultaneously on the primary path via one or more of the intermediate wireless communication stations and the same data on the secondary path via a different one or more of the intermediate wireless communication stations, for receipt by the destination wireless communication station toward overcoming link blockages of the primary path in response to data received on the secondary path.