WO2024196596A2

WO2024196596A2 - Directional wireless communication networks configured for operating in outdoor environments

Info

Publication number: WO2024196596A2
Application number: PCT/US2024/019180
Authority: WO
Inventors: Panganamala R. KUMAR; Santosh GANJI
Original assignee: The Texas A&M University System
Priority date: 2023-03-09
Filing date: 2024-03-08
Publication date: 2024-09-26

Abstract

A method for establishing a directional wireless communication network includes establishing in an outdoor environment a connection between a first electronic device and a second electronic device along a wireless, directional line-of-sight (LoS) path extending between the first electronic device and the second electronic device, discovering a wireless, directional non-line-of-sight (NLoS) path between the first electronic device and the second electronic device, and establishing in the outdoor environment a connection between the first electronic device and the second electronic device along the NLoS path in response to the occurrence of a blockage along the LOS path.

Description

DIRECTIONAL WIRELESS COMMUNICATION NETWORKS CONFIGURED FOR OPERATING IN OUTDOOR ENVIRONMENTS

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims benefit of U.S. provisional patent application Serial No. 63/451 ,140 filed March 9, 2023, and entitled "Methods for Operating Millimeter-Wave Communication Networks in Open Environments," which is hereby incorporated herein by reference in its entirety for all purposes.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

[0002] This invention was made with government support under OMA-2037890 awarded by the U.S. National Science Foundation, 70RSAT20CB0000017 awarded by the Department of Homeland Security, N00014-21 -1-2385 awarded by the Office of Naval Research, W911-NF-18-1 -0331 awarded by the Army Research Office, and W911 NF-22-1-0151 awarded by the Army Research Office. The government has certain rights in the invention.

BACKGROUND

[0003] Millimeter-wave (mm-wave) networks comprise wireless communication networks which operate in a band extending approximately between 30 gigahertz (GHz) and 300 GHz. These frequencies are generally significantly higher than those traditionally used in wireless communication systems (e.g., Wi-Fi and cellular networks). Mm-wave technology has garnered significant interest due to its potential to deliver high data rates and low latency, making it suitable for applications such as high-speed internet access, 5G networks, and wireless backhaul.

BRIEF SUMMARY OF THE DISCLOSURE

[0004] An embodiment of a method for establishing a directional wireless communication network comprises (a) establishing in an outdoor environment a connection between a first electronic device and a second electronic device along a wireless, directional line-of-sight (LoS) path extending between the first electronic device and the second electronic device, (b) discovering a wireless, directional non-line- of-sight (NLoS) path between the first electronic device and the second electronic device, and (c) establishing in the outdoor environment a connection between the first electronic device and the second electronic device along the NLoS path in response to the occurrence of a blockage along the LOS path. In some embodiments, the NLoS path comprises a ground reflected path. In some embodiments, at least one of the first electronic device and the second electronic device comprises a phased antenna array. In certain embodiments, at least one of the first electronic device and the second electronic device comprises a millimeter-wave (mm-wave) transceiver. In certain embodiments, (c) comprises establishing the connection along the NLoS path in response to a signal strength of the connection along the LoS path declining by a predefined magnitude over a predefined period of time. In some embodiments, (b) comprises conducting at least one of a neighbor beam search and an exhaustive search to discover the NLoS path. In some embodiments, (b) comprises conducting a neighbor beam search to discover the NLoS path using pose data of at least one of the first electronic device and the second electronic device. In certain embodiments, the method comprises (d) handing off the connection between the first electronic device and the second electronic device to a third electronic device whereby a connection is stablished between the second electronic device and the third electronic device in response to a signal strength of a beam of the first electronic device declining by a predefined threshold. In certain embodiments, (d) comprises (d1) discovering by the second electronic device beams of one or more other electronic devices prior to handing off the connection between the first electronic device and the second electronic device to the third electronic device, and (d2) tracking by the second electronic device a beam of the third electronic device as the connection between the first electronic device and the second electronic device is handed to the third electronic device.

[0005] An embodiment of an electronic device for connecting to a directional wireless communication system comprises a processor, and a memory storing instructions executable by the processor, wherein the instructions, when executed by the processor establish in an outdoor environment a connection between the electronic device and another device along a wireless, directional LoS path extending between the electronic device and the another device, discover a wireless, directional non-line-of-sight (NLoS) path between the electronic device and the another device, and establish in the outdoor environment a connection between the electronic device and the another device along the NLoS path in response to the occurrence of a blockage along the LOS path. In some embodiments, the reflected path comprises a ground reflected path. In some embodiments, the electronic device comprises a mm-wave transceiver. In certain embodiments, the instructions, when executed by the processor establish the connection along the NLoS path in response to a signal strength of the connection along the LoS path declining by a predefined magnitude over a predefined period of time. In certain embodiments, the instructions, when executed by the processor discover beams of one or more other electronic devices prior to handing off the connection between the electronic device and the another device to a first of the one or more other electronic devices, and track a beam of the first other electronic device as the connection between the electronic device and the another device is handed to the first other electronic device.

[0006] An embodiment of a method for establishing a millimeter-wave (mm-wave) communication network comprises (a) establishing in an outdoor environment a mm- wave/tera hertz signal connection between a first electronic device and a second electronic device along a LOS path extending between the first electronic device and the second electronic device, (b) discovering a NLoS path extending between the first electronic device and the second electronic device, and (c) establishing a mm- wave/terahertz signal connection between the first electronic device and the second electronic device along the NLoS path in response to the occurrence of a blockage along the LOS path. In some embodiments, the NLoS path comprises a ground reflected path. In some embodiments, at least one of the first and second electronic devices comprises a millimeter-wave (mm-wave) transceiver. In certain embodiments, the method comprises (d) handing off the mm-wave connection between the first electronic device and the second electronic device to a third electronic device whereby a mm- wave/terahertz signal connection is stablished between the second electronic device and the third electronic device in response to a signal strength of a beam of the first electronic device declining by a predefined threshold. In certain embodiments, (d) comprises (d1) discovering by the second electronic device beams of one or more other electronic devices prior to handing off the mm-wave connection between the first electronic device and the second electronic device to the third electronic device, and (d2) tracking by the second electronic device a beam of the third electronic device as the connection between the first electronic device and the second electronic device is handed to the third electronic device. In some embodiments, (c) comprises establishing the connection along the NLoS path in response to a signal strength of the mm-wave connection along the LoS path declining by a predefined magnitude over a predefined period of time.

BRIEF DESCRIPTION OF THE DRAWINGS

[0007] For a detailed description of exemplary embodiments of the disclosure, reference will now be made to the accompanying drawings in which:

[0008] FIG. 1 is a schematic view of an embodiment of a directional wireless communication system in accordance with principles described herein;

[0009] FIG. 2 is a block diagram of an embodiment of a directional wireless transceiver in accordance with principles described herein;

[0010] FIG. 3 is a block diagram of an embodiment of an exemplary wireless communication system protocol in accordance with principles described herein;

[0011] FIG. 4 is a flowchart of an embodiment of a method 150 for establishing a directional wireless communication network in accordance with principles described herein;

[0012] FIG. 5 is a flowchart of another embodiment of a method 150 for establishing a directional wireless communication network in accordance with principles described herein;

[0013] FIG. 6 is a graph illustrating signal strength as a function of time;

[0014] FIG. 7 is a graph illustrating the cumulative distribution function as a function of time;

[0015] FIG. 8 is a graph illustrating signal strength as a function of time; and

[0016] FIG. 9 is a block diagram of an embodiment of a computer system in accordance with principles described herein.

DETAILED DESCRIPTION OF THE DISCLOSED EMBODIMENTS

[0017] The following discussion is directed to various exemplary embodiments. However, one skilled in the art will understand that the examples disclosed herein have broad application, and that the discussion of any embodiment is meant only to be exemplary of that embodiment, and not intended to suggest that the scope of the disclosure, including the claims, is limited to that embodiment.

[0018] Certain terms are used throughout the following description and claims to refer to particular features or components. As one skilled in the art will appreciate, different persons may refer to the same feature or component by different names. This document does not intend to distinguish between components or features that differ in name but not function. The drawing figures are not necessarily to scale. Certain features and components herein may be shown exaggerated in scale or in somewhat schematic form and some details of conventional elements may not be shown in interest of clarity and conciseness.

[0019] In the following discussion and in the claims, the terms "including" and "comprising" are used in an open-ended fashion, and thus should be interpreted to mean "including, but not limited to...” Also, the term "couple" or "couples" is intended to mean either an indirect or direct connection. Thus, if a first device couples to a second device, that connection may be through a direct connection, or through an indirect connection via other devices, components, and connections. In addition, as used herein, the terms "axial" and "axially" generally mean along or parallel to a central axis (e.g., central axis of a body or a port), while the terms "radial" and "radially" generally mean perpendicular to the central axis. For instance, an axial distance refers to a distance measured along or parallel to the central axis, and a radial distance means a distance measured perpendicular to the central axis.

[0020] As described above, mm-wave communication systems are communication systems that operate in the mm-wave regime and which offer significant advantages in terms of high data rates over competing technologies. Particularly, mm-wave technology enables the transmission of large amounts of data at extremely high speeds, making it suitable for bandwidth-intensive applications like high-definition video streaming, virtual reality, and augmented reality. This is crucial for real-time applications such as online gaming, autonomous vehicles, and industrial automation. Mm-wave bands offer large available bandwidths, allowing for the provision of more capacity to support the growing demand for wireless data services.

[0021] However, while mm-wave communication systems offer several distinct advantages over competitor technologies, mm-wave communication systems face several continuing challenges. Particularly, mm-wave signals are susceptible to higher atmospheric attenuation and exhibit poor penetration through obstacles such as buildings and foliage. This limits their effective range and necessitates the deployment of a dense network of base stations. In addition, mm-wave signals are more prone to atmospheric absorption and interference from weather conditions such as rain, fog, and snow, which can degrade signal quality and affect network reliability. Further, mm-wave signals generally require a clear line of sight between the transmitter and receiver, making them more susceptible to blockages from buildings, terrain, and other obstacles. [0022] Mm-wave communication systems rely on directional transmission of wireless signals as opposed to omnidirectional transmission. As used herein, the term “directional,” “directional signal,” and “directional wireless” refers to wireless signals that are not omnidirectional and instead are focused or formed into a beam. Generally, there are fewer distinct multi-path components in the mm-wave bands. A narrow directional radio receiver beam can only receive signal components that arrive within a small angular spread of a beam direction.

[0023] A particular issue for mm-wave networks operating in outdoor environments is the blocking of mm-wave communication links by human pedestrians, resulting in user equipment (UE) such as mobile devices, smartphones, tables, laptops, and/or other electronic devices connected to the mm-wave network suffering from blockage events that may last for approximately 200 milliseconds (ms). The mobile device may lose connectivity during the blockage event and consequently may require the base station previously connected to the mobile device to perform a full spatial scan to reconnect with the mobile device at the conclusion of the blockage event, where full spatial scans may result in a long delay, possibly for more than 1.0 second (s), hampering the user experience of the UE.

[0024] Particularly, during a pedestrian blockage, the UE is left with one of two choices to continue communication with the network: (i) switch to a NLoS path if such a path exists between the base station and the UE, or (ii) perform a handover to a neighboring base station (or otherwise employ a neighboring base station through a technique such as coordinated multipoint transmission). Pedestrian blockage is sudden and unpredictable. To avoid outage by employing a NLoS path, the UE must typically have in hand an NLoS beam direction that it can quickly switch to. If the UE has no backup NLoS path to use in the event of blockage, link or signal outage occurs, and the UE is disconnected from the base station.

[0025] In this scenario, the disconnected UE will need to re-perform an initial network access procedure, as though it were a new user (taking up to a second or more), due to the following. To acquire new users, base stations periodically sweep directional beams with reference signals and broadcast information such as cell and network identity. UE also sweeps through all its receive beams (e.g., beams along which information may be received by a given device) to discover at least one of the base station’s beams when it is pointed towards it. The number of receive beams of the UE increases with the reciprocal of the beamwidth. Typically, to complete a bi-directional connection, the UE transmits a random preamble in the same direction as the discovered base station's beam, and awaits a response. After physical layer procedures to establish reliable data communication, the network authenticates the UE before granting network access.

[0026] On the other hand, were the UE to have an NLoS path in hand when blockage occurs, the UE may use the NLoS path to sustain connectivity in the following way. Particularly, while the NLoS path may not have the same bandwidth as the LoS path, the NLoS path may be employed to temporarily maintain time synchronization between the UE and the base station until the end of the blockage event. This is beneficial given that it permits the UE to revert to LoS communication without delay as soon as the blockage disappears and, typically, such blockage is temporary and only lasts a few hundred milliseconds. For such recovery from temporary blockages, it is important that it be performed without requiring any out-of-band communication, and this is what the NLoS path makes possible.

[0027] Accordingly, embodiments of systems and methods are described herein which provide reflected beam paths in outdoor environments for directional wireless (e.g., mm- wave) communication systems so as to minimize issues pertaining to blockage events resulting from solid obstructions such as pedestrian traffic. In an embodiment, in an outdoor environment, a connection (e.g., a mm-wave/terahertz signal connection) is established between a first electronic device and a second electronic device along a wireless, directional LoS path extending between the first electronic device and the second electronic device. As used herein, the term mm-wave/terahertz signal connection refers to a wireless signal connection having a frequency approximately between 30 gigahertz GHz and 3 terahertz (THz). In addition, a wireless, directional NLoS path between the first electronic device and the second electronic device may be discovered. Further, a connection may be established in the outdoor environment between the first electronic device and the second electronic device along the NLoS path in response to the occurrence of a blockage along the LOS path.

[0028] In addition, an embodiment of an electronic device is disclosed for connecting to a directional wireless (e.g., a mm-wave) communication system. The electronic device may include a processor and a memory. The memory may contain instructions executable by the processor to establish in an outdoor environment a connection between the electronic device and another device along a wireless, directional LoS path extending between the electronic device and the another device. In addition, the instructions, when executed by the processor, may discover a wireless, directional NLoS path between the electronic device and the another device, and establish in the outdoor environment a connection between the electronic device and the another device along the NLoS path in response to the occurrence of a blockage along the LOS path.

[0029] Referring to FIG. 1 , an embodiment of a directional wireless communication system 10 is shown. In this exemplary embodiment, directional wireless communication system 10 comprises a mm-wave communication system configured to transmit information between different electronic devices using mm-wave wireless signals. However, in other embodiments, directional wireless communication system 10 could transmit other types of directional wireless signals at higher frequencies, including the Terahertz range.

[0030] Generally, directional wireless communication system 10 includes one or more first electronic devices or base stations 12 and one more second electronic devices or UE 20 each located in an outdoor environment 5 and equipped for transmitting directional wireless signals between the base station 12 and UE 20 or vice versa. Particularly, directional wireless signals may be communicated between base station 12 and UE 20 along either a wireless, directional LoS path 14 or a wireless, directional NLoS path 16 in the form of a ground reflected path 16 that reflects off of the ground 11 . For example, UE 20 may communicate with base station 12 along NLoS path 16 when the LoS path 14 is occluded by an obstruction such as a pedestrian 13. In some embodiments, the base station 12 and/or the UE 20 includes a directional wireless transceiver such as a directional wireless transceiver for receiving and transmitting directional wireless signals such as mm-wave signals or directional signals other than mm-wave signals.

[0031] In cellular communication systems, the base station (e.g., base station 12) schedules data transmission and reception opportunities. Time synchronization helps UE (e.g., UE 20) adjust its timeline to that of base station’s. To align the UE’s time line, the base station transmits synchronization signals. The UE determines the temporal location of these signals in the captured over the air samples and adjusts its timeline. An acceptable received signal strength (RSS) and acceptable signal-to-noise ratio (SNR) are necessary to improve the accuracy of signal processing algorithms and help achieve tight timing alignment with the base station. Loss of timing alignment can cause packet losses as the UE’s transmissions fall out of the base station’s listening window and vice versa. The mobile must therefore continuously adapt its timeline to account for timing offsets. For at least this reason, UE 20 is configured to switch from a LoS mode of operation in which UE 20 attempts to communicate with base station 12 along LoS path 14, to a NLoS mode of operation in which UE 20 attempts to communicate with base station 12 along NLoS path 16 to maintain synchronization between UE 20 and base station 12 over the entire duration of a temporary blockage of the LoS path 14 due to, for example, the temporary presence of a pedestrian 13.

[0032] When a user carrying UE 20 moves to the boundary of the currently connected base station’s (e.g., base station 12) coverage region, called a “cell”, UE 20 experiences degraded radio conditions. At the edge of the cell, the RSS is weak and hence the SNR is poor. Generally, when SNR is poor, packet decoding can fail. A similar situation occurs when LoS path 14 is permanently blocked by a building or other permanent structure resulting in a permanent blockage of the signal between the base station 12 and UE 20.

[0033] In order to improve the quality of the network connection in permanent blockage conditions, UE 20 searches for neighboring base station 12 to establish a signal connection with as part of a handover procedure. While omni-directional mobile receivers need to perform only a frequency scan to discover the neighboring base station 12 and initiate a handover procedure, for directional wireless communication systems like system 10, UE 20 uses narrow directional beams and therefore necessarily performs a spatial scan to discover a neighboring base station 12. In certain embodiments, a 5G directional wireless base station (e g., base station 12) periodically sweeps broadcast information using narrow directional beams.

[0034] Typically, UE 20 adjusts its timeline to align with or match the timeline of the neighboring base station 12 as part of a process referred to as “time synchronization.” During the performance of a handover procedure, UE 20 informs the neighboring base station 12 of its presence in the coverage area assigned to the neighboring base station 12. In addition, UE 20 transmits an uplink preamble signal in a listening window of the neighboring base station 12 and anticipates a response from the neighboring base station 12. Tight time synchronization at UE 20 ensures that the transmitted preamble reaches the neighboring base station 12.

[0035] Generally, the initial base station 12 cannot assist UE 20 with obtaining required time schedules of a neighboring base station 12. Unless there is time synchronization among the base stations 12 in the directional wireless communication system [0036] To complete the handover, UE 20 must transmit precisely at the points in time when a neighboring base station 12 is listening in the direction of the beam discovered using the spatial scan. Typically, the neighboring base station 12 listens to the preamble transmitted by the UE 20 and responds when there is no resource collision in order to advance the handover procedure. Generally, upon receiving a response from the neighboring base station 12 to the preamble signal, UE 20 and the neighboring base station 12 exchange control plane messages configuring user authentication and connection transfer. Typically, UE 20 must maintain a tightly aligned beam relative to the neighboring base station 12 throughout the handover procedure to avoid handover failure

[0037] Prior to handover, the initial, serving base station 12 schedules persistent measurement occasions during which UE 20 is permitted to search for neighboring base stations 12. During such opportunities, UE 20 performs a directional search on frequencies that are provided by the serving base station 12. The UE 20 may first measure RSS by temporarily tuning a radio receiver of UE 20 to carrier frequencies of neighboring base station 12 while decoding information broadcasted by the neighboring base station 12 that contains the network related information.

[0038] In certain embodiments, UE 20 searches for neighboring base stations 12 using a single receive beam at a time. Given that transmit beam (e.g., beam along which information may be transmitted from a given device) schedules of neighboring base stations 12 are unknown to UE 20, UE 20 uses the same single receive beam for the entirety of the beam sweeping interval. The beam sweeping interval may correspond to the duration of the beam sweeping interval for the neighboring base stations 12. The search may conclude after UE 20 has discovered a neighboring base station 12, at which point UE 20 may report signal measurements to the serving base station 12. In some instances, the serving base station 12 may make the final decision as to whether handover will occur (e.g., based on the signal measurements collected by UE 20). UE 20 toggles between the serving base station 12 and the neighboring base stations 12 until the final decision has been made. Additionally, UE 20 must keep track of the beam of the serving base station 12 and each of the discovered neighboring base stations 12 until handover has been initiated. Failure to properly track the beam of the serving base station 12 may result in a “hard” handover whereas losing track of the beam of a neighboring base station 12 beam requires UE 20 to search again for the beam of the given neighboring base station 12. [0039] Mere one-time discovery of the beam of a neighboring base station 12 is insufficient to complete the handover. Instead, generally, UE 20 must maintain alignment with the beam of the targeted neighboring base station 12 to overcome mobility impairments and maintain sufficient RSS throughout the handover procedure. This process of maintaining beam alignment may be referred to as beam tracking and generally involves UE 20 switching its receive beams in order to maintain high RSS. In at least some instances, beam tracking is essential to complete all the handover protocol message exchanges and avoid a hard handover.

[0040] After discovering the beam of the neighboring base station 12 and timing synchronization, UE 20 may transmit a preamble signal to the neighboring base station 12 to announce its presence to the neighboring base station 12 as the neighboring base station 12 listens for all possible preamble signals. The preamble signal and time/frequency parameters for transmitting the preamble signal may be chosen randomly from a predefined set of parameters known to the base station 12 as part of a process referred to as “random access.” After listening to the preamble signal transmitted from the UE 20, the neighboring base station 12 responds to the preamble signal and allocates appropriate resources to permit UE 20 to complete the rest of the handover procedure.

[0041] Given that the communication of mm-wave signals is directional, the neighboring base station 12 listens in a particular direction in a given time window. UE 20 must therefore maintain tight time synchronization with the neighboring base station 12 to avoid a hard handoff. Upon UE 20 receiving a response to the preamble signal from the neighboring base station 12, both UE 20 and the neighboring base station 12 may exchange several protocol messages to complete the handover procedure. In this manner, UE 20 must typically maintain a receive beam adapted to a beam of the neighboring base station 12 during the handoff procedure as the UE 12 moves relative to the neighboring base station 12. Additionally, the neighboring base station 12 typically neither adapts its beam nor provides any other assistance to UE 20 in adapting its beam during the handover procedure.

[0042] As described above, maintaining tight time synchronization is often critical for maintaining a connection between UE 20 and a base station 12. As will be described further herein, while blockages may sever time synchronization between UE and a base station 12, by leveraging NLoS path 16, a connection may be maintained between UE 20 and the base station 12 over the entire duration of a temporary blockage whereby UE 20 may maintain time synchronization with the base station 12. By maintaining time synchronization with base station 12, the frustrating process of reconnecting the UE 20 to the base station 12 in order to reestablish a network connection may be avoided.

[0043] Referring to FIG. 2, an embodiment of a directional wireless transceiver 50 (e.g., a mm-wave transceiver) is shown. In some embodiments, directional wireless transceiver 50 (or at least some features thereof) may be incorporated into the base station 12 and/or the UE 20 of the directional wireless communication system 10 shown in FIG. 1 . Directional wireless transceiver 50 includes a transceiver unit 52 including both a directional wireless phased array receiver 54 and a directional wireless phased array transmitter 56. Additionally, directional wireless transceiver 50 includes an interface or up-down converter board 60 connected to the transceiver unit 52 and which provides as an output and receives as an input an analog baseband signal.

[0044] Directional wireless transceiver 50 additionally includes a baseband receiver 64, a digital input/output (I/O) family (FAM) 68, and a baseband transmitter 72. Baseband receiver 64 receives analog baseband signals from interface 60 and outputs a digital baseband signal. Additionally, baseband transmitter 72 receives a digital baseband signal as an input and outputs an analog baseband signal to the interface 60. Directional wireless transceiver 50 further includes a first processing field programmable gate array (FPGA) 76, a radio frequency (RF) control (Ctrl) FPGA 80, and a second processing FPGA 84. The first processing FPGA 76 receives digital baseband signals from baseband receiver 64 and provides data signals to a host 90 (e.g., a computer system such as a smartphone, a tablet, a laptop). RF Ctrl FPGA 80 receives control signals from host 90 and provides signals to the digital I/O fam 68. The second processing FPGA 84 receives digital signals from host 90 and provides digital baseband signals to the baseband transmitter 72.

[0045] Referring to FIG. 3, a block diagram of an exemplary wireless communication system protocol 100 of an embodiment of a directional wireless (e.g., mm-wave) communication system is shown. Wireless communication system 100 may be embedded in or implemented by one or more electronic devices (e.g., base stations, UE, other devices having a directional transceiver) of a wireless communication system. Wireless communication system protocol 100 may execute a NLoS beam adaption protocol or procedure whereby a beam of a computer system is adapted along a NLoS path (e.g., NLoS path 16 shown in FIG. 1). Wreless communication system protocol 100 as implemented by a computer system (e.g., UE 20 shown in FIG. 1 ) maximizes connectivity in transient blockages as well as conducts soft handover over directional beams if required. Also, it may be understood that wireless communication system protocol 100 is merely exemplary and other embodiments of wireless communication system protocols of directional wireless communication systems may not include features of protocol 100 and/or may include features in addition to those of protocol 100. [0046] Wireless communication system protocol 100 may be implemented by a computer system comprising a directional wireless transceiver. For example, wireless communication system protocol 100 may be implemented or executed by the directional wireless communication system 10 shown in FIG. 1 such as by, for example, the UE 20 of directional wireless communication system 10.

[0047] In this exemplary embodiment, wireless communication system protocol 100 includes a LoS operation or LoS.Op node 102, a NLoS operation or NLoS.Op node 106. In addition, wireless communication system protocol 100 includes a NLoS path discovery engine 110 including a NLoS path discovery node 112, a neighbor beam search (NBS) node 114, and an exhaustive search (ES) node 116.

[0048] LoS.Op node 102 corresponds to a LoS state or mode of a directional wireless communication system (e.g., directional wireless communication system 10 shown in FIG. 1). In this exemplary embodiment, implementing LoS.Op node 102 includes a UE (e.g., UE 20 shown in FIG. 1 ) executing wireless communication system protocol 100 continuously adapt a receive beam of the UE to maintain sufficient alignment with a beam of a serving base station (e.g., base station 12 shown in FIG. 1) as the UE moves relative to the serving base station.

[0049] In this exemplary embodiment, in addition to adapting the receive beam of the UE to maintain sufficient alignment with the beam of the serving base station, the UE when in the LoS state continuously (e.g., periodically, event driven) implements the NLoS path discovery node 112 of NLoS path discovery engine 110 to discover a NLoS path providing a signal pathway between the UE and the serving base station. The UE may store the NLoS path in a memory device thereof. In some embodiments, the NLoS path comprises a ground reflected beam (e.g., a beam reflected off of the ground) and NLoS path discovery node 112 comprises a ground reflected beam discovery (GRD) node configured to identify a reflected beam direction having a usable RSS. Usable RSS is anything that provides SNR greater than 0 at the receiver.

[0050] The NLoS path discovery node 112 may either implement NBS node 114 or ES node 116 to discover a current NLoS path providing signal connectivity (e.g., having a sufficiently great RSS). In this exemplary embodiment, the wireless communication system protocol 100 implements NBS node 114 if the pose of the UE is known (e.g., an estimated pose determined by one or more sensors of the UE) and, conversely, implements ES node 116 if the pose of the UE is unknown (e.g., the UE is unequipped with sensors for estimating the pose of the UE).

[0051] The NBS node 114 is configured to implement a NBS, a heuristic search algorithm, to discover NLoS paths such as ground reflected paths. The primary objective of a neighbor beam search is to perform a search on spatial neighbors of a predetermined beam. In NBS, at each step, the algorithm maintains a fixed number of neighbor beam candidates. At each step, the algorithm expands each beam by considering all possible next tokens according to the probabilistic model and selects the k spatial neighbor beams. These k candidates become the new set of beams for the next step of the search.

[0052] In certain embodiments, in a NBS implemented by NBS node 114, an additional step is introduced to explore variations or modifications of the k neighbor candidates. Particularly, instead of selecting the k candidates as beams for the next step, the algorithm also considers neighboring sequences k candidates but differ in a minor way. These neighboring sequences may result from minor perturbations. In some embodiments, the NBS implemented by NBS node 114 may include searching zenith neighbors to the current LoS beam to discover ground reflected paths.

[0053] The ES node 116 is configured to implement an ES, another heuristic search algorithm, to discover NLoS paths such as ground reflected paths. In an ES, also known as brute-force search, every possible solution is systematically examined to find the optimal solution. Additionally, in an ES, all combinations or permutations of candidate solutions within the search space are evaluated, without any heuristic guidance or pruning. In this manner, the ES exhaustively explores every possible solution, making it guaranteed to find the optimal solution if one exists, albeit at the cost of high computational complexity.

[0054] In some embodiments, LoS. Op node 102 may implement the NLoS path discovery node 112 whenever the UE adapts or adjusts the LoS beam direction as the adapting by the UE to the LoS beam may alter the NLoS path (e.g., the ground reflected direction). In certain embodiments, the UE may automatically delete the NLoS path currently saved in memory in response to the UE adapting the LoS beam direction prior to the discovery of the new NLoS path by NLoS path discovery node 112. In this manner, a new NLoS path may be discovered by the NLoS path discovery engine 110 which may be saved in the memory device of the UE.

[0055] Wireless communication system protocol 100 transitions from the LoS state to the NLoS state in response to the RSS of the signal received by the UE from the serving base station decreases by a predefined magnitude over a predefined period of time, where the decrease in RSS by the predefined magnitude over the predefined period of time corresponds to a blockage (e.g., a temporary blockage, a permanent blockage). For example, in some embodiments, a blockage may correspond to a decline in RSS by at least 15 decibels (dB) in less than 50-100 milliseconds. In this exemplary, wireless communication system protocol 100 initially assumes an identified blockage comprises a temporary blockage and thus shifts automatically to the NLoS state (e.g., NLoS. Op node 106) upon the identification of a blockage in an attempt to establish a connection between the UE and the serving base station across a NLoS path (e.g., NLoS path 16 shown in FIG.1 ). In this manner, signal communication may be established between the UE and the serving base station across a NLoS beam without losing time synchronization between the UE and the serving base station.

[0056] In some embodiments, when operating in the NLoS state, the UE may periodically search for available LoS paths (e.g., LoS path 14 shown in FIG. 1) between the serving base station and the UE. In some embodiments, the search conducted for available LoS paths may be a NBS or ES. The wireless communication system protocol 100 may automatically transition the UE to the LoS state (e.g., LoS. Op node 102) upon discovering an available LoS path between the UE and the receiving base station whereby signal communication may be established between the UE and the serving base station across a LoS beam without losing time synchronization between the UE and the serving base station.

[0057] Unlike transient blockage events (e.g., pedestrian blockages) which the UE may overcome by toggling between LoS and NLoS states, during a permanent blockage event where the beam of the UE is occluded by a building, tree or any other immovable obstacle, the UE must instead switch from the serving base station to a neighboring base station to maintain network connectivity. In this exemplary embodiment, 100 includes a handover engine 120 comprising a neighbor acquisition/reacquisition (N-A/r) node 122 and a neighboring base station beam adaptation (NBA) node 124.

[0058] Generally, handover engine 120 of wireless communication system protocol 100 is configured to search for neighboring base stations while keeping track of identified neighboring base stations such that a soft handover of the connection between the UE and the serving base station may be transferred from the serving base station to the neighboring base station. In this exemplary embodiment, N-A/r node 122 is configured to conduct by the UE a spatial scan in order to discover a beam (e.g., a transmit beam) of at least one neighboring base station. N-A/r node 122 is also configured to identify a receive beam to permit the UE to listen to the discovered neighboring base station.

[0059] In addition to discovering neighboring base stations, handover engine 120 is also configured to adapt the receive beam of the UE to counter motion of the UE and to monitor the beam of the neighboring base station during the handover of the UE to the neighboring base station. In this exemplary embodiment, NBA node 122 is employed for tracking the neighboring base station during handover of the UE to the neighboring state station. Particularly, NBA node 122 may be implemented in response to the signal strength (e.g., the RSS) of the beam of the neighboring base station declining by a predefined threshold (e.g., 5 dB or greater, 3 dB or greater, 1 dB or greater). Once implemented, NBA node 122 may test the signal strength of all spatially neighboring receive beams to the current receive beam of the UE and may select the receive beam having the best signal strength.

[0060] In some embodiments, while the UE maintains connectivity with the serving base station and tracks the beam of the neighboring base station, handover of the connection to the UE from the serving base station to the neighboring base station may be initiated should the signal strength of the beam of the neighboring base station exceed a predefined threshold (e.g., a predefined hysteresis threshold).

[0061] Referring now to FIG. 4, a flowchart of an embodiment of a method 150 for establishing a directional wireless communication network is shown. Initially, at bock 152 method 150 comprises establishing in an outdoor environment a connection between a first electronic device and a second electronic device along a wireless, directional LOS path extending between the first electronic device and the second electronic device. In some embodiments, block 152 comprises establishing in an outdoor environment 5 (shown in FIG. 1) a connection between base station 12 (shown in FIG. 1 ) and UE 20 (shown in FIG. 1) along a LoS path 14

[0062] At block 154, method 150 comprises discovering a wireless, directional NLoS path between the first electronic device and the second electronic device. In some embodiments, block 154 comprises discovering NLoS path 16 extending between base station 12 and UE 20. In certain embodiments, block 154 comprises implementing NLoS path discovery engine 110 of wireless communication system protocol 100. At block 156, method 150 establishing in the outdoor environment a connection between the first electronic device and the second electronic device along the NLoS path in response to the occurrence of a blockage along the LOS path. In certain embodiments, block 156 comprises establishing in outdoor environment 5 a connection between base station 12 and UE 20 along NLoS path 16 in response to the occurrence of a blockage (e.g., due to pedestrian 13) along LoS path 14.

[0063] Referring now to FIG. 4, a flowchart of an embodiment of a method 170 for establishing a directional wireless communication network is shown. Initially, at block 172 method 170 comprises establishing in an outdoor environment a directional wireless signal connection between a first electronic device and a second electronic device along a LOS path extending between the base station and the electronic device. In some embodiments, block 172 comprises establishing in an outdoor environment 5 (shown in FIG. 1) a mm-wave/terahertz signal connection between base station 12 (shown in FIG. 1 ) and UE 20 (shown in FIG. 1) along a LoS path 14.

[0064] At block 174, method 170 comprises discovering a NLoS path extending between the first electronic device and the second electronic device. In some embodiments, block 174 comprises discovering NLoS path 16 extending between base station 12 and UE 20. In certain embodiments, block 174 comprises implementing NLoS path discovery engine 110 of wireless communication system protocol 100. At block 176, method 170 establishing a mm-wave/terahertz signal connection between the first electronic device and the second electronic device along the NLoS path in response to the occurrence of a blockage along the LOS path. In certain embodiments, block 176 comprises establishing in outdoor environment 5 a mm-wave/terahertz signal connection between base station 12 and UE 20 along NLoS path 16 in response to the occurrence of a blockage (e.g., due to pedestrian 13) along LoS path 14.

[0065] Experiments were conducted pertaining to systems and methods for providing directional wireless communication systems in outdoor environments. Initially, it may be understood that the following experiments described herein are not intended to limit the scope of this disclosure and the embodiments described above and shown in Figures 1- 5. Particularly, a directional wireless communication system was evaluated under pedestrian blockages and for its ability to track a neighboring base station beam. The experiments and evaluation, although performed using 60 GHz directional wireless transceivers, can be reproduced on any available mm-wave hardware. [0066] Referring now to FIGS. 6 and 7, graphs 200 and 205 are shown, respectively. Graph 200 illustrates RSS as a function of time (graph 200) for both a LoS path 201 and a ground reflected path 202. Graph 205 illustrates the cumulative distribution function (CDF) as a function of RSS for a LoS path 206 and a ground reflected path 207 for both an unblocked region and a blocked region 208. Particularly, graph 200 illustrates the RSS of LoS path 201 dropping below the noise floor of the directional wireless transceiver (-70 dBm) during a pedestrian blockage that lasts for about 200 ms. The transceiver experienced a signal outage during this event as it could not decode transmitted information. However, the ground reflected path 202 did not suffer a signal outage as did the LoS path 201 during the temporary blockage. In this particular experiment trial which was conducted on a concrete surface, the RSS was -64 dBm for the ground reflected path 202 (obstructed or unobstructed) and -60 dBm for the LoS path 201 when unobstructed.

[0067] Graph 205 of FIG. 7 plots CDFs obtained by employing a blockage recovery scheme using NLoS paths (e.g., a scheme similar to protocol 100 shown in FIG. 3) during the performance of fifty blockage events. The experiment indicated that NLoS path 207 in an outdoor environment permitted the transceiver to maintain signal connectivity approximately 85% of the time and within 6 dB of normal operation (e.g., unblocked, LoS operation) 60% of the time. Additionally, when pose information of the transceiver was available, the blockage recovery scheme either discovered ground reflected radiation in only two measurements, or else the transceiver searched all available 25 beams until success was achieved.

[0068] As described above, embodiments of directional wireless communication systems disclosed herein tracks the beams of neighboring base stations in order to ensure a soft handover. Tracking performance when the UE is in motion is tabulated in Table 1 .

[0069] Referring to FIG. 8, graph 210 is shown of RSS as a function of time. Particularly, graph 210 illustrates RSS as the transceiver is subjected to translation motion such as when the transceiver is carried by someone walking. The different beam directions are indicated by the differently shaded regions of graph 210. Graph 210 illustrates the RSS of a blockage recovery scheme 211 , which switched between the different beams indicated by the shaded region of graph 210. Graph 210 also indicates that blockage recovery scheme 211 took advantage of the entire main lobe of the transceiver before switching to the next. [0070] Referring to FIG. 9, an embodiment of an electronic device or computer system 250 is shown suitable for implementing one or more embodiments (e.g., methods 150 and 170 of FIGS. 4 and 5) disclosed herein. Computer system 250 includes a processor 252 (which may be referred to as a central processor unit or CPU) that is in communication with memory devices including secondary storage 254, read only memory (ROM) 256, random access memory (RAM) 258, input/output (I/O) devices 260, and network connectivity devices 262. The processor 252 may be implemented as one or more CPU chips. It is understood that by programming and/or loading executable instructions onto the computer system 250, at least one of the CPU 252, the RAM 258, and the ROM 256 are changed, transforming the computer system 250 in part into a particular machine or apparatus having the novel functionality taught by the present disclosure.

[0071] Additionally, after the system 250 is turned on or booted, the CPU 252 may execute a computer program or application. For example, the CPU 252 may execute software or firmware stored in the ROM 256 or stored in the RAM 258. In some cases, on boot and/or when the application is initiated, the CPU 252 may copy the application or portions of the application from the secondary storage 254 to the RAM 258 or to memory space within the CPU 252 itself, and the CPU 252 may then execute instructions that the application is comprised of. In some cases, the CPU 252 may copy the application or portions of the application from memory accessed via the network connectivity devices 262 or via the I/O devices 260 to the RAM 258 or to memory space within the CPU 252, and the CPU 252 may then execute instructions that the application is comprised of. During execution, an application may load instructions into the CPU 252, for example load some of the instructions of the application into a cache of the CPU 252. In some contexts, an application that is executed may be said to configure the CPU 252 to do something, e.g., to configure the CPU 252 to perform the function or functions promoted by the subject application. When the CPU 252 is configured in this way by the application, the CPU 252 becomes a specific purpose computer or a specific purpose machine.

[0072] Secondary storage 254 may be used to store programs which are loaded into RAM 258 when such programs are selected for execution. The ROM 256 is used to store instructions and perhaps data which are read during program execution. ROM 256 is a non-volatile memory device which typically has a small memory capacity relative to the larger memory capacity of secondary storage 254. The secondary storage 254, the RAM 258, and/or the ROM 256 may be referred to in some contexts as computer readable storage media and/or non-transitory computer readable media. I/O devices 260 may include printers, video monitors, liquid crystal displays (LCDs), touch screen displays, keyboards, keypads, switches, dials, mice, track balls, voice recognizers, card readers, paper tape readers, or other well-known input devices.

[0073] The network connectivity devices 262 may take the form of modems, modem banks, Ethernet cards, universal serial bus (USB) interface cards, wireless local area network (WLAN) cards, radio transceiver cards (e.g., directional beam transceivers such as mm-wave transceivers), and/or other well-known network devices. The network connectivity devices 262 may provide wired communication links and/or wireless communication links. These network connectivity devices 262 may enable the processor 252 to communicate with the Internet or one or more intranets. With such a network connection, it is contemplated that the processor 252 might receive information from the network, or might output information to the network. Such information, which may include data or instructions to be executed using processor 252 for example, may be received from and outputted to the network, for example, in the form of a computer data baseband signal or signal embodied in a carrier wave.

[0074] The processor 252 executes instructions, codes, computer programs, scripts which it accesses from hard disk, floppy disk, optical disk, flash drive, ROM 256, RAM 258, or the network connectivity devices 262. While only one processor 252 is shown, multiple processors may be present. Thus, while instructions may be discussed as executed by a processor, the instructions may be executed simultaneously, serially, or otherwise executed by one or multiple processors. Instructions, codes, computer programs, scripts, and/or data that may be accessed from the secondary storage 254, for example, hard drives, floppy disks, optical disks, and/or other device, the ROM 256, and/or the RAM 258 may be referred to in some contexts as non-transitory instructions and/or non-transitory information.

[0075] In an embodiment, the computer system 250 may comprise two or more computers in communication with each other that collaborate to perform a task. For example, but not by way of limitation, an application may be partitioned in such a way as to permit concurrent and/or parallel processing of the instructions of the application. Alternatively, the data processed by the application may be partitioned in such a way as to permit concurrent and/or parallel processing of different portions of a data set by the two or more computers. In an embodiment, the functionality disclosed above may be provided by executing the application and/or applications in a cloud computing environment. Cloud computing may comprise providing computing services via a network connection using dynamically scalable computing resources.

[0076] While embodiments of the disclosure have been shown and described, modifications thereof can be made by one skilled in the art without departing from the scope or teachings herein. The embodiments described herein are exemplary only and are not limiting. Many variations and modifications of the systems, apparatus, and processes described herein are possible and are within the scope of the disclosure. For example, the relative dimensions of various parts, the materials from which the various parts are made, and other parameters can be varied. Accordingly, the scope of protection is not limited to the embodiments described herein, but is only limited by the claims that follow, the scope of which shall include all equivalents of the subject matter of the claims. Unless expressly stated otherwise, the steps in a method claim may be performed in any order. The recitation of identifiers such as (a), (b), (c) or (1 ), (2), (3) before steps in a method claim are not intended to and do not specify a particular order to the steps, but rather are used to simplify subsequent reference to such steps.

Claims

CLAIMS What is claimed is:

1. A method for establishing a directional wireless communication network, the method comprising:

(a) establishing in an outdoor environment a connection between a first electronic device and a second electronic device along a wireless, directional line-of-sight (LoS) path extending between the first electronic device and the second electronic device;

(b) discovering a wireless, directional non-line-of-sight (NLoS) path between the first electronic device and the second electronic device; and

(c) establishing in the outdoor environment a connection between the first electronic device and the second electronic device along the NLoS path in response to the occurrence of a blockage along the LOS path.

2. The method of claim 1 , wherein the NLoS path comprises a ground reflected path.

3. The method of claim 1 , wherein at least one of the first electronic device and the second electronic device comprises a phased antenna array.

4. The method of claim 1 , wherein at least one of the first electronic device and the second electronic device comprises a millimeter- wave (mm-wave) transceiver.

5. The method of claim 1 , wherein (c) comprises establishing the connection along the NLoS path in response to a signal strength of the connection along the LoS path declining by a predefined magnitude over a predefined period of time.

6. The method of claim 1 , wherein (b) comprises conducting at least one of a neighbor beam search and an exhaustive search to discover the NLoS path.

7. The method of claim 1 , wherein (b) comprises conducting a neighbor beam search to discover the NLoS path using pose data of at least one of the first electronic device and the second electronic device.

8. The method of claim 1 , further comprising:

(d) handing off the connection between the first electronic device and the second electronic device to a third electronic device whereby a connection is stablished between the second electronic device and the third electronic device in response to a signal strength of a beam of the first electronic device declining by a predefined threshold.

9. The method of claim 8, wherein (d) comprises:

(d1 ) discovering by the second electronic device beams of one or more other electronic devices prior to handing off the connection between the first electronic device and the second electronic device to the third electronic device; and

(d2) tracking by the second electronic device a beam of the third electronic device as the connection between the first electronic device and the second electronic device is handed to the third electronic device.

10. An electronic device for connecting to a directional wireless communication system, the electronic device comprising: a processor; and a memory storing instructions executable by the processor, wherein the instructions, when executed by the processor: establish in an outdoor environment a connection between the electronic device and another device along a wireless, directional line-of-sight (LoS) path extending between the electronic device and the another device; discover a wireless, directional non-line-of-sight (NLoS) path between the electronic device and the another device; and establish in the outdoor environment a connection between the electronic device and the another device along the NLoS path in response to the occurrence of a blockage along the LOS path.

11 . The electronic device of claim 10, wherein the reflected path comprises a ground reflected path.

12. The electronic device of claim 10, wherein the electronic device comprises a mm- wave transceiver.

13. The electronic device of claim 10, wherein the instructions, when executed by the processor: establish the connection along the NLoS path in response to a signal strength of the connection along the LoS path declining by a predefined magnitude over a predefined period of time.

14. The electronic device of claim 10, wherein the instructions, when executed by the processor: discover beams of one or more other electronic devices prior to handing off the connection between the electronic device and the another device to a first of the one or more other electronic devices; and track a beam of the first other electronic device as the connection between the electronic device and the another device is handed to the first other electronic device.

15. A method for establishing a millimeter-wave (mm-wave) communication network, the method comprising:

(a) establishing in an outdoor environment a mm-wave/Tera hertz signal connection between a first electronic device and a second electronic device along a line-of- sight (LOS) path extending between the first electronic device and the second electronic device;

(b) discovering a non-line-of-sight (NLoS) path extending between the first electronic device and the second electronic device; and

(c) establishing a mm-wave/terahertz signal connection between the first electronic device and the second electronic device along the NLoS path in response to the occurrence of a blockage along the LOS path.

16. The method of claim 15, wherein the NLoS path comprises a ground reflected path.

17. The method of claim 15, wherein at least one of the first electronic device and the second electronic device comprises a millimeter-wave (mm-wave) transceiver.

18. The method of claim 15, further comprising:

(d) handing off the mm-wave connection between the first electronic device and the second electronic device to a third electronic device whereby a mm- wave/terahertz signal connection is stablished between the second electronic device and the third electronic device in response to a signal strength of a beam of the first electronic device declining by a predefined threshold.

19. The method of claim 15, wherein (d) comprises:

(d1 ) discovering by the second electronic device beams of one or more other electronic devices prior to handing off the mm-wave connection between the first electronic device and the second electronic device to the third electronic device; and

20. The method of claim 15, wherein (c) comprises establishing the connection along the NLoS path in response to a signal strength of the mm-wave connection along the LoS path declining by a predefined magnitude over a predefined period of time.