WO2010114487A1

WO2010114487A1 - Methods for transmitting a message, methods for storing information, message transmission devices and information storage devices

Info

Publication number: WO2010114487A1
Application number: PCT/SG2010/000085
Authority: WO
Inventors: Ananth Subramanian; Xiaoming Peng; Po Shin Francois Chin
Original assignee: Agency For Science, Technology And Research
Priority date: 2009-03-31
Filing date: 2010-03-11
Publication date: 2010-10-07
Also published as: CN102439864A; CN102439864B

Abstract

In an embodiment, a method for transmitting a message may be provided. The method may include: generating a message including information specifying a radio wave transmission/reception region out of a plurality of radio wave transmission/reception region candidates which specified radio wave transmission/reception region a first radio communication device configured to perform directional radio communication may use for communication with a second radio communication device; and transmitting the generated message.

Description

METHODS FOR TRANSMITTING A MESSAGE, METHODS FOR STORING INFORMATION, MESSAGE TRANSMISSION DEVICES AND INFORMATION

STORAGE DEVICES

Technical Field

[0001] Embodiments relate to methods for transmitting a message, methods for storing information, message transmission devices and information storage devices.

Background

[0002] Demands for radio data transmission bandwidths are constantly increasing. However, resources, for example frequencies, that may be used for radio communication are limited.

[0003] Therefore, there is a need for methods and devices that efficiently use radio resources catering to an increased overall data transmission capacity.

Summary

[0004] In various embodiments, a method for transmitting a message, a method for storing information, a message transmission device and an information storage device may be provided. The method for transmitting a message may include: generating a message including information specifying a radio wave transmission/reception region out of a plurality of radio wave transmission/reception region candidates which specified radio wave transmission/reception region a first radio communication device configured to perform directional radio communication may use for communication with a second radio communication device; and transmitting the generated message. The method for storing information may include: receiving a message including information specifying a radio wave transmission/reception region out of a plurality of radio wave transmission/reception region candidates which specified radio wave transmission/reception region a first radio communication device configured to perform directional radio communication may use for communication with a second radio communication device; and storing the information included in the received message. The message transmission device may include a message generator configured to generate a message including information specifying a radio wave transmission/reception region out of a plurality of radio wave transmission/reception region candidates which specified radio wave transmission/reception region a first radio communication device configured to perform directional radio communication may use for communication with a second radio communication device; and a transmitter configured to transmit the message generated by the message generator. The information storage device may include a message receiver configured to receive a message including information specifying a radio wave transmission/reception region out of a plurality of radio wave transmission/reception region candidates which specified radio wave transmission/reception region a first radio communication device configured to perform directional radio communication may use for communication with a second radio communication device; and a storage configured to store the information included in the message. Brief Description of the Drawings

[0005] In the drawings, like reference characters generally refer to the same parts throughout the different views. The drawings are not necessarily to scale, emphasis instead generally being placed upon illustrating the principles of various embodiments, hi the following description, various embodiments of the invention are described with reference to the following drawings, in which:

FIG. 1 shows a flow diagram illustrating a method for transmitting a message according to an embodiment;

FIG. 2 shows a flow diagram illustrating a method for storing information according to an embodiment;

FIG. 3 shows a message transmission device according to an embodiment;

FIG. 4 shows an information storage device according to an embodiment;

FIG. 5 shows an information storage device according to an embodiment;

FIG. 6 shows a flow diagram illustrating a radio wave transmission/reception region determination method according to an embodiment;

FIG. 7 shows a flow diagram illustrating a radio wave transmission/reception region determination method according to an embodiment;

FIG. 8 shows radio wave transmission/reception region determination system according to an embodiment;

FIG. 9 shows a format of a topology information element according to an embodiment;

FIG. 10 shows a network of devices according to an embodiment; FIG. 11 shows payload of a request to send frame according to an embodiment;

FIG. 12 shows payload of a clear to send frame according to an embodiment;

FIG. 13 shows an illustration of reservations according to an embodiment;

FIG. 14 shows an illustration of reservations according to an embodiment;

FIG. 15 shows an illustration of beacon transmission in a beacon slot according to an embodiment;

FIG. 16 shows a discovery data-block according to an embodiment;

FIG. 17 shows a pair wise discovery data-block according to an embodiment;

FIG. 18 shows a format of a topology information element according to an embodiment;

FIG. 19 shows a superframe structure according to an embodiment;

FIG. 20 shows a format of the payload of a topology command/control frame according to an embodiment;

FIG. 21 shows a diagram illustrating various spatial reuse and device discovery strategies according to an embodiment;

FIG. 22 shows a format of a topology information element according to an embodiment;

FIG. 23 shows a CF (contention free)-poll-response frame according to an embodiment;

FIG. 24 shows a device-discovery-request frame according to an embodiment;

FIG. 25 shows a device-discovery-response frame according to an embodiment; FIG. 26 shows a diagram illustrating frame transactions in contention free period (CFP) according to an embodiment;

FIG. 27 shows a discovery data-block according to an embodiment; and FIG. 28 shows a pair wise discovery data block according to an embodiment;

Description

[0006] The following detailed description refers to the accompanying drawings that show, by way of illustration, specific details and embodiments in which the invention may be practiced. These embodiments are described in sufficient detail to enable those skilled in the art to practice the invention. Other embodiments may be utilized and structural, logical, and electrical changes may be made without departing from the scope of the invention. The various embodiments are not necessarily mutually exclusive, as some embodiments may be combined with one or more other embodiments to form new embodiments.

[0007] The word "exemplary" is used herein to mean "serving as an example, instance, or illustration". Any embodiment or design described herein as "exemplary" is not necessarily to be construed as preferred or advantageous over other embodiments or designs.

[0008] The various devices, as will be described in more detail below, according to various embodiments may comprise a memory which is for example used in the processing carried out by the various devices.

[0009] In an embodiment, a "circuit" may be understood as any kind of a logic implementing entity, which may be special purpose circuitry or a processor executing software stored in a memory, firmware, or any combination thereof. Thus, in an embodiment, a "circuit" may be a hard-wired logic circuit or a programmable logic circuit such as a programmable processor, e.g. a microprocessor (e.g. a Complex Instruction Set Computer (CISC) processor or a Reduced Instruction Set Computer (RISC) processor). A "circuit" may also be a processor executing software, e.g. any kind of computer program, e.g. Java. Any other kind of implementation of the respective functions which will be described in more detail below may also be understood as a "circuit" in accordance with an alternative embodiment.

[0010] FIG. 1 shows a flow diagram 100 illustrating a method for transmitting a message according to an embodiment. In 102, a message including information specifying a radio wave transmission/reception region out of a plurality of radio wave transmission/reception region candidates which specified radio wave transmission/reception region a first radio communication device configured to perform directional radio communication may use for communication with a second radio communication device may be generated. In 104, the generated message may be transmitted.

[0011] In various embodiments, the message may furthermore include information specifying a plurality of radio wave transmission/reception regions out of the plurality of radio wave transmission/reception region candidates which specified radio wave transmission/reception regions the first radio communication device may use for communication with the second radio communication device.

[0012] In various embodiments, the message may be generated in the second radio communication device. [0013] In various embodiments, the generated message may be transmitted from the second radio communication device.

[0014] In various embodiments, the message may furthermore include information specifying a respective radio wave transmission/reception region out of a respective plurality of radio wave transmission/reception region candidates which specified radio wave transmission/reception region a respective further radio communication device out of one or more further radio communication devices configured to perform directional radio communication may use for communication with the second radio communication device.

[0015] In various embodiments, the first radio communication device may sequentially transmit a first signal omnidirectionally, a second signal in a first radio wave transmission/reception region and a third signal in a second radio wave transmission/reception region, the second radio communication device may receive from the first radio communication device at a first reception time the first signal and at a second reception time one of the second signal and the third signal, and the second radio communication device may determine the radio wave transmission/reception region which the first radio communication device may use for communication with the second radio communication device based on the difference between the first reception time and the second reception time.

[0016] In various embodiments, at least one of the first signal, the second signal and the third signal may be sent using a radio communication technology different from the radio communication technology used for the directional radio communication. [0017] In various embodiments, the range of at least one of the first signal, the second signal and the third signal may be essentially the same or the same as the range of the radio communication technology used for the directional radio communication.

[0018] In various embodiments, at least one of the first signal, the second signal and the third signal may be sent using the radio communication technology used for the directional radio communication.

[0019] In various embodiments, at least one of the first signal, the second signal and the third signal may include information identifying the first radio communication device.

[0020] In various embodiments, the message may be generated in the first radio communication device.

[0021] In various embodiments, the generated message may be transmitted from the first radio communication device.

[0022] In various embodiments, the message may furthermore include information specifying one or more respective further radio wave transmission/reception regions out of the plurality of radio wave transmission/reception region candidates which specified one or more respective further radio wave transmission/reception regions the first radio communication device may use for communication with one or more respective further radio communication devices.

[0023] In various embodiments, the second radio communication device may transmit a signal omnidirectionally, the first radio communication device may sequentially determine whether at a first reception time a first signal transmitted omnidirectionally by the second radio communication device may be received in a first radio wave transmission/reception region and whether at a second reception time a second signal transmitted omnidirectionally by the second radio communication device may be received in a second radio wave transmission/reception region, and the first radio communication device may determine a radio wave transmission/reception region which the first radio communication device may use for communication with the second radio communication device based on the determination whether at a first reception time a first signal transmitted omnidirectionally by the second radio communication device may be received in a first radio wave transmission/reception region and whether at a second reception time a second signal transmitted omnidirectionally by the second radio communication device may be received in a second radio wave transmission/reception region.

[0024] In various embodiments, at the first time, a reception circuit of the first radio wave transmission/reception region of the first radio communication device may be activated, and a reception circuit for all other radio wave transmission/reception regions except the first radio wave transmission/reception of the first radio communication device may be deactivated. Accordingly, at the first time, the first radio communication device may only receive signals using its reception circuit of the first radio wave transmission/reception region.

[0025] In various embodiments, at the second time, a reception circuit of the second radio wave transmission/reception region of the first radio communication device may be activated, and a reception circuit for all other radio wave transmission/reception regions except the second radio wave transmission/reception region of the first radio communication device may be deactivated. Accordingly, at the second time, the first radio communication device may only receive signals using its reception circuit of the second radio wave transmission/reception region.

[0026] In various embodiments, the omnidirectionally transmitted signal may be sent using a radio communication technology different from the radio communication technology used for the directional radio communication.

[0027] In various embodiments, the omnidirectionally transmitted signal may be sent using the radio communication technology used for the directional radio communication.

[0028] In various embodiments, the range of the omnidirectionally transmitted signal may be essentially the same as the range of the radio communication technology used for the directional radio communication.

[0029] In various embodiments, the omnidirectionally transmitted signal may include information identifying the second radio communication device.

[0030] In various embodiments, the message may be generated in a further radio communication device, different from the first radio communication device and the second radio communication device.

[0031] In various embodiments, the second radio communication device may be configured to perform directional radio communication.

[0032] In various embodiments, the generated message may be transmitted in a frame according to a standard selected from a list of standards consisting of: WiMedia standard;

ECMA standard; IEEE 802.11 standard; IEEE 802.15.3 standard, IEEE 802.15.3b standard and IEEE 802.15.3c standard.

[0033] hi various embodiments, the generated message may be transmitted in an information element (IE). [0034] In various embodiments, at least one radio wave transmission/reception region of the plurality of radio wave transmission/reception regions may include at least a part of a sector defined by an angular region relative to a pre-determined point with respect to the first radio communication device.

[0035] In various embodiments, the plurality of radio wave transmission/reception regions may include parts of a plurality of sectors, wherein each sector may be defined by an angular region relative to a pre-determined point with respect to the first radio communication device.

[0036] hi various embodiments, the angles of the angular regions of each of the plurality of sectors may be equal.

[0037] In various embodiments, the angles of at least two angular regions of each of the plurality of sectors may be different.

[0038] In various embodiments, at least one radio wave transmission/reception region of the plurality of radio wave transmission/reception regions may include at least a part of a region defined by an area between a first half-line and a second half line, the first half- line starting from a first pre-determined point with respect to the first radio communication device and having a first pre-determined angle with respect to the first radio communication device, and the second half-line starting from a second predetermined point with respect to the first radio communication device and having a second pre-determined angle with respect to the first radio communication device. [0039] In various embodiments, the message may be generated while no radio communication connection is established between the first radio communication device and the second radio communication device. [0040] In various embodiments, the method may be generated while no radio communication connection for interchange of user data is established between the first radio communication device and the second radio communication device.

[0041] In various embodiments, the transmitted message may be received in a third radio communication device.

[0042] In various embodiments, the third radio communication device may be configured to perform directional radio communication.

[0043] In various embodiments, in at least one of the first radio communication device and the second radio communication device a topology matrix including information specifying a radio wave transmission/reception region out of a plurality of radio wave transmission/reception region candidates which specified radio wave transmission/reception region a third radio communication device configured to perform directional radio communication may use for communication with a fourth radio communication device may be stored.

[0044] FIG. 2 shows a flow diagram 200 illustrating a method for storing information according to an embodiment. In 202, a message including information specifying a radio wave transmission/reception region out of a plurality of radio wave transmission/reception region candidates which specified radio wave transmission/reception region a first radio communication device configured to perform directional radio communication may use for communication with a second radio communication device may be received. In 204, the information included in the received message may be stored. [0045] In various embodiments, the message may furthermore include information specifying a plurality of radio wave transmission/reception regions out of the plurality of radio wave transmission/reception region candidates which specified radio wave transmission/reception regions the first radio communication device may use for communication with the second radio communication device.

[0046] hi various embodiments, one or more further messages may be received, each further message including respective information specifying a respective further radio wave transmission/reception region out of a respective plurality of further radio wave transmission/reception region candidates which specified respective radio wave transmission/reception region a respective further first radio communication device configured to perform directional radio communication may use for communication with a respective further second radio communication device, and the respective information included in the one or more further received messages may be stored.

[0047] hi various embodiments, information indicating that communication between a fifth radio communication device and a sixth radio communication device has started may be received and stored.

[0048] In various embodiments, the message may be received in a third radio communication device configured to perform directional radio communication in a plurality of radio wave transmission/reception regions, and the information included in the received message may be stored in the third radio communication device.

[0049] In various embodiments, upon a request to the third radio communication device to start communication with a fourth radio communication device, it may be determined whether to start communication with the fourth radio communication device, based on the stored information. In various embodiments, the determination may be performed by the third radio communication device. In various embodiments, the determination may be performed by a predetermined radio communication device different from the third radio communication device. In various embodiments, the determination may be performed by a radio resource manager outside the radio communication device.

[0050] In various embodiments, upon a request to the third radio communication device to start communication with a fourth radio communication device, a radio wave transmission/reception region that the third radio communication device may use for communication with the fourth radio communication device may be determined, and, upon a request to the third radio communication device to start communication with a fourth radio communication device, it may be determined not to start communication with the fourth radio communication device, in case the determined radio wave transmission/reception region may be used for radio communication with one of the fifth radio communication device and the sixth radio communication device. [0051] In various embodiments, upon a request to the third radio communication device to start communication with a fourth radio communication device, a communication start time for communication with the fourth radio communication device may be determined based on the stored information. In various embodiments, the determination may be performed by the third radio communication device. In various embodiments, the determination may be performed by a predetermined radio communication device different from the third radio communication device, hi various embodiments, the determination may be performed by a radio resource manager outside the radio communication device.

[0052] In various embodiments, upon a request to the third radio communication device to start communication with a fourth radio communication device, a radio wave transmission/reception region that it may use for communication with the fourth radio communication device may be determined, and, upon the request to the third radio communication device to start communication with a fourth radio communication device, the communication start time may be determined to be equal or higher than a remaining communication time between the fifth radio communication device and the sixth radio communication device, in case the determined radio wave transmission/reception region may be used for radio communication with one of the fifth radio communication device and the sixth radio communication device.

[0053] In various embodiments, a radio wave transmission/reception region that may be used for radio communication with one of the fifth radio communication device and the sixth radio communication device may be determined, and a connection start restriction for the determined radio wave transmission/reception region may be set. [0054] In various embodiments, information about the communication time between the fifth radio communication device and the sixth radio communication device may be received, and the connection start time restriction may be set to last at least for the communication time between the fifth radio communication device and the sixth radio communication device.

[0055] FIG. 3 shows a message transmission device 300 according to an embodiment. The message transmission device 300 may include a message generator 302 configured to generate a message including information specifying a radio wave transmission/reception region out of a plurality of radio wave transmission/reception region candidates which specified radio wave transmission/reception region a first radio communication device configured to perform directional radio communication may use for communication with a second radio communication device; and a transmitter 304 configured to transmit the message generated by the message generator 302. The message generator 302 and the transmitter 304 may be may be coupled with each other, e.g. via an electrical connection 306 such as e.g. a cable or a computer bus or via any other suitable electrical connection to exchange electrical signals.

[0056] In various embodiments, the message may furthermore include information specifying a plurality of radio wave transmission/reception regions out of the plurality of radio wave transmission/reception region candidates which specified radio wave transmission/reception regions the first radio communication device may use for communication with the second radio communication device.

[0057] In various embodiments, the message transmission device 300 may be configured to be provided in the second radio communication device. In other words: a second radio communication device may be provided and may include the message transmission device 300.

[0058] In various embodiments, the message may furthermore include information specifying a respective radio wave transmission/reception region out of a respective plurality of radio wave transmission/reception region candidates which specified radio wave transmission/reception region a respective further radio communication device out of one or more further radio communication devices configured to perform directional radio communication may use for communication with the second radio communication device.

[0059] In various embodiments, the first radio communication device may be further configured to sequentially transmit a first signal omnidirectionally, a second signal in a first radio wave transmission/reception region and a third signal in a second radio wave transmission/reception region, the second radio communication device may furthermore be configured to receive from the first radio communication device at a first reception time the first signal and at a second reception time one of the second signal and the third signal, and the second radio communication device may furthermore be configured to determine the radio wave transmission/reception region which the first radio communication device may use for communication with the second radio communication device based on the difference between the first reception time and the second reception time.

[0060] In various embodiments, at least one of the first signal, the second signal and the third signal may be sent using a radio communication technology different from the radio communication technology used for the directional radio communication.

[0061] In various embodiments, the range of at least one of the first signal, the second signal and the third signal may be essentially the same as the range of the radio communication technology used for the directional radio communication.

[0062] In various embodiments, at least one of the first signal, the second signal and the third signal may be sent using the radio communication technology used for the directional radio communication. [0063] In various embodiments, at least one of the first signal, the second signal and the third signal may include information identifying the first radio communication device. [0064] In various embodiments, the message transmission device 300 may be provided in the first radio communication device. In other words: a first radio communication device may be provided and may include the message transmission device 300.

[0065] In various embodiments, the message furthermore may include information specifying one or more respective further radio wave transmission/reception regions out of the plurality of radio wave transmission/reception region candidates which specified one or more respective further radio wave transmission/reception regions the first radio communication device may use for communication with one or more respective further radio communication devices.

[0066] hi various embodiments, the second radio communication device may be configured to transmit a signal omnidirectionally, the first radio communication device may further be configured to sequentially determine whether at a first reception time a first signal transmitted omnidirectionally by the second radio communication device may be received in a first radio wave transmission/reception region and whether at a second reception time a second signal transmitted omnidirectionally by the second radio communication device may be received in a second radio wave transmission/reception region, and the first radio communication device may further be configured to determine a radio wave transmission/reception region which the first radio communication device may use for communication with the second radio communication device based on the determination whether at a first reception time a first signal transmitted omnidirectionally hy the second radio communication device may be received in a first radio wave transmission/reception region and whether at a second reception time a second signal transmitted omnidirectionally by the second radio communication device may be received in a second radio wave transmission/reception region.

[0067] In various embodiments, the message transmission device 300 may further include a first reception circuit configured to provide transmission/reception in the first radio wave transmission/reception region; a second reception circuit configured to provide transmission/reception in the second radio wave transmission/reception region; wherein the first radio communication device may further be configured to, at the first time, activate the first reception circuit and deactivate the second reception circuit. Accordingly, at the first time, the first radio communication device may only receive signals using its first reception circuit.

[0068] It is to be noted that although the first reception circuit and the second reception circuit have been described above as being provided in the message transmission device 300, which may be provided in the second radio communication device, the first reception circuit and the second reception circuit may also be provided in the second radio communication device outside the message transmission device 300. [0069] In various embodiments, the first radio communication device may further be configured to, at the second time, activate the second reception circuit and deactivate the first reception circuit. Accordingly, at the second time, the first radio communication device may only receive signals using its second reception circuit. [0070] In various embodiments, the omnidirectionally transmitted signal may be sent using a radio communication technology different from the radio communication technology used for the directional radio communication.

[0071] In various embodiments, the omnidirectionally transmitted signal may be sent using the radio communication technology used for the directional radio communication.

[0072] hi various embodiments, the range of the omnidirectionally transmitted signal may be essentially the same as the range of the radio communication technology used for the directional radio communication.

[0073] hi various embodiments, the omnidirectionally transmitted signal may include information identifying the second radio communication device.

[0074] In various embodiments, the message transmission device 300 may be configured to be provided in a further radio communication device different from the first radio communication device and the second radio communication device. In other words: a further radio communication device different from the first radio communication device and the second radio communication device may be provided and may include the message transmission device.

[0075] In various embodiments, the message may be generated in a further radio communication device, different from the first radio communication device and the second radio communication device.

[0076] hi various embodiments, the second radio communication device may be configured to perform directional radio communication.

[0077] In various embodiments, the transmitter 304 may be further configured to transmit the generated message in a frame according to a standard selected from a list of standards consisting of: WiMedia standard; ECMA standard; IEEE 802 standard; IEEE 802.11 standard; IEEE 802.15.3 standard, IEEE 802.15.3b standard, IEEE 802.15.3c standard; and an Ultra Wide Band standard.

[0078] In various embodiments, the transmitter 304 may further be configured to transmit the generated message in an information element.

[0079] In various embodiments, at least one radio wave transmission/reception region of the plurality of radio wave transmission/reception regions may include at least a part of a sector defined by an angular region relative to a pre-determined point with respect to the first radio communication device.

[0080] In various embodiments, the plurality of radio wave transmission/reception regions may include parts of a plurality of sectors, wherein each sector may be defined by an angular region relative to a pre-determined point with respect to the first radio communication device.

[0081] In various embodiments, the angles of the angular regions of each of the plurality of sectors may be equal.

[0082] In various embodiments, the angles of at least two angular regions of each of the plurality of sectors may be different.

[0083] In various embodiments, at least one radio wave transmission/reception region of the plurality of radio wave transmission/reception regions may include at least a part of a region defined by an area between a first half-line and a second half line, the first half- line starting from a first pre-determined point with respect to the first radio communication device and having a first pre-determined angle with respect to the first radio communication device, and the second half-line starting from a second pre- determined point with respect to the first radio communication device and having a second pre-determined angle with respect to the first radio communication device.

[0084] hi various embodiments, the message generator 302 may be further configured to generate the message while no radio communication connection is established between the first radio communication device and the second radio communication device.

[0085] In various embodiments, the message generator 302 may be further configured to generate the message while no radio communication connection for interchange of user data is established between the first radio communication device and the second radio communication device.

[0086] In various embodiments, the transmitted message may be received in a third radio communication device.

[0087] hi various embodiments, the third radio communication device may be configured to perform directional radio communication.

[0088] In various embodiments, at least one of the first radio communication device and the second radio communication device may be configured to store a topology matrix including information specifying a radio wave transmission/reception region out of a plurality of radio wave transmission/reception region candidates which specified radio wave transmission/reception region a third radio communication device configured to perform directional radio communication may use for communication with a fourth radio communication device.

[0089] FIG. 4 shows an information storage device 400 according to an embodiment.

The information storage device 400 may include a message receiver 402 configured to receive a message including information specifying a radio wave transmission/reception region out of a plurality of radio wave transmission/reception region candidates which specified radio wave transmission/reception region a first radio communication device configured to perform directional radio communication may use for communication with a second radio communication device; and a storage 404 configured to store the information included in the message. The message receiver 402 and the storage 404 may be may be coupled with each other, e.g. via an electrical connection 406 such as e.g. a cable or a computer bus or via any other suitable electrical connection to exchange electrical signals.

[0090] In various embodiments, the message may furthermore include information specifying a plurality of radio wave transmission/reception regions out of the plurality of radio wave transmission/reception region candidates which specified radio wave transmission/reception regions the first radio communication device may use for communication with the second radio communication device.

[0091] In various embodiments, the message receiver 402 may further be configured to receive one or more further messages, each further message including respective information specifying a respective further radio wave transmission/reception region out of a respective plurality of further radio wave transmission/reception region candidates which specified respective radio wave transmission/reception region a respective further first radio communication device configured to perform directional radio communication may use for communication with a respective further second radio communication device; and the storage 404 may further be configured to store the respective information included in the one or more further received messages. [0092] In various embodiments, the information storage device 400 may furthermore be configured to receive and store information indicating that communication between a fifth radio communication device and a sixth radio communication device has started. [0093] hi various embodiments, the information storage device 400 may furthermore be configured to communicate with a third radio communication device configured to perform directional radio communication in a plurality of radio wave transmission/reception regions.

[0094] FIG. 5 shows an information storage device 500 according to an embodiment. The information storage device 500, similar to the information storage device 400 of FIG. 4, may include a message receiver 402 configured to receive a message including information specifying a radio wave transmission/reception region out of a plurality of radio wave transmission/reception region candidates which specified radio wave transmission/reception region a first radio communication device configured to perform directional radio communication may use for communication with a second radio communication device; and a storage 404 configured to store the information included in the message. The information storage device 500 may further include a communication start determiner 502 as will be explained in more detail below. The information storage device 500 may further include a communication start time determiner 504 as will be explained in more detail below. The information storage device 500 may further include an other party radio wave transmission/reception region determiner 506 as will be explained in more detail below. The information storage device 500 may further include a communication start restriction setter 508 as will be explained in more detail below. The message receiver 402, the storage 404, the communication start determiner 502, the communication start time determiner 504, the other party radio wave transmission/reception region determiner 506, and the communication start restriction setter 508 may be may be coupled with each other, e.g. via an electrical connection 510 such as e.g. a cable or a computer bus or via any other suitable electrical connection to exchange electrical signals.

[0095] In various embodiments, the communication start determiner 502 may be configured to, upon a request to the third radio communication device to start communication with a fourth radio communication device, determine whether to start communication with the fourth radio communication device, based on the information stored in the storage 404.

[0096] In various embodiments, upon a request to the third radio communication device to start communication with a fourth radio communication device, a radio wave transmission/reception region that the third radio communication device may use for communication with the fourth radio communication device may be determined, and upon a request to the third radio communication device to start communication with a fourth radio communication device, it may be determined not to start communication with a fourth radio communication device, in case the determined radio wave transmission/reception region may be used for radio communication with one of the fifth radio communication device and the sixth radio communication device. In various embodiments, the determination may be performed by the third radio communication device. In various embodiments, the determination may be performed by a predetermined radio communication device different from the third radio communication device. In various embodiments, the determination may be performed by a radio resource manager outside the radio communication device.

[0097] In various embodiments, the communication start time determiner 504 may be configured to upon a request to the third radio communication device to start communication with a fourth radio communication device, determine a communication start time for communication with the fourth radio communication device, based on the stored information. In various embodiments, the determination may be performed by the third radio communication device. In various embodiments, the determination may be performed by a predetermined radio communication device different from the third radio communication device. In various embodiments, the determination may be performed by a radio resource manager outside the radio communication device. [0098] hi various embodiments, the information storage device 500 may further be configured to, upon a request to the third radio communication device to start communication with a fourth radio communication device, determine a radio wave transmission/reception region that it may use for communication with the fourth radio communication device, and, the communication start time determiner 504 may be further configured to, upon the request to the third radio communication device to start communication with a fourth radio communication device, determine the communication start time to be equal or higher than a remaining communication time between the fifth radio communication device and the sixth radio communication device, in case the determined radio wave transmission/reception region may be used for radio communication with one of the fifth radio communication device and the sixth radio communication device. [0099] In various embodiments, the other party radio wave transmission/reception region determiner 506 may be configured to determine a radio wave transmission/reception region that may be used for radio communication with one of the fifth radio communication device and the sixth radio communication device, hi various embodiments, the connection start restriction setter 508 may be configured to set a connection start restriction for the determined radio wave transmission/reception region. [00100] In various embodiments, the connection start restriction setter 508 may be configured to receive information about the communication time between the fifth radio communication device and the sixth radio communication device, and to set the connection start time restriction to last at least for the communication time between the fifth radio communication device and the sixth radio communication device. [00101] FIG. 6 shows a flow diagram 600 illustrating a radio wave transmission/reception region determination method according to an embodiment. In 602, a first radio communication device, configured to perform directional radio communication in a plurality of radio wave transmission/reception regions, may sequentially transmit a first signal omnidirectionally, a second signal in a first radio wave transmission/reception region and a third signal in a second radio wave transmission/reception region. In 604, a second radio communication device may receive from the first radio communication device at a first reception time the first signal and at a second reception time one of the second signal and the third signal. In 606, the second radio communication device may determine a radio wave transmission/reception region which the first radio communication device may use for communication with the second radio communication device based on the difference between the first reception time and the second reception time.

[00102] FIG. 7 shows a flow diagram 700 illustrating a radio wave transmission/reception region determination method according to an embodiment. In 702, a second radio communication device may transmit a signal omnidirectionally. In 704, a first radio communication device, configured to perform directional radio communication in a plurality of radio wave transmission/reception regions, may sequentially determine whether at a first reception time a first signal transmitted omnidirectionally by the second radio communication device may be received in a first radio wave transmission/reception region and whether at a second reception time a second signal transmitted omnidirectionally by the second radio communication device may be received in a second radio wave transmission/reception region, hi 706, the first radio communication device may determine a radio wave transmission/reception region which the first radio communication device may use for communication with the second radio communication device based on the determination 704 whether at a first reception time a first signal transmitted omnidirectionally by the second radio communication device may be received in a first radio wave transmission/reception region and whether at a second reception time a second signal transmitted omnidirectionally by the second radio communication device may be received in a second radio wave transmission/reception region.

[00103] FIG. 8 shows radio wave transmission/reception region determination system 800 according to an embodiment. The radio wave transmission/reception region determination system 800 may include a first radio communication device 802 and a second radio communication device 804. The first radio communication device 802 and the second radio communication device 804 may perform radio communication by a radio link 806.

[00104] In various embodiments, the first radio communication device 802 may be configured to perform directional radio communication in a plurality of radio wave transmission/reception regions and to sequentially transmit a first signal omnidirectionally, a second signal in a first radio wave transmission/reception region and a third signal in a second radio wave transmission/reception region; the second radio communication device 804 may be configured to receive from the first radio communication device 802 at a first reception time the first signal and at a second reception time one of the second signal and the third signal; and the second radio communication device 804 may be further configured to determine a radio wave transmission/reception region which the first radio communication device 802 may use for communication with the second radio communication device based on the difference between the first reception time and the second reception time.

[00105] In various embodiments, the second radio communication device 804 may be configured to transmit a signal omnidirectionally; the first radio communication device 802 may be configured to perform directional radio communication in a plurality of radio wave transmission/reception regions, and to sequentially determine whether at a first reception time a first signal transmitted omnidirectionally by the second radio communication device 804 may be received in a first radio wave transmission/reception region and whether at a second reception time a second signal transmitted omnidirectionally by the second radio communication device 804 may be received in a second radio wave transmission/reception region; and the first radio communication device 802 may be further configured to determine a radio wave transmission/reception region which the first radio communication device 802 may use for communication with the second radio communication device 804 based on the determination whether at a first reception time a first signal transmitted omnidirectionally by the second radio communication device 804 may be received in a first radio wave transmission/reception region and whether at a second reception time a second signal transmitted omnidirectionally by the second radio communication device 804 may be received in a second radio wave transmission/reception region.

[00106] According to various embodiments, spatial reuse strategies for contention based medium access and for reservation based medium access for devices that use directional antennas may be provided.

[00107] According to various embodiments, spatial reuse strategies for directional antenna usage in wireless ad hoc networks may be provided. One of the applications of the proposed strategies may be systems that work in 55GHz to 70GHz range. At this range of frequencies, the channel attenuation may be larger than that for channels that operate at lower frequencies. The use of directional antennas may result in increase of range of transmission for systems that operate at 55GHz to 70GHz range due to the gain offered by the directional antennas. Moreover, the use of directional antennas may result in increased network throughput because of the possibility of spatial reuse. Medium access delay by a packet may also be lowered by the use of directional antennas since several simultaneous transmissions are possible because of spatial reuse. Use of directional antennas may also alleviate certain issues and problems posed by multipath propagation and inter symbol interference, since use of directional antennas more or less result in single path or line of sight communication. For systems that may operate at 55GHz to 70 GHz range of frequencies and also for systems that operate at any other frequency or in any other frequency range, spatial reuse strategies catered for directional transmission and reception may be provided in various embodiments. The strategies of various embodiments may also be applicable to general communication systems that may benefit from spatial reuse.

[00108] Spatial reuse strategies in accordance with various embodiments cater for both contention based access and reservation based access to the medium using directional transmission and reception. To illustrate the strategies according to various embodiments, the methodologies will be explained in view of Prioritized Channel Access (PCA) and Distributed Reservation Protocol (DRP) of WiMedia standard and in view of the IEEE 802.11 and IEEE 802.15.3b standards. However, the spatial reuse schemes according to various embodiments may be applicable to any general contention based access strategy or any general reservation based medium access strategy. As a side note, contention based access may some times result in reduced delay in accessing the medium by a packet since time needed to negotiate reservation of channel is bypassed, and reservation based access may ensure some Quality of Service metrics for voice and video traffic. [00109] As explained below, spatial reuse strategies may be provided for directional transmission and reception in various embodiments. In various embodiments, every node (or device) 'n' may divide its transmission range (for example omni-directional reachable area by transmission) in to S_n logical radio wave transmission/reception regions, for example sectors. It will be understood in the following that a sector may be addressed as a general radio wave transmission/reception region. Every node (or device) 'n' may also label its logical sectors with fixed integers (1, 2, 3, ..., S_n), for example consecutively in clock wise direction or anti-clock wise direction. In various embodiments, irrespective of whether a node has sector antennas or phased array antennas, such logical radio wave transmission/reception regions, for example sectors (for example fixed with respect to a point in the device), may be maintained at every node.

[00110] Spatial reuse strategies for WiMedia/ECMA MAC (medium access control) based networks may be provided in various embodiments as given below. [00111] In various embodiments, beacons may be sent in all directions a radio communication device may send, for example omni-directionally, during a beacon period. The devices may perform frequent device discovery phases (for example at least once every one, two or any fixed number of superframes) to keep themselves updated of their respective neighborhood orientations (for example the relative angle), not necessarily locations (for example, in various embodiments, the location of the devices in the neighborhood may be not determined, for example, a distance may not be determined in addition to an angle.). In the following, first various embodiments will be explained assuming S_n=S=4 for the sake of brevity and for the purpose of illustrating the associated concepts.

[00112] In various embodiments, a request to send (RTS) signal may be sent by the first radio communication device only using radio wave transmission/reception regions that are determined not to affect an ongoing communication. In various embodiments, a RTS frame may be replaced by any initiation frame. [00113] It will be understood that the methods and devices according to various embodiments described herein may be applied for general and arbitrary values of S_n. [00114] In various embodiments, every node may transmit a Topology Information Element, for example every superframe, as will be explained in more detail below. [00115] In various embodiments, every node may also maintain the following caches: Topology Matrix, as will be explained below and S (for example four) Directional Network Allocation Vectors (DNAVs), details of which are given further below. [00116] According to various embodiments, a new information element called the Topology Information Element or the Topology IE is provided.

[00117] It will be understood that properties of devices or methods according to various embodiments described above with reference to FIG. 1, FIG. 2, FIG. 3, FIG. 4 and FIG. 5 may also be analogously applied to the embodiments described above with reference to FIG. 6, FIG. 7 and FIG. 8 above.

[00118] FIG. 9 shows a format of a topology information element 900 transmitted by a device according to an embodiment.

[00119] hi the format of the topology information element 900, a first device address field 920, using 2 octets, up to an N-th device address 924, using 2 octets, may be provided. The device addresses between the first device address and the N-th device address may be indicated by dots 922. The device address fields may be the Device Addresses of the device's neighbors. The Topology Information Bitmap field 918 may include or consist of K octets of 4-bit elements, as indicated by the field 906, to indicate the logical sector usage, that may be the logical sector of a neighbor used by the neighbor to communicate with the device, where K = Ceiling (N/2), where N may be the total number of neighbors of the device. Each element 'n' may correspond to neighbor 'n' and may indicate the logical sectors of the neighbor 'n' used by the neighbor 'n' to communicate with the device. Each device address 920 , 924 may have a length of 2 octets, as indicated by fields 908 and 912 respectively. The least significant bit in each element may correspond to logical sector numbered 4 and the most significant bit in each element may correspond to logical sector numbered 1. Each of the four bits in an element 'n' may either be a zero or a one to signify if the corresponding logical sector is unused (for example bit =0) or used (for example bit =1) respectively to communicate with the device by the corresponding neighbor 'n'. Element one may be the least-significant four bits of the Topology Information Bitmap field. Unused elements, if any, may be set to zero. An element ID 914 may be provided, for example to uniquely identify the type of the information element as a topology information element. The element ID 914 may have a length of 1 octet, as indicated by field 902. The total length of the information in the information element may be given in a length field 916. The length field may have a length of 1 octet, as indicated by field 904. For example, the length of the information element with N device addresses may have a length of K + 2 N octets (for example, K octets for the topology information bitmap 918, and 2 octets for each of the device addresses).

[00120] In various embodiments, every device may include the Topology IE in its beacon every superframe. The sector of a neighbor to be used by that neighbor to communicate with the device may be normally found by the device during device discovery phase, as will be explained below. The device after collecting information from device discovery process may later encode the information in the Topology IE. The information included in the Topology IE may be applicable to the superframe in which the IE may be sent. If a beacon is not received from a device for up to a constant number (for example mTopologyConstancy, for example 3) of superframes after receiving a beacon from that device in a previous superframe, the Topology IE in the last beacon received from that device may be used as if it were received in the current superframe (in regards to Topology IE).

[00121] In various embodiments, a further (in other words: alternative) format of the Topology Information Bitmap may be provided as will be explained below. [00122] In various embodiments, the Topology Information Bitmap field 918 may include or consists of N octets of 8-bit elements to indicate the logical sector usage, that may be the logical sector of a neighbor used by that neighbor to communicate with the device, where N may be the total number of neighbors of the device. Each element 'n', numbered from 1 to N, may correspond to neighbor 'n' and may indicate the logical sectors used by a neighbor 'n' to communicate with the device. The least six significant bits of an element 'n' may indicate the number of the logical sector which may be any of zero (or 1) to sixty three (or 64) used by the neighbor 'n' to communicate with the device. The most significant bit of an element 'n' may indicate if the logical sector that is one higher (modulo 64) than the one indicated by the least six significant bits of the element may also be used by the neighbor 'n' (if that bit is set to one) to communicate with the device. The second most significant bit of an element 'n' may indicate if the logical sector that is one lower (modulo 64; -1 is equivalent to 63) than the one indicated by the least six significant bits of the element may also be used by the neighbor 'n' (if that bit is set to one) to communicate with the device. It is to be noted that a neighbor 'n' may then use up to three sectors to communicate with the device.

[00123] In various embodiments, the most significant bit and the second most significant bit, both of an element 'n' together (as two bits) may signify how many sectors of the neighbor 'n' on both sides of the logical sector mentioned by the six least significant bits of the corresponding element are used for communication by that neighbor 'n' to communicate with the device. Then, the neighbor 'n' may use up to 7 logical sectors (three on either side of the logical sector given by the six least significant bits) to communicate with the device, hi various embodiments, the two most significant bits of an element 'n' may inform how many sectors of neighbor 'n' on one predetermined side of the logical sector given by the six (or any other pre-determined number) least significant bits of the corresponding element are used for communication by the neighbor 'n' to communicate with the device.

[00124] In various embodiments, one or more nodes (for example every node) may maintain caches, as will be explained below.

[00125] In various embodiments, one or more devices (for example every device) that transmits or receives frames using PCA or DRP may maintain a Topology Matrix (TM). The TM may have ten columns as shown in table 1 below. Each row may correspond to a particular link (between two devices) in the network. Each row may contain link information in regards to first device address of the corresponding link (for example a source) or in other words Device Address 1 of Link, second device address of the corresponding link (for example a sink) or in other words Device Address 2 of Link, first device address's best logical sectors) for that link, and second device address's best logical sector(s) for that link. Each of the four columns in the "Device Address l's Logical Sector(s)" tab in the TM may correspond to a bit and corresponds to one logical sector, and may be set to one if the corresponding logical sector is used by device address 1 for communicating with device address 2. Each of the four columns in the "Device Address 2's Logical Sector(s)" tab in the TM may correspond to a bit and may correspond to one logical sector, and may be set to one if the corresponding logical sector is used by device address 2 for communicating with device address 1. The TM may be updated every superframe or once in every L₀ superframes (where L₀ may be a natural number greater than 1) by the device based on device discovery results and Topology IEs received. Information from other devices about other links (where the device may be not a vertex) that may be needed to update the TM may be received through beacons using the Topology IEs described above.

Table 1 : Columns of Topology Matrix (TM) [00126] One or more devices (for example each device) may maintain a TM pertaining to itself and its neighbors as to which logical sector the device or its neighbor may use to communicate as a source with another device.

[00127J FIG. 10 shows a network 1000 of devices according to an embodiment. In the network 1000 of devices using directional antennas, for the following explanation, it may be assumed that all devices may be within the transmission range of each other. For sake of brevity, the radio communication devices shown in FIG. 10 may also be referred to as nodes or as devices. A first radio communication device 1002 may communicate in its first sector 10021 , in its second sector 10022, ^m i^ts third sector IOO23, and in its fourth sector IOO24. A second radio communication device 1004 may communicate in its first sector 1004], in its second sector 10042, ^m its third sector 10043, and in its fourth sector IOO44. A third radio communication device 1006 may communicate in its first sector IOO61, in its second sector IOO62, in its third sector IOO63, and in its fourth sector IOO64. A fourth radio communication device 1008 may communicate in its first sector IOO81, in its second sector IOO82, in its third sector IOO83, and in its fourth sector IOO84. A fifth radio communication device 1010 may communicate in its first sector IOIO1, in its second sector 10102, in its third sector IOIO3, and in its fourth sector 10104. A sixth radio communication device 1012 may communicate in its first sector 1012i, in its second sector 10122, ^m its third sector IOI23, and in its fourth sector IOI24. A seventh radio communication device 1014 may communicate in its first sector 1014^, in its second sector 10142, in its third sector IOH3, and in its fourth sector IOI44.

[00128] An example of a TM maintained by first device 1002 is illustrated in table 2.

Table 2: Example of a TM pertaining to device 1002 in FIG. 10.

[00129] As may for example be seen from first row of table 2 maintained by the first device 1002, the first device 1002 may use it's first logical sector 1002} to communicate

with the second device 1004, and the second device 1004 may use it's third logical sector 10043 to communicate with the first device 1002. The first device 1002 may get this

information through its own device discovery process and through the Topology IE sent by the second device 1004. It may for example be also seen from table 2 maintained by the first device 1002, that the seventh device 1014 may use two logical sectors (its first sector 1014i and its fourth sector IOH4) to communicate with the fifth device 1010, and

the fifth device 1010 in turn may use two of its logical sectors (it second sector IOIO2 and its third sector IOIO3) to communicate with the seventh device 1014. The above

information may be gathered by the first device 1002 through the Topology IEs received from the seventh device 1014 and the fifth device 1010. It may be assumed that the seventh device 1014 and the fifth device 1010 have device discovery results. [00130] hi various embodiments, a device that transmits or receives frames may maintain four Directional Network Allocation Vectors (DNAVs), one for each of its logical sector that may contain the remaining time that the logical sector may not be used for transmission or reception, for example because of a neighbor device's transmission or reception. A device that receives a frame header not addressed to it and not addressed to a broadcast address may update its DNAVs (as will be explained below) for the concerned logical sector with the received Duration field if the new DNAV value for the concerned sector is greater than the current DNAV value for that sector. A device that receives a beacon announcing an established reservation may update its concerned DNAVs (as will be explained below) at the start of the first of the contiguous Medium Access Slots (MASs) advertised in the received DRP IE with the duration that may cover all the remaining contiguous MASs of the reservation advertised in the received DRP IE. More details about the update of DNAVs will be given below.

[00131] In various embodiments, a device may reduce each of its DNAV as time elapses until it reaches zero. The DNAVs may be maintained to at least a parameter mClockResolution.

[00132] hi various embodiments, methods and devices for spatial reuse with DRP may be provided, as will be explained below. [00133] In various embodiments, if a device wants to start a DRP negotiation, it first may gather information pertaining to all the existing DRP reservations through the DRP IEs received in the beacons of all its neighbors. The device may also look at its TM to infer which logical sectors it intends to use to communicate with its proposed recipient device. The device may also infer from its TM which logical sectors its proposed recipient device may use to communicate with it. If the above logical sectors as inferred from the device's TM may not be reachable by any of the currently used logical sectors of devices that are using existing reservations, then the device may start a DRP negotiation with its recipient device.

[00134] For example, with reference to FIG. 10, it may be assumed that the first device 1000 and the third device 1006 may have reserved a set of MASs. If the second device 1004 desires to start a DRP negotiation with the fourth device 1008 for the above same set of MASs, it may first infer from the beacons it receives that the first node 1002 and the third node 1006 may have an existing reservation and it may also infer from its

TM that the first device 1002 may use its first logical sector 1002i and the third device

1006 may use its fourth logical sector IOO64. The second device 1004 may also infer

from its TM that it may intend to use its second logical sector 10042 which may be

unreachable by the first logical sector 1002} of the first device 1002 and the fourth

logical sector IOO64 of the third device 1006. The second device 1004 may also infer

from its TM that the fourth device 1008 may desire to use its first logical sector 1008j and second logical sector IOO82 to communicate with it, and that these logical sectors

may be unreachable by the first logical sector 1002i of the first device 1002 and the

fourth logical sector IOO64 of the third device 1006. With the above, the second device

1004 may be able to start a DRP negotiation to use the same MASs or MASs overlapping with those used by the first device 1002 and the third device 1006. A target device before it grants any reservation may ensure that the logical sectors proposed to be used by itself and the owner of the reservation negotiation shall be unreachable from any of the currently used logical sectors of devices that are using existing reservations. Once the second device 1004 establishes a DRP reservation with fourth device 1008, the second device 1004 and the fourth device 1008 may simultaneously use the medium when the first device 1002 and the third device 1006 communicate. The negotiation rules using DRP IEs may be similar to those as given in an ECMA specification subject to the above rules. However, the devices negotiating any reservation may rely on their respective TMs and DNAVs as well. If a device intends to use a logical sector for DRP related transmission, the DNAV of that logical sector may be desired to be zero at the start of (and during) the MASs proposed to be reserved or used by the device in a superframe. [00135] In various embodiments, when a reservation is established, some of or all the nodes that are neighbors of either the owner or target may update their DNAVs just before the reserved MASs begin. A neighbor of an owner or a target of an exiting reservation may update its DNAVs for its logical sectors (at the start of the reserved MASs) that are reachable by the owner's used logical sector(s) or/and the target's used logical sector(s) for the existing reservation. As an example, with reference to FIG. 10, the sixth node 1012, when it hears beacons from the first node or the third node advertising a reservation establishment for a set of MASs, may update its DNAV for its

second logical sector 10012 at the start of (and for example not before) the above set of

MASs in every superframe the reservation holds, since its second logical sector 10122

may be reachable by the first logical sector 1002j of the first node 1002 (that may use the

DRP reservation with the third node 1006). It is to be noted that the sixth node 1012 may set its DNAV for its second logical sector 10122 ^{to a} duration that may cover the set of

MASs reserved by 1002 and 1006. Similarly, the seventh node 1014 may update it's DNAV for its first logical sector 1014i at the start of the above set of reserved MASs in

every superframe the above reservation between the first node 1002 and the third node 1006 holds, since its first logical sector 1014j is reachable by the fourth logical sector

IOO64 of the third node 1006 (that may use the DRP reservation with the first node

1002). DNAVs at the sixth node 1012 and the seventh node 1014 may be not updated in a superframe concerning the above reservation until the start of the MASs reserved by the first node 1002 and the third node 1006. The sixth node 1012 and the seventh node 1014 may remember to update their DNAVs during the data transfer period of the superframe after hearing beacons from the first node 1002 and the third node 1006 in the beacon period. If the first device 1002 and the third device 1006 have several contiguous MAS segments reserved that are disjoint with each other, their neighbors may update their concerned DNAVs at the start of every contiguous segment with duration covering that contiguous segment.

[00136] In various embodiments, conflicts (for example subject to above spatial reuse rules) between two reservation negotiations both of a same type may be resolved according to one of various methods, for example to resolve conflicts between two "Hard

Reservation" type negotiations. If a logical sector of a device that is to be used in one reservation is reachable from a logical sector of another device that is to be used in another reservation that claims overlapping set of MASs claimed by the first reservation, then the above two reservations may be in conflict with each other.

[00137] In various embodiments, if a device receives a DRP IE from an owner whose target is not a neighbor of the device, the device may update its DNAVs of the sectors that may reach the owner at the start of the MASs reserved by the owner with a duration value that may cover the entire above reserved MASs. If a device receives a DRP IE from a target whose owner is not a neighbor of the device, the device may update its DNAVs of the sectors that may reach the target at the start of the MASs reserved by the corresponding owner with a duration value that may cover the entire reserved MASs.

[00138] In various embodiments, methods and devices for spatial reuse with PCA may be provided, as will be explained below.

[00139] In various embodiments, a device may use a logical sector for communication only if its corresponding DNAV is zero and the medium in that logical sector is idle

(medium is available if these conditions are satisfied).

[00140] In various embodiments, for PCA purposes, a device may consider the medium in a logical sector to be busy for any of the following conditions: [00141] - when its Clear Channel Assessment (CCA) mechanism indicates that the medium in this logical sector is busy (though the medium may be directionally available or idle in other logical sectors);

[00142] - when the device's DNAV for this logical sector is greater than zero;

[00143] - when the device is transmitting or receiving a frame on the medium using this logical sector;

[00144] - when the Duration announced in a previously transmitted frame from or to a logical sector of a neighbor of the device that is reachable by this logical sector of the device (inferred using TM) has not yet expired;

[00145] - when the medium in this logical sector is unavailable for PCA, because of a reservation of neighbor(s) using logical sector(s) reachable by this logical sector of the device.

[00146] At all other times a device may consider the medium in a logical sector to be idle. The medium may be considered to be idle by the device omni-directionally if the medium is idle for each of its logical sectors. Even if the medium in one of its logical sectors is busy, the device may consider the medium busy for omni-directional transmission.

[00147] In various embodiments, a device may maintain a back off counter for every

Access Category (AC), for example as in an ECMA specification for omni-directional transmission purposes. This back off counter may be decremented in a similar manner as given in an ECMA specification. Rules pertaining to invoking and decrementing the above back off counter may be as given in an ECMA specification. In addition to the above, in various embodiments, a device may maintain an independent back off counter for every AC for every logical sector. The back off counter for an AC for a logical sector may be decremented only if the medium in the corresponding logical sector (whose DNAV is zero) is idle for past AIFS[AC] (wherein AIFS may be the Arbitration Inter- Frame Spacing, which may be an idle time, where AIFS[AC] may denote the AIFS of a given AC) and a predetermined time, for example pSlotTime. Rules pertaining to invoking and decrementing the above back off counter for a logical sector may be similar to those as given in an ECMA specification for PCA and omni-directional transmission, with the exception that the medium may be restricted to the medium in that logical sector. A device shall be able to independently perform Clear Channel Assessment (CCA) in each of its four logical sectors. A device shall also be able to independently invoke a back off for the medium in any logical sector.

[00148] In various embodiments, when a device has a buffered packet for an AC to be sent using PCA, the device may first check from its TM which of the logical sectors it intends to use to send directionally transmitted data. Using conditions given above (for checking medium idleness), the device may then ascertain if the medium in the logical sectors) it intends to use for directional data transmission is idle. If the medium in the above logical sector(s) is busy, the device may also invoke a back off counter corresponding to the logical sector it intends to use for directional data transmission. The device may simultaneously also invoke another independent back off counter for omnidirectional transmission.

[00149] hi various embodiments, a device may be considered or may consider itself to have obtained a transmission opportunity (TXOP) in a logical sector for an AC if it meets the following conditions: [00150] - the device has one or more newly arrived data frames or newly generated command frames belonging to this AC;

[00151] - the device had a backoff counter corresponding to that logical sector of zero value for this AC and had no frames belonging to this AC prior to the arrival or generation of the new frames;

[00152] - the device determines that the medium in that logical sector has been idle and available for AIFS[AC] or longer; and

[00153] - the device has no backoff counters corresponding to that logical sector of zero value for other ACs, or has backoff counters corresponding to that logical sector of zero value for some other ACs, but such ACs have a lower priority than this AC or the device has no frames belonging to those ACs that are ready for transmission.

[00154] In various embodiments, the device may start transmitting a frame belonging to this AC, which may be a RTS frame, directionally in that logical sector as soon as the above conditions are satisfied (subject to rules described above and below). The device may also consider itself to have obtained a TXOP for an AC in a logical sector if it meets the following conditions:

[00155] - the device has one or more frames belonging to this AC buffered for transmission, including retry;

[00156] - the device decremented its backoff counter corresponding to that logical sector for this AC from one to zero and no frame was transmitted by the device in that logical sector with medium in that logical sector having remained idle and available since then; [00157] - the device has no backoff counters corresponding to that logical sector of zero value for other ACs, or has backoff counters corresponding to that logical sector of zero value for some other ACs, but such ACs have a lower priority than this AC or the device has no frames belonging to those ACs that are ready for transmission. [00158] In various embodiments, the device may not initiate transmission in any logical sector unless it had obtained a TXOP in one of the logical sectors subject to rules described in above and below. The device may consider itself to have obtained a TXOP for omni-directional transmission using procedure as given in an ECMA specification but with the use of the back off counter for omni-directional transmission for an AC. [00159] In various embodiments, before any RTS packet may be sent, the device may determine if it had obtained a TXOP in the logical sector it intends to send the directional data. If the device had obtained a TXOP for omni-directional transmission, the device may send the RTS packet omni-directionally (if RTS is sent). In various embodiments, concerning transmission of RTS, only if the device has the medium unavailable for omnidirectional transmission, the device may send a directional RTS in case it decides to send a RTS. If the device had obtained a TXOP only in the logical sector it intends to send the directional data (with medium busy in other sectors), the device may send the RTS packet directionally in the logical sector it intends to send directional data. The upper bound on the duration field in the RTS packet that is sent omni-directionally may be a predetermined number, for example mTXOPLimit. The upper bound on the duration field in the RTS packet that is sent directionally may be the value of the least of the device's nonzero DNAVs for its logical sectors minus RTS frame header transmission time. No RTS packet may be sent by a device if the expected duration (to be included in the RTS packet) infringes upon an upcoming reservation of a neighbor that may be affected given the information from device's TM, received DRP IEs, and the DNAVs. [00160] In various embodiments, concerning sending a directional RTS frame or directional CTS frame, the device may send the frame simultaneously in every logical sector whose DNAV has a zero value and whose medium has been idle for more than AIFS/AIFS[AC] while sending the frame in the logical sector it intends to transmit or receive data. This may be done using sector antennas or through beamforming with phased array antennas.

[00161] In various embodiments, a device may not transmit a directional RTS frame (or initial frame at the start of a TXOP) in a logical sector if the DNAV of any of the other logical sectors is zero and the medium in that other logical sector whose DNAV is zero has been idle for less than AIFS/AIFS[AC].

[00162] When a RTS packet is received by a device (with device address in RTS packet matching the device address of the device), the device may first check from its TM which of its logical sectors it may use to receive directionally transmitted data from the sender of the RTS. Using the above conditions (for checking medium idleness), the device may also ascertain if the medium in the logical sector(s) it intends to use for reception is idle. If the medium is idle and available in all of its logical sectors, the device may send the CTS packet omni-directionally with duration field, for example as given in an ECMA specification. If the medium is not idle in all the logical sectors but idle and available only in the logical sector it intends to receive the directional data, the device may send the CTS packet directionally in the logical sector it intends to receive directional data. In the CTS packet sent directionally by the device, the upper bound on the duration field in the CTS packet may be the minimum of

[00163] (i) value of the least of the device's non-zero DNAVs for its logical sectors minus CTS frame header transmission time; and

[00164] (ii) the duration field (for omni-directional CTS) as inferred using the procedure given in an ECMA specification from the RTS packet received by the device. [00165] In various embodiments, if the duration field (for omni-directional CTS) as inferred using the procedure given in an ECMA specification from the RTS packet received by the device exceeds the least of its non-zero DNAVs for its logical sectors minus CTS frame header transmission time, a CTS packet may not need to be sent by the device in response to a received RTS packet. Moreover, a CTS packet may not be sent if the duration (as derived from above) infringes upon an upcoming reservation of a neighbor that may be affected given the information from device's TM, received DRP IEs, and the DNAVs. If CTS packet is sent directionally, the duration may be desired to be less than or equal to the least non-zero DNAV for the device's logical sectors minus CTS frame header transmission time.

[00166] In various embodiments, if a device has a sector (numbered S) with non zero DNAV, the device may not send a CTS frame in a sector that is diametrically and geometrically opposite to that sector S (for the purpose of receiving data in the sector geometrically opposite S). In various embodiments, whenever RTS is sent directionally, it may be sent with reduced power (for example with power control). Similarly, a CTS frame if sent directionally, may be sent with reduced transmit power (for example with power control). In various embodiments, all control frames transmitted directionally may be transmitted with power control to offset the directional transmit antenna gain. [00167] As an example, referring to FIG. 10, if the first device 1002 sends an omnidirectional RTS to the third device 1006, then upon reception of the above RTS, all the neighbors of the first device 1002 may infer from the frame header of RTS received that the intended destination is the third device 1006. Each of the neighbors of the first device 1002 may also after looking at its TM set it's DNAVs after inferring that the first device

1002 may intend to use its first logical sector 1002j to communicate with the fourth

logical sector IOO64 of the third device 1006. The seventh device 1014 may desire to set

its DNAV for its first sector 1014j as its first sector 1014j is reachable from the fourth

sector IOO64 of the third device 1006. The sixth device 1012 may set the DNAV for its

second logical sector 10122 using the duration field from received RTS packet, the fourth

device 1008 may set the DNAV for its third logical sector IOO83, and the second device

1004 may set the DNAV for its third logical sector IOO43. Upon reception of the RTS

packet from the first device 1002, the third device 1006 may infer from its TM that it may desire to use its fourth logical sector IOO64 for receiving packets from the first device

1002 and assuming its DNAV for its fourth sector IOO64 is zero along with all of its other

DNAVs, the third device 1006 may respond with a CTS packet with duration decided using rules given in an ECMA specification. The third device 1006 may also send omni- directional CTS since the DNAVs of all its sectors may have been zero (just prior to transmission of CTS). Upon reception of a CTS from the third device 1006, each of the seventh device 1014, the sixth device 1012, the fourth device 1008 and the second device 1004 with the use of its own TM may desire to update its DNAVs. It is to be noted that the fourth sector IOO64 of the third device 1006 may be unreachable from all other nodes

(excluding the seventh device 1014 and the first device 1002 which may be the recipient of the CTS from the third device 1006). Now if the second device 1004 desires to send a RTS packet to the fourth device 1008 when the first device 1002 and the third device

1006 communicate, it may infer that its DNAV for its third sector IOO83 is non zero.

Hence should it choose to send an RTS, it may send RTS directionally to the fourth device 1008 using the second sector 10042 if it is available (and also using all the other

available sectors). Since the fourth device 1008 may have a non-zero DNAV for its third sector IOO83 (because of link first device 1002 - third device 1006), the fourth device

1008 may send a CTS packet directionally to the second device 1004 using its first sector IOO81 and its second sector IOO82 if these are available (and also using all other available

sectors) with duration field set to a value less than or equal to the DNAV of its third sector IOO83 (say it is least non-zero DNAV) minus CTS frame header transmission

time.

[00168] In various embodiments, if a device receives a RTS or a CTS frame destined to another device (recipient of RTS or CTS is another device) which is not the neighbor of the device, then the device may update its DNAVs of its sectors that may reach the sender of the RTS or CTS frame and update its DNAVs of its other sectors that are in the one-half of its transmission reachable area facing the sender of the RTS or CTS frame taking in to account the duration value included in the received RTS or CTS frame. [00169] In various embodiments, optional payloads of RTS and CTS frames may be provided, as will be explained below.

[00170] In the above it may have been assumed that the RTS and CTS frames have formats similar to those specified by ECMA specification. In various embodiments, optional alternate formats for RTS and CTS frames may be provided. In various embodiments, a payload of one octet may be added to each of the RTS and CTS frames. The TM of every device may be updated based on the Topology IEs received in the beacons and device discovery results. IfRTS and CTS frames have such above payloads, flexibility may be increased for the device to update its TM more frequently within a superframe based on the frames it receives (other than beacon frames) from its neighbors. [00171] hi various embodiments, payload for RTS frame may be provided as will be explained below.

[00172] In various embodiments, the payload of a RTS frame may be two 4-bit elements. The first element may occupy the 4 least significant bits of the octet. The first element may give information about sector usage at the sender of the RTS frame intended for the directional data communication with the recipient device (destination of RTS). The second element may give information about the sector usage at the recipient (destination of RTS) as inferred from TM for directional data reception. The least significant bit in the first element may signify the usage of the sender's (sender of RTS) 4^th sector. The least significant bit in the second element may signify the usage of recipient's (recipient of RTS) 4^th sector. If a bit in an element is one, then the corresponding sector may be intended to be used, otherwise not. The sender of the RTS frame may derive the information to be included in this octet from the Topology IEs from neighbors and its TM.

[00173] In various embodiments, payload for the CTS frame may be provided as will be explained below.

[00174] In various embodiments, the payload of CTS frame may be two 4-bit elements. The first element may occupy the 4 least significant bits of the octet. The first element may give information about sector usage at the sender of the CTS frame intended for the directional data communication with the sender of RTS (or destination of CTS). The second element may give information about the sector usage at the sender of RTS for communication with the sender of the CTS. The least significant bit in the first element may signify the usage of the sender's (sender of CTS) 4^th sector. The least significant bit in the second element may signify the usage of recipient's (recipient of CTS) 4^th sector. If a bit in an element is one, then the corresponding sector may be intended to be used, else not. The sender of the CTS frame may derive the information to be included in this octet from the Topology IEs from neighbors and its TM. Referring to FIG. 10, as an example, a RTS packet sent by the first device 1002 to the third device 1006 may have the following payload as shown in FIG. 11. An example of a CTS packet sent by the third device 1006 to the first device 1002 may have the payload as shown in FIG. 12. [00175] FIG. 11 shows payload 1100 of a request to send frame according to an embodiment. In the example of a payload of RTS frame 1100, the first element may occupy the four least significant bits, for example the zero-th bit bO (1116) which may represent the fourth sector of the sender of the RTS frame, the first bit bl (1114) which may represent the third sector of the sender of the RTS frame, the second bit b2 (1112) which may represent the second sector of the sender of the RTS frame, and the third bit b3 (1110) which may represent the first sector of the sender of the RTS frame. The second element may occupy the four most significant bits, for example the fourth bit b4 (1108) which may represent the fourth sector of the recipient of the RTS frame, the fifth bit b5 (1106) which may represent the third sector of the recipient of the RTS frame, the sixth bit b6 (1104) which may represent the second sector of the recipient of the RTS frame, and the seventh bit b7 (1102) which may represent the first sector of the recipient of the RTS frame. The value of the zero-th bit 1116 is indicated by reference sign 1132. The value of the first bit 1114 is indicated by reference sign 1130. The value of the second bit 1112 is indicated by reference sign 1128. The value of the third bit 1110 is indicated by reference sign 1126. The value of the fourth bit 1108 is indicated by reference sign 1124. The value of the fifth bit 1106 is indicated by reference sign 1122. The value of the sixth bit 1104 is indicated by reference sign 1120. The value of the seventh bit 1102 is indicated by reference sign 1118. The first device 1002 may send the

RTS frame using its first sector 10021 , and thus the third bit b3 (1110) may be 1, and the

other bits (1112, 1114, 1116) in the first element may be set to 0. Furthermore, the third device 1006 may receive the RTS frame using its fourth sector IOO64, and thus the fourth

bit b4 (1108) may be set to 1, and the other bits (1102, 1104, 1106) in the second element may be set to 0. [00176] FIG. 12 shows payload 1200 of a clear to send frame according to an embodiment. In the example of a payload of CTS frame 1200, the first element may occupy the four least significant bits, for example the zero-th bit b0 (1216) which may represent the fourth sector of the sender of the CTS frame, the first bit bl (1214) which may represent the third sector of the sender of the CTS frame, the second bit b2 (1212) which may represent the second sector of the sender of the CTS frame, and the third bit b3 (1210) which may represent the first sector of the sender of the CTS frame. The second element may occupy the four most significant bits, for example the fourth bit b4 (1208) which may represent the fourth sector of the recipient of the CTS frame, the fifth bit b5 (1206) which may represent the third sector of the recipient of the CTS frame, the sixth bit b6 (1204) which may represent the second sector of the recipient of the CTS frame, and the seventh bit b7 (1202) which may represent the first sector of the recipient of the CTS frame. The value of the zero-th bit 1216 is indicated by reference sign 1232. The value of the first bit 1214 is indicated by reference sign 1230. The value of the second bit 1212 is indicated by reference sign 1228. The value of the third bit 1210 is indicated by reference sign 1226. The value of the fourth bit 1208 is indicated by reference sign 1224. The value of the fifth bit 1206 is indicated by reference sign 1222. The value of the sixth bit 1204 is indicated by reference sign 1220. The value of the seventh bit 1202 is indicated by reference sign 1218. The third device 1006 may send the

CTS frame using its fourth sector IOO64, and thus the zero-th bit b0 (1216) may be 1, and

the other bits (1210, 1212, 1214) in the first element may be set to 0. Furthermore, the first device 1002 may receive the CTS frame using its first sector 10021 , and thus the seventh bit b7 (1202) may be set to 1, and the other bits (1204, 1206, 1208) in the second element may be set to 0.

[00177] In various embodiments, if the above formats are used for the payloads of RTS and CTS, any node may update its DNAVs (and/or TM) using the payloads of received RTS and CTS frames. The above may give opportunities to devices to update their TMs within a superframe (covering scenarios of loss of beacons etc.). In various embodiments, the proposed payloads for RTS and CTS frames may also be included in the headers of RTS and CTS frames. Similar octets (similar to formats given above) may also be used in the headers of data, aggregated data, control, and command frames so that nodes may have opportunities to update their TMs and DNAVs within a superframe hearing communication between neighbors. In the case of the above option, the first 4 bit element of an octet to be included in the header (for example of a data, aggregated data, control, or command frame) may carry information pertaining to sender's logical sector usage and the second 4 bit element of the octet may carry information pertaining to receiver's logical sector usage.

[00178] In various embodiments, a RTS or CTS frame payload or header may carry the following information in two octets. The first octet may carry information pertaining to sender's logical sector usage and the second octet may carry information pertaining to receiver's logical sector usage. The six least significant bits in any of the above two octets may inform the logical sector usage of the sender or receiver accordingly. The two most significant bits of any of the above two octets may inform how many sectors on both sides of the logical sector given by the six least significant bits of the corresponding octet may be used by the sender or receiver accordingly. In various embodiments, the two most significant bits of any of the above two octets may inform how many sectors on one a priori known side of the logical sector given by the six least significant bits of the corresponding octet are used by the sender or receiver accordingly. [00179] In various embodiments, methods and device for simultaneous DRP and PCA using spatial reuse may be provided as will be explained below.

[00180] In various embodiments, a node may access the medium using PCA during MASs where a DRP reservation holds (for example with the exceptions of DRP reservation of type "Alien BP" and type "Device Discovery" which will be explained below) under the rules given above and when opportunities are allowed by spatial reuse as explained above and below. For example, with reference to FIG. 10, if a first device 1002 and a third device 1006 have a DRP reservation for a few MASs, then the second device 1004 and the fourth device 1008 may either make a simultaneous DRP reservation as explained above, or the second device 1004 may choose to contend for the channel and use its second logical sector 10042 (after inference from its own DNAVs and TM) by

obtaining a TXOP to communicate with the fourth device 1008.

[00181] hi various embodiments, there may be no hard boundaries in terms of MASs in a superframe for DRP and PCA, but a device may choose to reserve slots in a superframe upon availability and a device may contend for channel if allowed given the entries in its DNAVs and TM and opportunities provided by spatial reuse as described above and below.

[00182] hi various embodiments, methods and devices for device discovery may be provided, as will be explained below. [00183] In various embodiments, protocols by which a device may discover other devices within its transmission range and may also discover their respective orientations with respect to itself may be provided.

[00184] With reference to FIG. 10, it may be assumed that all the devices in FIG. 10 are within the transmission range of each other. According to various embodiments, methods and device by which each of the devices in FIG. 10 may discover the orientations of others with respect to itself may be provided.

[00185] In various embodiments, one or more devices (for example each device) may be configured to establish a sole reservation (for example with no associated target address) of type "Device Discovery" for a few Medium Access Slots (MASs) in a superframe in the current operating channel where the device may be able to transmit omni-directionally. In any DRP IE of this type, the target address may be treated as reserved and not containing any valid target address or is as in a manner given for the type "Alien BP" reservation in an ECMA standard. However, the above reservation for omni-directional transmission may be desired not to conflict any of the existing reservations, or reservations being negotiated, or be the cause of interference to transmissions that may take place during the MASs sought in the light of the contents in the device's TM, DNAVs, and IEs received by the device including the received DRP IEs. In various embodiments, if a reservation negotiation of type "Device Discovery" is in conflict with another reservation negotiation, for example a "Hard Reservation" according to an ECMA standard, then in any conflict resolution protocol, "Device Discovery" type may be given priority over other types except the type "Alien BP". Conflicts between two reservation negotiations both of a same type may be resolved in a manner similar to the one given in an ECMA standard (for example to resolve conflicts between two "Device Discovery" type negotiations). Once a device establishes a reservation of few MASs of type "Device Discovery", the device may transmit or receive or communicate a discovery data block. In the discovery data-block given above, the device first may transmit an omni-directional beacon or a control or a command frame (for example with fixed transmission duration) and subsequently may transmit sequentially in every sector a directional beacon or a control or a command frame (for example each with fixed transmission duration and with inter frame spacings embedded). [00186] FIG. 13 shows an illustration 1300 of reservations according to an embodiment.

[00187] For example, in the illustration of sole reservations of type "Device Discovery" by the devices in FIG. 10, various data is shown over a timeline 1302. The discovery data-block transmission using an established reservation is shown in FIG. 13 for a N-th superframe (superframe N) indicated by arrow 1342, and a N+l-th superframe (superframe N+l) indicated by arrow 1344. An N-th beacon period (BP) 1304 may be provided in the N-th superframe 1342. An N+l-th beacon period (BP) 1306 may be provided in the N+l-th superframe 1344.

[00188] hi various embodiments, every device may make an established sole reservation (for example a reservation with no associated target address) of type "Device Discovery" at pre-determined times, for example once every one or two or any other fixed number of superframes, and may transmit a discovery data-block. For example, the first device 1002 of FIG. 10 may make a reservation of type "Device Discovery", and may transmit a first device discovery data-block 1310. For example, the second device 1004 of FIG. 10 may make a reservation of type "Device Discovery", and may transmit a second device discovery data-block 1312. For example, the third device 1006 of FIG. 10 may make a reservation of type "Device Discovery", and may transmit a third device discovery data-block 1308. For example, the fourth device 1008 of FIG. 10 may make a reservation of type "Device Discovery", and may transmit a fourth device discovery data- block (not shown). For example, the fifth device 1010 of FIG. 10 may make a reservation of type "Device Discovery", and may transmit a fifth device discovery data-block 1314. For example, the sixth device 1012 of FIG. 10 may make a reservation of type "Device Discovery", and may transmit a sixth device discovery data-block (not shown). For example, the seventh device 1014 of FIG. 10 may make a reservation of type "Device Discovery", and may transmit a seventh device discovery data-block 1316. [00189] A more detailed illustration 1318 of the third device discovery data-block 1308 will be explained below.

[00190] For example, the third device discovery data-block 1308 may include beacon/control/command frames. For example, an omnidirectional frame 1322 and S (for example four) directional frames, for example a first directional frame 1326, a second directional frame 1330, a third directional frame 1334 and a fourth directional frame 1338 may be part of the third discovery data block. A first guard time 1320, for example at the beginning of the third device discovery data-block 1308, and a second guard time 1340, for example at the end of the third device discovery data-block 1308, may be provided in the third device discovery data-block 1308. A first interframe spacing 1324 may be provided between the omnidirectional frame 1322 and the first directional frame 1326. A second interframe spacing 1328 may be provided between the first directional frame 1326 and the second directional frame 1330. A third interframe spacing 1332 may be provided between the second directional frame 1330 and the third directional frame 1334. A fourth interframe spacing 1336 may be provided between the third directional frame 1334 and the fourth directional frame 1338. [00191] The first directional frame 1326 may be transmitted only in the first sector

1006j of the third device 1006. The second directional frame 1330 may be transmitted

only in the second sector IOO62 of the third device 1006. The third directional frame

1334 may be transmitted only in the third sector IOO63 of the third device 1006. The

fourth directional frame 1338 may be transmitted only in the fourth sector IOO64 of the

third device 1006.

[00192] In various embodiments, the DRP IE announcing the associated reservation of type "Device Discovery" may be sent in the superframe in which the discovery data block is to be sent. For example, considering the MAS reserved by the third device 1006 of FIG. 10 as illustrated in FIG. 13, the sixth device 1012 in FIG. 10 with the knowledge of the end time of the preamble of the omni-directional frame 1322 from the third device 1006 and with the reception of 3^rd directional frame 1334 from the third device 1006 may know that the third device 1006 may use the third sector IOO63 of the third device 1006

to communicate with itself (i.e. with the sixth device 1012). The sixth device 1012 may also update its TM with the above information. It is to be noted that in the above, every device in the neighborhood of the third device 1006 may be able to determine at the end of the above reservation of the third device, which of the sectors of the third device 1006 the third device may use to communicate with itself.

[00193] When the sixth device 1012 sends a similar discovery data block in its own reservation, the third device 1006 may infer in a similar manner that the sixth device

1012 may use its first sector 1012j to communicate with the third device 1006 and update

its TM. With the above, the third device 1006 and the sixth device 1012 may establish their respective orientations. With the reception of Topology IEs from the third device

1006 and the sixth device 1012, the third device 1006, the sixth device 1012 and the other devices may update their TMs. Hence with the usage of the reserved MASs of type

"Device Discovery" and with every device transmitting its Topology IE, a device may get the neighborhood orientations concerning all the devices in its neighborhood.

[00194] In various embodiments, the order of transmission of the directional frames from a device may be in a pre-determined order, for example from the first sector of that device going sequentially up to the last sector of that device.

[00195] In various embodiments, instead of making a sole reservation of type "Device

Discovery", each device may make a reservation of type "Device Discovery" now with an associated target address (for example in the DRP IE). This may advocate device to device pair wise discovery process.

[00196] FIG. 14 shows an illustration 1400 of reservations according to an embodiment.

[00197] In the illustration of device to device reservations of type "Device Discovery" by devices shown in FIG. 10, various data is shown over a timeline 1412 for an N-th superframe (superframe N) indicated by arrow 1404. A N-th beacon period (BP) 1406 may be provided in the N-th superframe 1404. An N+l-th beacon period (BP) 1414 may be provided in the subsequent superframe (not shown in detail).

[00198] In various embodiments, if a particular device desires to discover the orientation of another device, the device may desire to establish a reservation of type "Device Discovery" with the other device. For example, the third device 1006 of FIG. 10 may make a reservation of type "Device Discovery" with the sixth device 1012, and may exchange a first device discovery data block 1408. For example, the first device 1002 of FIG. 10 may make a reservation of type "Device Discovery" with the fifth device 1010, and may exchange a second device discovery data block 1410.

[00199] In various embodiments, the owner of the reservation may start the transmission of an omni-directional beacon or a control or a command frame (for example with fixed transmission duration) followed by subsequent sequential transmission in every sector a directional beacon or a control or a command frame (for example with fixed transmission duration and with inter frame spacings embedded). Subsequently, the target device may sequentially transmit in each of its sectors a directional beacon or a command or a control frame (for example with fixed transmission duration and with inter frame spacings embedded).

[00200] An example of a format of the discovery data block that may be communicated between the two devices participating in such a reservation in accordance with various embodiments is shown in more detail 1416 for the first discovery data block 1408. For example the frames 1420, 1424, 1428, 1432, 1436, 1440, 1444, 1448, and 1452, as will be explained below, may be part of the discovery data block exchange. [00201] For example, the first device discovery block 1408 may include beacon/control/command frames. For example, an omnidirectional frame 1420 and 2S (for example eight) directional frames, for example a first directional frame 1424, a second directional frame 1428, a third directional frame 1432, a fourth directional frame 1436, a fifth directional frame 1440, a sixth directional frame 1444, a seventh directional frame 1448, and an eighth directional frame 1452 may be part of the discovery data block. A first guard time 1418, for example at the beginning of the first device discovery data block 1408, and a second guard time 1454, for example at the end of the first device discovery data block 1408, may be provided in the first device discovery data block 1408. A first interframe spacing 1422 may be provided between the omnidirectional frame 1420 and the first directional frame 1424. A second interframe spacing 1426 may be provided between the first directional frame 1424 and the second directional frame 1428. A third interframe spacing 1430 may be provided between the second directional frame 1428 and the third directional frame 1432. A fourth interframe spacing 1434 may be provided between the third directional frame 1432 and the fourth directional frame 1436. A fifth interframe spacing 1438 may be provided between the fourth directional frame 1436 and the fifth directional frame 1440. A sixth interframe spacing 1442 may be provided between the fifth directional frame 1440 and the sixth directional frame 1444. A seventh interframe spacing 1446 may be provided between the sixth directional frame 1444 and the seventh directional frame 1448. An eighth interframe spacing 1450 may be provided between the seventh directional frame 1448 and the eighth directional frame 1452. [00202] The first directional frame 1424 may be transmitted by the third device 1006 only in the first sector lOOόj of the third device 1006. The second directional frame 1428 may be transmitted by the third device 1006 only in the second sector IOO62 of the third

device 1006. The third directional frame 1432 may be transmitted by the third device 1006 only in the third sector IOO63 of the third device 1006. The fourth directional frame

1436 may be transmitted by the third device 1006 only in the fourth sector IOO64 of the

third device 1006. The fifth directional frame 1440 may be transmitted by the sixth device 1012 only in the first sector 1012χ of the sixth device 1012. The sixth directional

frame 1444 may be transmitted by the sixth device 1012 only in the second sector 10122

of the sixth device 1012. The seventh directional frame 1448 may be transmitted by the sixth device 1012 only in the third sector IOI23 of the sixth device 1012. The eighth

directional frame 1452 may be transmitted by the sixth device 1012 only in the fourth sector IOI24 of the sixth device 1012.

[00203] For example, considering a reservation of type "Device Discovery" established between third device 1006 and the sixth device 1012 with the third device 1006 as the owner, with the knowledge of the end time of the preamble of the omnidirectional frame from the third device 1006 and the reception of the third directional frame 1432 from the third device 1006, the sixth device 1012 may determine that the third device 1006 may use the third sector IOO63 of the third device 1006 to communicate

with itself (i.e. with the sixth device 1012). With respect to the above same discovery data-block exchange, with the knowledge of the end time of the preamble of the omni- directional frame from the third device 1006 and the reception of the first directional frame from the sixth device 1012, the third device 1006 may determine that the sixth device 1012 may use the first sector 1012i of the sixth device 1012 to communicate with

itself (i.e. with the third device 1006). Then after reception of Topology IEs from each other, the sixth device 1012 and the third device 1006 may update their TMs accordingly. [00204] In the embodiment of FIG. 6, the frames 1420, 1424, 1428, 1432, and 1436 may be transmitted from the third device 1006 and the frames 1440, 1444, 1448, and 1452 may be transmitted from the sixth device 1012. Using several more similar pair wise reservations of type "Device Discovery" and using associated discovery data block exchanges, a device may establish the orientations in the device's neighborhood. Topology IEs may be used by devices to exchange orientations related information as has been described above.

[00205] In various embodiments, the above described reservation for omni-directional transmission by both participants of the reservation may be desired not to conflict any of the existing reservations, or reservations being negotiated, or be the cause of interference to transmissions that may take place during the MASs sought in the light of the contents in the participants' TMs, DNAVs, and received IEs including the received DRP IEs. [00206] FIG. 15 shows an illustration 1500 of beacon transmission in a beacon slot catering according to an embodiment.

[00207] Various data is shown over a timeline 1502 for a N-th superframe (superframe N) indicated by arrow 1558. A N-th beacon period (BP) 1504 may be provided in the N- th superframe 1558. [00208] In various embodiments, one or more devices (for example every device) may transmit a beacon block in its beacon slot. In its beacon slot, a device may first transmit an omni-directional beacon of fixed transmission duration followed subsequently by directional beacons (for example sequentially transmitted in every sector), for example each of fixed duration (for example with inter frame spacings embedded). For example, a first beacon slot 1506 of the first device 1002 may be provided. For example, a second beacon slot 1508 of the third device 1006 may be provided.

[00209] In a more detailed illustration 1510 of the first beacon slot 1506, the first beacon slot may include a first guard time 1512, an omnidirectional frame 1514, a first interframe spacing 1516, a first directional frame 1518, a second interframe spacing 1520, a second directional frame 1522, a third interframe spacing 1524, a third directional frame 1526, a fourth interframe spacing 1528, a fourth directional frame 1530, and a second guard time 1532. The first directional frame 1518 may be transmitted only in the first sector 1002i of the first device 1002. The second directional frame 1522 may be

transmitted only in the second sector 10022 of the first device 1002. The third directional

frame 1526 may be transmitted only in the third sector IOO23 of the first device 1002.

The fourth directional frame 1530 may be transmitted only in the fourth sector IOO24 of

the first device 1002.

[00210] In a more detailed illustration 1534 of the second beacon slot 1508, the second beacon slot may include a first guard time 1536, an omnidirectional frame 1538, a first interframe spacing 1540, a first directional frame 1542, a second interframe spacing 1544, a second directional frame 1546, a third interframe spacing 1548, a third directional frame 1550, a fourth interframe spacing 1552, a fourth directional frame 1554, and a second guard time 1556. The first directional frame 1542 may be transmitted only in the first sector 1006χ of the third device 1006. The second directional frame 1546 may be

transmitted only in the second sector IOO62 of the third device 1006. The third directional

frame 1550 may be transmitted only in the third sector IOO63 of the third device 1006.

The fourth directional frame 1554 may be transmitted only in the fourth sector IOO64 of

the third device 1006.

[00211] As an example, the sixth device 1012 in FIG. 10, with the knowledge of the end time of the preamble of the omni-directional beacon 1538 from the third device 1006 and the reception of 3^rd directional beacon 1550 from the third device 1006 may know that the third device 1006 may use the third sector IOO63 of the third device 1006 to

communicate with itself (i.e. with the sixth device 1012). The sixth device 1012 may also update its TM with the above information. It is to be noted that in the above, every device in the neighborhood of the third device 1006 may be able to determine at the end of the beacon slot of the third device 1006, which of the sectors of the third device 1006 the third device 1006 may use to communicate with it. Topology IEs may be transmitted by devices to exchange orientation related information.

[00212] In various embodiments, when the sixth device 1012 sends a similar beacon block in its own beacon slot, the third device 1006 may infer in a similar manner that the sixth device 1012 may use its first sector 10012j to communicate with the third device 1006 and update its TM. With the above, the third device 1006 and the sixth device 1012 may establish their respective orientations. With the reception of Topology IEs from the third device 1006 and the sixth device 1012, the other devices may update their TMs. Hence with the usage of the beacons and by every device transmitting its Topology IE, a device may get the neighborhood orientations concerning all the devices in its neighborhood. The above described methodology is illustrated in FIG. 15, where the frames 1518, 1522, 1526, and 1530 are directional beacon frames and frame 1514 is omni-directional .

[00213] In various embodiments, every device may transmit a discovery data-block using contention access of the medium instead of reserved MASs. However, the device that intends to transmit a discovery data-block may desire to ensure that the medium is available omni-directionally based on its TM and its DNAVs.

[00214] FIG. 16 shows a discovery data-block 1600 according to an embodiment. Various beacon/control/command data is shown over a timeline 1602. During a first period of time, the medium may be busy as indicated by block 1604. Then, after an Arbitration Inter-Frame Spacing (AIFS) 1606, one or more back off slots 1636 may be provided, for example a first back off slot 1608, a second back off slot 1610, one or more further back off slots 1612, and a last back off slot 1614. During the AIFS 1606 and the back off slots 1636, the medium may be idle, as indicated by arrow 1634. Thereafter an omnidirectional frame 1616, a first inter frame spacing 1618, a first directional frame 1620, a second inter frame spacing 1622, a second directional frame 1624, a third inter frame spacing 1626, a third directional frame 1628, a fourth inter frame spacing 1630, a fourth directional frame 1632 may be provided. [00215] In various embodiments, the frames 1616, 1620, 1624, 1628, and 1632 may be part of the discovery data block. In various embodiments, the duration field in the first omni-directional frame 1616 (for example a control frame which may be a "Device Discovery Initiate" frame having a format similar to RTS/CTS frame) transmitted during the discovery data-block of a device may cover the period required to complete the discovery data-block transmission. A device receiving the omni-directional frame (for example typically a control frame) from the device sending the discovery data-block may set its DNAVs either for all its sectors with the duration included in the omni-directional frame received subject to rules given above.

[00216] In various embodiments, Topology IEs may be transmitted by devices to exchange orientation related information.

[00217] In various embodiments, one or more devices (for example every device) may exchange a discovery data-block with another device using contention access of the medium instead of reserved MASs. However, the device that intends to initiate the discovery data-block may desire to ensure that the medium is available omnidirectionally based on its TM and its DNAVs.

[00218] FIG. 17 shows a pair wise discovery data-block 1700 according to an embodiment. For example, for pair wise discovery data block communication using contention access of the medium (for illustration purposes with the pair of the third device 1006 and the sixth device 1012), various data is shown over a timeline in FIG. 17. During a first period of time, the medium may be busy as indicated by block 1704. Then, after an AIFS 1706, one or more back off slots 1736 may be provided, for example a first back off slot 1708, a second back off slot 1710, one or more further back off slots 1712, and a last back off slot 1714. During the AIFS 1706 and the back off slots 1736, the medium may be idle, as indicated by arrow 1734. Thereafter a first omnidirectional frame 1716, a first inter frame spacing 1718, a second omnidirectional frame 1738, a second inter frame spacing 1740, first directional frame 1720, a third inter frame spacing 1722, a second directional frame 1724, a fourth inter frame spacing 1726, a third directional frame 1728, a fifth inter frame spacing 1730, a fourth directional frame 1732, a sixth inter frame spacing 1742, a fifth directional frame 1744, a seventh inter frame spacing 1746, a sixth directional frame 1748, an eighth inter frame spacing 1750, a seventh directional frame 1752, and a ninth inter frame spacing 1754, an eighth directional frame 1756, may be provided.

[00219] For example, the third device 1006 shown in FIG. 10 may get a TXOP to initiate a discovery data-block exchange with the sixth device 1012. The frames 1716, 1738, 1720, 1724, 1728, 1732, 1744, 1748, 1752, and 1756 may be part of the discovery data block. For example, the frames 1716, 1720, 1724, 1728, and 1732 may be transmitted from the third device 1006 and the frames 1738, 1744, 1748, 1752, and 1756 may be transmitted from the sixth device 1012.

[00220] The directional frames may be transmitted in respective sectors only, like described above.

[00221] In various embodiments, the duration field in the omni-directional frame transmitted during the discovery data-block of a device may cover the remaining period required to complete the discovery data-block transmission. A device receiving the omnidirectional frame from a device participating in the discovery data-block exchange may set its DNAVs (for example subject to rules described above) for all its sectors. [00222] For example, pertaining to device discovery, when the third device 1006 obtains a TXOP for omni-directional transmission (for example according to rules given above), it may first transmit an omni-directional frame which typically may be a "Device Discovery Request" control frame (for example a frame that may have a similar format as a RTS frame) referred to in FIG. 17 as frame 1716. In the duration field of this frame, the third device 1006 may include the duration value that covers a period from the end of the preamble of this frame up to the end of the transmission of frame 1756. When all the neighbors of the third device 1006 hear the above frame 1716, they may set their respective DNAVs according to rules given above. When the sixth device 1012 receives frame 1716, it may check its DNAVs and TM and if (for example by the rules given above) it is able to participate in communication with the third device 1006 in an omnidirectional manner, it may send an omni-directional frame which may be a "Device Discovery Response" control frame (for example a frame that may have a similar format as a CTS frame) referred to in FIG. 17 as frame 1738. After the receipt of frame 1738, all the devices may update their respective DNAVs, for example according to the rules given above. Upon the receipt of frame 1738, the third device 1006 may start its sequential directional transmissions of frames for device discovery and the sixth device 1012 may follow suite with similar sequential transmissions as shown in FIG. 17. [00223] In various embodiments, Topology IEs may be transmitted by devices to exchange orientation related information.

[00224] In various embodiments, device discovery in control channel may be provided, as will be explained below. [00225] In various embodiments, as explained above, the device discovery mechanisms may take place in the channel in which the beacons in beacon slots are sent by the devices, for example the normal operating channel of the devices. However, it may be possible that device discovery may be permitted to take place in one particular control channel dedicated for such a use. Various embodiments described above may apply with the use of separate control channel for device discovery. In various embodiments, it may be understood by all devices receiving reservation negotiation (for example by seeing the type of the reservation which is "Device Discovery") that reservation may be sought in the control channel. In this case, other devices may be able to simultaneously reserve or access medium in the same time slots in the normal operating channel where beacons in beacon slots are sent. Timing reference for the control channel may be provided in accordance with various embodiments to be the same as the superframe timing of the normal operating channel where beacons in beacon slots are sent. A device, in case it participates in device discovery process may tune its antenna to the control channel during the time slots it intends to use for device discovery. Various embodiments may also work in the control channel with the constraint that a device in the control channel may only be able to discover the orientation of the devices which are in the control channel at the times the device itself is in the control channel. In various embodiments, the devices (for example not restricted to owner/target) that seek to participate in the discovery process after hearing a reservation establishment of an owner or a target may tune their antennas to the control channel during the time slots indicated in the concerned DRP IE from the owner or target. [00226] In various embodiments, methods and devices for spatial reuse for devices with differing numbers of sectors may be provided, as will be explained below. [00227] In the above, examples have been provided for spatial reuse with the exemplary assumption that each device has the same number 'S' (S=4) of sectors. Examples or modifications of the examples given above for the purpose of spatial reuse with devices that may have differing numbers of sectors are explained in the following. [00228] FIG. 18 shows a format 1800 of a topology information element according to an embodiment. Several items of the format 1800 of a topology information element do not differ from respective items of the format 900 shown in FIG. 9, and therefore may be denoted with the same reference signs, and duplicate description may be omitted. [00229] In various embodiments, comparing the format 900 of Fig. 9 with the format 1800 of Fig. 18, an additional octet 1808 to denote the number of sectors to be used by a device may be added to the format of the Topology IE 1800 in comparison to the format described above.

[00230] The field for the numbers of sectors 1808 may have a length of 1 octet, as indicated by field 1806. The total length of the information in the information element 1800 may be given in a length field 1804. The length field may have a length of 1 octet, as indicated by field 1802. For example, the length of the information element with N device addresses may have a length of 1 + K + 2 N octets (for example, 1 octet for the number of sectors 1808, K octets for the topology information bitmap 918, and 2 octets for each of the device addresses 920, 924). In various embodiments, the alternative format for the Topology Information Bitmap described with reference to FIG. 9 in the above may be used with the format 1800 of the Topology IE. [00231] In various embodiments, the maximum number of sectors for a device may be 64.

[00232] In various embodiments, methods and devices for spatial reuse with DRP and

PCA for devices with differing numbers of antennas may be similar to those described above, however with the format 1800 of Topology IE and an alternate format of TM (as will be explained below) in use.

[00233] In various embodiments, an alternate format of the TM (for example as given in table 3) if the devices have variable or differing number of sectors, may be provided.

Table 3 : Columns of the alternate format of the Topology Matrix (TM)

[00234] In various embodiments, the alternate format of the TM may have eighteen columns as shown in table 3. Each row may correspond to a particular link (for example between two devices) in the network. Each row may contain link information in regards to first device address of the corresponding link (for example a source) or in other words Device Address 1 of Link, second device address of the corresponding link (for example a sink) or in other words Device Address 2 of Link, first device address's best logical sector(s) for that link and second device address's best logical sectors) for that link. Each of the eight columns in the "Device Address l's Logical Sectors)" tab in the TM may correspond to a bit. The six least significant bits in the "Device Address l's Logical Sector(s)" tab may be set to the corresponding logical sector used by device address 1 for communicating with device address 2. The six least significant bits in the "Device Address l 's Logical Sector(s)" tab may indicate the number of the logical sector used by device address 1 which may be any of zero (or 1) to sixty three (or 64) to communicate with device address 2. The most significant bit (column) of the "Device Address l's Logical Sector(s)" tab may indicate if the logical sector that is one higher (modulo 64) than the one indicated by the six least significant bits of the tab may be also used by the device (if that bit is set to one) to communicate with the device address 2. The second most significant bit of the "Device Address l's Logical Sector(s)" tab may indicate if the logical sector that is one lower (modulo 64; -1 is equivalent to 63) than the one indicated by the six least significant bits of the tab may also be used by the device (if that bit is set to one) to communicate with the device address 2. Note that a device may then use up to three sectors to communicate.

[00235] In various embodiments, each of the eight columns in the "Device Address 2's Logical Sector(s)" tab in the TM may correspond to a bit. The six least significant bits in the "Device Address 2's Logical Sector(s)" tab may be set to the corresponding logical sector used by device address 2 for communicating with device address 1. The six least significant bits in the "Device Address 2's Logical Sector(s)" tab may indicate the number of the logical sector used by device address 2 which may be any of zero (or 1) to sixty three (or 64) to communicate with device address 1. The most significant bit (column) of the "Device Address 2's Logical Sector(s)" tab may indicate if the logical sector that is one higher (modulo 64) than the one indicated by the six least significant bits of the tab may be also used by the device (if that bit is set to one) to communicate with the device address 1. The second most significant bit of the "Device Address 2's Logical Sector(s)" tab may indicate if the logical sector that is one lower (modulo 64; -1 is equivalent to 63) than the one indicated by the six least significant bits of the tab may also be used by the device (if that bit is set to one) to communicate with the device address 1. An example is given in table 4 that illustrates a TM maintained by the first node 1002 of FIG. 10.

Table 4: Example of alternate format of TM pertaining to the first device 1002 of FIG. 10

[00236] In various embodiments, the most significant bit and the second most significant bit, both of either "Device Address l's Logical Sector(s)" tab or "Device Address 2's Logical Sectors)" tab together (as two bits) may signify how many sectors on both sides of the logical sector mentioned by the six least significant bits of the corresponding tab may be used for communication by device address 1 or device address 2 respectively. In this case then, a device may use up to 7 logical sectors to communicate with another device. In various embodiments, the above two most significant bits of either "Device Address l's Logical Sector(s)" tab or "Device Address 2's Logical Sector(s)" tab may inform how many sectors on one a priori known side of the logical sector given by the six least significant bits of the corresponding tab may be used for communication by device address 1 or device address 2 respectively. [00237] In various embodiments, the alternate format of the TM may be updated every pre-determined period of time, for example every superframe (or once in every L₀ superframes, where L₀ may be a natural number larger than 1) by the device based on device discovery results and Topology IEs received. Information from other devices about other links (where the device is not a vertex) that are needed to update the alternate format of the TM may be received through beacons using the Topology IEs discussed earlier.

[00238] In various embodiments, each device may have as many DNAVs as the number of sectors it has. It is to be noted that every device may know how many sectors each of its neighbors has from the received Topology IEs. Therefore as described above, a device may know how many directional frames to expect from the owner of the reservation (Device Discovery) and at what time to expect the directional frame transmitted from a particular sector of the owner. As described above, a target device may know how many directional frames to expect from the owner of the reservation, at what time to expect the directional frame transmitted from particular sector of the owner, and at what time it should start its directional transmission in the data block period (since the inter frame spacing, order of transmission of directional frames sequentially sector wise, and the omni-directional and directional frame transmission durations may be fixed and known). Similarly, an owner device may know how many directional frames to expect from the target of the reservation, at what time to expect the directional frame transmitted from a particular sector of the target, and at what time it may expect the data block exchange to complete (since it knows the number of sectors in the target through Topology IE from target; the owner may use this as a guideline to reserve amount of time slots). As described above, the number of directed beacons sent may be the same as the number of sectors the device transmitting the directed beacons has. Every neighbor of a device may know how may directed beacons (in a beacon block) it may expect from that device in a beacon slot from information gathered through Topology IE (included in the omni-directional beacon) received from that device. In various embodiments, a beacon slot of a device may be large enough to accommodate a beacon block catering to up to say one omni-directional beacon and 64 directional beacon transmissions. As described above, every device may know how many directional frames to expect from the owner of the TXOP (device transmitting the discovery data block) and at what time to expect the directional frame transmitted from a particular sector of the owner of the TXOP. As described above, the recipient device may know how many directional frames to expect from the owner of the TXOP, at what time to expect the directional frame transmitted from particular sector of the owner of the TXOP, and at what time it may it start its directional transmission in the data block period (since the inter frame spacing, order of transmission of directional frames sequentially sector wise, and the omni-directional and directional frame transmission durations may be fixed and known). Similarly, an owner of the TXOP may know how many directional frames to expect from the recipient device (device to which its omni-directional frame at the start of the discovery data block was addressed to), at what time to expect the directional frame transmitted from a particular sector of the recipient device, and at what time it may expect the data block exchange to be completed (since it knows the number of sectors in the recipient device through Topology IE from recipient device; the owner of TXOP may use this as a guideline to set the duration field in the omni-directional frame it sends at the start of the TXOP for transmitting discovery data block).

[00239] In various embodiments, alternatives for device discovery related frames may be used for each of the embodiments described above pertaining to device discovery. In these alternatives, a device may replace each of its directional frame it transmits pertaining to device discovery with an omni-directional frame (in any of the embodiments for device discovery). That is, a device may never transmit a directional frame in a discovery data block or beacon block or a discovery data block exchange. In these alternatives, the recipient device after receiving in omni-directional mode the first omni-directional frame from the sender may later tune its direction of listening sequentially sector by sector during the times of subsequent omni-directional frame transmissions by the sender. As an example, the third device 1006 of FIG. 10 may transmit five omni-directional frames and the sixth device 1012 after the reception of first omni-directional frame from the third device 1006, may tune its antenna to its sector one in the second omni-directional frame transmission time, and subsequently tune its antenna to the next sequential sectors in the subsequent omni-directional frames' transmission times. With the above alternatives, the Topology Information Bitmap field in a Topology IE may have the same format but that the logical sector usage signified by an element 'n' in the Topology Information Bitmap field may denote the logical sector of the device used by the device to communicate with its neighbor 'n'. [00240] In various embodiments, methods and devices for spatial reuse for IEEE 802.15.3 based network with centralized controller may be provided, as will be explained below.

[00241] As described above, spatial reuse strategies for a distributed network where no node may have centralized control over other nodes may be provided in accordance with various embodiments. As will be explained below, spatial reuse strategies for a centralized network based on IEEE 802.15.3 may be provided in accordance with various embodiments. With reference to FIG. 10, it may be assumed that the nodes shown in FIG. 10 form a Pico Net and that a pre-determined node, for example the third node 1006 may be the Pico Net Coordinator (PNC). It may further be assumed that the nodes may work on the proposed superframe structure, as will be explained with reference to FIG. 19 below.

[00242] In various embodiments, methods and devices may be provided by which the nodes in FIG. 10 (for example with the third node 1006 as the PNC) may incorporate spatial reuse during Contention Access Period (CAP) and Channel Time Allocation Period (CTAP). In various embodiments, in a centralized network as alluded to in the above, the PNC (for example the third node 1006) may maintain a TM as described above. Other nodes may also maintain their own TMs. In various embodiments, each device (for example even the PNC) may maintain a set of DNAVs commensurate to the number of sectors it has. As will be described below, methods and devices for spatial reuse for CAP and CTAP and device discovery strategies may be provided. [00243] FIG. 19 shows an illustration 1900 of a superframe structure for a centralized network according to an embodiment. [00244] Various data is shown over a timeline 1970 for a N-th superframe (superframe N) indicated by arrow 1968. A beacon block 1904 of the PNC (for example the third device 1006 may be provided in the N-th superframe 1968. One or more device discovery slots 1916 may be provided, for example a first device discovery slot 1906, a second device discovery slot 1908, one or more further device discovery slots 1910, and a last device discovery slot 1912.

[00245] A Contention Access Period (CAP) 1914 may be provided, for example between the beacon 1904 block of the PNC, and the device discovery slots 1916. A Channel Time Allocation Period (CTAP) 1918 may be provided, for example after the device discovery slots 1916.

[00246] In a more detailed illustration 1944 of the beacon/command/control frames of the beacon block 1904 of the PNC, the beacon block of the PNC may include a first guard time 1946, an omnidirectional frame 1948, a first interframe spacing 1950, a first directional frame 1952, a second interframe spacing 1954, a second directional frame 1956, a third interframe spacing 1958, a third directional frame 1960, a fourth interframe spacing 1962, a fourth directional frame 1964, and a second guard time 1966. The first directional frame 1952 may be transmitted only in the first sector of the PNC. The second directional frame 1956 may be transmitted only in the second sector of the PNC. The third directional frame 1960 may be transmitted only in the third sector of the PNC. The fourth directional frame 1964 may be transmitted only in the fourth sector of the PNC. [00247] In a more detailed illustration 1920 of the beacon/command/control frames of the first device discovery slot 1906, for example the device discovery slot of the first device 1002, the first device discovery slot 1906 may include a first guard time 1922, an omnidirectional frame 1924, a first interframe spacing 1926, a first directional frame 1928, a second interframe spacing 1930, a second directional frame 1932, a third interframe spacing 1934, a third directional frame 1936, a fourth interframe spacing 1938, a fourth directional frame 1940 and a second guard time 1942. The first directional frame 1928 may be transmitted only in the first sector 1002j of the first device 1002. The

second directional frame 1932 may be transmitted only in the second sector 10022 of the

first device 1002. The third directional frame 1936 may be transmitted only in the third sector IOO23 °f the fi^rst device 1002. The fourth directional frame 1940 may be

transmitted only in the fourth sector IOO24 of the first device 1002.

[00248] In various embodiments, the PNC may allocate a 'Device Discovery Slot' (DDS) of fixed duration to every device in a superframe. In its Device Discovery Slot, a device transmits a device discovery block as described above, for example with frames as illustrated with reference to FIG. 13. In its device discovery block, a device may transmit an omni-directional frame followed by a set of directional frames, hi various embodiments, the PNC on its part may also transmit a beacon block 1904 consisting of an omni-directional beacon 1948 followed by a set of directional beacons 1952, 1956, 1960, 1964 (as described above, and for example with frames as illustrated with reference to FIG. 15) every superframe. In other words, in various embodiments, an omni-directional beacon sent by the PNC may be replaced by a beacon block as alluded to in the above. A superframe structure in accordance with various embodiments with the PNCs beacon block 1904, CAP 1914, CTAP 1918, and Device Discovery Slots 1916 is illustrated in FIG. 19. In FIG. 19, the Device Discovery Slots are shown to be contiguous. However, the Device Discovery Slots may be during any portion of the superframe and dis-contiguous with the constraint that every device may be allocated by the PNC at-least one Device Discovery Slot every pre-determined time, for example every superframe (or every fixed number of superframes). hi various embodiments, the PNC may always include a Topology IE (for example with a format as described above) in its omnidirectional beacon every superframe. In various embodiments, every device may transmit a Topology IE in its omni-directional frame in its Device Discovery Slot, for example every superframe (or once every fixed number of superframes). The format and usage of the Topology IE by the PNC and other devices may be similar to the details given above, and duplicate description will be omitted.

[00249] In various embodiments, the reserved bit available in a Channel Time Request (CTRq) Control field of a Channel Time Request command frame (in IEEE 802.15.3 specification) may be used. If this bit is set to ONE, the requested CTA (Channel Time Allocation) may be for device discovery, hi various embodiments, the reserved bit available in the CTRq Control field in IEEE 802.15.3 specification may be used to extend the size of the CTRq Control field to two octets, and one of the reserved bits in the second octet (additionally introduced new octet) may be used to indicate if the reservation request is for device discovery (DDS). The SrcID (source ID) and the DestID (destination ID) for a CTA of type "Device Discovery" may be the same. A device (DEV) may not be allowed to use either CTAP or CAP in a superframe if it had not transmitted discovery data block in each of the past pre-determined number, for example mMaxLostBeacons, superframes. [00250] As an example, the sixth device 1012' of FIG. 10, with the knowledge of the end time of the preamble of the omni-directional beacon frame 1948 from the third device 1006 and with the reception of 3^rd directional beacon frame 1960 from the third device 1006 may know that the third device 1006 may use the third sector IOO63 to

communicate with it (i.e. with the sixth device 1012). The sixth device 1012 may also update its TM with the above information. It is to be noted that in the above, every device in the neighborhood of the third device 1006 may be able to determine at the end of the beacon block of the third device 1006, which of sectors of the third device 1006 the third device 1006 may use to communicate with itself.

[00251] In various embodiments, when the sixth device 1012 sends a discovery data block in its own Device Discovery Slot allocated by the PNC (for example the third device 1006), the third device 1006 may infer in a similar manner that the sixth device

1012 may use the first sector 1012j to communicate with the third device 1006 and

update its TM. With the above, the third device 1006 and the sixth device 1012 may establish their respective orientations. With the reception of Topology IEs from the third device 1006 and the sixth device 1012, all the devices may update their TMs. Hence with the usage of the PNCs beacon block, Device Discovery Slots, and with every device transmitting its Topology IE, a device may get the neighborhood orientations concerning all the devices in its neighborhood including the PNC.

[00252] In various embodiments, two command frames called the "Device Discovery Request" and "Device Discovery Response" frames that use the reserved command types in IEEE 802.15.3 standard may be provided. Uses of these frames may be similar to what is described above. The omni-directional frame 1924 transmitted by the first device

1002 in its Device Discovery Slot may be a Device Discovery Request frame. The payloads of the Device Discovery Request and Response frames may include Topology

IEs.

[00253] In various embodiments, a PNC may allocate CTAs to a pair of devices for pair-wise device discovery. In this case, the device discovery block communicated between the pair may be similar to one given above (for example with frames as illustrated in FIG. 14). The Topology IEs may be desired to be used by each of the devices in the pair to convey the discovered information to other nodes so that other nodes may update their TMs.

[00254] hi various embodiments, the Topology IEs may be omni-directionally broadcast by one or more devices, for example by every device during CAP.

[00255] In various embodiments, each Device Discovery Slot may be treated as a CTA

(for example for a pair of devices as given in IEEE 802.15.3 standard), however herein with only one device address associated with the CTA (for example with other device address treated as reserved).

[00256] hi various embodiments, methods and devices for spatial reuse during CTAP may be provided, as will be explained below.

[00257] When the PNC allocates CTAs to devices through the omni-directional beacon (it for example sends every superframe), it may do so in the light of the TM it maintains. For example, in FIG. 10, it may give CTAs to pairs first device 1002 - seventh device 1014 and second device 1004 - fourth device 1008 that span overlapping time periods. Hence, under the assumption that the PNC maintains an updated TM every superframe (for example upon reception of Topology IEs), it may allocate CTAs to pairs of devices incorporating spatial reuse after consulting with its own TM.

[00258] In various embodiments, spatial reuse strategies during CAP may be provided, for example similar to the details described above.

[00259] In various embodiments, methods and devices for spatial reuse with general device discovery strategies may be provided, as will be explained below.

[00260] hi various embodiments, spatial reuse strategies may be built upon general device discovery strategies.

[00261] As an example, any device discovery scheme that is backward compatible to

IEEE 802.15.3b MAC may be considered, hi the above, it may be assumed that a device discovery scheme backward compatible to IEEE 802.15.3b MAC may have the minimal capability to allow a device to discover each of its neighbors' orientation with respect the device, hi various embodiments, irrespective of the number of superframes taken for all the devices in the network including the PNC to discover their respective neighbors' orientations (though a device's neighborhood orientations may be known only locally to that device), each device may send either a Topology IE according to various embodiments or a Topology command/control frame according to various embodiments.

[00262] FIG. 20 shows a format 2000 of the payload of a topology command/control frame according to an embodiment, hi the format 2000 of the payload of the Topology command/control frame according to various embodiments, details of the octets in the payload of the Topology command/control frame as shown in FIG. 20 may be as given above for similar fields, and thus the same reference signs may be used and duplicate description may be omitted. [00263] In various embodiments, the Topology Information Bitmap field 918 in

FIG. 20 may be the least significant bits of the payload. The order of the fields in FIG. 20 may vary. Furthermore, the order of the fields in any data according to various embodiments may vary.

[00264] In various embodiments, the PNC may be able to send the above described IE or command/control frame in its omni-directional beacon or CAP and each of the other devices may be able to omni-directionally (for example as a broadcast) send the above described IE or command/control frame using CAP. In various embodiments, the PNC may be made to allocate a CTA for a device for omni-directional transmission as alluded above. In various embodiments, each device (even the PNC) may maintain a TM and may update its TM based on the Topology IEs or Topology command/control frames received by the device.

[00265] In various embodiments, irrespective of the device discovery strategy used, each device with the use of Topology IEs or Topology command/control frames may maintain a knowledge of relative orientations of all pairs of neighbor devices and also relative orientations of all its neighbors with respect to the device. With the above, the device may use the spatial reuse strategies according to various embodiments.

[00266] FIG. 21 shows a diagram 2100 illustrating various spatial reuse and device discovery strategies according to an embodiment.

[00267] As shown in the diagram 2100 illustrating coexistence of the spatial reuse and device discovery strategies according to various embodiments with other device discovery strategies, the device discovery strategy (indicated by reference sign 2104) according to various embodiments may co-exist with any other device discovery strategy (2106 or 2108) that may be backward compatible to the IEEE 802.15.3b MAC and that may be over IEEE 802.15.3b MAC (2102). Moreover, as shown in FIG. 21, the spatial reuse strategy according to various embodiments may be incorporated over the device discovery strategy according to various embodiments (such a spatial re-use strategy being indicated by reference sign 2110) and IEEE 802.15.3b MAC or over any other device discovery strategy (for example indicated by reference signs 2106 and 2108) that may be backward compatible to IEEE 802.15.3 MAC (for example with additions according to various embodiments, for example simple and low complexity backward compatible additions of a topology information element and/or command/control frames and/or TMs, as indicated by reference sign 2112) and IEEE 802.15.3b MAC (such a spatial re-use strategy being indicated by reference sign 2114).

[00268] In various embodiments, methods and devices for spatial reuse for network based on IEEE 802.11 MAC may be provided, as will be explained below. [00269] According to various embodiments, spatial reuse strategies may be provided catered for IEEE 802.11 MAC protocol using directional transmission and reception. Every node (for example device or station (STA)) 'n' may divide its transmission range (omni-directional reachable area by transmission) in to S_n logical sectors. Every node 'n' may also label its logical sectors with fixed integers (1, 2, 3, ..., S_n), for example consecutively, for example in clock wise direction or anti-clock wise direction. It is to be noted that irrespective of whether a node has sector antennas or phased array antennas, such logical sectors (for example fixed with respect to a point in the device) may be maintained at every node. In various embodiments, devices may perform frequent device discovery phases to keep themselves updated of their respective neighborhood orientations (but in some embodiments not locations). In various embodiments, every node may transmit a Topology Information Element. In various embodiments, every node may maintain the following caches: Topology Matrix (TM) and Directional Network Allocation Vectors (DNAVs).

[00270] In various embodiments, a new information element may be provided called the Topology Information Element or the Topology IE, as has already been explained above.

[00271] FIG. 22 shows a format 2200 of a topology information element according to an embodiment. Several items of the format 2200 of the topology information element do not differ from respective items of the format 900 shown in FIG. 9, and therefore may be denoted with the same reference signs, and duplicate description may be omitted. The device addresses 2208, 2216 (which may be similar to the device addresses 920, 924 respectively) may each have a length of 6 octets, as indicated by fields 2206, 2214. The total length of the information in the information element 2200 may be given in a length field 2204. The length field may have a length of 1 octet, as indicated by field 2202. For example, the length of the information element with N device addresses may have a length of 1 + K + 6 N octets (for example, 1 octet for the number of sectors 1808, K octets for the topology information bitmap 918, and 6 octets for each of the device addresses 2208, 2216).

[00272] In FIG. 22, Device Address fields 2208, 2212, 2216 may be the Device Addresses of the device's neighbors. The Topology Information Bitmap field 918 may include N (=K) octets of 8-bit elements to indicate the logical sector usage, that may be the logical sector of a neighbor used by that neighbor to communicate with the device, where N may be the total number of neighbors of the device. Each element 'n', numbered from 1 to N, may corresponds to neighbor 'n' and may indicate the logical sectors used by neighbor 'n' to communicate with the device. The least six (or any other per- determined number) significant bits of an element 'n' may indicate the number of the logical sector which may be any of zero (or 1) to sixty three (or 64) used by the neighbor 'n' to communicate with the device. The most significant bit of an element 'n' may indicate if the logical sector that is one higher (modulo 64) than the one indicated by the least six significant bits of the element may also be used by the neighbor 'n' (if that bit is set to one) to communicate with the device. The second most significant bit of an element 'n' may indicate if the logical sector that is one lower (modulo 64; -1 is equivalent to 63) than the one indicated by the least six significant bits of the element may also be used by the neighbor 'n' (if that bit is set to one) to communicate with the device. It is to be noted that a neighbor 'n' may then use up to three sectors to communicate with the device. Element one may be the least-significant eight bits of the Topology Information Bitmap field.

[00273] In various embodiments, the sector of a neighbor to be used by that neighbor to communicate with the device may normally be found by the device during device discovery phase as described above. The device after collecting information from device discovery process later may encode the information in the Topology IE. [00274] In various embodiments, the maximum number of sectors for a device may be 64. The above may not put any limitation on the number of beams a device may have or steer. In various embodiments, if a device has several neighbors, it may accommodate their device addresses in multiple Topology IEs. Moreover, a device may not include a neighbor's device address in its Topology IE if it has inadequate information concerning the element related to that neighbor in the Topology Information Bitmap field or if it had not established orientation (device discovery information) with that neighbor (as will be explained below) in the past 2 x aMaxDiscoveryLatency TUs (a parameter aMaxDiscoveryLatency is proposed which may take a value 64 or 128). [00275] In various embodiments, a device may be able to dynamically change the number of logical sectors it has, but for example not more than once in every predetermined number, for example 32 x aMaxDiscoveryLatency TUs (time units), hi various embodiments, the maximum number of sectors for a device may be 63 (instead of 64; wherein sector count may be taken modulo 63 instead of modulo 64) and if all the least six significant bits of an element in the Topology Information Bitmap are ones, then the device may be inferred to have inadequate information concerning its corresponding neighbor. In various embodiments, the maximum number of sectors for a device may be 16 or 24.

[00276] hi various embodiments, every device (STA; even Point Coordinator (PC) or Hybrid Coordinator (HC)) may generate a unique 16 bit address (Dev. Addr.), for example according to an ECMA standard. A Topology IE transmitted by a device may have an additional field called the Transmitting Dev. Addr. field which may be the unique 16 bit address generated by the transmitting device (the device transmitting the Topology IE) for itself. In this case, each of the Device Address fields in a Topology IE may be of two octets length instead of 6 octets if the generated addresses are used. Conflicts between 16 bit Dev. Addrs. may be discovered if a device receives a topology IE with two or more Device Address fields having the same value or using the Transmitting Dev. Addr. field of a received Topology IE. If a device discovers that its

Dev. Addr. is in conflict it may generate a new Dev. Addr. applicable from the end of transmission of its next discovery data block (as will be explained in more detail below).

[00277] In various embodiments, caches may be provided as have been described above.

[00278] In various embodiments, methods and devices for spatial reuse strategies may be provided, as will be explained below.

[00279] With reference to FIG. 10, it may be assumed that the nodes in FIG. 10 form an IEEE 802.11 network either using

[00280] - Point Coordination Function (PCF) or Hybrid Coordination Function (HCF) with the third node 1006 as the Point Coordinator (PC) or Hybrid Coordinator (HC) respectively or

[00281] - Enhanced Distributed Channel Access (EDCA).

[00282] As will be explained below, methods and devices, by which nodes shown in

FIG. 10 may incorporate spatial reuse during Contention Period (CP), Contention Free

Period (CFP) and Controlled Access Phase (CAP) may be provided in various embodiments. During CP, it may be assumed that nodes incorporate EDCA or HCF

Controlled Channel Access (HCCA). In various embodiments, the PC or HC (for example the third node 1006) may maintain a TM. Other nodes may also maintain their own TMs. In various embodiments, each device (even PC or HC) may maintain a set of

DNAVs commensurate to the number of sectors it has.

[00283] In various embodiments, additions/modifications in frame types and frame subtypes given in IEEE 802.11 Standard may be provided, as will be explained below. [00284] In various embodiments, the addition of a CF-Poll-Response frame may be provided. This frame may be desired if the PC incorporates only PCF and is not a HC with HCF implemented in it in entirety.

[00285] hi various embodiments, the addition of a Device-Discovery-Request frame may be provided.

[00286] hi various embodiments, the addition of a Device-Discovery-Response frame may be provided.

[00287] FIG. 23 shows a CF (contention free)-poll-response frame 2300 according to an embodiment.

[00288] hi various embodiments, the frame format 2300 for the CF-Poll-Response frame may include a frame control field 2304, a duration field 2308, a Recipient Address (RA) field 2312, a Transmitter Address (TA) field 2316, and a Frame Check Sequence (FCS) field 2320. The frame control field 2304 may have a length of 2 octets, as indicated by field 2302. The duration field 2308 may have a length of 2 octets, as indicated by field 2306. The RA field 2312 may have a length of 6 octets, as indicated by field 2310. The TA field 2316 may have a length of 6 octets, as indicated by field 2314. The FCS field 2320 may have a length of 4 octets, as indicated by field 2318. [00289] hi various embodiments, the RA 2312 of the CF-Poll-Response frame 2300 may be the address of the STA which may be the intended immediate recipient of the frame 2300. The TA 2316 may be the address of the STA transmitting the CF-Poll- Response frame 2300. The duration value 2308 may be the time in microseconds required to transmit the pending frames (fragments) or remaining time duration of transmission opportunity (TXOP) (for example bounded by a maximum; for example aTXOPLimit). The Frame Control field 2304 of the CF-Poll-Response frame 2300 may be as given in IEEE 802.11 Standard (for example, Frame type for this frame may be '01 ' and frame subtype may be '0111 ').

[00290] In various embodiments, the CF-Poll-Response frame may be a data frame with format given in IEEE 802.11 Standard for data frames. However, duration value may be set to the time in microseconds required to transmit the pending frames (fragments) following the CF-Poll-Response frame.

[00291] FIG. 24 shows a device-discovery-request frame 2400 according to an embodiment.

[00292] In the frame format for the device-discovery-request frame 2400, a frame control field 2404 of length of 2 octets (as indicated by field 2402), a duration field 2408 of length of 2 octets (as indicated by field 2406), a Destination Address (DA) field 2412 of length of 6 octets (as indicated by field 2410), a Source Address (SA) field 2416 of length of 6 octets (as indicated by field 2414), a BSS (basic service set) ID (identifier) field 2420 of length of 6 octets (as indicated by field 2418), a sequence control field 2424 of length of 2 octets (as indicated by field 2422), a frame body field 2428 of length of N octets (where N may be a natural number as indicated by field 2426), and a FCS field 2432 of length of 2 octets (as indicated by field 2430) may be provided. [00293] In various embodiments, the DA 2412 of the Device-Discovery-Request frame 2400 may be the address of the STA which may be the intended destination of the frame 2400. The SA 2416 may the address of the STA transmitting the Device- Discovery-Request frame 2400. The duration value 2408 may be the time in microseconds required to transmit the pending frames (fragments) of the discovery data block (for example as will be explained below). The Frame Control field 2404 of the frame 2400 may be as given in IEEE 802.11 standard (for example, Frame type for this frame may be OO' and frame subtype may be '0110').

[00294] FIG. 25 shows a device-discovery-response frame 2500 according to an embodiment.

[00295] hi the frame format for the Device-Discovery-Response frame 2500, a frame control field 2504 of length of 2 octets (as indicated by field 2502), a duration field 2508 of length of 2 octets (as indicated by field 2506), a Destination Address (DA) field 2512 of length of 6 octets (as indicated by field 2510), a Source Address (SA) field 2516 of length of 6 octets (as indicated by field 2514), a BSS field 2520 of length of 6 octets (as indicated by field 2518), a sequence control field 2524 of length of 2 octets (as indicated by field 2522), a frame body field 2528 of length of N octets (where N may be a natural number as indicated by field 2526), and a FCS field 2532 of length of 2 octets (as indicated by field 2530) may be provided.

[00296] hi various embodiments, the DA 2512 of the Device-Discovery-Response frame 2500 may be the address of the STA which may be the intended destination of the frame 2500. The SA 2516 may be the address of the STA transmitting the Device- Discovery-Response frame 2500. The duration value 2508 may be the time in microseconds required to transmit/receive the pending frames (fragments) of the discovery data block. The Frame Control field 2504 of the frame 2500 may be as given in IEEE 802.11 Standard (for example, frame type for this frame 2500 may be '00' and frame subtype may be '0111 '). [00297] In various embodiments, the frame bodies of at least one of the Device- Discovery-Request frame 2400 and the Device-Discovery-Response frame 2500 may contain a Topology Information Element with formats as explained above. [00298] In various embodiments, the Device-Discovery-Request frame and/or Device- Discovery-Response frame may be control frames using the reserved sub-types according to IEEE 802.11 Standard. In this case, DA may be replaced by RA and SA may be replaced by TA. In various embodiments, BSS ID may also be optional. In this case, the duration value may be still the time in microseconds required to transmit the pending frames (fragments) of the discovery data block.

[00299] In various embodiments, methods and devices for spatial reuse with CP may be provided, as will be explained below.

[00300] In various embodiments, a device may use a logical sector for communication only if its corresponding DNAV is zero and the medium in that logical sector is idle (medium is considered available if these conditions are satisfied).

[00301] In various embodiments, for CP purposes, a device may consider the medium in a logical sector to be busy for any of the following conditions:

[00302] - when its Clear Channel Assessment (CCA) mechanism indicates that the medium in this logical sector is busy (though the medium may be directionally available or idle in other logical sectors);

[00303] - when the device's DNAV for this logical sector is greater than zero; [00304] - when the device is transmitting or receiving a frame on the medium using this logical sector; [00305] - when the Duration announced in a previously transmitted frame from or to a logical sector of a neighbor of the device that is reachable by this logical sector of the device (inferred using TM) has not yet expired.

[00306] In various embodiments, at all other times a device may consider the medium in a logical sector to be idle. The medium may be considered to be idle by the device omni-directionally if the medium is idle for each of its logical sectors. Even if the medium in one of its logical sectors is busy, the device may consider the medium busy for omni-directional transmission.

[00307] hi various embodiments, a device may maintain a back off counter for omnidirectional transmission purposes. This back off counter may be decremented in a similar manner as given in IEEE 802.11 specification. Rules pertaining to invoking and decrementing the above back off counter may be as given in IEEE 802.11 specification. In addition to the above, in accordance with various embodiments, a device may maintain an independent back off counter for every logical sector. The back off counter for a logical sector may begin decrementing its value only if the medium in the corresponding logical sector (whose DNAV is zero) is idle for past DIFS (DCF (Distributed Coordination Function) Interframe Space) or more. Rules pertaining to invoking and decrementing the above back off counter for a logical sector may be similar to those given in IEEE 802.11 specification (for back off counter pertaining to omni-directional transmission purposes) with an exception that the medium may be restricted to the medium in that logical sector. A device may desire to be able to independently perform CCA in each of its logical sectors. A device may also be able to independently invoke a back off for the medium in any logical sector. [00308] In various embodiments, when a device has a buffered packet to be sent using CP, the device may first check from its TM which of the logical sectors it may intend to use to send directionally transmitted data. For example, using conditions described above (for checking medium idleness), the device may then ascertain if the medium in the logical sector(s) it may intend to use for directional data transmission is idle (as will be explained in more detail below). If the medium in the logical sector or sectors is busy, the device may also invoke a back off counter corresponding to the logical sector it may intend to use for directional data transmission (subject to rules alluded to in the above). The device may simultaneously also invoke another independent back off counter for omni-directional transmission.

[00309] In various embodiments, a device may consider itself to have obtained a transmission opportunity (TXOP) in a logical sector if it meets the following conditions: [00310] - the device has one or more newly arrived frames or newly generated frames; [00311] - the device had a backoff counter corresponding to that logical sector of zero value and had no frames prior to the arrival or generation of the new frames; and [00312] - the device determines that the medium in that logical sector has been idle and available for DIFS/ AIFS or longer.

[00313] In various embodiments, the device may start transmitting a frame, which may be a RTS frame, directionally in that logical sector as soon as the above conditions are satisfied (for example subject to the rules explained above and below). The device may also consider itself to have obtained a TXOP in a logical sector if it meets the following conditions: [00314] - the device has one or more frames buffered for transmission, including retry; and

[00315] - the device decremented its backoff counter corresponding to that logical sector from one to zero and no frame was transmitted by the device in that logical sector with medium in that logical sector having remained idle and available since then. [00316] In various embodiments, the device may not initiate transmission in any logical sector unless it had obtained a TXOP in one of the logical sectors, for example subject to rules as explained above and below.

[00317] hi various embodiments, similar rules as have been explained above may apply concerning omni-directional TXOP and TXOPs for ACs. Before any RTS packet is sent, the device may determine if it had obtained a TXOP in the logical sector it intends to send the directional data. If the device had obtained a TXOP for omni-directional transmission, the device may send the RTS packet omni-directionally (if RTS is sent), hi various embodiments, concerning transmission of RTS, only if the device has the medium unavailable for omni-directional transmission, the device may send a directional RTS in case it decides to send a RTS. If the device had obtained a TXOP only in the logical sector it intends to send the directional data (with medium busy in other sectors), the device may send the RTS packet directionally in the logical sector it intends to send directional data (for example as described below). The upper bound on the duration field in the RTS packet that is sent omni-directionally may be a pre-determined parameter, for example aTXOPLimit. The upper bound on the duration field in the RTS packet that is sent directionally may be the value of the least of the device's non-zero DNAVs for its logical sectors minus RTS frame transmission time. A device may choose not to send directional RTS at any time.

[00318] In various embodiments, concerning sending a directional RTS frame or directional CTS frame, the device may send the frame simultaneously in every logical sector whose DNAV has a zero value and whose medium has been idle for more than DIFS while sending the frame in the logical sector it intends to transmit or receive data. This may easily be done using sector antennas or through beamforming with phased array antennas.

[00319] hi various embodiments, a device may not transmit a directional RTS frame (or initial frame at the start of a TXOP) in a logical sector if the DNAV of any of the other logical sectors is zero and the medium in that other logical sector whose DNAV is zero has been idle for less than DIFS.

[00320] In various embodiments, the rules explained above and below may be extended to the case where there are ACs. \

[00321] In various embodiments, when a RTS packet is received by a device (for example with a device address in RTS packet matching the device address of the device), the device may first check from its TM which of its logical sectors it may use to receive directionally transmitted data from the sender of the RTS. Using the above conditions (for example for checking medium idleness), the device may also ascertain if the medium in the logical sector(s) it intends to use for reception is idle. If the medium is idle and available in all of its logical sectors, the device may send the CTS packet omnidirectionally with duration field which is duration field of received RTS minus CTS frame transmission time minus SIFS (Short Interframe Space). If the medium is not idle in all the logical sectors but idle and available only in the logical sector it intends to receive the directional data, the device may send the CTS packet directionally in the logical sector it intends to receive directional data, hi the CTS packet sent directionally by the device, the upper bound on the duration field in the CTS packet may be the minimum of:

[00322] (i) value of the least of the device's non-zero DNAVs for its logical sectors minus CTS frame transmission time; and

[00323] (ii) the duration field (for omni-directional CTS) as inferred using the procedure described above from the RTS packet received by the device.

[00324] In various embodiments, the CTS frame may have the same header as the RTS frame (for example, the addition of a TA field to the format of CTS frame given in IEEE

802.11 specification may be provided). Alternatively, another control frame using the reserved subtypes in IEEE 802.11 specification may be used with the above feature

(inclusion of both TA and RA fields in the header to serve the functionality of CTS frame). In various embodiments, the term CTS may be used to name such a control frame according to various embodiments (that may include RA and TA).

[00325] In various embodiments, if the duration field derived (for omni-directional

CTS as inferred using the procedure as has been described above) from the RTS packet received by the device exceeds the least of its non-zero DNAVs for its logical sectors minus CTS frame transmission time, a CTS packet may not be sent by the device in response to the received RTS packet. If CTS packet is sent directionally, the duration may be desired to be less than or equal to the least non-zero DNAV for the device's logical sectors minus CTS frame transmission time. [00326] In various embodiments, a device that receives a CTS frame header (with both RA and TA included) not addressed to it and not addressed to a broadcast address may update its DNAV for every logical sector that may reach the concerned logical sector of the sender of the CTS frame using the received Duration field.

[003271 In various embodiments, if a device has a sector (numbered S) with non zero DNAV, the device may not send a CTS frame in a sector that is diametrically and geometrically opposite to that sector S (for example for the purpose of receiving data in the sector geometrically opposite S). In various embodiments, whenever RTS is sent directionally, it may be sent with reduced power (for example with power control). Similarly CTS frame if sent directionally, may be sent with reduced transmit power (for example with power control). In various embodiments, all control frames transmitted directionally may be transmitted with power control to offset the directional transmit antenna gain.

[00328] For example, referring to FIG. 10, if ^v the first device 1002 sends an omnidirectional RTS to the third device 1006, then upon reception of the above RTS, all the neighbors of the first device 1002 may infer from the frame of RTS received that the intended destination may be the third device 1006. Each of the neighbors of the first device 1002 may also after looking at its TM set it's DNAVs after inferring that the first device 1002 intends to use its first logical sector 1002i to communicate with the fourth

its DNAV for its first sector 1014j as its first sector 1014i may be reachable from the

fourth sector IOO64 of the third device 1006. The sixth device 1012 may set the DNAV for its second logical sector 10122 using the duration field from received RTS packet, the

fourth device 1008 may set the DNAV for its third logical sector IOO83 and the second

device 1004 may set the DNAV for its third logical sector IOO43. Upon reception of the

RTS packet from the first device 1002, the third device 1006 may infer from its TM that it may desire to use its fourth logical sector IOO64 for receiving packets from the first

device 1002 and assuming its DNAV for its fourth sector IOO64 is zero along with all of

its other DNAVs, the third device 1006 may respond with a CTS packet with duration decided using rules given above. The third device 1006 may also send omni-directional CTS (assuming the DNAVs of all its sectors may have been zero (just prior to transmission of CTS)). Upon reception of a CTS from the third device 1006, each of the fifth device 1010, the seventh device 1014, the sixth device 1012, the fourth device 1008 and the second device 1004 with the use of its own TM may desire to update its DNAVs. Now if the second device 1004 wants to send a RTS packet to the fourth device 1008 when the first device 1002 and the third device 1006 communicate, it may infer that its

DNAV for its third sector 10043 may be non zero. Hence should it choose to send a RTS,

it may send RTS directionally to the fourth device 1008 using its second sector 10042

(and its first sector 1004i and fourth sector IOO44; if medium is idle and DNAVs are zero

in these). Since the fourth device 1008 has a non-zero DNAV for its third sector IOO83

(because of link first device 1002 - third device 1006), the fourth device 1008 may send a CTS packet directionally to the second device 1002 using its first sector 1008[ and its

second sector IOO82 (and its fourth sector IOO84- if medium is idle and DNAVs are zero

in these), for example with duration field set to a value less than or equal to the DNAV of its third sector IOO83 minus CTS frame transmission time.

[00329] In various embodiments, if a device receives a RTS or a CTS or a CF-PoIl- Response or an initiation frame destined to another device (for example where the recipient of RTS or CTS is another device) which is not the neighbor o.f the device, then ^' the device may update its DNAVs of its sectors that may reach the sender of the RTS or CTS or CF-Poll-Response or initiation frame and update its DNAVs of its other sectors in the one-half of its transmission reachable area facing the sender of the above frame taking in to account the duration value included in the received above frame. [00330] In various embodiments, methods and devices for spatial reuse using CFP may be provided, as will be explained in more detail below.

[00331] hi various embodiments, methods and devices for spatial reuse using PCF may be provided, as will be explained in more detail below.

[00332] hi various embodiments, when the PC transmits a CF-PoIl frame (or data frame of subtype OOlO', '0011' or '0111 ') to any device, the device may utilize the opportunity to send either a Null frame or a CF-Poll-Response frame omni-directionally or Device-Discovery-Request frame or data (allowed subtypes) or CF-ACK frame SIFS after the reception of the CF-PoIl frame. Only in the case of the device transmitting a CF- Poll-Response frame, other devices may utilize the medium using spatial reuse strategies simultaneously along with the device after the transmission time of the current frame (CF-Poll-Response) transmitted by the device (for example as will be explained with reference to FIG. 26 below). In various embodiments, a device may be allowed to send a sequence of frames/fragments (for example with SIFS embedded; for example in fragment burst; for example as in IEEE 802.11 specification) during CFP. However, before a device may send a fragment burst in a CFP, the device may first send a CF-Poll- Response frame in response to a received CF-PoIl frame. The duration field in the CF- Poll-Response frame may include a duration that may cover the entire frame burst until the last acknowledgment to be received. The CF-Poll-Response frame may be addressed to the device that will receive frames/fragments subsequent to the CF-Poll-Response frame.

[00333] FIG. 26 shows a diagram 2600 illustrating frame transactions in contention free period (CFP) according to an embodiment. In the illustration 2600 of CFP for devices shown in FIG. 10, various data in a CFP 2656 is shown over a timeline 2602. A beacon 2658 of the PC or HC (for example the, third device 1006) may be provided. Furthermore, for example thereafter, a CF-poll frame 2604 of PC (for example the third device 1006) to the first device 1002 or QoS (quality of service) CF-poll frame 2604 of HC (for example the third device 1006) to the first device 1002 may be provided. Furthermore, for example thereafter, a SIFS 2606 may be provided. Furthermore, CF-poll response frame 2608 of the first device 1002 may be provided (for example only if PCF is used). Furthermore, frame transmissions 2612 from the second device 1004 to the fourth device 1008 simultaneously during the frame transmission period of another pair of devices (as will be seen below) may be provided. Furthermore, together with frame 2608, and as indicated by arrow 2616, frame transmissions 2610 of the first device 1002 to the seventh device 1014 may be provided. Furthermore, for example thereafter, a discovery data block 2614 of the PC or HC (for example the third device 1006) may be provided.

[00334] In a more detailed illustration 2616 of the frame/fragment transmissions from the first device 1002 to the seventh device 1014, for example, an omnidirectional frame 2618, a first interframe spacing 2620, a first directional frame 2622 which may be a data frame, a second inter-frame spacing 2624, a second directional frame 2626 which may include a first acknowledgement (ACK), a third interframe spacing 2628, a third directional frame 2630 which may be a data frame, a fourth interframe spacing 2632, and a fourth directional frame 2634 which may include a second ACK may be provided. [00335] hi a more detailed illustration 2636 of the discovery data block 2614 of the PC or HC (for example of the third device 1006), the discovery data block 2614 of the PC or HC may include an omnidirectional frame 2638, a first interframe spacing 2640, a first directional frame 2642, a second interframe spaping 2644, a second directional frame 2646, a third interframe spacing 2648, a third directional frame 2650, a fourth interframe spacing 2652, and a fourth directional frame 2654. The first directional frame 2642 may be transmitted only in the first sector of the PC or HC. The second directional frame 2646 may be transmitted only in the second sector of the PC or HC. The third directional frame 2650 may be transmitted only in the third sector of the PC or HC. The fourth directional frame 2654 may be transmitted only in the fourth sector of the PC or HC. [00336] As an example, after the reception of the omnidirectional frame 2618 from the first device 1002, the second device 1004 may be able to initiate frame transactions to the fourth device 1008 after consulting with its TM and DNAVs. However, the second device 1004 may ensure that frame transactions initiated by it to the fourth device 1008 may complete before the duration mentioned in the CF-Poll-Response frame from the first device 1002 elapses. The second device 1004 may send a RTS frame as the first of its frame transactions and the fourth device 1008 may respond with a CTS frame (for example subject to rules described above). The above may allow other pairs of devices to use the medium as well using spatial reuse strategies. Moreover, the second device 1004 may not initiate any frame transaction during the frame transmission time of the first device 1002 to the seventh device 1014 using the above rules unless it had established the orientation (for example by device discovery as described above and below) information at-least once with each of the first device 1002, the seventh device 1014, and the fourth device 1008 in the past pre-determined time, for example 2 x aMaxDiscoveryLatency (for example twice a parameter of any value, for example 64) Time Units (TUs), and unless its TM had been updated at least once in the past 2 x aMaxDiscoveryLatency TUs concerning the link between the first device 1002 and the seventh device 1014. [00337] In various embodiments, methods arid device for spatial reuse using HCF may be provided, as will be explained below.

[00338] In various embodiments, when the HC transmits a QoS CF-PoIl frame 2604 (or data frame of subtype ' 1010', ' 1011 ' or ' 1111 ') to any device, the device may utilize the opportunity (TXOP) to send either a QoS Null frame or a Device-Discovery-Request frame or data frame (allowed subtypes) SIFS after the reception of the QoS CF-PoIl frame.

[00339] As an example, referring to FIG. 26 which may illustrate CFP for devices shown in FIG. 10, if a first device 1002 received a QoS CF-PoIl frame from the HC, the first device may desire not to transmit any CF-Poll-Response frame omni-directionally in its TXOP. After the reception of QoS CF-PoIl frame from the third device 1006, a first device 1002 may utilize the TXOP by sending a RTS or an initiating frame or a Device- Discovery-Request frame as the first frame. The second device 1004 may also be able to initiate frame transactions to the fourth device 1008 after consulting with its TM and DNAVs (if the first device 1002 did not send a Device Discovery Request frame). However, the second device 1004 may ensure that frame transactions initiated by it to the fourth device 1008 may complete before the duration of TXOP specified in the RTS (or initiation) frame from the first device 1002 elapses. In various embodiments, the second device 1004 may send a RTS frame as the first of its frame transactions and the fourth device 1008 may respond with a CTS frame (subject to rules given above). The above may allow other pairs of devices to use the medium as well using spatial reuse strategies. Moreover, the second device 1004 may not initiate any frame transaction during the frame transmission time of the first device 1002^v to the seventh device 1014 using the above rules unless it had established the orientation (device discovery) information at- least once with each of the first device 1002, the seventh device 1014, and the fourth device 1008 in the past 2 x aMaxDiscoveryLatency (which may be a parameter of any value, for example 64) Time Units (TUs) and unless its TM had been updated at least once in the past 2 x aMaxDiscoveryLatency TUs concerning the link between the first device 1002 and the seventh device 1014.

[00340] In various embodiments, the first device 1002 may send a QoS CF-PoIl Response frame (for example with the same format as for CF-PoIl response frame except with the addition of QoS control field) in response to a received QoS CF-PoIl frame. [00341] In various embodiments, whether using DCF (Distributed Coordination Function) or HCF (Hybrid Coordination Function), a device may not initiate a frame transaction with a neighbor (using spatial reuse strategies given above) during the frame transmission period between another pair of devices (from which it had received a RTS or a CTS or a CF-Poll-Response frame) unless its TM had been updated (confirmed) at least once in the past 2 x aMaxDiscoveryLatency TUs concerning the link between the other pair of devices and it had established orientation (device discovery) information with both the devices (each of them) of the other pair at least once in the past 2 x aMaxDiscoveryLatency TUs and the entries in its TM concerning all the links where any device of the other pair is a vertex had not changed in the past 4 x aMaxDiscoveryLatency TUs. In this regard, the device must have received topology IEs from both the devices of the other pair including each other's device address at-least once (from, each of the devices of the other pair) in the past 2 x aMaxDiscoveryLatency TUs. hi various embodiments, whether using DCF, PCF or HCF, a device may initiate frame transaction with a neighbor during the frame transmission period between another pair of devices (from which it had received say for example, a RTS or a CTS or a CF-Poll- Response frame) if one of the devices in the other pair is not a neighbor of the device and if the logical sector proposed to be used by the neighbor of the device in the other pair may be unreachable from the device (subject to details in the above). [00342] In various embodiments, a device may not consider another device a neighbor if the device had not received any discovery data block in the past 4 x aMaxDiscoveryLatency TUs from the other device.

Ill [00343] In various embodiments, a device may be said to have established orientation

(device discovery) information with a neighbor if the device has obtained information about the device's best logical sector(s) to communicate with the neighbor and the neighbor's best logical sector(s) to communicate with the device. In this regard, the device must have transmitted a Topology IE with the neighbor's address included in it and must have also received a Topology IE from the neighbor with it's address included in the neighbor's Topology IE.

[00344] In various embodiments, a device may consider a sector as to be used to communicate with a. neighbor if the signal- strength received in that sector from the neighbor is above a certain threshold or/and above a certain fraction of the maximum signal strength in any of its sector(s) (direction) while receiving frames from that neighbor.

[00345] In various embodiments, spatial reuse strategies during CAP similar to those described above for CFP using HCF may be provided.

[00346] In various embodiments, protocols by which a device may discover other devices within its transmission range and may also discover their respective orientations with respect to itself may be provided.

[00347] As an example, with reference to FIG. 10, it may be assumed that all the devices shown in FIG. 10 are within the transmission range of each other. In the following, methods and device will be explained by which each of the devices shown in

FIG. 10 may discover the orientations of others with respect to itself.

[00348] hi various embodiments, in order to discover a neighbor, a device may transmit a discovery data block. In the discovery data-block, the device may first transmit an omni-directional beacon or a control or a management frame (for example with fixed transmission duration) and subsequently transmit sequentially in every sector a directional beacon or a control or a data or a management frame (for example each with fixed transmission duration and with inter frame spacings embedded). The device discovery procedure may include a directed transmission step and an additional optional step as will be explained below.

[00349] In various embodiments, the order of transmission of the directional frames from a device may be in a pre-determined order, for example from the first sector of that device going sequentially up to the last sector of that device.

[00350] In various embodiments, the following directed transmission step may be provided: Every device may transmit a discovery data-block using contention access of the medium or during CFP. However, the device that intends to transmit a discovery data- block' may desire to ensure that the medium is available omni-directionally based on its TM and its DNAVs. This step is illustrated in FIO. 27, as will be explained in more detail below. In various embodiments, the duration field in the first omni-directional frame (for example a "Device-Discovery-Request" frame) transmitted during the discovery data- block of a device may cover the period required to complete the discovery data-block transmission. Any device receiving the omni-directional frame (for example a "Device Discovery Request" frame) from the device sending the discovery data-block may update its DNAVs for all its sectors using the duration included in the omni-directional frame received subject to rules described above.

[00351] FIG. 27 shows an illustration 2700 of a discovery data-block according to an embodiment. The discovery data-block may be transmitted using contention access of the medium. In the illustration 2700, various beacon/control/command data is shown over a timeline 2702. During a first period of time, the medium may be busy as indicated by block 2704. Then, after DIFS 2706, one or more back off slots 2736 may be provided, for example a first back off slot 2708, a second back off slot 2710, one or more further back off slots 2712, and a last back off slot 2714. During the DIFS 2706 and the back off slots 2736, the medium may be idle, as indicated by arrow 2734. Thereafter an omnidirectional frame 2716, a first inter frame spacing 2718, a first directional frame 2720, a second inter frame spacing 2722, a second directional frame 2724, a third inter frame spacing 2726, a third directional frame.2728, a fourth inter frame spacing 2730, a fourth directional frame 2732 may be provided. The directional frames may be transmitted in respective sectors only, like described above.

[00352] In FIG. 27, the frames 2716, 2720, 2724, 2728, and 2732 may be part of the discovery data block. Assuming that the third device 1006 is involved in transmission of the discovery data block, the sixth device 1012 shown in FIG. 10, with the knowledge of the end time of the preamble or frame end of the omni-directional frame 2716 from the third device 1006 and with the reception of 3^rd directional frame 2728 from the third device 1006 may know that the third device 1006 may use the third sector IOO63 of the

third device 1006 to communicate with it (i.e. with the sixth device 1012). The sixth device 1012 may also update its TM with the above information. It is to be noted that in the above, every device in the neighborhood of the third device 1006 may be able to determine at the end of the transmission of the third device 1006's discovery data block, which of the sectors of the third device 1006 the third device 1006 may use to communicate with it. [00353] As an example, when the sixth device 1012 sends a similar discovery data block, the third device 1006 may infer in a similar manner that the sixth device 1012 may use the first sector 1012i of the sixth device 1012 to communicate with the third device

1006 and update its TM. With the above, the third device 1006 and the sixth device 1012 may establish their respective orientations. With the reception of Topology IEs from the third device 1006 and the sixth device 1012, the other devices may update their TMs. Hence with every device transmitting its Topology IE, a device may get the neighborhood orientations concerning all the devices in its neighborhood. [00354] hi various embodiments, the following optional step may be provided: Every device may exchange a discovery data-block with another device using contention access of the medium or CFP. However, the device that intends to initiate the discovery data- block may desire to ensure that the medium is available omni-directionally based on its TM and its DNAVs. This will be described in more detail with reference to FIG. 28 below, where the third device 1006 shown in FIG. 10 may get a TXOP to initiate a discovery data-block exchange with the sixth device 1012.

[00355] FIG. 28 shows an illustration 2800 describing a pair wise discovery data-block according to an embodiment. For example, for pair wise discovery data block communication using contention access of the medium (for illustration purposes with the pair of the third device 1006 and the sixth device 1012), various data is shown over a timeline in FIG. 28. During a first period of time, the medium may be busy as indicated by block 2804. Then, after DIFS 2806, one or more back off slots 2836 may be provided, for example a first back off slot 2808, a second back off slot 2810, one or more further back off slots 2812, and a last back off slot 2814. During the DIFS 2806 and the back off slots 2836, the medium may be idle, as indicated by arrow 2834. Thereafter a first omnidirectional frame 2816, a first inter frame spacing 2818, a second omnidirectional frame 2838, a second inter frame spacing 2840, first directional frame 2820, a third inter frame spacing 2822, a second directional frame 2824, a fourth inter frame spacing 2826, a third directional frame 2828, a fifth inter frame spacing 2830, a fourth directional frame 2832, a sixth inter frame spacing 2842, a fifth directional frame 2844, a seventh inter frame spacing 2846, a sixth directional frame 2848, an eighth inter frame spacing 2850, a seventh directional frame 2852, a ninth inter frame spacing 2854 and an eighth directional frame 2856 may be provided.

(00356] For example, the frames 2816, 2838, 2820, 2824, 2828, 2832, 2844, 2848, 2852, and 2856 in FIG. 28 may be part of the discovery data block. In FIG. 28, the frames 2816 (Device-Discovery-Request frame), 2820, 2824, 2828 and 2832 may be transmitted from the third device 1006 and the frames 2838 (Device-Discovery-Response frame), 2844, 2848, 2852, and 2856 may be transmitted from the sixth device 1012. In various embodiments, the duration field in an omni-directional frame transmitted during the discovery data-block of a device may cover the remaining period required to complete the discovery data-block transmission.

[00357] As an example, a device receiving the omni-directional frame from a device participating in the discovery data-block exchange may set its DNAVs (for example subject to rules described above) for all its sectors. More details will be provided referring to FIG. 28. As an example, pertaining to device discovery, when the third device 1006 obtains a TXOP for omni-directional transmission (for example according to rules described above), it first may transmit an omni-directional frame which may be a "Device-Discovery-Request" frame referred to as frame 2816 in FIG. 28. In the duration field of this frame, the third device 1006 may include the duration value that may cover a period up to the end of the transmission of frame 2856. When a neighbor of the third device 1006 hears the above frame 2816, it may set its DNAVs according to rules given above. When the sixth device 1012 receives frame 2816, it may check its DNAVs and TM and if (for example by the rules described above) it is able to participate in communication with the third device 1006 in an omni-directional manner, it may send an omni-directional frame which may be a "Device-Discovery-Response" frame referred to as frame 2838 in FIG. 28. After the receipt of frame 2838, all the devices may update their respective DNAVs according to the rules given above. Upon the receipt of frame 2838, the third device 1006 may start its sequential directional transmissions of frames for device discovery and the sixth device 1012 may follow suite with similar sequential transmissions as shown in FIG. 28.

[00358] As an example, the device discovery data block exchange between the third device 1006 and the sixth device 1012 may be considered. With the knowledge of the end time of the preamble or frame end of the omni-directional frame from the third device 1006 and the reception of the third directional frame 2828 from the third device 1006, the sixth device 1012 may determine that the third device 1006 may use the third sector

IOO63 of the third device 1006 to communicate with it (i.e. with the sixth device 1012).

With respect to the above same discovery data-block exchange, with the knowledge of the end time of the preamble or frame end of the omni-directional frame 2816 from the third device 1006 and the reception of the first directional frame 2844 from the sixth device 1012, the third device 1006 may determine that the sixth device 1012 may use the first sector 1012i of the sixth device 1012 to communicate with it. Then the sixth device

1012 and the third device 1006 may update their TMs accordingly. Using several more similar pair wise exchanges, a device may establish the orientations in the device's neighborhood. Topology IEs may be used by devices to exchange orientations related information as described in the above.

[00359] In various embodiments, every device may know how many sectors each of its neighbors has from the received Topology IEs. In the directed transmission step according to various embodiments as described above, every device may know how many directional frames to expect from the owner of the TXOP (device transmitting the discovery data block) and at what time to expect the directional frame transmitted from a particular sector of the owner of the TXOP.

[00360] In various embodiments, for two devices to participate in device discovery procedure using the optional step according to various embodiments above, each of them may be desired to have received at least one discovery data block using the directed transmission step according to various embodiments from the other in the past 2x aMaxDiscoveryLatency TUs. In the optional step above, the recipient device may know how many directional frames to expect from the owner of the TXOP, at what time to expect the directional frame transmitted from particular sector of the owner of the TXOP, and at what time it may start its directional transmission in the data block period (since the inter frame spacing, order of transmission of directional frames sequentially sector wise, and the omni-directional and directional frame transmission durations may be all fixed and known). Similarly, an owner of the TXOP may know how many directional frames to expect from the recipient device (for example the device to which its omni- directional frame at the start of the discovery data block was addressed to), at what time to expect the directional frame transmitted from a particular sector of the recipient device, and at what time it may expect the data block exchange to be completed (for example since it knows the number of sectors in the recipient device through Topology IE from recipient device; the owner of TXOP may use this as a guideline to set the duration field in the omni-directional^' frame it sends at the start of the TXOP for transmitting discovery data block).

[00361] In various embodiments, for DCF, the device discovery strategies may be as described above with the use of Device-Discovery-Request and Device-Discovery- Response frames as proposed in the above. Frames 2716 and 2816 in FIG. 27 and FIG. 28, respectively, may be Device-Discovery-Request frames. Frame 2838 in FIG. 28 may be a Device-Discovery-Response frame. The duration field included in frame 2716 in the directed transmission step according to various embodiments may cover the transmission period until the end of transmission of the last directionally transmitted frame (for example as described with reference to FIG. 27). The duration field included in frame 2816 in the optional step according to various embodiments may cover the transmission period until the end of transmission of the last directionally transmitted frame 2856 (for example as described with reference to FIG. 28). After the exchange of device discovery blocks between two devices, the devices may exchange their neighborhood orientation related information by transmitting frames with Topology Information Element.

[00362] In various embodiments, a device that just completed its TXOP (for example the duration of RTS frame has just elapsed) may be allowed to send a Device-Discovery- Request frame SIFS after the end of the TXOP. Other devices may invoke a back off DIFS after the medium becomes idle. In various embodiments, if a device chooses not to send a Device-Discovery-Request frame SIFS after the end of the previous TXOP, it may invoke a back off DIFS after the medium becomes idle.

[00363] hi various embodiments, for PCF or HCF, the device discovery may be done as follows: When PC or HC desires to transmit a discovery data block as described above, it may do so at any time it is allowed to transmit. However, the PC or HC may always transmit a Device-Discovery-Request frame as the first frame of any discovery data block it may transmit. When the PC or HC transmits a CF-PoIl frame or a QoS CF- PoIl frame to any device, the device may utilize the opportunity (or TXOP) to send a discovery data block. In this regard the PC or HC may send at least one CF-PoIl frame or a QoS CF-PoIl frame to a device every aMaxDiscoveryLatency TUs or 'x' DTIMs (Delivery Traffic Indication Message), where 'x' may be a parameter. SIFS after the reception of the CF-PoIl frame or a QoS CF-PoIl frame, the device may transmit a Device-Discovery-Request frame and subsequently sequential directional frames as part of the discovery data block. The PC after the receipt of the omni-directional Device- Discovery-Request frame may wait for the duration mentioned in the received frame plus PIFS before transmitting any other frame. Transmission of device discovery data block may be completed before the end of a granted TXOP.

[00364] hi various embodiments, a HC may also give TXOPs in CP for device discovery data block transmission to other devices.

[00365] hi various embodiments, a device may not send any RTS or CTS frame or any other frame other than Device Discovery Request frame if it had not sent even one discovery data block in past aMaxDiscoveryLatency Time Units (TUs). A device may not send a RTS or CTS frame to a neighbor with which it had not established orientation (device-discovery) information even once in the past 2 x aMaxDiscoveryLatency TUs. If a device receives a RTS or CTS not addressed to itself from a neighbor or to a neighbor with which it had not established orientation (for example by device-discovery as described above) information in the past 2 x aMaxDiscoveryLatency Time Units (TUs), the device may update all its DNAVs of its logical sectors using the duration mentioned in the received RTS or CTS frame. If a device receives a directional or omni-directional RTS addressed to itself from a neighbor with which it had not established orientation (device-discovery) information even once in the past 2 x aMaxDiscoveryLatency TUs, it may not respond with a CTS frame. A device may be allowed to send RTS or CTS to a neighbor only if the orientation (device-discovery) information had not changed in is TM concerning that neighbor (for all the links the neighbor is involved with as a vertex) for the past 4 x aMaxDiscoveryLatency TUs. »

[00366] In various embodiments, data transfers may always be directional. [00367] In various embodiments, a Topology IE may always be sent in every Device- Discovery-Request frame and every Device-Discovery-Response frame. The RA or DA of Device-Discovery-Request frame sent using a directed transmission step according to various embodiments as has been described above may be a broadcast address. [00368] In various embodiments, a device may update its TM (immediately within SIFS) concerning all the links a neighbor is involved with after receiving a Topology IE from that neighbor, hi various embodiments, if a link (where a neighbor may be a vertex) has been modified in the device's TM or added to the device's TM, the device may not send any RTS or CTS to that neighbor in the next 4 x aMaxDiscoveryLatency TUs after the above SIFS.

[00369] While the invention has been particularly shown and described with reference to specific embodiments, it should be understood by those skilled in the art that various changes in form and detail may be made therein without departing from the spirit and scope of the invention as defined by the appended claims. The scope of the invention is thus indicated by the appended claims and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced.

Claims

ClaimsWhat is claimed is:

1. A method for transmitting a message comprising: generating a message including information specifying a radio wave transmission/reception region out of a plurality of radio wave transmission/reception region candidates which specified radio wave transmission/reception region a first radio communication device configured to perform directional radio communication may use for communication with a second radio communication device; and transmitting the generated message.

2. ^• The method of claim 1, wherein the message is generated in the second radio communication device; wherein the generated message is transmitted from the second radio communication device.

3. The method of claim 2, further comprising: the first radio communication device sequentially transmitting a first signal omnidirectionally, a second signal in a first radio wave transmission/reception region and a third signal in a second radio wave transmission/reception region; the second radio communication device receiving from the first radio communication device at a first reception time the first signal and at a second reception time one of the second signal and the third signal; and the second radio communication device determining the radio wave transmission/reception region which the first radio communication device may use for communication with the second radio communication device based on the difference between the first reception time and the second reception time.

4. The method of claim 2, wherein at least one of the first signal, the second signal and the third signal include information identifying the first radio communication device.

5. , The method of claim 1, wherein the message is generated in the firsjt radio communication device, wherein the generated message is transmitted from the first radio communication device.

6. The method of claim 5, further comprising: the second radio communication device transmitting a signal omnidirectionally; the first radio communication device sequentially determining whether at a first reception time a first signal transmitted omnidirectionally by the second radio communication device may be received in a first radio wave transmission/reception region and whether at a second reception time a second signal transmitted omnidirectionally by the second radio communication device may be received in a second radio wave transmission/reception region; the first radio communication device determining a radio wave transmission/reception region which the first radio communication device may use for communication with the second radio communication device based on the determination whether at a first reception time a first signal transmitted omnidirectionally by the second radio communication device may be received in a first radio wave transmission/reception region and whether at a second reception time a second signal transmitted .omnidirectionally by the second radio communication device may be received in a second radio wave transmission/reception region.

7. - The method of claim 6, wherein at the first time, a reception circuit of the first radio wave transmission/reception region of the first radio communication device is activated, and a reception circuit for all other radio wave transmission/reception regions of the first radio communication device except the first radio wave transmission/reception region of the first radio communication device are deactivated;

8. The method of any one of claims 5 to 7, wherein the omnidirectionally transmitted signal includes information identifying the second radio communication device.

9. The method of any one of claims 1 to 8, wherein the second radio communication device is configured to perform directional radio communication.

10. The method of any one of claims 1 to 9, wherein the generated message is transmitted in a frame according to a standard selected from a list of standards consisting of:

WiMedia standard;

ECMA standard; IEEE 802 standard;

IEEE 802.i l standard; . IEEE 802.15.3 standard; IEEE 802.15.3a standard, IEEE 802.15.3c standard; and an Ultra Wide Band standard.

11. The method of any one of claims 1 to 10, wherein at least one radio wave transmission/reception region of the plurality of radio wave transmission/reception regions comprises at least a part of a sector defined by an angular region relative to a pre-determined point with respect to the first radio communication device.

12. The method of any one of claims 1 to 11, wherein the message is generated while no radio communication connection for interchange of user data is established between the first radio communication device and the second radio communication device.

13. A method for storing information comprising: receiving a message including information specifying a radio wave transmission/reception region out of a plurality of radio wave transmission/reception region candidates which specified radio wave transmission/reception region a first radio communication device configured to perform directional radio communication may use for communication with a second radio communication device; and storing the information included in the received message.

14. The method of claim 13, further comprising: receiving one or more further messages, each further message including respective information specifying a respective further radio wave transmission/reception region out of a respective plurality of further radio wave transmission/reception region candidates which specified respective radio wave transmission/reception region a respective further first radio communication device configured to perform directional radio communication may use for communication with a respective further second radio communication device; and storing the respective information included in the one or more further received messages.

15. The method of claim 13 or 14, further comprising: receiving and storing information indicating that communication between a fifth radio communication device and a sixth radio communication device has started.

16. The method of claim 14 or 15, wherein the message is received in a third radio communication device configured to perform directional radio communication in a plurality of radio wave transmission/reception regions, and the information included in the received message is stored in the third radio communication device.

17. The method of any one of claims 14 to 16,vfurther comprising: upon a request to the third radio communication device to start communication with a fourth radio communication device, determining whether to start communication with the fourth radio communication device, based on the stored information.

18. The method of claim 14 or 17, further comprising: upon a request to the third radio communication device to start communication with a fourth radio communication device, determining a communication start time for communication with the fourth radio communication device, based on the stored information.

19. The method of claims 14 - 15, further comprising: determining a radio wave transmission/reception region that may be used for radio communication with one of the fifth radio communication device and the sixth radio communication device; and setting a connection start restriction for the determined radio wave transmission/reception region.

20. A message transmission device, comprising: a message generator configured to generate a message including information specifying a radio wave transmission/reception region out of a plurality of radio wave transmission/reception region candidates which specified radio wave transmission/reception region a first radio communication device configured to perform directional radio communication may use for communication with a second radio communication device; and a transmitter configured to transmit the message generated by the message generator.

21. The message transmission device of claim 20, wherein the message transmission device is configured to be provided in the second radio communication device.

22. The message transmission device of claim 21, wherein the first radio communication device is further configured to sequentially transmit a first signal omnidirectionally, a second signal in a first radio wave transmission/reception region and a third signal in a second radio wave transmission/reception region; the second radio communication device is furthermore configured to receive from the first radio communication device at a first reception time the first signal and at a second reception time one of the second signal and the third signal; and the second radio communication device is furthermore configured to determine the radio wave transmission/reception region which the first radio communication device may use for communication with the second radio communication device based on the difference between the first reception time and the second reception time.

23. The message transmission device of claim 20, wherein the message transmission device is configured to be provided in the first radio communication device.

24. The message transmission device of claim 23, wherein the second radio communication device is configured to transmit a signal omnidirectionally; wherein the first radio communication device is further configured to sequentially determine whether at a first reception time a first signal transmitted omnidirectionally by the second radio communication device may be received in a first radio wave transmission/reception region and whether at a second reception time a second signal transmitted omnidirectionally by the second radio communication device may be received in a second radio wave transmission/reception region; wherein the first radio communication device is further configured to determine a radio wave transmission/reception region which the first radio communication device may use for communication with the second radio communication device based on the determination whether at a first reception time a first signal transmitted omnidirectionally by the second radio communication device may be received in a first radio wave transmission/reception region and whether at a second reception time a second signal transmitted omnidirectionally by the second radio communication device may be received in a second radio wave transmission/reception region.

25. The message transmission device of claim 24, further comprising: a first reception circuit configured to provide transmission/reception in the first radio wave transmission/reception region; a second reception circuit configured to provide transmission/reception in the second radio wave transmission/reception region; wherein the first radio communication device is further configured to, at the first time, activate the first reception circuit and deactivate the second reception circuit.

26. An information storage device, comprising: a message receiver configured to receive a message including information specifying a radio wave transmission/reception region out of a plurality of radio wave transmission/reception region candidates which specified radio wave transmission/reception region a first radio communication device configured to perform directional radio communication may use for communication with a second radio communication device; and a storage configured to store the information included in the message.

27. The information storage device of claim 26 wherein the information storage device is furthermore configured to receive and store information indicating that communication between a fifth radio communication device and a sixth radio communication device has started.

28. The information storage device of claim 26 or 27, further configured to communicate with a third radio communication device configured to perform directional radio communication in a plurality of radio wave transmission/reception regions.

29. The information storage device of claim 26 or claim 27, further comprising: a communication start determiner configured to, upon a request to the third radio communication device to start communication with a fourth radio communication device, determine whether to start communication with the fourth radio communication device, based on the stored information.

30. The information storage device of claim 28 or 29, further comprising: a communication start time determiner configured to upon a request to the third radio communication device to start communication with a fourth radio communication device, determine a communication start time for communication with the fourth radio communication device, based on the stored information.

31. The information storage device of any one of claims 28 to 30, further comprising: a other party radio wave transmission/reception region determiner configured to determine a radio wave transmission/reception region that may be used for radio communication with one of the fifth radio communication device and the sixth radio communication device; and a connection start restriction setter configured to set a connection start restriction for the determined radio wave transmission/reception region.

32. A radio wave transmission/reception region determination method comprising: a first radio communication device, configured to perform directional radio communication in a plurality of radio wave transmission/reception regions, sequentially transmitting a first signal omnidirectionally, a second signal in a first radio wave transmission/reception region and a third signal in a second radio wave transmission/reception region; a second radio communication device receiving from the first radio communication device at a first reception time the first signal and at a second reception time one of the second signal and the third signal; the second radio communication device determining a radio wave transmission/reception region which the first radio communication device may use for communication with the second radio communication device based on the difference between the first reception time and the second reception time.

33. A radio wave transmission/reception region determination method comprising: a second radio communication device transmitting a signal omnidirectionally; a first radio communication device, configured to perform directional radio communication in a plurality of radio wave transmission/reception regions, sequentially determining whether at a first reception time a first signal transmitted omnidirectionally by the second radio communication device may be received in a first radio wave transmission/reception region and whether at a second reception time a second signal transmitted omnidirectionally by the second radio communication device may be received in a second radio wave transmission/reception region; the first radio communication device determining a radio wave transmission/reception region which the first radio communication device may use for communication with the second radio communication device based on the determination whether at a first reception time a first signal transmitted omnidirectionally by the second radio communication device may be received in a first radio wave transmission/reception region and whether at a second reception time a second signal transmitted omnidirectionally by the second radio communication device may be received in a second radio wave transmission/reception region.

34. A radio wave transmission/reception region determination system comprising: a first radio communication device, configured to perform directional radio communication in a plurality of radio wave transmission/reception regions and to sequentially transmit a first signal omnidirectionally, a second signal in a first radio wave transmission/reception region and a third signal in a second radio wave transmission/reception region; ₍ a second radio communication device Configured to receive from the first radio communication device at a first reception time the first signal and at a second reception time one of the second signal and the third signal; wherein the second radio communication device is further configured to determine a radio wave transmission/reception region which the first radio communication device may use for communication with the second radio communication device based on the difference between the first reception time and the second reception time.

5. A radio wave transmission/reception region determination system comprising: a second radio communication device configured to transmit a signal omnidirectionally; a first radio communication device, configured to perform directional radio communication in a plurality of radio wave transmission/reception regions, and to sequentially determine whether at a first reception time a first signal transmitted omnidirectionally by the second radio communication device may be received in a first radio wave transmission/reception region and whether at a second reception time a second signal transmitted omnidirectionally by the second radio communication device may be received in a second radio wave transmission/reception region; wherein the first radio communication device is further configured to determine a radio wave transmission/reception region which the first radio communication device may use for communication with the second radio communication device based on the determination whether at a first reception time a first signal transmitted omnidirectionally by the second radio communication device may be received in a first radio wave transmission/reception region and whether at a second reception time a second signal transmitted omnidirectionally by the second radio communication device may be received in a second radio wave transmission/reception region.