Patent Publication Number: US-10778818-B2

Title: Apparatus, system and method of controlling data flow over a communication network

Description:
CROSS REFERENCE 
     This application is a Continuation Application of U.S. patent application Ser. No. 13/798,594, filed on Mar. 13, 2013, which claims the benefit of and priority from U.S. Provisional Patent application No. 61/729,369 entitled “Apparatus, System, and Method of Controlling Data Flow Over a Wireless Communication Link”, filed Nov. 22, 2012, the entire disclosure of which is incorporated herein by reference. 
    
    
     TECHNICAL FIELD 
     Embodiments described herein generally relate to controlling data flow over a communication network. 
     BACKGROUND 
     Some wireless communication technologies may be configured for communication of various dedicated services. 
     For example, the Wireless-Gigabit (WiGig) technology, e.g., according to the  Wireless Gigabit Alliance, Inc WiGig MAC and PHY Specification Version  1.1 , April  2011 , Final specification , is designed to carry multiple dedicated services, such as audio-visual (A/V) and input output (I/O). 
     The WiGig Alliance (WGA) has defined a set of Protocol Abstraction Layers (PALs), e.g., a WiGig Serial Extension (WSE) PAL and a WiGig Display Extension (WDE) PAL, that standardize the method of transporting traffic of specific industry-standard protocols, e.g. Universal Serial Bus (USB) and DisplayPort, over the WiGig media access control (MAC) layer. 
     The WSE defines a WSE host communicating with a WSE device over a WiGig wireless link interface. The WSE host can connect and control several WSE devices. Each WSE device can include several USB ports, and each USB port can be attached to a USB device or be extended to several ports via a USB hub. 
     Since USB devices and/or USB hosts may be configured for communicating over a physical medium, e.g., a USB cable, there may be a problem to perform some operations, e.g., in an efficient seamless and/or transparent manner, via the WSE PAL. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       For simplicity and clarity of illustration, elements shown in the figures have not necessarily been drawn to scale. For example, the dimensions of some of the elements may be exaggerated relative to other elements for clarity of presentation. Furthermore, reference numerals may be repeated among the figures to indicate corresponding or analogous elements. The figures are listed below. 
         FIG. 1  is a schematic block diagram illustration of a system, in accordance with some demonstrative embodiments. 
         FIG. 2  is a schematic illustration of a sequence of communications between a Wireless-Gigabit (WiGig) Serial Extension (WSE) host, a WSE device and a Universal-Serial-Bus (USB) device, in accordance with some demonstrative embodiments. 
         FIG. 3  is a schematic flow-chart illustration of a method of controlling data flow, in accordance with some demonstrative embodiments. 
         FIG. 4  is a schematic illustration of a product, in accordance with some demonstrative embodiments. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     In the following detailed description, numerous specific details are set forth in order to provide a thorough understanding of some embodiments. However, it will be understood by persons of ordinary skill in the art that some embodiments may be practiced without these specific details. In other instances, well-known methods, procedures, components, units and/or circuits have not been described in detail so as not to obscure the discussion. 
     Discussions herein utilizing terms such as, for example, “processing”, “computing”, “calculating”, “determining”, “establishing”, “analyzing”, “checking”, or the like, may refer to operation(s) and/or process(es) of a computer, a computing platform, a computing system, or other electronic computing device, that manipulate and/or transform data represented as physical (e.g., electronic) quantities within the computer&#39;s registers and/or memories into other data similarly represented as physical quantities within the computer&#39;s registers and/or memories or other information storage medium that may store instructions to perform operations and/or processes. 
     The terms “plurality” and “a plurality”, as used herein, include, for example, “multiple” or “two or more”. For example, “a plurality of items” includes two or more items. 
     References to “one embodiment,” “an embodiment,” “demonstrative embodiment,” “various embodiments,” etc., indicate that the embodiment(s) so described may include a particular feature, structure, or characteristic, but not every embodiment necessarily includes the particular feature, structure, or characteristic. Further, repeated use of the phrase “in one embodiment” does not necessarily refer to the same embodiment, although it may. 
     As used herein, unless otherwise specified the use of the ordinal adjectives “first,” “second,” “third,” etc., to describe a common object, merely indicate that different instances of like objects are being referred to, and are not intended to imply that the objects so described must be in a given sequence, either temporally, spatially, in ranking, or in any other manner. 
     Some embodiments may be used in conjunction with various devices and systems, for example, a Personal Computer (PC), a desktop computer, a mobile computer, a laptop computer, a notebook computer, a tablet computer, a server computer, a handheld computer, a handheld device, a Personal Digital Assistant (PDA) device, a handheld PDA device, an on-board device, an off-board device, a hybrid device, a vehicular device, a non-vehicular device, a mobile or portable device, a consumer device, a non-mobile or non-portable device, a wireless communication station, a wireless communication device, a wireless Access Point (AP), a wired or wireless router, a wired or wireless modem, a video device, an audio device, an audio-video (A/V) device, a wired or wireless network, a wireless area network, a Wireless Video Area Network (WVAN), a Local Area Network (LAN), a Wireless LAN (WLAN), a Personal Area Network (PAN), a Wireless PAN (WPAN), and the like. 
     Some embodiments may be used in conjunction with devices and/or networks operating in accordance with existing Wireless-Gigabit-Alliance (WGA or WiGig) specifications ( Wireless Gigabit Alliance, Inc WiGig MAC and PHY Specification Version  1.1 , April  2011 , Final specification ) and/or future versions and/or derivatives thereof, devices and/or networks operating in accordance with existing WiGig Serial Extension (WSE) protocols ( WiGig Serial Extension  ( WSE )  Specification Draft  1.02 , August  2012) and/or future versions and/or derivatives thereof, devices and/or networks operating in accordance with existing WiGig Display Extension (WDE) protocols ( WDE Draft Specification  1.04 , August  2012) and/or future versions and/or derivatives thereof, devices and/or networks operating in accordance with existing WiGig Bus Extension (WBE) protocols ( WiGig Bus Extension Spec  ( WBE ),  Version  1.0  June  2011) and/or future versions and/or derivatives thereof, devices and/or networks operating in accordance with existing WiGig Secure Digital (SD) Extension (WSD) protocols ( WiGig SD Extension  ( WSD )  PAL Specification Draft  1.0  August  2012) and/or future versions and/or derivatives thereof, devices and/or networks operating in accordance with existing Bulk Only Transfer (BOT) Protocols ( Universal Serial Bus  ( USB )  Mass Storage Class Bulk - Only Transport, Revision  1.0 , Sep.  31, 1999) and/or future versions and/or derivatives thereof, devices and/or networks operating in accordance with existing IEEE 802.11 standards ( IEEE  802.11-2012 , IEEE Standard for Information technology—Telecommunications and information exchange between systems Local and metropolitan area networks—Specific requirements Part  11 : Wireless LAN Medium Access Control  ( MAC )  and Physical Layer  ( PHY )  Specifications, Mar.  29, 2012; IEEE802.11 task group ac (TGac) ( “IEEE 802.11-09/0308 r 12 —TGac Channel Model Addendum Document” );  IEEE  802.11  task group ad  ( TGad ) ( IEEE P 802.11 ad/D 9.0  Draft Standard for Information Technology—Telecommunications and Information Exchange Between Systems—Local and Metropolitan Area Networks—Specific Requirements—Part  11 : Wireless LAN Medium Access Control  ( MAC )  and Physical Layer  ( PHY )  Specifications—Amendment  5 : Enhancements for Very High Throughput in the  60  GHz Band )), and/or future versions and/or derivatives thereof, devices and/or networks operating in accordance with existing IEEE 802.16 standards ( IEEE - Std  802.16, 2009  Edition, Air Interface for Fixed Broadband Wireless Access Systems; IEEE - Std  802.16 e,  2005  Edition, Physical and Medium Access Control Layers for Combined Fixed and Mobile Operation in Licensed Bands; amendment to IEEE Std  802.16-2009 , developed by Task Group m ) and/or future versions and/or derivatives thereof, devices and/or networks operating in accordance with existing WirelessHD™ specifications and/or future versions and/or derivatives thereof, units and/or devices which are part of the above networks, and the like. 
     Some embodiments may be used in conjunction with one way and/or two-way radio communication systems, cellular radio-telephone communication systems, a mobile phone, a cellular telephone, a wireless telephone, a Personal Communication Systems (PCS) device, a PDA device which incorporates a wireless communication device, a mobile or portable Global Positioning System (GPS) device, a device which incorporates a GPS receiver or transceiver or chip, a device which incorporates an RFID element or chip, a Multiple Input Multiple Output (MIMO) transceiver or device, a Single Input Multiple Output (SIMO) transceiver or device, a Multiple Input Single Output (MISO) transceiver or device, a device having one or more internal antennas and/or external antennas, Digital Video Broadcast (DVB) devices or systems, multi-standard radio devices or systems, a wired or wireless handheld device, e.g., a Smartphone, a Wireless Application Protocol (WAP) device, or the like. 
     Some embodiments may be used in conjunction with one or more types of wireless communication signals and/or systems, for example, Radio Frequency (RF), Infra Red (IR), Frequency-Division Multiplexing (FDM), Orthogonal FDM (OFDM), Time-Division Multiplexing (TDM), Time-Division Multiple Access (TDMA), Extended TDMA (E-TDMA), General Packet Radio Service (GPRS), extended GPRS, Code-Division Multiple Access (CDMA), Wideband CDMA (WCDMA), CDMA 2000, single-carrier CDMA, multi-carrier CDMA, Multi-Carrier Modulation (MDM), Discrete Multi-Tone (DMT), Bluetooth®, Global Positioning System (GPS), WiGig, Wi-Fi, Internet-Protocol (IP), Wi-Max, ZigBee™, Ultra-Wideband (UWB), Global System for Mobile communication (GSM), 3rd Generation Partnership Project (3GPP), 2G, 2.5G, 3G, 3.5G, Long Term Evolution (LTE), LTE advanced, Fifth Generation (5G) mobile networks, Enhanced Data rates for GSM Evolution (EDGE), or the like. Other embodiments may be used in various other devices, systems and/or networks. 
     The term “wireless device”, as used herein, includes, for example, a device capable of wireless communication, a communication device capable of wireless communication, a communication station capable of wireless communication, a portable or non-portable device capable of wireless communication, or the like. In some demonstrative embodiments, a wireless device may be or may include a peripheral that is integrated with a computer, or a peripheral that is attached to a computer. In some demonstrative embodiments, the term “wireless device” may optionally include a wireless service. 
     The term “communicating” as used herein with respect to a communication signal includes transmitting the communication signal and/or receiving the communication signal. For example, a communication unit, which is capable of communicating a communication signal, may include a transmitter to transmit the communication signal to at least one other communication unit, and/or a communication receiver to receive the communication signal from at least one other communication unit. 
     Some demonstrative embodiments may be used in conjunction with suitable limited-range or short-range wireless communication networks, for example, a wireless area network, a “piconet”, a WPAN, a WVAN and the like. Other embodiments may be used in conjunction with any other suitable wireless communication network. 
     Some demonstrative embodiments may be used in conjunction with a wireless communication network communicating over a frequency band of 60 GHz. However, other embodiments may be implemented utilizing any other suitable wireless communication frequency bands, for example, an Extremely High Frequency (EHF) band (the millimeter wave (mmwave) frequency band), e.g., a frequency band within the frequency band of between 30 Ghz and 300 GHZ, a WLAN frequency band, a WPAN frequency band, a WiGig frequency band according to the WGA specification, a WiFi band, a P2P band, and the like. 
     The term “antenna”, as used herein, may include any suitable configuration, structure and/or arrangement of one or more antenna elements, components, units, assemblies and/or arrays. In some embodiments, the antenna may implement transmit and receive functionalities using separate transmit and receive antenna elements. In some embodiments, the antenna may implement transmit and receive functionalities using common and/or integrated transmit/receive elements. The antenna may include, for example, a phased array antenna, a single element antenna, a set of switched beam antennas, and/or the like. 
     The term “station” (STA), as used herein, may include any logical entity that is a singly addressable instance of a medium access control (MAC) and a physical layer (PHY) interface to a wireless medium (WM). 
     The phrase “access point” (AP), as used herein, may include an entity that contains one station (STA) and provides access to distribution services, via the WM for associated STAs. 
     The term “beamforming”, as used herein, may relate to a spatial filtering mechanism, which may be used at a transmitter and/or a receiver to improve the received signal power or signal-to-noise ratio (SNR) at an intended receiver. 
     The phrase “non-access-point (non-AP) station (STA)”, as used herein, may relate to a STA that is not contained within an AP. 
     The phrases “directional multi-gigabit (DMG)” and “directional band” (DBand), as used herein, may relate to a frequency band wherein the Channel starting frequency is above 40 GHz. 
     The phrases “DMG STA” and “mmWave STA (mSTA)” may relate to a STA having a radio transmitter, which is operating on a channel that is within the DMG band. 
     The phrase “peer to peer (PTP or P2P) communication”, as used herein, may relate to device-to-device communication over a wireless link (“peer-to-peer link”) between a pair of devices. The P2P communication may include, for example, wireless communication over a direct link within a QoS basic service set (BSS), a tunneled direct-link setup (TDLS) link, a STA-to-STA communication in an independent basic service set (IBSS), or the like. 
     A wireless P2P wireless communication network (“P2P network” or “P2P group”) may include a plurality of wireless communication devices capable of supporting device-to device communication. 
     The phrase “Protocol Adaptation Layer (PAL)”, as used herein, may include an abstraction layer configured to enable transporting traffic of at least one predefined protocol over a communication link. The predefined standard may include, for example, a specific industry-standard protocol, e.g. USB, DisplayPort, and the like. The PAL may be above a data link layer, for example, a MAC layer, and/or above a transport layer, e.g., a Transmission Control Protocol (TCP) or User Datagram Protocol (UDP), which is above the data link layer. In one example, the data link layer may include, for example, a MAC layer of a wireless link, e.g., a WiFi MAC layer, a WiGig MAC layer, a P2P MAC layer, and the like. In another example, the PAL may be above a transport layer, e.g., a TCP or UDP, which may be configured for transporting traffic over an IP network, e.g., a wired or wireless Internet link and/or Ethernet link. 
     Some demonstrative embodiment are described herein with respect to a PAL connection over a wireless communication link, for example, a WiGig link, e.g., as described below. However, other embodiments may include a PAL connection over any other wired or wireless communication MAC layer link, e.g., an IP link. 
     The phrase “PAL communication unit”, as used herein, may include a communication element to manage and/or control a PAL connection between a first architectural element, for example, a PAL host, e.g., a USB host, and a second architectural element, for example, a PAL device, e.g., a USB device, over a communication link, e.g., a MAC layer link or a transport layer link, between the PAL communication unit and another PAL communication unit. 
     In some demonstrative embodiments, the PAL communication unit (also referred to as “PAL manager” or “PAL controller”) may perform the functionality of, may include, or may be implemented as part of a WSE Service Set (WSS). For example, the PAL communication unit may perform at least part of the functionality of a WSE device or a WSE host, e.g., as described below. In other embodiments, the PAL communication unit may perform the functionality of any other PAL device, element and/or module. 
     The phrase “WSE device”, as used herein, may include, for example, a WSE architectural element that integrates, and/or is associated with, at least one device, e.g., a USB device, and manages transfers, e.g., USB transfers, targeting the integrated device over a network connection. In one example, the integrated device may be connected, for example, through a wired USB, e.g., USB cable, USB chip-to-chip interconnect, and/any other technologies. In one example, the integrated device may be presented through the WSE device to a host as a USB device compliant with a USB specification, e.g., the USB 2.0 and/or USB 3.0 Specifications. 
     In one example, the WSE device may optionally include any computing platform, e.g., a portable device, which houses and/or performs the functionality of the WSE device and, optionally, one or more additional elements, e.g., drivers and/or application software, configured to perform the functionality of a peripheral device. In other embodiments, the WSE device may include and/or may be implemented by any other portable or non-portable device. 
     In some demonstrative embodiments, the WSE device may include USB device logic, e.g., for communicating with a USB device according to a USB Specification, a WSE device PAL, e.g., to control communication over the PAL, and a network interface, e.g., to communicate over the communication link. For example, the WSE device PAL may interface between the USB device logic and the network interface, e.g., in a transparent manner In other embodiments, the WSE device may include any other elements. In one example, the PAL communication unit may perform the functionality of at least the WSE device PAL. 
     The phrase “WSE host”, as used herein, may include an architectural element of the WSE PAL that includes a communication architecture, e.g., a WiGig MAC and PHY, and USB host logic, e.g., as defined by a USB specification, e.g., the USB 2.0 and/or USB 3.0 Specifications. 
     In one example, the WSE host may optionally include any computing platform, e.g., a personal computer, which houses and/or performs the functionality of the WSE host and, optionally, one or more additional elements, e.g., drivers and/or application software, configured to perform the functionality of a host device. In other embodiments, the WSE host may include and/or may be implemented by any other portable or non-portable device. 
     In some demonstrative embodiments, the WSE host may include USB host logic, e.g., for communicating with a USB host according to a USB Specification, a WSE host PAL, e.g., to control communication over the PAL, and a network interface, e.g., to communicate over the communication link. For example, the WSE host PAL may interface between the USB host logic and the network interface, e.g., in a transparent manner. In other embodiments, the WSE host may include any other elements. In one example, the PAL communication unit may perform the functionality of at least the WSE host PAL. 
     An endpoint may include, for example, an architectural element, which is associated with a first device, which in turn is configured to interface between the endpoint and a second device over a communication link. For example, the endpoint may be integrated as part of the first device or connected to the first device via one or more other devices and/or connections. The endpoint may be implemented, for example, using any technology, e.g., software, hardware and/or any combination thereof. The first device may include and/or interface between one or more endpoints and the second device. 
     In one example, the first device may include a WSE device and the second device may include a WSE host. For example, the endpoint may belong to a USB device, e.g., a USB device, which may be integrated into the WSE device or connected, e.g., through a wired USB connection, to the WSE device, e.g., via a hub integrated into the WSE device. 
     According to this example, the endpoint may be uniquely identified by the WSE host. For example, a combination of a WSE device address of the WSE device and a WSE EP handle assigned to the endpoint may uniquely identify a USB device endpoint within a WSE service set. 
     In other examples, the first and second devices may include any other, e.g., non-WSE and/or non-USB, device and the endpoint may perform the functionality of any other, e.g., non-USB and/or non-WSE, element. 
     Reference is now made to  FIG. 1 , which schematically illustrates a block diagram of a system  100 , in accordance with some demonstrative embodiments. 
     As shown in  FIG. 1 , in some demonstrative embodiments, system  100  may include a communication network including one or more communication devices, e.g., communication devices  102  and/or  104 , capable of communicating content, data, information and/or signals over a communication medium, for example, a radio channel, an IR channel, a RF channel, a Wireless Fidelity (WiFi) channel, and the like. One or more elements of system  100  may optionally be capable of communicating over any suitable wired communication links. 
     In some demonstrative embodiments, devices  102  and/or  104  may include, for example, a PC, a desktop computer, a mobile computer, a laptop computer, a notebook computer, a tablet computer, an Ultrabook™, a server computer, a media center, a mobile internet device, a handheld computer, a handheld device, a storage device, a mass storage device, a USB mass storage (UMS) device, a hard drive, an optical drive, a flash memory device, a PDA device, a handheld PDA device, an on-board device, an off-board device, a hybrid device (e.g., combining cellular phone functionalities with PDA device functionalities), a consumer device, a vehicular device, a non-vehicular device, a mobile or portable device, a non-mobile or non-portable device, a mobile phone, a cellular telephone, a PCS device, a PDA device which incorporates a wireless communication device, a mobile or portable GPS device, a DVB device, a relatively small computing device, a non-desktop computer, a “Carry Small Live Large” (CSLL) device, an Ultra Mobile Device (UMD), an Ultra Mobile PC (UMPC), a Mobile Internet Device (MID), an “Origami” device or computing device, a device that supports Dynamically Composable Computing (DCC), a context-aware device, a video device, an audio device, an A/V device, a Set-Top-Box (STB), a Blu-ray disc (BD) player, a BD recorder, a Digital Video Disc (DVD) player, a High Definition (HD) DVD player, a DVD recorder, a HD DVD recorder, a Personal Video Recorder (PVR), a broadcast HD receiver, a video source, an audio source, a video sink, an audio sink, a stereo tuner, a broadcast radio receiver, a flat panel display, a Personal Media Player (PMP), a digital video camera (DVC), a digital audio player, a speaker, an audio receiver, an audio amplifier, a gaming device, a data source, a data sink, a Digital Still camera (DSC), a media player, a Smartphone, a television, a music player, or the like. 
     In some demonstrative embodiments, devices  102  and/or  104  may include network interfaces  110  and  120 , respectively, to perform communication over a communication network between communication devices  102  and  104  and/or with one or more other devices, e.g., as described below. 
     Devices  102  and/or  104  may also include, for example, one or more of a processor  191 , an input unit  192 , an output unit  193 , a memory unit  194 , and a storage unit  195 . Wireless communication devices  102  and/or  104  may optionally include other suitable hardware components and/or software components. In some demonstrative embodiments, some or all of the components of one or more of wireless communication devices  102  and/or  104  may be enclosed in a common housing or packaging, and may be interconnected or operably associated using one or more wired or wireless links. In other embodiments, components of one or more of wireless communication devices  102  and/or  104  may be distributed among multiple or separate devices. 
     Processor  191  includes, for example, a Central Processing Unit (CPU), a Digital Signal Processor (DSP), one or more processor cores, a single-core processor, a dual-core processor, a multiple-core processor, a microprocessor, a host processor, a controller, a plurality of processors or controllers, a chip, a microchip, one or more circuits, circuitry, a logic unit, an Integrated Circuit (IC), an Application-Specific IC (ASIC), or any other suitable multi-purpose or specific processor or controller. Processor  191  executes instructions, for example, of an Operating System (OS) of wireless communication devices  102  and/or  104  and/or of one or more suitable applications. 
     Input unit  192  includes, for example, a keyboard, a keypad, a mouse, a touch-screen, a touch-pad, a track-ball, a stylus, a microphone, or other suitable pointing device or input device. Output unit  193  includes, for example, a monitor, a screen, a touch-screen, a flat panel display, a Cathode Ray Tube (CRT) display unit, a Liquid Crystal Display (LCD) display unit, a plasma display unit, one or more audio speakers or earphones, or other suitable output devices. 
     Memory unit  194  includes, for example, a Random Access Memory (RAM), a Read Only Memory (ROM), a Dynamic RAM (DRAM), a Synchronous DRAM (SD-RAM), a flash memory, a volatile memory, a non-volatile memory, a cache memory, a buffer, a short term memory unit, a long term memory unit, or other suitable memory units. Storage unit  195  includes, for example, a hard disk drive, a floppy disk drive, a Compact Disk (CD) drive, a CD-ROM drive, a DVD drive, or other suitable removable or non-removable storage units. Memory unit  194  and/or storage unit  195 , for example, may store data processed by wireless communication devices  102  and/or  104 . 
     In some demonstrative embodiments, network interfaces  110  and/or  120  may include wireless communication units, e.g., including radios  111  and  121 , to communicate over a wireless communication medium. For example, radios  111  and/or  121  may include, or may be associated with, one or more antennas  107  and/or  108 , respectively. Antennas  107  and/or  108  may include any type of antennas suitable for transmitting and/or receiving wireless communication signals, blocks, frames, transmission streams, packets, messages and/or data. For example, antennas  107  and/or  108  may include any suitable configuration, structure and/or arrangement of one or more antenna elements, components, units, assemblies and/or arrays. Antennas  107  and/or  108  may include, for example, antennas suitable for directional communication, e.g., using beamforming techniques. For example, antennas  107  and/or  108  may include a phased array antenna, a single element antenna, a set of switched beam antennas, and/or the like. In some embodiments, antennas  107  and/or  108  may implement transmit and receive functionalities using separate transmit and receive antenna elements. In some embodiments, antennas  107  and/or  108  may implement transmit and receive functionalities using common and/or integrated transmit/receive elements. 
     In some demonstrative embodiments, radios  111  and/or  121  may include one or more wireless transmitters, receivers and/or transceivers able to send and/or receive wireless communication signals, RF signals, frames, blocks, transmission streams, packets, messages, data items, and/or data. For example, radios  111  and/or  121  may include or may be implemented as part of a wireless Network Interface Card (NIC), and the like. 
     In some demonstrative embodiments, devices  102  and  104  may establish a communication link  103 . Link  103  may be configured for communication over a data link layer, e.g., the MAC layer, a logical link control (LLC) and/or a transport layer. Link  103  may include an uplink and/or a downlink. For example, the uplink may include a link for communicating data from device  104  to device  102 , and/or the downlink may include a link for communicating data from device  102  to device  104 . The downlink may include, for example, a unidirectional link from an AP to one or more non-AP stations (STAs) or a unidirectional link from a non-AP Destination STA to a non-AP Source STA. The uplink may include, for example, a unidirectional link from a non-AP STA to an AP or a unidirectional link from a non-AP Source STA to a non-AP Destination STA. 
     In some demonstrative embodiments, link  103  may include a wireless communication link, for example, a WiGig link, e.g., as described below. In other embodiments, link  103  may include any other wireless or wired link, e.g., an IP link. According to these embodiments, network interfaces  110  and/or  120  may include any suitable communication unit, e.g., a wired or wireless communication unit, to communicate over the communication network. 
     In some demonstrative embodiments, devices  102  and  104  may form, or may be part of, a wireless communication network. The wireless communication network may include, for example, a P2P network or any other network. 
     In some demonstrative embodiments, devices  102  and/or  104  may perform the functionality of DMG stations (“DMG STA”). For example, communication devices  102  and/or  104  may be configured to communicate over the DMG band. 
     In some demonstrative embodiments, device  102  may include a mobile device and device  104  may include a docking device to connect device  102  to one or more other devices (“peripherals”), for example, including one or more USB devices, e.g., devices  162 ,  164 ,  166  and/or  168 , and/or any other device. 
     For example, device  102  may include, or may be included as part of a mobile or portable device, for example, a mobile computer, a laptop computer, a notebook computer, a tablet computer, an Ultrabook™, a Smartphone, a handheld computer, a handheld device, a PDA device, a handheld PDA device, an on-board device, an off-board device, a hybrid device, e.g., combining cellular phone functionalities with PDA device functionalities, a consumer device, a vehicular device, a non-vehicular device, a cellular telephone, a PCS device, a PDA device which incorporates a wireless communication device, a mobile or portable GPS device, a relatively small computing device, a non-desktop computer, a CSLL device, a UMD, a UMPC, a MID, an “Origami” device or computing device, a device that supports DCC, a context-aware device, a video device, an audio device, an A/V device, a data source, a Digital Still camera (DSC), a media player, or the like. 
     In one example, device  104  may include a docking device configured to connect between device  102  and devices  162 ,  164 ,  166  and/or  168  via one or more interfaces  139 , for example, serial interfaces, e.g., USB interfaces and/or any other interface. Devices  162 ,  164 ,  166  and/or  168  may include for example, a mass storage device, e.g., a USB mass storage (UMS) device, a hard drive, an optical drive, a flash memory device, and the like. 
     In some demonstrative embodiments, device  104  may be connected to devices  162 ,  164 ,  166  and/or  168  via one or more USB interfaces  139  supporting one or more data transfer rates. For example, device  104  may be connected to one or more of devices  162 ,  164 ,  166  and/or  168  via a first USB interface  139  supporting a first data transfer rate, e.g., a USB1.1 interface supporting a data transfer rate of 12 Mega bit per second (Mbps), device  104  may be connected to one or more of devices  162 ,  164 ,  166  and/or  168  via a second USB interface  139  supporting a second data transfer rate, e.g., a USB2 interface supporting a data rate of 480 Mbps, and/or device  104  may be connected to one or more of devices  162 ,  164 ,  166  and/or  168  via a third USB interface  139  supporting a third data transfer rate, e.g., a USB3 interface supporting a data transfer rate of up to 4.8 Giga bit per second (Gbps). 
     In some demonstrative embodiments, device  104  may include a hub  132 , e.g., a USB hub, to connect between device  104  and one or more of devices  162 ,  164 ,  166  and  168 . Additionally or alternatively, device  104  may be connected to one or more of devices  162 ,  164 ,  166  and  168  via any USB tree, which may include, for example, one or more USB hubs  142 . For example, device  102  may include, or may be connected to, one or more USB ports, and each USB port may be connected to a USB device or be extended to several ports via USB hub  132  and/or USB hub  142 . 
     In some demonstrative embodiments, devices  162 ,  164 ,  166  and/or  168  may perform the functionality of one or more Endpoints (EPs). For example, a USB device may perform the functionality of one EP or more than one EP. In one example, device  162  may perform the functionality of an EP  134 , device  164  may perform the functionality of an EP  135  and an EP  136 , device  166  may perform the functionality of an EP  138 , and/or device  168  may perform the functionality of an EP  138 . 
     In some demonstrative embodiments, device  102  may include a PAL communication unit  130 , and device  104  may include a PAL communication unit  131 . PAL communication units  103  and  131  may be configured to manage a PAL connection between devices  102  and  104  over link  103 . 
     In some demonstrative embodiments, devices  102  and  104  may communicate over link  103  according to a WiGig protocol. 
     In some demonstrative embodiments, devices  102  and  104  may be configured for communication of various dedicated services. For example, the WiGig technology is designed to carry multiple dedicated services, such as audio-visual (A/V) and input output (I/O). 
     Some demonstrative embodiments are described herein with reference to communicating a data stream including USB data over a wireless communication link according to a WSE protocol. However, other embodiments may be implemented with respect to communicating any other suitable data over any other communication link, according to any other communication protocol and/or over any other layer or PAL. 
     In some demonstrative embodiments, device  102  may perform the functionality of a USB host and device  104  may perform the functionality of a USB device. 
     In some demonstrative embodiments, PAL communication unit  130  may perform the functionality of a WSE host and PAL communication unit  131  may perform the functionality of a WSE device. 
     In some demonstrative embodiments, PAL communication units  130  and  131  may communicate USB traffic over the WSE PAL via link  103 . The USB traffic may include, for example, non-periodic (NP) traffic, e.g., bulk and/or control traffic, and/or periodic traffic, e.g., Isochronous and/or Interrupt traffic, which may be communicated by the EPs  134 ,  135 ,  136 ,  138  and/or  140 . 
     In some demonstrative embodiments, the USB traffic may include traffic (“USB IN”) delivered from the EPs the EPs  134 ,  135 ,  136 ,  138  and/or  140 , via device  104 , to device  102 , and/or traffic (“USB OUT”) delivered from device  102 , via device  104 , to the EPs the EPs  134 ,  135 ,  136 ,  138  and/or  140 . 
     In some demonstrative embodiments, the USB PAL may enable transport of USB data over media other than USB cable, for example, wireless links, e.g., Wi-Fi or WiGig links, or wired links, e.g., Ethernet. The USB PAL may directly interface with network interfaces  110  and  120 , e.g., to replace a network layer in the Open Systems Interconnection (OSI) model, or may be an IP application, interfacing with an IP (e.g., TCP/IP or UDP/IP) stack. 
     In some demonstrative embodiments, PAL communication unit  130  and PAL communication unit  131  may be configured to enable media-agnostic connectivity of a PAL between devices  102  and  104 . 
     In some demonstrative embodiments, PAL communication unit  130  and PAL communication unit  131  may be configured to enable connectivity of the PAL between devices  102  and  104  over a wireless communication link, for example, a WiGig link, e.g., as described below. However, in other embodiments, PAL communication unit  130  and PAL communication unit  131  may be configured to enable media-agnostic connectivity of the PAL between devices  102  and  104  over any other medium, for example, a Wi-Fi link, an IP link, e.g., internet, Ethernet, over wire or wireless, and the like. 
     In some demonstrative embodiments the USB PAL may replace a USB physical cable. 
     For example, PAL communication units  130  and  131  may be configured to interface, e.g., over link  103 , between USB host logic, for example, a USB driver at a host platform, e.g., a USB device interface (USBDI) of device  102 , and a USB controller of device  104 . 
     According to this example, the combination of PAL communication unit  130 , network interface  110 , network interface  120 , and PAL communication unit  131  may be configured to replace and/or emulate the USB physical cable for connecting between a host device, e.g., device  102 , and a USB device, e.g., included by or connected to device  104 . 
     In some demonstrative embodiments, PAL communication units  130  and  131  may be configured to communicate over a USB PAL between a USB host and a USB device. The USB PAL may enable efficient transport of USB traffic by transmitting USB transfers, as opposed to USB transactions. USB transfers may include larger pieces of data, which may be more appropriate for transmission over the wireless links. 
     However, built-in flow mechanisms for transport of data in USB may not be used, for example, if USB link access mechanisms are not used by the USB PAL. 
     In some demonstrative embodiments, the USB PAL may utilize a dedicated USB PAL transfer protocol, which may be configured to effectively handle transfer scenarios that may happen as in wired USB, including, for example, a pending IN transfer, which includes data pending to be transferred from a USB device, e.g., an endpoint, to the WSE host. 
     In some demonstrative embodiments, a host, e.g., device  102 , may initiate a USB IN transfer, for example, for transferring a data block (“the requested data block”) from an EP of a USB device to the host, e.g., via device  104 . For example, PAL communication unit  130  may initiate the USB IN transfer, for example, by transmitting to PAL communication unit  131  a transfer request including an identifier (“Request Identifier (ID)”) to identify the requested data block. 
     In some demonstrative embodiments, the USB IN transfer for the requested data block may be pending, for example, when the USB device is not transferring the requested block of data to device  104 . 
     In such a case, the USB device may send to PAL communication unit  131  a non-acknowledge (NAK) message to inform the host that there is no data to be transmitted. 
     In some demonstrative embodiments, the PAL communication unit  131  may not forward the NAK messages to the host, for example, to increase the efficiency of the USB PAL transfer protocol. 
     In some demonstrative embodiments, the PAL communication unit  131  may send a transfer response to PAL communication unit  130 , e.g., in response to the transfer request. The transfer response may include an error status, e.g., a Transfer-Pending status, which indicates the transfer of the requested block is pending at the USB device. 
     Configuring PAL communication unit  131  to wait until PAL communication unit  130  retransmits the transfer request, prior to transmitting the transfer response, configuring PAL communication unit  130  to stop retransmissions, e.g., after receiving the transfer response, and/or configuring PAL communication unit  130  to passively wait for PAL communication unit  131  to respond to the transfer, may result in one or more error cases, e.g., unrecoverable error cases. Such error cases may occur, for example if the communication link between PAL communication unit  130  and PAL communication unit  131  is lost, e.g., while the host is waiting for a response. 
     In some demonstrative embodiments, PAL communication unit  130  and/or PAL communication unit  131  may utilize a recovery mechanism, which may be configured to enable PAL communication unit  130  and/or PAL communication unit  131  to recover from the error cases, e.g., while maintaining the efficiency of the PAL transfer protocol. 
     In some demonstrative embodiments, PAL communication unit  131  may be configured to respond to an IN transfer request from PAL communication unit  130  with a transfer-pending status (error), for example, if the transfer request includes a “duplicate” request ID. The transfer request may include a “duplicate” request ID, for example, if the request ID of the transfer request is equal to a request ID, which is already being handled by PAL communication unit  131 , e.g., if the transfer request includes a request ID identical to a request ID of a previously received transfer request. 
     In some demonstrative embodiments, the transfer request may include a retry indicator (“flag”) having a first value, e.g., zero, to indicate that the transfer request is to be treated as a first request for the data block, or a second value, e.g., one, to indicate that the transfer request is to be treated as a retried request for the data block. 
     In some demonstrative embodiments, PAL communication unit  131  may transmit the transfer response including the transfer pending status indicating the requested data block is pending to be received from the endpoint, for example, regardless of whether the retry indicator of the transfer request represents a first request for the data block or a retried request for the data block. 
     For example, PAL communication unit  131  may be configured to transmit the transfer response including the transfer pending status indicating the requested data block is pending to be received from the endpoint, for example, if the transfer request includes the retry indicator (“flag”) having a first value (“the reset value”), e.g., zero, representing that the transfer request should be treated as a first request for the requested data block, or if the transfer request includes the retry indicator having a second value (“the set value”), e.g., one, representing that the transfer request should be treated as a retried request for the requested data block. 
     This configuration of PAL communication unit  131  may be different from an implementation, which allows PAL communication unit  131  to respond with a transfer-pending status only if the retry flag is set in the transfer request packet from the host. 
     In some demonstrative embodiments, PAL communication unit  130  may be configured to wait for a pre-determined wait period (“the long timeout”), e.g., upon receipt of a transfer response packet with transfer-pending status, before retransmitting the transfer request. 
     In some demonstrative embodiments, PAL communication unit  130  may be configured to retransmit the transfer request, e.g., upon completion of the predefined wait period. 
     In some demonstrative embodiments, the wait period may be set to be long enough, e.g., as not to have an impact on the efficiency of the PAL protocol between PAL communication units  130  and  131 , while allowing for PAL communication unit  130  to detect whether or not there has been any change in network conditions of the communication link between PAL communication units  130  and  131 . 
     In some demonstrative embodiments, PAL communication unit  130  may be configured to retransmit the transfer request including the retry flag at the reset value, e.g., the value zero, which may represent that the transfer request should be treated as a first request for the requested data block, for example, although the transfer request is being retransmitted. For example, PAL communication unit  130  may reset a retransmission counter of PAL communication unit  130  upon receiving the transfer response packet with transfer-pending status. 
     In some demonstrative embodiments, the retransmitted transfer request may be handled as a first (new) transfer request packet transmitted, e.g., as if there has not been any transfer-pending status detected earlier, for example, since the retry flag of the retransmitted transfer request may be set to the reset value. 
     In some demonstrative embodiments, this configuration of PAL communication unit  130  may be different from an implementation, which may require a PAL host not to take any action upon receiving the transfer response with the pending status, and/or to passively wait for PAL communication unit  131  to send the requested data block in a later transfer response. 
     In some demonstrative embodiments, PAL communication unit  131  may transmit to PAL communication unit  130  a transfer response including the requested data block, e.g., upon receiving the requested data block from the USB device. 
     In some demonstrative embodiments, PAL communication unit  130  and/or PAL communication unit  131  may be configured to implement an acknowledge (ACK) mechanism for acknowledging receipt of the requested data block at PAL communication unit  130 . 
     In some demonstrative embodiments, PAL communication unit  131  may require PAL communication unit  130  to acknowledge the receipt of the transfer response including the requested data block, for example, by setting an ACK-required indicator (flag) in the transfer response packet. 
     In some demonstrative embodiments, PAL communication unit  130  may acknowledge the receipt of the transfer response including the requested data block, for example, by responding to the transfer request with a transfer acknowledgement packet. 
     In some demonstrative embodiments, PAL communication unit  131  may retransmit the packet, e.g., for a pre-defined number of times, for example, if PAL communication unit  131  does note receive the ACK packet from PAL communication unit  130 . 
     In some demonstrative embodiments, configuring PAL communication unit  130  and/or PAL communication unit  131  to utilize the acknowledgement mechanism may be different from an implementation, which does not require PAL communication unit  130  to acknowledge the first transfer response packet following a transfer pending status, and/or does not allow PAL communication unit  131  to retransmit a transfer response. 
     Reference is made to  FIG. 2 , which schematically illustrates a sequence of communications between a WSE host  202 , a WSE device  204  and a USB device  206 , in accordance with some demonstrative embodiments. For example, PAL communication unit  130  ( FIG. 1 ) may perform the functionality of WSE host  202 , PAL communication unit  131  ( FIG. 1 ) may perform the functionality of WSE device  204 , and/or devices  162 ,  164 ,  166  and/or  168  ( FIG. 1 ) may perform the functionality of USB device  206 . 
     In some demonstrative embodiments, WSE host  202  may transmit to WSE device  204  a transfer request (TransferRequest) packet  208  including a request identifier (Request ID)  209  having a value, e.g., “Req ID  1 ”, identifying a requested data block to be transferred from USB device  206  to WSE host  202  via WSE device  204 . 
     In some demonstrative embodiments, the transfer request  208  may include a retry indicator  210 , e.g., a retry flag, for example, in the form of a bit (Retry bit), having either a first value, e.g., “0”, or a second value, e.g., “1”. For example, the retry bit may be set to the value “0” to represent a first request for transfer, e.g., in a first transmission of the transfer request, or a retried request, e.g., in a subsequent transmission of the transfer request. 
     In some demonstrative embodiments, WSE device  204  may send one or more requests  212  to USB device  206  for transferring the requested data block. 
     In some demonstrative embodiments, WSE device  204  may experience delay in receiving data from USB device  206 . For example, in some demonstrative embodiments, USB device  206  may respond to the USB requests with a NAK  214  indicating that the transfer of the requested data block is still pending. 
     In some demonstrative embodiments, WSE host  202  may retransmit the transfer request to WSE device  204 , e.g., after a predefined timeout period. For example, the retransmitted transfer request may include a duplicate Transfer Request packet for the same Request ID. For example, WSE host  202  may transmit a retransmitted transfer request  216  including the same request ID, “request ID  1 ”, as transfer request  208 . Retransmitted transfer request  216  may include the retry bit set to the value “1”, to indicate that the transfer request  216  is to be treated as a retried transfer request. 
     In some demonstrative embodiments, WSE device  204  may transmit to WSE host  202  a transfer response (TransferResp) packet  218 , e.g., in response to retransmitted packet  216 . 
     In some demonstrative embodiments, TransferResp packet  218  may include no payload. Packet  218  may include a transfer pending status (Transfer_Pending)  219  indicating that data is pending to be received from USB device  206 . 
     In some demonstrative embodiments, WSE device  204  may respond with Transfer Response packet  218  to a duplicate Transfer Request, e.g., transfer Request  216 , having the same Request ID as a previous Transfer Request, e.g., regardless of the value of the retry bit of the duplicate transfer request. 
     In some demonstrative embodiments, WSE host  202  may receive Transfer Response packet  218  having the transfer pending status  219 . WSE host  202  may reset a retransmission counter of WSE host, e.g., upon receiving Transfer Response packet  218  having the transfer pending status  219 . 
     In some demonstrative embodiments, WSE host  202  may wait for a predefined timeout period, e.g., a WSELongKeepAlive period, before attempting to retransmit the transfer request. 
     In some demonstrative embodiments, WSE host  202  may retransmit the transfer request  220  to WSE device  204 , e.g., after the predefined long timeout period. 
     In some demonstrative embodiments, retransmitted transfer request  220  may include the same request ID, “request ID  1 ”, as the first transfer request  208 , and may include the retry bit  220  set to the value zero. Setting the retry bit  222  to the value “zero” may indicate that the transfer request  220  is to be treated as a first transfer request, e.g., although the transfer request  220  is actually a retransmitted transfer request. 
     In some demonstrative embodiments, WSE device  204  may transmit to WSE host  202  a transfer response  224 , in response to the second retransmitted transfer request  220 . The transfer response  224  may include the transfer pending status code to indicate the transfer of the requested data block is still pending, e.g., although the second retransmitted transfer request  220  included the retry bit  222  set to the value zero, thereby indicating that the transfer request  220  is to be treated as a first transfer request. 
     In some demonstrative embodiments, WSE device  204  may receive the requested data block  226  from USB device  206 . 
     In some demonstrative embodiments, WSE device  204  may transmit to WSE host  202  a transfer response  228  including the requested data block and an acknowledgement (ACK) request (ARQ) indicator indicating that an ACK is required. For example, the ARQ may include an ARQ bit set to a first value, e.g., “1”, to indicate that an ACK is required. The ARQ bit may be set to a second value, e.g., “0”, to indicate that an ACK is not required. 
     In some demonstrative embodiments, a transfer response including data transmitted by WSE device  204  may include a retry indicator, e.g., the retry bit, having a first value, e.g., “0”, to indicate first transmission of the transfer response, or a second value, e.g., “1”, to indicate the transfer response is retransmitted. 
     In some demonstrative embodiments, a first transfer response carrying data and transmitted by WSE device  204  following a transfer request having the transfer pending status code may include the ARQ bit set to “1”. For example, the transfer response  228  may include the ARQ set to “1”. 
     In some demonstrative embodiments, WSE device  204  may retransmit transfer response message  228 , e.g., with the retry bit set to “1” and the ARQ bit set to “1”, for example, if WSE device  204  does not receive a transfer acknowledgement (TransferACK) response within a predefined time period, e.g., a WSETransferKeepAlive period, after transmitting transfer response  228 . 
     For example, as shown in  FIG. 2  WSE host  202  may not receive the transfer response  228  including the requested data block. WSE device  204  may retransmit to WSE device  202  a transfer response  230  including the requested data block, the acknowledge bit indicating that an ACK is required, and the retry bit indicating that the transfer response is retransmitted. 
     In some demonstrative embodiments, WSE device may repeat the retransmission of transfer response  230 , e.g., for a predefined number of times. 
     In some demonstrative embodiments, WSE host  202  may receive the retransmitted transfer response  230  including the requested data block. 
     In some demonstrative embodiments, WSE host  202  may transmit to WSE device  204  a transfer acknowledgement  232  to acknowledge receipt of the requested data block  230 . 
     Reference is made to  FIG. 3 , which schematically illustrates a method of controlling data flow, in accordance with some demonstrative embodiments. In some embodiments, one or more of the operations of the method of  FIG. 3  may be performed by a system, e.g., system  100  ( FIG. 1 ); a device, e.g., device  102  ( FIG. 1 ) and/or device  104  ( FIG. 1 ); a PAL communication unit, e.g., PAL communication unit  130  ( FIG. 1 ) and/or PAL communication unit  131  ( FIG. 1 ); a WSE host, e.g., WSE host  202  ( FIG. 2 ); and/or a WSE device, e.g., WSE device  204  ( FIG. 2 ). 
     As indicated at block  302 , the method may include communicating a transfer request over a communication link between a first device and a second device. For example, the transfer request may include a request for data to be transferred from the second device to the first device. For example, PAL communication unit  130  ( FIG. 1 ) may transmit to PAL communication unit  131  ( FIG. 1 ) a transfer request for data from EP  134 , EP  135 , EP  136 ,  138  and/or EP  140  ( FIG. 1 ), e.g., as described above. In one example, WSE host  202  ( FIG. 2 ) may transmit to WSE device  204  ( FIG. 2 ) a transfer request for transferring data from USB device  206  ( FIG. 2 ) to WSE host  202  ( FIG. 2 ), e.g., as described above. 
     As indicated at block  304 , the method may include, regardless of whether a retry indicator of the transfer request represents a first request or a retried request, communicating a transfer response in response to the transfer request, wherein the transfer response includes a transfer pending status indicating the data is pending to be received at the second device. For example, PAL communication unit  131  ( FIG. 1 ) may transmit the transfer response to PAL communication unit  130  ( FIG. 1 ), e.g., as described above. In one example, WSE device  204  ( FIG. 2 ) may transmit to WSE host  202  ( FIG. 2 ), transfer response  218  ( FIG. 2 ), e.g., in response to transfer request  216  ( FIG. 2 ) including the retry bit set to “1”; and transfer response  224  ( FIG. 2 ), e.g., in response to transfer request  220  ( FIG. 2 ) including the retry bit set to “0”. 
     As indicated at block  306 , the method may include resetting a retransmission counter, e.g., upon receiving the transfer response with the transfer pending status. For example, WSE host  202  ( FIG. 2 ) may reset a retransmission counter of WSE host  202  ( FIG. 2 ), e.g., upon receiving transfer response  218  ( FIG. 2 ), e.g., as described above. 
     As indicated at block  308 , the method may include communicating a retransmitted transfer request after waiting a predefined timeout period. For example, WSE host  202  ( FIG. 2 ) may retransmit transfer request  220  ( FIG. 2 ), e.g., after waiting a WSELongKeepAlive period, e.g., as described above. 
     As indicated at block  310 , the method may include communicating a transfer response, the transfer response including data requested by the transfer request, and an acknowledgement-request indicator requesting to acknowledge receipt of the transfer response including the data. The transfer response including the data may be transmitted from the WSE device to the WSE host, for example, upon receipt from the USB device, e.g., prior to communicating the retransmitted transfer request or after communicating the retransmitted transfer request one or more times. For example, PAL communication unit  131  ( FIG. 1 ) may transmit to PAL communication unit  130  ( FIG. 1 ) the transfer response including the requested data, e.g., as described above. In one example, WSE device  204  ( FIG. 2 ) may transmit to WSE host  202  ( FIG. 2 ) the Transfer Response  228  including the ARQ bit set to “1”, e.g., as described above. 
     As indicated at block  312 , the method may include retransmitting the transfer response including the data and a retry bit set to a predefined retransmit value, e.g., if a transfer acknowledgement response is not received within a predefined time period. The transfer response may be retransmitted for one or more times, e.g., if a transfer ACK is not received within a predefined period. For example, PAL communication unit  131  ( FIG. 1 ) may retransmit the transfer response including the data and the retry bit set to “1”, e.g., if the transfer acknowledgement response is not received from PAL communication unit  130  ( FIG. 1 ) within a predefined time period, e.g., as described above. In one example, WSE device  204  ( FIG. 2 ) may retransmit transfer response  230  ( FIG. 2 ) including the retry bit set to “1”, e.g., as described above. 
     As indicated at block  314 , the method may include communicating a transfer acknowledgement, in response to the transfer response including the data. For example, PAL communication unit  130  ( FIG. 1 ) may transmit to PAL communication unit  131  ( FIG. 1 ) and ACK message to acknowledged receipt of the transfer response including the requested data. In one example, WSE host  202  ( FIG. 2 ) may transmit TransferACK  232  ( FIG. 2 ) to WSE device  204  ( FIG. 2 ), e.g., as described above. 
     Reference is made to  FIG. 4 , which schematically illustrates a product of manufacture  400 , in accordance with some demonstrative embodiments. Product  400  may include a non-transitory machine-readable storage medium  402  to store logic  404 , which may be used, for example, to perform at least part of the functionality of device  102  ( FIG. 1 ), device  104  ( FIG. 1 ), PAL communication unit  130  ( FIG. 1 ), and/or PAL communication unit  131  ( FIG. 1 ), to perform one or more of the operations  FIG. 2 , and/or to perform one or more operations of the method of  FIG. 3 . The phrase “non-transitory machine-readable medium” is directed to include all computer-readable media, with the sole exception being a transitory propagating signal. 
     In some demonstrative embodiments, product  400  and/or machine-readable storage medium  402  may include one or more types of computer-readable storage media capable of storing data, including volatile memory, non-volatile memory, removable or non-removable memory, erasable or non-erasable memory, writeable or re-writeable memory, and the like. For example, machine-readable storage medium  402  may include, RAM, DRAM, Double-Data-Rate DRAM (DDR-DRAM), SDRAM, static RAM (SRAM), ROM, programmable ROM (PROM), erasable programmable ROM (EPROM), electrically erasable programmable ROM (EEPROM), Compact Disk ROM (CD-ROM), Compact Disk Recordable (CD-R), Compact Disk Rewriteable (CD-RW), flash memory (e.g., NOR or NAND flash memory), content addressable memory (CAM), polymer memory, phase-change memory, ferroelectric memory, silicon-oxide-nitride-oxide-silicon (SONOS) memory, a disk, a floppy disk, a hard drive, an optical disk, a magnetic disk, a card, a magnetic card, an optical card, a tape, a cassette, and the like. The computer-readable storage media may include any suitable media involved with downloading or transferring a computer program from a remote computer to a requesting computer carried by data signals embodied in a carrier wave or other propagation medium through a communication link, e.g., a modem, radio or network connection. 
     In some demonstrative embodiments, logic  404  may include instructions, data, and/or code, which, if executed by a machine, may cause the machine to perform a method, process and/or operations as described herein. The machine may include, for example, any suitable processing platform, computing platform, computing device, processing device, computing system, processing system, computer, processor, or the like, and may be implemented using any suitable combination of hardware, software, firmware, and the like. 
     In some demonstrative embodiments, logic  404  may include, or may be implemented as, software, a software module, an application, a program, a subroutine, instructions, an instruction set, computing code, words, values, symbols, and the like. The instructions may include any suitable type of code, such as source code, compiled code, interpreted code, executable code, static code, dynamic code, and the like. The instructions may be implemented according to a predefined computer language, manner or syntax, for instructing a processor to perform a certain function. The instructions may be implemented using any suitable high-level, low-level, object-oriented, visual, compiled and/or interpreted programming language, such as C, C++, Java, BASIC, Matlab, Pascal, Visual BASIC, assembly language, machine code, and the like. 
     EXAMPLES 
     The following examples pertain to further embodiments. 
     Example 1 is an apparatus comprising a communication unit to perform the functionality of a device selected from the group consisting of a first device and a second device, the second device is to transfer data from an endpoint to the first device over a communication link, wherein the communication unit is to communicate between the first and second devices a transfer response, the transfer response in response to a transfer request, the transfer response including a transfer pending status indicating data is pending to be received from the endpoint at the second device, the communication unit is to communicate the transfer response regardless of whether a retry indicator of the transfer request represents a first request for transfer or a retried request. 
     Example 2 includes the subject matter of Example 1 and optionally, wherein in response to the transfer request including the retry indicator set to a first value representing the retried request, the communication unit is to communicate the transfer response including the transfer pending status, and to communicate a subsequent transfer request including the retry indicator set to a second value, different from the first value, representing the first request for transfer. 
     Example 3 includes the subject matter of Example 2 and optionally, wherein the communication unit is to communicate the subsequent transfer request at least a predefined timeout period after the transfer response. 
     Example 4 includes the subject matter of any one of Examples 1-3 and optionally, wherein the communication unit is to perform the functionality of the first device, the communication unit is to transmit the transfer request, to receive the transfer response including the transfer pending status, to reset a retransmission counter, and to retransmit the transfer request after waiting a predefined timeout period. 
     Example 5 includes the subject matter of any one of Examples 1-3 and optionally, wherein the communication unit is to perform the functionality of the second device, the communication unit is to receive the transfer request including a duplicate transfer request of a previously received transfer request for a same request identifier, and to transmit the transfer response including the transfer pending status without a payload. 
     Example 6 includes the subject matter of any one of Examples 1-5 and optionally, wherein the communication unit is to communicate a subsequent transfer response including data requested by the transfer request, and an acknowledgement-request indicator requesting the first device to acknowledge receipt of the subsequent transfer response. 
     Example 7 includes the subject matter of Example 6 and optionally, wherein the subsequent transfer response comprises a first transfer response including data following the transfer response including the transfer pending status. 
     Example 8 includes the subject matter of Example 6 or 7 and optionally, wherein the communication unit is to communicate a transfer acknowledgement, in response to the subsequent transfer response. 
     Example 9 includes the subject matter of any one of Examples 6-8 and optionally, wherein the subsequent transfer response includes a retry indicator having a first value to indicate first transmission of the subsequent transfer response, or a second value to indicate the subsequent transfer response is retransmitted. 
     Example 10 includes the subject matter of any one of Examples 6-9 and optionally, wherein the communication unit is to perform the functionality of the second device, the communication unit is to transmit the subsequent transfer response, and to retransmit the subsequent transfer response including a retry bit set to a predefined retransmit value, if a transfer acknowledgement response is not received from the first device within a predefined time period. 
     Example 11 includes the subject matter of Example 1 and optionally, wherein the communication unit is to perform the functionality of the first device, the communication unit is to transmit the transfer request to the second device, and to receive the transfer response from the second device. 
     Example 12 includes the subject matter of Example 1 and optionally, wherein the communication unit is to perform the functionality of the second device, the communication unit is to receive the transfer request from the first device, and to transmit the transfer response to the first device. 
     Example 13 includes the subject matter of any one of Examples 1-12 and optionally, wherein the first device comprises a Universal Serial Bus (USB) host Protocol Adaptation Layer (PAL), and wherein the second device comprises a USB Device PAL. 
     Example 14 includes the subject matter of any one of Examples 1-13 and optionally, wherein the communication link comprises a wireless communication link. 
     Example 15 includes the subject matter of Example 14 and optionally, wherein the wireless communication link comprises a wireless gigabit (WiGig) link. 
     Example 16 includes the subject matter of any one of Examples 1-15 and optionally, wherein the first device comprises a wireless gigabit (WiGig) Serial Extension (WSE) host, and wherein the second device comprises a WSE Device. 
     Example 17 includes a communication system comprising a communication device comprising a network interface to communicate over a network; and a communication unit to perform the functionality of a first device or a second device, the second device is to transfer data to the first device over a communication link, wherein the communication unit is to communicate between the first and second devices a transfer response, the transfer response in response to a transfer request, the transfer response including a transfer pending status indicating data is pending to be received at the second device, the communication unit is to communicate the transfer response regardless of whether a retry indicator of the transfer request represents a first request for transfer or a retried request. 
     Example 18 includes the subject matter of Example 17 and optionally, wherein in response to the transfer request including the retry indicator set to a first value representing the retried request, the communication unit is to communicate the transfer response including the transfer pending status, and to communicate a subsequent transfer request including the retry indicator set to a second value, different from the first value, representing the first request for transfer. 
     Example 19 includes the subject matter of Example 18 and optionally, wherein the communication unit is to communicate the subsequent transfer request at least a predefined timeout period after the transfer response. 
     Example 20 includes the subject matter of any one of Examples 17-19 and optionally, wherein the communication unit is to perform the functionality of the first device, the communication unit is to transmit the transfer request, to receive the transfer response including the transfer pending status, to reset a retransmission counter, and to retransmit the transfer request after waiting a predefined timeout period. 
     Example 21 includes the subject matter of any one of Examples 17-19 and optionally, wherein the communication unit is to perform the functionality of the second device, the communication unit is to receive the transfer request including a duplicate transfer request of a previously received transfer request for a same request identifier, and to transmit the transfer response including the transfer pending status without a payload. 
     Example 22 includes the subject matter of any one of Examples 17-21 and optionally, wherein the communication unit is to communicate a subsequent transfer response including data requested by the transfer request, and an acknowledgement-request indicator requesting the first device to acknowledge receipt of the subsequent transfer response. 
     Example 23 includes the subject matter of Example 22 and optionally, wherein the subsequent transfer response comprises a first transfer response including data following the transfer response including the transfer pending status. 
     Example 24 includes the subject matter of Example 22 or 23 and optionally, wherein the communication unit is to communicate a transfer acknowledgement, in response to the subsequent transfer response. 
     Example 25 includes the subject matter of any one of Examples 22-24 and optionally, wherein the subsequent transfer response includes a retry indicator having a first value to indicate first transmission of the subsequent transfer response, or a second value to indicate the subsequent transfer response is retransmitted. 
     Example 26 includes the subject matter of any one of Examples 22-25 and optionally, wherein the communication unit is to perform the functionality of the second device, the communication unit is to transmit the subsequent transfer response, and to retransmit the subsequent transfer response including a retry bit set to a predefined retransmit value, if a transfer acknowledgement response is not received from the first device within a predefined time period. 
     Example 27 includes the subject matter of Example 17 and optionally, wherein the communication unit is to perform the functionality of the first device, the communication unit is to transmit the transfer request to the second device, and to receive the transfer response from the second device. 
     Example 28 includes the subject matter of Example 17 and optionally, wherein the communication unit is to perform the functionality of the second device, the communication unit is to receive the transfer request from the first device, and to transmit the transfer response to the first device. 
     Example 29 includes the subject matter of any one of Examples 17-28 and optionally, wherein the first device comprises a Universal Serial Bus (USB) host Protocol Adaptation Layer (PAL), and wherein the second device comprises a USB Device PAL. 
     Example 30 includes the subject matter of any one of Examples 17-29 and optionally, wherein the communication link comprises a wireless communication link. 
     Example 31 includes the subject matter of Example 30 and optionally, wherein the wireless communication link comprises a wireless gigabit (WiGig) link. 
     Example 32 includes the subject matter of any one of Examples 17-31 and optionally, wherein the first device comprises a wireless gigabit (WiGig) Serial Extension (WSE) host, and wherein the second device comprises a WSE Device. 
     Example 33 includes a system comprising a device comprising a network interface to communicate over a network; and a wireless gigabit (WiGig) Serial Extension (WSE) controller to perform the functionality of a WSE host or a WSE device to communicate Universal Serial Bus (USB) data between a USB device and a USB host over the network, the data including data to be delivered from the USB device to the USB host, wherein the WSE controller is to communicate between the WSE host and WSE device a transfer request, and to communicate a transfer response, the transfer response in response to the transfer request, the transfer response including a data payload from the USB device and an acknowledgement-request indicator requesting the WSE host to acknowledge receipt. 
     Example 34 includes the subject matter of Example 33 and optionally, wherein the WSE controller is to communicate a transfer acknowledgement, in response to the transfer response. 
     Example 35 includes the subject matter of Example 33 or 34 and optionally, wherein the transfer response includes a retry indicator having a first value to indicate first transmission of the transfer response, or a second value to indicate the transfer response is retransmitted. 
     Example 36 includes the subject matter of any one of Examples 33-35 and optionally, wherein the WSE controller is to perform the functionality of the WSE device, the WSE device is to transmit the transfer response, and to retransmit the transfer response including a retry bit set to a predefined retransmit value, if a transfer acknowledgement response is not received from the WSE host within a predefined time period. 
     Example 37 includes the subject matter of any one of Examples 33-35 and optionally, wherein the WSE controller is to perform the functionality of the WSE device, the WSE device is to transmit the transfer response to the WSE host. 
     Example 38 includes the subject matter of any one of Examples 33-35 and optionally, wherein the WSE controller is to perform the functionality of the WSE host, the WSE host is to receive the transfer response from the WSE device. 
     Example 39 includes the subject matter of any one of Examples 33-38 and optionally, wherein the communication link comprises a wireless communication link. 
     Example 40 include a communication method comprising communicating a transfer request over a communication link between a first device and a second device, the transfer request including a request for data from to be transferred from the second device to the first device; and communicating a transfer response, the transfer response in response to the transfer request, the transfer response including a transfer pending status indicating the data is pending to be received at the second device, wherein communicating the transfer response comprises communicating the transfer response regardless of whether a retry indicator of the transfer request represents a first request or a retried request. 
     Example 41 includes the subject matter of Example 40 and optionally, including in response to the transfer request including the retry indicator set to a first value representing the retried request, communicating the transfer response including the transfer pending status; and communicating a subsequent transfer request including the retry indicator set to a second value, different from the first value, representing the first request for transfer. 
     Example 42 includes the subject matter of Example 41 and optionally, comprising communicating the subsequent transfer request at least a predefined timeout period after the transfer response. 
     Example 43 includes the subject matter of any one of Examples 40-42 and optionally, comprising transmitting the transfer request, receiving the transfer response including the transfer pending status, resetting a retransmission counter, and retransmitting the transfer request after waiting a predefined timeout period. 
     Example 44 includes the subject matter of any one of Examples 40-42 and optionally, comprising receiving the transfer request including a duplicate transfer request of a previously received transfer request for a same request identifier, and transmitting the transfer response including the transfer pending status without a payload. 
     Example 45 includes the subject matter of any one of Examples 40-44 and optionally, comprising communicating a subsequent transfer response including data requested by the transfer request, and an acknowledgement-request indicator requesting the first device to acknowledge receipt of the subsequent transfer response. 
     Example 46 includes the subject matter of Example 45 and optionally, wherein the subsequent transfer response comprises a first transfer response including data following the transfer response including the transfer pending status. 
     Example 47 includes the subject matter of Example 45 or 46 and optionally, comprising communicating a transfer acknowledgement, in response to the subsequent transfer response. 
     Example 48 includes the subject matter of any one of Examples 45-47 and optionally, wherein the subsequent transfer response includes a retry indicator having a first value to indicate first transmission of the subsequent transfer response, or a second value to indicate the subsequent transfer response is retransmitted. 
     Example 49 includes the subject matter of any one of Examples 45-48 and optionally, comprising transmitting the subsequent transfer response, and retransmitting the subsequent transfer response including a retry bit set to a predefined retransmit value, if a transfer acknowledgement response is not received from the first device within a predefined time period. 
     Example 50 includes the subject matter of Example 40 and optionally, comprising transmitting the transfer request to the second device, and receiving the transfer response from the second device. 
     Example 51 includes the subject matter of Example 40 and optionally, comprising receiving the transfer request from the first device, and transmitting the transfer response to the first device. 
     Example 52 includes the subject matter of any one of Examples 40-51 and optionally, wherein the first device comprises a Universal Serial Bus (USB) host Protocol Adaptation Layer (PAL), and wherein the second device comprises a USB Device PAL. 
     Example 53 includes the subject matter of any one of Examples 40-52 and optionally, wherein the communication link comprises a wireless communication link. 
     Example 54 includes the subject matter of Example 53 and optionally, wherein the wireless communication link comprises a wireless gigabit (WiGig) link. 
     Example 55 includes the subject matter of any one of Examples 40-54 and optionally, wherein the first device comprises a wireless gigabit (WiGig) Serial Extension (WSE) host, and wherein the second device comprises a WSE Device. 
     Example 56 includes a product including a non-transitory storage medium having stored thereon instructions that, when executed by a machine, result in communicating a transfer request over a communication link between a first device and a second device, the transfer request to request data to be transferred from the second device to the first device; and communicating a transfer response, the transfer response in response to the transfer request, the transfer response including data and an acknowledgement request indicator requesting the first device to acknowledge receipt. 
     Example 57 includes the subject matter of Example 56 and optionally, wherein the instructions result in: in response to the transfer request including the retry indicator set to a first value representing the retried request, communicating the transfer response including the transfer pending status; and communicating a subsequent transfer request including the retry indicator set to a second value, different from the first value, representing the first request for transfer. 
     Example 58 includes the subject matter of Example 57 and optionally, wherein the instructions result in communicating the subsequent transfer request at least a predefined timeout period after the transfer response. 
     Example 59 includes the subject matter of any one of Examples 56-58 and optionally, wherein the instructions result in transmitting the transfer request, receiving the transfer response including the transfer pending status, resetting a retransmission counter, and retransmitting the transfer request after waiting a predefined timeout period. 
     Example 60 includes the subject matter of any one of Examples 56-58 and optionally, wherein the instructions result in receiving the transfer request including a duplicate transfer request of a previously received transfer request for a same request identifier, and transmitting the transfer response including the transfer pending status without a payload. 
     Example 61 includes the subject matter of any one of Examples 56-60 and optionally, wherein the instructions result in communicating a subsequent transfer response including data requested by the transfer request, and an acknowledgement-request indicator requesting the first device to acknowledge receipt of the subsequent transfer response. 
     Example 62 includes the subject matter of Example 61 and optionally, wherein the subsequent transfer response comprises a first transfer response including data following the transfer response including the transfer pending status. 
     Example 63 includes the subject matter of Example 61 or 62 and optionally, wherein the instructions result in communicating a transfer acknowledgement, in response to the subsequent transfer response. 
     Example 64 includes the subject matter of any one of Examples 61-63 and optionally, wherein the subsequent transfer response includes a retry indicator having a first value to indicate first transmission of the subsequent transfer response, or a second value to indicate the subsequent transfer response is retransmitted. 
     Example 65 includes the subject matter of any one of Examples 61-64 and optionally, wherein the instructions result in transmitting the subsequent transfer response, and retransmitting the subsequent transfer response including a retry bit set to a predefined retransmit value, if a transfer acknowledgement response is not received from the first device within a predefined time period. 
     Example 66 includes the subject matter of Example 56 and optionally, wherein the instructions result in transmitting the transfer request to the second device, and receiving the transfer response from the second device. 
     Example 67 includes the subject matter of Example 56 and optionally, wherein the instructions result in receiving the transfer request from the first device, and transmitting the transfer response to the first device. 
     Example 68 includes the subject matter of any one of Examples 56-67 and optionally, wherein the first device comprises a Universal Serial Bus (USB) host Protocol Adaptation Layer (PAL), and wherein the second device comprises a USB Device PAL. 
     Example 69 includes the subject matter of any one of Examples 56-68 and optionally, wherein the communication link comprises a wireless communication link. 
     Example 70 includes the subject matter of Example 69 and optionally, wherein the wireless communication link comprises a wireless gigabit (WiGig) link. 
     Example 71 includes the subject matter of any one of Examples 56-70 and optionally, wherein the first device comprises a wireless gigabit (WiGig) Serial Extension (WSE) host, and wherein the second device comprises a WSE Device. 
     Example 72 includes a communication apparatus comprising means for communicating a transfer request over a communication link between a first device and a second device, the transfer request to request data to be transferred from the second device to the first device; and means for communicating a transfer response, the transfer response in response to the transfer request, the transfer response including data and an acknowledgement request indicator requesting the first device to acknowledge receipt. 
     Example 73 includes the subject matter of Example 72 and optionally, wherein in response to the transfer request including the retry indicator set to a first value representing the retried request, the means for communicating the transfer response is to communicate the transfer response including the transfer pending status, and wherein the means for communicating the transfer request is to communicate a subsequent transfer request including the retry indicator set to a second value, different from the first value, representing the first request for transfer. 
     Example 74 includes the subject matter of Example 73 and optionally, wherein the means for communicating the transfer request is to communicate the subsequent transfer request at least a predefined timeout period after the transfer response. 
     Example 75 includes the subject matter of any one of Examples 72-74 and optionally, wherein the means for communicating the transfer request is to transmit the transfer request, the means for communicating the transfer response is to receive the transfer response including the transfer pending status, the apparatus comprising means for resetting a retransmission counter, and the means for communicating the transfer request is to retransmit the transfer request after waiting a predefined timeout period. 
     Example 76 includes the subject matter of any one of Examples 72-74 and optionally, wherein the means for communicating the transfer request is receive the transfer request including a duplicate transfer request of a previously received transfer request for a same request identifier, and the means for communicating the transfer response is to transmit the transfer response including the transfer pending status without a payload. 
     Example 77 includes the subject matter of any one of Examples 72-76 and optionally, comprising means for communicating a subsequent transfer response including data requested by the transfer request, and an acknowledgement-request indicator requesting the first device to acknowledge receipt of the subsequent transfer response. 
     Example 78 includes the subject matter of Example 77 and optionally, wherein the subsequent transfer response comprises a first transfer response including data following the transfer response including the transfer pending status. 
     Example 79 includes the subject matter of Example 77 or 78 and optionally, comprising means for communicating a transfer acknowledgement, in response to the subsequent transfer response. 
     Example 80 includes the subject matter of any one of Examples 77-79 and optionally, wherein the subsequent transfer response includes a retry indicator having a first value to indicate first transmission of the subsequent transfer response, or a second value to indicate the subsequent transfer response is retransmitted. 
     Example 81 includes the subject matter of any one of Examples 77-80 and optionally, comprising means for transmitting the subsequent transfer response, and retransmitting the subsequent transfer response including a retry bit set to a predefined retransmit value, if a transfer acknowledgement response is not received from the first device within a predefined time period. 
     Example 82 includes the subject matter of Example 72 and optionally, comprising means for transmitting the transfer request to the second device, and means for receiving the transfer response from the second device. 
     Example 83 includes the subject matter of Example 72 and optionally, comprising means for receiving the transfer request from the first device, and means for transmitting the transfer response to the first device. 
     Example 84 includes the subject matter of any one of Examples 72-83 and optionally, wherein the first device comprises a Universal Serial Bus (USB) host Protocol Adaptation Layer (PAL), and wherein the second device comprises a USB Device PAL. 
     Example 85 includes the subject matter of any one of Examples 72-84 and optionally, wherein the communication link comprises a wireless communication link. 
     Example 86 includes the subject matter of Example 85 and optionally, wherein the wireless communication link comprises a wireless gigabit (WiGig) link. 
     Example 87 includes the subject matter of any one of Examples 72-86 and optionally, wherein the first device comprises a wireless gigabit (WiGig) Serial Extension (WSE) host, and wherein the second device comprises a WSE Device. 
     Functions, operations, components and/or features described herein with reference to one or more embodiments, may be combined with, or may be utilized in combination with, one or more other functions, operations, components and/or features described herein with reference to one or more other embodiments, or vice versa. 
     While certain features have been illustrated and described herein, many variations, modifications, substitutions, changes, additions, improvements and equivalents may occur to those skilled in the art. It is, therefore, to be understood that the appended claims are intended to cover all such modifications and changes as fall within the true spirit of the invention.