One embodiment of the disclosure relates to wireless digital networks, and in particular, to the problem of efficiently managing radio frequency (RF) resources and effectively sharing RF resources between two or more wireless network devices.
Network-device-to-network-device interference in wireless digital networks has been and remains to be one of the major bottlenecks that negatively affect the overall system capacity in dense deployments where wireless network devices are routinely ceiling-mounted.
The draft IEEE 802.11ac standard introduces wider 80-megahertz (MHz) and 160-MHz RF channels. While the 5-gigahertz (GHz) ISM band specified by the draft IEEE 802.11ac standard offers a higher total bandwidth than the 2.4 GHz frequency band, wider channels and utilization of the dynamic frequency selection (DFS) technique, as well as other regulatory restrictions mean the number of channels available in a particular deployment of a wireless digital network operating in accordance with the draft IEEE 802.11ac standard remains limited. Oftentimes, only 3 or 4 channels are available in such a deployment.
Therefore, the introduction of the draft IEEE 802.11ac standard does not by itself alleviate the problem of network-device-to-network-device interference. In either IEEE 802.11n networks or draft IEEE 802.11ac networks, it is inevitable that in dense deployments in both the 2.4 GHz and the 5 GHz bands, some wireless network devices will be within the interference and communication ranges of other wireless network devices operating on the same channel or on adjacent channels.
Techniques that address the network-device-to-network-device interference problem by adjusting transmit power of the wireless network devices are not always the best solution, as they may adversely affect the reliability of connections between wireless network devices and client devices.
Embodiments of the disclosure may best be understood by referring to the following description and accompanying drawings that are used to illustrate embodiments of the disclosure by way of example and not limitation. In the drawings, in which like reference numerals indicate similar elements:
In the following description, numerous specific details are set forth. However, it is understood that embodiments of the disclosure may be practiced without these specific details. In other instances, well-known circuits, structures and techniques have not been shown in detail in order not to obscure the understanding of this description.
Disclosed herein, one embodiment of the disclosure is directed to a system, apparatus, and method for RF management using device-to-device channel estimation and standard beamforming techniques. The exemplary method comprises: obtaining a first information corresponding to a first device that is a target device for transmitting at least one of a plurality of wireless signals by a network device; obtaining a second information corresponding to a second device that is to be avoided by propagation of any wireless signals transmitted by the network device; computing a radiation pattern for transmitting the plurality of wireless signals based at least on the first information associated with the first device and the second information associated with the second device; and transmitting the plurality of wireless signals based on the radiation pattern.
Further disclosed is an embodiment wherein subsequent to transmission, the plurality of wireless signals propagate to the first device at a first received signal strength that is above a first minimum strength and do not propagate to the second device at a signal strength that is above a second minimum strength.
Of course, other features and advantages of the disclosure will be apparent from the accompanying drawings and from the detailed description that follows below.
In the following description, certain terminology is used to describe features of the disclosure. For example, in certain situations, the term “logic” is representative of hardware, firmware and/or software that is configured to perform one or more functions. As hardware, logic may include circuitry having data processing or storage functionality. Examples of such circuitry may include, but is not limited or restricted to a microprocessor, one or more processor cores, a programmable gate array, a microcontroller, an application specific integrated circuit, wireless receiver, transmitter and/or transceiver circuitry, semiconductor memory, or combinatorial logic.
Logic may be software in the form of one or more software modules, such as executable code in the form of an executable application, an application programming interface (API), a subroutine, a function, a procedure, an applet, a servlet, a routine, source code, object code, a shared library/dynamic load library, or one or more instructions. These software modules may be stored in any type of suitable non-transitory storage medium, or transitory storage medium (e.g., electrical, optical, acoustical or other form of propagated signals such as carrier waves, infrared signals, or digital signals). Examples of non-transitory storage medium may include, but are not limited or restricted to a programmable circuit; a semiconductor memory; non-persistent storage such as volatile memory (e.g., any type of random access memory “RAM”); persistent storage such as non-volatile memory (e.g., read-only memory “ROM”, power-backed RAM, flash memory, phase-change memory, etc.), a solid-state drive, hard disk drive, an optical disc drive, or a portable memory device. As firmware, the executable code is stored in persistent storage.
The disclosure herein describes embodiments of the disclosure with reference to the IEEE 802.11n and the draft IEEE 802.11ac standards. However, the invention is not so limited and can be adapted for wireless digital networks operating under other standards within the spirit and scope of the embodiments disclosed herein.
Of course, it is contemplated that the invention is not so limited and a number of different combinations of supported IEEE 802.11 standards are possible, and embodiments of the disclosure require only that the wireless network devices 102 and 104 support at least one of the IEEE 802.11n and the draft IEEE 802.11ac standards. The wireless network devices 102 and 104 may operate on either one or both of the 2.4 GHz RF band and the 5 GHz RF band while operating in conformity with the IEEE 802.11n standard, and operate on the 5 GHz RF band only while operating in conformity with the draft IEEE 802.11ac standard.
Although in the wireless digital network 100 illustrated in
Moreover, although the wireless digital network 100 of
In the example shown in
The IEEE 802.11n standard allows up to four separate spatial streams, while the draft IEEE 802.11ac standard allows up to eight separate spatial streams. Each spatial stream may be transmitted through one or more transmit antennas. Therefore, the number of spatial streams supported by the wireless network device 102 is limited by the number of transmit antennas it is capable of driving. Moreover, some implementations of the wireless network device 102 may support fewer spatial streams than would be allowed by the number of transmit antennas present.
The description relating to antennas of the wireless network device 102 applies equally to antennas of the wireless network device 104 and at least some of the other wireless network devices possibly present in the wireless digital network 100. The wireless digital network 100 may also contain wireless network devices capable of driving only one transmit antenna. However, exemplary methods described herein may be utilized only by wireless network devices capable of driving at least two transmit antennas.
Herein, client devices 122, 124, and 126 may be any electronic devices capable of accessing wireless digital networks operating in accordance with one or more standards in the IEEE 802.11 family of standards. Examples include laptops, cellphones, tablets, game consoles, smart TVs, set-top boxes, etc.
Referring now to
Processor 140 is further coupled to persistent storage 160 via transmission medium 165. According to one embodiment of the disclosure, persistent storage 160 may include channel estimation logic 170, RF management logic 180, beamforming logic 190, and radio driving logic 195. Of course, when implemented as hardware, channel estimation logic 170, RF management logic 180, beamforming logic 190, and radio driving logic 195 would be implemented separately from persistent memory 160.
Wireless network device 104 and other wireless network devices in the wireless digital network 100 are associated with the same or similar logic as is shown in
The IEEE 802.11n standard includes the technique of transmit beamforming (TxBF) for use in transmitting data between a wireless network device and a single client device at a time, and the draft IEEE 802.11ac standard specifies the technique of downlink multi-user multiple-input multiple-output (MU-MIMO), through the use of which a wireless network device can transmit separate data on separate spatial streams to multiple client devices simultaneously. The draft IEEE 802.11ac standard utilizes the beamforming technique at the wireless network device in the MU-MIMO mode to minimize interference among spatial streams intended for different client devices.
Embodiments of the disclosure are practiced in the context of the beamforming technique. Beamforming allows a transmitting device with more than one transmit antenna to steer RF signal power maxima onto a receiving device using Digital Signal Processing techniques, enabling higher data rates and/or lower error rates. This is achieved by carefully controlling the phase of the signal transmitted from multiple antennas to optimize the overall radiation pattern of the beamformed signal. Moreover, the beamforming technique also allows a transmitting device with more than one transmit antenna to steer RF signal power minima (i.e., nulls) onto a device using Digital Signal Processing techniques to minimize interference to the device.
An estimate at the beamformer of RF conditions between transmit antennas at the beamformer and receive antennas at the beamformee, such as the channel state, for example, is utilized to derive one or more steering matrices. The steering matrices are used to weight streams of data transmitted through the multiple transmit antennas to generate beamformed RF signals.
Conventionally, a wireless network device utilizes the beamforming technique to steer signal power maxima onto client devices for which the signal is intended, and in some instances also to steer signal power minima onto client devices for which the signal is not intended. Embodiments of the disclosure adapt the conventional beamforming technique such that a wireless network device steers signal minima onto other wireless network devices to actively minimize interference to other wireless network devices.
It is also contemplated that in a similar fashion, a wireless network device may steer signal minima onto client devices associated with other wireless network devices to minimize interference to such client devices. All the references to “other wireless network devices” herein may also include unassociated client devices, where applicable.
Embodiments of the disclosure are described herein as exemplary methods with reference to the wireless network device 102 as the beamformer and the wireless network device 104 as the beamformee. A skilled artisan, however, should recognize that the example methods are equally applicable to other wireless network devices in the wireless digital network 100 as either beamformers or beamformees and are fully reciprocal with the sole exception that a wireless network device capable of driving only one transmit antenna cannot operate as a beamformer. In other words, according to one embodiment of the disclosure, each and every wireless network device meeting the criteria in the digital wireless network 100 utilizes the exemplary methods described herein and steers signal minima onto one or more of the other wireless network devices so that interference among wireless network devices across the whole wireless digital network 100 is minimized.
Referring to
At operation 220, the wireless network device 102 receives the channel state information from other wireless network devices within interference and communication ranges operating on the same or adjacent channels. These other wireless network devices may include two or more wireless network devices or a single wireless network device such as wireless network device 104. The channel state information may be received directly from other wireless network devices or may be exchanged through an external controller.
In one embodiment, the channel state information is transmitted among wireless network devices over a wired interface to avoid unnecessary over-the-air overhead. The frequency at which the channel state information is transmitted or exchanged may be selected strategically, and may be different from the frequency at which the data frame transmission of operation 210 is performed. In one embodiment, both frequencies are dynamically adjusted at runtime based on changes in the channel matrix or other configured parameters.
It should be appreciated that the channel state information for the RF link from the wireless network device 102 to another wireless network device (e.g., wireless network device 104) transmitted at operation 220 is derived at said another wireless network device (e.g., wireless network device 104) after said another wireless network device (e.g., wireless network device 104) has received and analyzed the frames for channel state estimation transmitted by the wireless network device 102 at operation 210. Because the exemplary methods described herein are fully reciprocal, it should be further appreciated that the wireless network device 102 during operations 210 and 220 may simultaneously also be engaged in receiving frames for channel state estimation from other wireless network devices, including wireless network device 104, generating channel state information for RF links from other wireless network devices to the wireless network device 102, and transmitting channel state information to other wireless network devices, including the wireless network device 104.
In one embodiment, the wireless network device 102 associates as a client to another wireless network device (e.g., the wireless network device 104) in order to solicit and collect channel state information utilizing mechanisms specified in IEEE 802.11 standards.
In the embodiments where a client device associated with a wireless network device other than the wireless network device 102 is to be avoided by the wireless network device 102, the wireless network device 102 may obtain the channel state information by listening to frames transmitted by the client device and estimating the channel, or by using either the implicit feedback method or the explicit feedback method specified in the IEEE 802.11 standards. If the explicit feedback method is to be used, the wireless network device 102 may spoof the wireless network device with which the client device is associated and send a sounding frame directly to the client device in order to obtain the channel state information for the RF channel from the wireless network device 102 to the client device to be avoided.
Next, at operation 230, the wireless network device 102 selects one or more of the other wireless network devices for nullification or receives a list of selected wireless network devices for nullification from an external controller. These wireless network devices selected for nullification may include two or more wireless network devices or a single wireless network device such as wireless network device 104. The wireless network device 102 can nullify one or more of the other wireless network devices (e.g., wireless network device 104) by steering RF signal power minima onto the one or more of the other wireless network devices. The maximum number of the other wireless network devices that the wireless network device 102 can nullify is limited by the particular hardware and/or software implementation of the wireless network device 102.
Due to constraints on the number of wireless network devices that the wireless network device 102 can nullify, an RF management logic is utilized to select the one or more of the other wireless network devices to be nullified based on RF management criteria. In one embodiment, the wireless network device 102 executes the RF management logic and selects the one or more wireless network devices to be nullified; in another embodiment, the RF management logic is executed on an external controller to determine which of the other wireless network devices is to be nullified for each of the wireless network devices in the wireless digital network 100, and the wireless network device 102 receives a list of the selection for itself from the external controller.
Next, at operation 240, the wireless network device 102 calculates one or more null-steering matrices. A null-steering matrix is a steering matrix, which, when applied to a data frame under transmission, steers signal power minima (i.e., nulls) onto a null-beamformee (e.g., the wireless device 104) to nullify the null-beamformee so that interference to the null-beamformee caused by the wireless network device 102 is minimized. According to embodiments of the disclosure, null-beamformees are one or more of the other wireless network devices in the wireless digital network 100. One null-steering matrix is calculated for every wireless network device to be nullified by the wireless network device 102. As described above, it is contemplated that client devices not associated with the wireless network device 102 may also be null-beamformees so that interference to these client devices caused by the wireless network device 102 is minimized.
Last, at operation 250, the wireless network device 102 applies one or more null-steering matrices to its RF transmissions to nullify one or more of the other wireless network devices (e.g., the wireless network device 104). The one or more null-steering matrices are applied to all transmissions, including but not limited to beacons, probe responses, and other unicast frames including control frames, to all client devices such that signal power minima are always steered onto the one or more of the other wireless network devices selected at operation 230 for nullification.
The null-steering matrices may be applied with or without the standard TxBF or MU-MIMO techniques. It should be appreciated that applying the one or more null-steering matrices to all transmissions is equivalent to creating a default radiation pattern with the beamforming technique such that interference between wireless network devices is minimized. When the exemplary methods described herein is combined with the standard TxBF or MU-MIMO techniques, signal maxima are steered onto intended client devices to increase performance, while signal minima are steered onto one or more of the other wireless network devices such that interference between wireless network devices is minimized.
A skilled artisan would recognize that with beamformed radiation patterns, the null-beamformee(s) may be physically closer to the beamformer than a device onto which signal maxima are steered by the beamformer. It is also possible that a null-beamformee is physically situated between two devices onto which signal maxima are steered. Description herein regarding physical locations of the null-beamformee(s) is illustrative, and does not limit the invention in any way.
Utilizing embodiments of the disclosure described herein allows for increased overall system capacity of a wireless digital network and denser deployments of wireless network devices without adverse impacts on reliability of connections because the RF transmit power need not be reduced. Moreover, embodiments of the disclosure described herein may be combined with receiver cancellation techniques to further reduce interference between wireless network devices.
While the invention has been described in terms of various embodiments, the invention should not be limited to only those embodiments described, but can be practiced with modification and alteration within the spirit and scope of the appended claims. The description is to be regarded as illustrative rather than limiting.
Number | Name | Date | Kind |
---|---|---|---|
4012740 | Lenneper | Mar 1977 | A |
7039013 | Ruutu | May 2006 | B2 |
7433322 | Alapuranen | Oct 2008 | B1 |
7848444 | Yamaura | Dec 2010 | B2 |
8111782 | Kim | Feb 2012 | B2 |
8332216 | Kurniawati | Dec 2012 | B2 |
8396162 | Thomas | Mar 2013 | B2 |
8406332 | Bayesteh | Mar 2013 | B2 |
8542776 | Kim | Sep 2013 | B2 |
8885453 | Stager | Nov 2014 | B2 |
8976761 | Stager | Mar 2015 | B2 |
9123986 | Shamblin | Sep 2015 | B2 |
9241275 | Kloper | Jan 2016 | B2 |
9444577 | Zhang | Sep 2016 | B1 |
9571316 | Kim | Feb 2017 | B2 |
20040114546 | Seshadri et al. | Jun 2004 | A1 |
20070117590 | Aldana | May 2007 | A1 |
20070206504 | Koo | Sep 2007 | A1 |
20070286303 | Yamaura | Dec 2007 | A1 |
20080056414 | Kim | Mar 2008 | A1 |
20080075033 | Shattil | Mar 2008 | A1 |
20080273618 | Forenza et al. | Nov 2008 | A1 |
20090135754 | Yavuz | May 2009 | A1 |
20090137221 | Nanda | May 2009 | A1 |
20100111223 | Thomas | May 2010 | A1 |
20100124212 | Lo | May 2010 | A1 |
20110032173 | Chang | Feb 2011 | A1 |
20110176629 | Bayesteh | Jul 2011 | A1 |
20110205968 | Kim | Aug 2011 | A1 |
20110273977 | Shapira | Nov 2011 | A1 |
20120114028 | Davydov | May 2012 | A1 |
20120170674 | Kim | Jul 2012 | A1 |
20120202431 | Hawryluck et al. | Aug 2012 | A1 |
20120213300 | Yamaura | Aug 2012 | A1 |
20120231739 | Chen | Sep 2012 | A1 |
20120315938 | Van Nee | Dec 2012 | A1 |
20140062784 | Rison | Mar 2014 | A1 |
20140093005 | Xia | Apr 2014 | A1 |
20140098681 | Stager | Apr 2014 | A1 |
20140334473 | Zhang et al. | Nov 2014 | A1 |
20150030094 | Zhang | Jan 2015 | A1 |
20150084744 | Havens | Mar 2015 | A1 |
20150117324 | Ponnuswamy | Apr 2015 | A1 |
20150131593 | Stager | May 2015 | A1 |
20150155623 | Shamblin | Jun 2015 | A1 |
20150244430 | Shattil | Aug 2015 | A1 |
20150270882 | Shattil | Sep 2015 | A1 |
20150282144 | Tomeba | Oct 2015 | A1 |
20150289155 | Gao | Oct 2015 | A1 |
20150318878 | Damodaran | Nov 2015 | A1 |
20150350942 | Wei | Dec 2015 | A1 |
20160006595 | Mueller | Jan 2016 | A1 |
20160119049 | Cui | Apr 2016 | A1 |
20160127024 | Morita | May 2016 | A1 |
20160142117 | Rahman | May 2016 | A1 |
20160182135 | Onodera | Jun 2016 | A1 |
20160268676 | Chang | Sep 2016 | A1 |
20160294589 | Kim | Oct 2016 | A1 |
20160373230 | Morita | Dec 2016 | A1 |
20160373939 | Buskgaard | Dec 2016 | A1 |
Entry |
---|
Dawod et al., Improved Transmit Null Steering for MIMO-OFDM Downlinks With Distributed Base Station Antenna Arrays, Mar. 2006, IEEE Journal on Selected Areas in Communications, vol. 24 No. 3, pp. 419-426. |
Qamar et al., Null Steering, A Comparative Analysis, Dec. 15, 2009, IEEE 13th International Multitopic Conference, pp. 1-5. |
Hakkarainen et al., RF-Aware Widely-Linear Beamforming and Null-Steering in Cognitive Radio Transmitters, Jul. 10, 2013, 2013 8th International Conference on Cognitive Radio Oriented Wireless Networks (CROWNCOM), pp. 172-177. |
Number | Date | Country | |
---|---|---|---|
20150117324 A1 | Apr 2015 | US |