Abstract: One example discloses a method for beamforming feedback reduction in a WLAN (wireless local area network), including: generating a per-tone beamforming feedback matrix by vectorizing a set of steering vectors using vectorization based dimension reduction (DR-Vec); performing lossy compression on the vectors; reducing the per-tone beamforming feedback matrix to one vector; and generating per-tone beamforming angle information using only the one vector.

Abstract: Non-flammable refrigerants with low GWP and secondary refrigerant systems including such refrigerants are provided. The refrigeration system may contain a high temperature refrigerant circuit with a first refrigerant and a low temperature refrigerant circuit with a second refrigerant, wherein the second refrigerant comprises a blend of R1234ze(Z), R1234ze(E), R1336mzz(E) and optionally R227ea, or a blend of R1234ze(Z) R1234ze(E) R1224yd(Z), and optionally R(227ea). The refrigerant fluids may have one of the following characteristics: (i) a global warming potential (GWP) of less than 150; (ii) an evaporator glide of less than 5.5° C.; (iii) non-flammability according to ASHRAE Standard 34; and/or (iv) a boiling point of less than 6° C.

Abstract: In an IEEE 802.11 wireless system, a sharing AP device (1A) shares a transmission opportunity with a shared AP device (2A) by transmitting a coordinated spatial reuse opportunity announcement control frame packet having defined signal fields which are used by the shared AP device (2A) to compute a transmit power limit for limiting interference at a first sharing STA device (1S) associated with the sharing AP device (1A) when transmitting one or more first downlink packets from the shared AP device (2A) to a first shared STA (2S) device associated with the shared AP device (2A).

Abstract: A transmitter, including: a plurality of antennas; and a controller configured to: receive a first steering matrix for a first feedback tone; receive a second steering matrix for a second feedback tone; estimate an ideal second steering matrix including: estimating a set of random phasors applied to the columns of the second feedback matrix; and estimating a set of row-dependent delays applied to the rows of the second feedback matrix; estimate a vector of angles based upon the estimated set of random phasors; and calculate a steering matrix for a tone between the first feedback tone and the second feedback tone by interpolating between the first steering matrix and the ideal second steering matrix based upon the estimated vector of angles.

Abstract: Low-flammability and low-GWP refrigerants based on mixtures of R-32, R-1132(E), and R-1234yf and uses thereof in air conditioning systems and methods in general and reversible heat pump systems and methods.

Abstract: Disclosed are cascaded refrigeration systems, comprising: a plurality of refrigeration units, each refrigeration unit containing a first refrigeration circuit, each first refrigeration circuit comprising an evaporator and a heat exchanger; and a second refrigeration circuit; wherein each first circuit heat exchanger is arranged to transfer heat energy between its respective first refrigeration circuit and the second refrigeration circuit.

Abstract: Embodiments of a method and an apparatus for wireless communications are disclosed. In an embodiment, a method for wireless communications involves generating a packet for transmission to a user, where generating the packet includes: encoding user signaling parameters and setting a station-identification (STA-ID) of the user to a value, where the signaling parameters include a number of space time streams (nSTS) spatial streams, establishing a dummy user without changing the user signaling parameters, setting a STA-ID of the dummy user to a value that is different from the STA-ID value of the user, indicating the nSTS spatial streams that are allocated to the dummy user and that are to include Long Training Field (LTF) symbols, and transmitting the packet to the user with the LTF symbols.

Abstract: The present invention provides cascade refrigeration systems in which the low stage consists essentially of R454A and the high stage comprises a refrigerant that is either Class A1 or Class A2L and comprises at least about 75% by weight of HFO-1234ze(E).

Abstract: A receiver receives a wireless signal comprising a plurality of fields including a legacy short training field (L-STF), legacy long training field (L-LTF), and legacy signal (L-SIG) field transmitted to a plurality of antenna of the receiver. For each sub-band in a receiver bandwidth and when samples of the L-STF is received, a first angle based autocorrelation is performed to determine a group of sub-bands which maximize a magnitude based on the first autocorrelations for one or more sub-bands. For each sub-band in the receiver bandwidth and when samples of the L-LTF is received, a second angle based autocorrelation is then performed to refine the crude bandwidth pattern estimate. One or more signal fields and one or more data fields of the received signal are decoded based on the refined bandwidth pattern estimate.

Abstract: Disclosed are methods of retrofitting heat transfer systems containing or designed to containing HFC-134a as the refrigerant comprising: removing at least a portion of said HFC-134a from said system; and introducing into said system a refrigerant comprising at least about 97.5% by weight of the following four components, with each compound being present in the following relative percentages: (a) from 2% to about 7% by weight of difluoromethane (HFC-32); (b) from 2% to about 7 by weight of pentafluoroethane (HFC-125); (c) from about 35% to about 50% by weight of 1,1,1,2-tetrafluoroethane (HFC-134a); and (d) from about 50% to about 55% by weight of trans-1,3,3,3-tetrafluoropropene (HFO-1234ze(E)).

Abstract: Methods for forming an improved refrigeration system comprising: (a) providing an existing refrigeration circuit comprising an existing refrigerant having a GWP of greater than 1200, a plurality of evaporators in a refrigerated space containing products accessible to consumers, a rack of compressors and at least one condenser located remotely from the areas accessible to consumers; (b) disconnecting the fluid connection between the existing liquid refrigerant from said condenser and said evaporators; (c) disconnecting the fluid connection between said existing refrigerant vapor from said evaporators in step (b) and said suction of said compressor or compressor rack; and (d) establishing a new first refrigeration circuit comprising the compressor rack and said condenser; (e) establishing a new second refrigeration circuit comprising at least one of the evaporators by steps comprising: (i) removing the existing refrigerant from the evaporators and at least a portion of said conduits which have been disconnected

Abstract: Cascaded refrigeration systems containing: a plurality of refrigeration units, each refrigeration unit containing a first refrigeration circuit, each first refrigeration circuit comprising an evaporator and a heat exchanger; and a second refrigeration circuit; wherein each first circuit heat exchanger is arranged to transfer heat energy between its respective first refrigeration circuit and the second refrigeration circuit.

Abstract: The present invention relates to a refrigerant composition, including difluoromethane (HFC-32), pentafluoroethane (HFC-125), and trifluoroiodomethane (CF3I) for use in a heat exchange system, including air conditioning and refrigeration applications and in particular aspects to the use of such compositions as a replacement of the refrigerant R-410A for heating and cooling applications and to retrofitting heat exchange systems, including systems designed for use with R-410A.

Abstract: A wireless network includes a client device and an access point (AP). The client device generates a data packet having a physical layer protocol data unit frame format. The client device transmits the data packet to the AP such that a plurality of long training fields (LTFs) of the data packet is transmitted at higher power as compared to a data field of the data packet, and a preamble portion of the data packet is transmitted at higher power as compared to the plurality of LTFs. Further, the data field includes various resource units (RUs) and one such RU is utilized for data transmission between the client device and the AP. The transmission of the data packet from the client device to the AP in the aforementioned manner results in the range extension of the wireless network.

Abstract: Method for retrofitting an existing heat transfer system comprising adding to said existing system a refrigerant consisting essentially of: (i) from about 25% to about 45% by weight of 1,1,1,2-tetrafluoroethane (HFC-134a); (ii) from 25% to about 35% by weight of trans-1,3,3,3-tetrafluoropropene (HFO-1234ze(E)) and/or 2,3,3,3-tetrafluoropropene (HFO-1234yf); and (iii) from about 37% to about 46% by weight of a combination of difluoromethane (HFC-32) and pentafluoroethane (HFC-125), provided that the weight ratio of HFO-32:HFC-125 is from about 1.21:1 to about 0.8:1, wherein the refrigerant preferably is a non-flammable refrigerant having a GWP of 1350 or less.

Abstract: One example discloses a method for beamforming feedback reduction in a WLAN (wireless local area network), including: generating a per-tone beamforming feedback matrix by vectorizing a set of steering vectors using vectorization based dimension reduction (DR-Vec); performing lossy compression on the vectors; reducing the per-tone beamforming feedback matrix to one vector; and generating per-tone beamforming angle information using only the one vector.

Abstract: Embodiments of an apparatus and method for wireless communications are disclosed. In an embodiment, a wireless device includes a controller configured to construct an orthogonal matrix, and a wireless transceiver configured to conduct wireless communications based on the orthogonal matrix. The size of the orthogonal matrix is 12×12 or 16×16.

Abstract: Refrigerant comprising from about 15% to about 22% by weight of R-32; from about 61% to about 71.5% by weight of HF0-1234yf; from about 4% to about 14.5% by weight of HFO-1132(E); and from 1% to 4% by weight of CO2.

Abstract: Refrigerant comprising from more than 84% to less than 91% by weight of HFO-1234yf; from more than 7% to less than 15% by weight of HFO-1132(E); and from more than 1% to 2.5% by weight of CO2.

Abstract: Novel non-flammable refrigerants having a GWP of less than 750 and containing R-32, R-125, R-134a and R-1234yf, and novel air conditioning systems (including heat pumps) which use such refrigerants, and method of retrofitting standard single refrigerant vapor compression air conditioning systems using said refrigerants, including especially residential heat pumps and residential split direct expansion air conditioning systems.