US20080310336A1

US20080310336A1 - Dynamic receiver filter adjustment across preamble and information payload

Info

Publication number: US20080310336A1
Application number: US12/213,176
Authority: US
Inventors: Rohit V. Gaikwad
Original assignee: Broadcom Corp
Current assignee: Avago Technologies International Sales Pte Ltd
Priority date: 2007-06-15
Filing date: 2008-06-16
Publication date: 2008-12-18
Also published as: US20140133609A1; US20080310559A1; US8194808B2; US20120238229A1; US8634501B2; US9112481B2; US20080310557A1; US8116408B2

Abstract

A method and apparatus is disclosed to dynamically select among two or more receiver filter bandwidths to more closely approximate a bandwidth of a corresponding signal field included in a received communications signal. A communications transmitter may transmit a transmitted communication signal in at least one formatted blocks of data or packets. Each one of the at least one formatted blocks of data or packets include at least one single stream signal field such as, but not limited to, a single stream preamble, a single stream signal field, and/or a single stream single stream information payload in accordance with the known single stream communications standard and/or at least one multiple stream signal field such as, but not limited to, a multiple stream preamble, a multiple stream signal field, and/or a multiple stream multiple stream information payload in accordance with the known multiple stream communications standard. The communications receiver may include one or more receiver filters to select among one or more receiver filter bandwidths to filter the at least one single stream signal field and/or the at least one multiple stream signal field.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application claims the benefit of: U.S. Provisional Patent Appl. No. 60/929,154, filed Jun. 15, 2007, entitled “Carrier Selection for Multiple Antennas”; U.S. Provisional Patent Appl. No. 60/929,155, filed Jun. 15, 2007, entitled “Dynamic Receiver Filter Adjustment Across Preamble and Information Payload”; U.S. Provisional Patent Appl. No. 60/929,156, filed Jun. 15, 2007, entitled “Adjacent Channel Interference (ACI) Detection”; U.S. Provisional Patent Appl. No. 60/960,706, filed Oct. 10, 2007, entitled “Gain Control for Reduced Interframe Spacing (RIFS),” each of which is incorporated by reference herein in its entirety.
The present application is related to: U.S. Provisional Patent Appl. No. 60/929,149, filed Jun. 15, 2007, entitled “Spur Avoidance Via Static Changes to PHY Clock Frequency”; U.S. Provisional Patent Appl. No. 60/960,384, filed Sep. 27, 2007, entitled “Guard Interval Cyclic Filtering for Short Guard Interval (GI)”; U.S. patent application Ser. No. 12/004,406, filed Dec. 21, 2007, entitled “Single-Chip Wireless Transceiver”; U.S. patent application Ser. No. ______ (SKGF Ref No. 2875.1600001), filed Jun. 16, 2008, entitled “Carrier Selection for Multiple Antennas”; U.S. patent application Ser. ______ No. (SKGF Ref No. 2875.1930001), filed Jun. 16, 2008, entitled “Gain Control for Reduced Interframe Spacing (RIFS)”; and U.S. patent application Ser. No. ______ (SKGF Ref No. 2875.2510000), filed Jun. 16, 2008, entitled “Apparatus to Reconfigure an 802.11a/n Transceiver to Support 802.11j/10 MHz Mode of Operation,” each of which is incorporated by reference herein in its entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention
The present invention relates generally to a communications receiver, more specifically selecting among two or more receiver filter bandwidths to a bandwidth of a corresponding signal field included in a received communications signal.
2. Related Art
A communication system typically involves transmitting an information signal as a communications signal from a communications transmitter to a communications receiver over a communication channel. The communications transmitter may include a single transmit antenna to produce a single stream communications signal or multiple transmit antenna to produce a multiple stream communications signal.
The communication receiver may include multiple receive antenna to receive the communications signal as it traverses through the communication channel. Commonly, the communication receiver includes at least one conventional receiver filter to filter a received communication signal prior to processing the received communications signal according to a known single stream communications standard, such as, but not limited to, the Institute of Electrical and Electronics Engineers (IEEE) 802.11a™ standard, the IEEE 802.11b™ standard, the IEEE 802.11g™ standard, or a known multiple stream communications standard, such as, but not limited to, the IEEE 802.11n™ standard, but not both. The IEEE 802.11a™ standard, the IEEE 802.11b™ standard, the IEEE 802.11g™, and the IEEE 802.11n™ standard are incorporated by reference herein in their entirety.
A conventional receiver filter typically includes a conventional receiver filter bandwidth having a single or individual receiver filter bandwidth. The conventional receiver filter filters the received communications signal in its entirety using the conventional receiver filter bandwidth. However, the received communications signal includes one or more signal fields that have a bandwidth substantially less than or equal to the conventional receiver filter bandwidth. As a result, using the conventional receiver filter to filter these one or more signal fields results in a degradation of a signal to noise ratio (SNR).
Therefore, what is needed is a receiver filter that is capable of selecting among two or more one receiver filter bandwidths to more closely approximate a bandwidth of a corresponding signal field included in the received communications signal

BRIEF DESCRIPTION OF THE DRAWINGS/FIGURES

The accompanying drawings illustrate the present invention and, together with the description, further serve to explain the principles of the invention and to enable one skilled in the pertinent art to make and use the invention.

FIG. 1A illustrates a block diagram of a communications environment according to an exemplary embodiment of the present invention.

FIG. 1B illustrates a block diagram of another communications environment according to another exemplary embodiment of the present invention.

FIG. 2 illustrates a block diagram of a communications receiver according to an exemplary embodiment of the present invention.

FIG. 3 illustrates a block diagram of a physical layer interface (PHY) according to an exemplary embodiment of the present invention.

FIG. 4 illustrates a block diagram of a radio receiver according to an exemplary embodiment of the present invention.

FIG. 5A illustrates a single stream communications packet according to the known single stream communications standard.

FIG. 5B illustrates a frequency domain representation of the single stream communications packet encoded in accordance with the IEEE 802.11a™ standard.

FIG. 6A illustrates a multiple stream communications packet according to the known multiple stream communications standard.

FIG. 6B illustrates a frequency domain representation of the multiple stream communications packet encoded in accordance with the IEEE 802.11n™ standard.

FIG. 7A illustrates a receiver filter according to an exemplary embodiment of the present invention.

FIG. 7B illustrates a frequency domain representation of the receiver filter according to an exemplary embodiment of the present invention.

FIG. 8 is a flowchart of exemplary operational steps of a communications environment according to an aspect of the present invention.

FIG. 9 is a flowchart of exemplary operational steps of a communications receiver according to an aspect of the present invention.

FIG. 10 is a flowchart of exemplary operational steps of the receiver filter according to an exemplary embodiment of the present invention.

The present invention will now be described with reference to the accompanying drawings. In the drawings, like reference numbers generally indicate identical, functionally similar, and/or structurally similar elements. The drawing in which an element first appears is indicated by the leftmost digit(s) in the reference number.

DETAILED DESCRIPTION OF THE INVENTION

The following detailed description of the present invention refers to the accompanying drawings that illustrate exemplary embodiments consistent with this invention. Other exemplary embodiments are possible, and modifications may be made to the exemplary embodiments within the spirit and scope of the invention. Therefore, the detailed description is not meant to limit the invention. Rather, the scope of the invention is defined by the appended claims.
References in the specification to “one exemplary embodiment,” “an exemplary embodiment,” “an example exemplary embodiment,” etc., indicate that the exemplary embodiment described may include a particular feature, structure, or characteristic, but every exemplary embodiment may not necessarily include the particular feature, structure, or characteristic. Moreover, such phrases are not necessarily referring to the same exemplary embodiment. Further, when a particular feature, structure, or characteristic is described in connection with an exemplary embodiment, it is submitted that it is within the knowledge of one skilled in the art to effect such feature, structure, or characteristic in connection with other exemplary embodiments whether or not explicitly described.
Furthermore, it should be understood that spatial descriptions (e.g., “above,” “below,” “up,” “left,” “right,” “down,” “top,” “vertical,” “horizontal,” etc.) used herein are for purposes of illustration only, and that practical implementations of the structures described herein may be spatially arranged in any orientation or manner. Likewise, particular bit values of “0” or “1” (and representative voltage values) are used in illustrative examples provided herein to represent information for purposes of illustration only. Information described herein may be represented by either bit value (and by alternative voltage values), and exemplary embodiments described herein may be configured to operate on either bit value (and any representative voltage value), as would be understood by persons skilled in the relevant art(s).
The example exemplary embodiments described herein are provided for illustrative purposes, and are not limiting. Further structural and operational exemplary embodiments, including modifications/alterations, will become apparent to persons skilled in the relevant art(s) from the teachings herein.

Exemplary Communications Environments

FIG. 1A illustrates a block diagram of a communications environment according to an exemplary embodiment of the present invention. A communications environment 100 is an exemplary representation of a single-input and multiple-output (SIMO) communications environment that includes the use of a single transmit antenna at a communications transmitter 102 and multiple receive antennas at a communications receiver 106. The communications environment 100 includes a communications transmitter 102 to transmit at least one information signal as received from at least one transmitter user device, denoted as information signals 150.1 through 150.K, to the communications receiver 106 via a communication channel 104. The transmitter user devices may include, but are not limited to, personal computers, data terminal equipment, telephony devices, broadband media players, personal digital assistants, software applications, or any other medium capable of transmitting or receiving data. However, those skilled in the relevant art(s) will recognize that the information signals 150.1 through 150.K may include a single information signal, such as the information signal 150.1 to provide an example, without departing from the spirit and scope of the present invention.
The communications transmitter 102 produces a transmitted communications signal 152 by encoding the information signals 150.1 through 150.K according to a known single stream communications standard, such as, but not limited to, the Institute of Electrical and Electronics Engineers (IEEE) 802.11a™ standard, the IEEE 802.11b™ standard, the IEEE 802.11g™ standard, and/or any other suitable single stream communications standard. The IEEE 802.11a™ standard, the IEEE 802.11b™ standard, and the IEEE 802.11g™ standard are incorporated herein by reference in their entirety. As shown in FIG. 1A, the transmitted communications signal 152 represents a single stream communication signal. In other words, the communications transmitter 102 may encode the information signals 150.1 through 150.K to produce the transmitted communications signal 152.
The transmitted communications signal 152 passes through the communication channel 104 to produce received communication signals 154.1 through 154.N. The communication channel 104 may include, but is not limited to, a microwave radio link, a satellite channel, a fiber optic cable, a hybrid fiber optic cable system, or a copper cable to provide some examples. The communication channel 104 contains a propagation medium that the transmitted communications signal 152 passes through before reception by the communications receiver 106. The propagation medium of the communication channel 104 introduces interference and/or distortion into the transmitted communications signal 152 to produce received communication signals 154.1 through 154.N. For example, noise such as, but not limited to, thermal noise, burst noise, impulse noise, interference, signal strength variations known as fading, phase shift variations, to provide some examples, may introduce interference and/or distortion into the transmitted communications signal 152. In addition, the propagation medium of the communication channel 104 may cause the transmitted communications signal 152 to reach the communications receiver 106 by multiple communication paths, reflecting from different objects, surface areas, surface boundaries, and interfaces in the communications environment 100. Potential causes of multipath propagation may include, but are not limited, to atmospheric ducting, ionospheric reflection and/or refraction, and/or reflection from terrestrial objects such as mountains and/or buildings to provide some examples.
The communications receiver 106 may include at least one receiving antenna to capture the received communication signals 154.1 through 154.N. In an exemplary embodiment, the communications receiver 106 includes two receiving antenna to capture the received communication signals 154.1 through 154.2. The received communication signals 154.1 through 154.N represent the multiple communication paths traversed by the transmitted communications signal 152 resulting from the multipath propagation introduced by the communication channel 104. For example, the received communications signal 154.1 represents the transmitted communications signal 152 as it traverses through a first communication path of the communication channel 104. Likewise, the received communications signal 154.N represents the transmitted communications signal 152 as it traverses through an N^thcommunication path of the communication channel 104. The communications receiver 106 may recover the at least one information signal from the at least one transmitter user device to produce at least one recovered information signal, denoted as recovered information signals 156.1 through 156.K, for at least one receiver user device by operating upon the received communication signals 154.1 through 154.N according to the known single stream communications standard. The receiver user devices may include, but are not limited to, personal computers, data terminal equipment, telephony devices, broadband media players, personal digital assistants, software applications, or any other medium capable of transmitting or receiving data. However, those skilled in the relevant art(s) will recognize that the recovered information signals 156.1 through 156.K may include a single recovered information signal, such as the recovered information signal 156.1 to provide an example, without departing from the spirit and scope of the present invention.
FIG. 1B illustrates a block diagram of another communications environment according to another exemplary embodiment of the present invention. A communications environment 120 is an exemplary representation of a multiple-input and multiple-output (MIMO) communications environment that includes the use of multiple transmit antennas at a communications transmitter 108 and multiple receive antennas at the communications receiver 106. The communications environment 120 includes the communications transmitter 108 to transmit at least one information signal as received from at least one transmitter user device, denoted as information signals 160.1 through 160.K, to the communications receiver 106 via a communication channel 104. The transmitter user devices may include, but are not limited to, personal computers, data terminal equipment, telephony devices, broadband media players, personal digital assistants, software applications, or any other medium capable of transmitting or receiving data. However, those skilled in the relevant art(s) will recognize that the information signals 160.1 through 160.K may include a single information signal, such as the information signal 160.1, without departing from the spirit and scope of the present invention.
The communications transmitter 108 produces transmitted communication signals 162.1 through 162.1 by encoding the information signals 160.1 through 160.K according to a known multiple stream communications standard such as, but not limited to, the IEEE 802.11n™ standard, and/or any other suitable multiple stream communications standard. The IEEE 802.11n™ standard is incorporated herein by reference in its entirety. As shown in FIG. 1B, the transmitted communication signals 162.1 through 162.I together represent a multiple stream communication signal. The communications transmitter 108 may encode at least one of the information signals 160.1 through 160.K to produce the transmitted communication signals 162.1 through 162.I. For example, the communications transmitter 108 may encode the information signal 160.1 to produce the transmitted communications signal 162.1. Alternatively, the communications transmitter 108 may encode more than one of information signals 160.1 through 160.K to produce at least one transmitted communication signal 162.1 through 162.I. For example, the communications transmitter 108 may encode the information signal 160.1 and the information signal 160.2 to produce the transmitted communications signal 162.1.
The transmitted communication signals 162.1 through 162.I pass through the communication channel 104 to produce received communication signals 164.1 through 164.N. The transmitted communication signals 162.1 through 162.I may include a similar or a dissimilar number of communication signals as the received communication signals 164.1 through 164.N. The propagation medium of the communication channel 104 introduces interference and/or distortion into the transmitted communication signals 162.1 through 162.I to produce the received communication signals 164.1 through 164.N. For example, noise such as, but not limited to, thermal noise, burst noise, impulse noise, interference, signal strength variations known as fading, phase shift variations, to provide some examples, may introduce interference and/or distortion into the transmitted communication signals 162.1 through 162.I. In addition, the propagation medium of the communication channel 104 may cause each of transmitted communication signals 162.1 through 162.I to reach the communications receiver 106 by multiple communication paths, reflecting from different objects, surface areas, surface boundaries, and interfaces in the communications environment 120. Potential causes of multipath propagation may include, without limitation, atmospheric ducting, ionospheric reflection and/or refraction, and/or reflection from terrestrial objects such as mountains and/or buildings to provide some examples.
Referring back to FIG. 1B, the communications receiver 106 includes multiple receiving antenna to capture the received communication signals 164.1 through 164.N. In an exemplary embodiment, the communications receiver 106 includes two receiving antennas to capture the received communication signals 164.1 through 164.2. The received communication signals 164.1 through 164.N represent the multiple communication paths traversed by each of the transmitted communication signals 162.1 through 162.1 resulting from the multipath propagation introduced by the communication channel 104. For example, the received communications signal 164.1 represents the transmitted communication signals 162.1 through 162.1 as they traverse through a first communication path of the communication channel 104. Likewise, the received communications signal 164.N represents the transmitted communication signals 162.1 through 162.I as they traverse through an N^thcommunication path of the communication channel 104.
The communications receiver 106 may recover the at least one information signal from the at least one transmitter user device to produce at least one recovered information signal, denoted as recovered information signals 166.1 through 166.K, for at least one receiver user device by operating upon the received communication signals 164.1 through 164.N according to the known multiple stream communications standard. The receiver user devices may include, but are not limited to, personal computers, data terminal equipment, telephony devices, broadband media players, personal digital assistants, software applications, or any other medium capable of transmitting or receiving data. However, those skilled in the relevant art(s) will recognize that the recovered information signals 166.1 through 166.K may include a single recovered information signal, such as the recovered information signal 166.1 to provide an example, without departing from the spirit and scope of the present invention.
As shown in FIG. 1A and FIG. 1B, the communications receiver 106 may, according to the invention, operate in the SIMO communications environment represented by the communications environment 100 and/or the MIMO communications environment represented by the communications environment 120. However, this example is not limiting, the communications receiver 106 may operate in any suitable communications environment that will be apparent to one skilled in the relevant art(s) without departing from the spirit and scope of the present invention.

Exemplary Communications Receiver

FIG. 2 illustrates a block diagram of a communications receiver according to an exemplary embodiment of the present invention. More specifically, FIG. 2 illustrates a block diagram of an exemplary embodiment of the communications receiver 106 as shown in FIG. 1A and FIG. 1B. As will be understood by persons skilled in the relevant art(s) from the teachings provided herein, the communications receiver 106 may be readily implemented in hardware, software, or a combination of hardware and software. For example, based on the teachings provided herein, a person skilled in the relevant art(s) could implement the communications receiver 106 via a combination of at least one application specific integrated circuit and a processor core for implementing software commands stored in at least one attached memory. However, this example is not limiting, and other implementations are within the scope and spirit of the present invention.
As shown in FIG. 2, the communications receiver 106 includes receiving antennas 202.1 through 202.N, a radio receiver 204, a physical layer interface (PHY) 206, and a media access controller (MAC) 208. The receiving antennas 202.1 through 202.N capture the received communications signals 154.1 through 154.N, the received communications signals 164.1 through 164.N, and/or any suitable combination thereof as shown in FIG. 1A through FIG. 1B. The receiving antennas 202.1 through 202.N convert either the received communications signals 154.1 through 154.N, the received communications signals 164.1 through 164.N, and/or the suitable combination thereof from electromagnetic waves to modulated radio frequency (RF) currents, denoted as received communications signals 250.1 through 250.N in FIG. 2. For example, the receiving antenna 202.1 may produce the received communications signal 250.1 by converting the received communications signal 154.1 from an electromagnetic wave to a modulated RF current. In an exemplary embodiment, the communications receiver 106 includes the receiving antennas 202.1 through 202.N. However, this example is not limiting, the receiving antenna 202 may include any suitable number of antenna without departing the scope and spirit of the present invention.
The radio receiver 204 operates on the received communications signals 250.1 through 250.N to produce downconverted communications signals 252.1 through 252.N. For example, the radio receiver 204 may downconvert the received communications signals 250.1 through 250.N to baseband or any suitable intermediate frequency (IF) to produce the downconverted communications signals 252.1 through 252.N. The radio receiver 204 may additionally perform functions such as, but not limited to, filtering, and/or automatic gain control (AGC).
The PHY 206 provides an interface between the radio receiver 204 and the MAC 208. However, those skilled in the relevant art(s) will recognize that the PHY 206 may directly receive a baseband or near baseband communications signal, such as Asymmetric Digital Subscriber Line (ADSL) to provide an example, from the communication channel 104 without departing from the spirit and scope of the present invention. In other words, herein the radio receiver 204 is optional, the PHY 206 may receive a communications signal, such as the received communications signals 154.1 through 154.N and/or the received communications signals 164.1 through 164.N, directly from the communication channel 104 via the receiving antennas 202.1 through 202.N. The PHY 206 processes the downconverted communications signals 252.1 through 252.N to produce decoded communications signals 254.1 through 254.M. More specifically, the PHY 206 decodes the downconverted communications signals 252.1 through 252.N to produce the decoded communications signal 254 according to the known single stream communications standard and/or the known multiple stream communications standard. In an exemplary embodiment, the PHY 206 produces the decoded communications signal 254.1 and the decoded communications signal 254.2, wherein the decoded communications signal 254.1 corresponds to the received communications signals 164.1 through 164.N in the communications environment 120 as shown in FIG. 1B and the decoded communications signal 254.2 corresponds to the received communications signals 154.1 through 154.N in the communications environment 100 as shown in FIG. 1A. However, this example is not limiting, the decoded communications signals 254.1 through 254.M may include any suitable number of decoded communications signals without departing the scope and spirit of the present invention.
The MAC 208 may produce at least one recovered information signal, denoted as recovered information signals 256.1 through 256.K, for at least one receiver user device by operating upon the decoded communications signals 254.1 through 254.M according to the known single stream communications standard and/or the known multiple stream communications standard. The recovered information signals 256.1 through 256.K may represent the recovered information signals 156.1 through 156.K as discussed in the communications environment 100 of FIG. 1A, the recovered information signals 166.1 through 166.K as discussed in the communications environment 120 of FIG. 1B, and/or any suitable combination thereof. The MAC 208 may process at least one decoded communications signal 254.1 through 254.M according to the known single stream communications standard and/or the known multiple stream communications standard to produce at least one recovered information signal 256.1 through 256.K. For example, the MAC 208 may process decoded communications signals 254.1 through 254.4 according to the known single stream communications standard and/or the known multiple stream communications standard to produce the recovered information signal 256.1. Alternatively, the MAC 208 may process the decoded communications signal 254.1 according to the known single stream communications standard and/or the known multiple stream communications standard to produce the recovered information signals 256.1 and 256.2. The MAC 208 may additionally, without limitation, provide addressing and channel access control mechanisms that make it possible for multiple terminals or network nodes to communicate within the multipoint network, typically a local area network (LAN), metropolitan area network (MAN), or a wide area network (WAN).

Exemplary Physical Layer Interface

FIG. 3 illustrates a block diagram of a physical layer interface (PHY) according to an exemplary embodiment of the present invention. A PHY 300 provides an interface between a media access controller, such as the MAC 208, and a communication channel, such as the communication channel 104, in accordance with the known single stream communications standard and/or the known multiple stream communications standard. The PHY 300 may represent an exemplary embodiment of the PHY 206 as shown in FIG. 2.
The PHY 300 includes an analog to digital converter (ADC) 302, a receiver filter 304, a multiple stream baseband processing module 306, and a single stream baseband processing module 308. The ADC 302 produces digital communication signals 350.1 through 350.N based on the downconverted communication signals 252.1 through 252.N. More specifically, the ADC 302 converts the downconverted communication signals 252.1 through 252.N from an analog representation to a digital representation to produce the digital communication signals 350.1 through 350.N.
The receiver filter 304 produces encoded multiple stream communication signals 352.1 through 352.N based on the digital communication signals 350.1 through 350.N. More specifically, the receiver filter 304 filters out of band noise and/or interference from the digital communication signals 350.1 through 350.N. The out of band noise and/or interference may result from, without limitation, noise and/or interference resulting from the communication channel 104, noise and/or interference resulting from the radio receiver 204 and/or the ADC 302, and/or noise and/or interference resulting from adjacent channels in the received communication signals 154.1 through 154.N and/or the received communication signals 164.1 through 164.N to provide some examples. The receiver filter 304 is described in further detail below in FIG. 6 through FIG. 11.
The multiple stream baseband processing module 306 produces the decoded communications signal 254.1 based on the digital communication signals 350.1 through 350.N and/or the encoded multiple stream communication signals 352.1 through 352.N. The functionality of the multiple stream baseband processing module 306 may include, without limitation, calculating the magnitude of at least one digital communication signal 350.1 through 350.N, detecting the presence of the multiple stream communications signal from the encoded multiple stream communication signals 352.1 through 352.N, and/or decoding of the encoded multiple stream communication signals 352.1 through 352.N according to the known multiple stream communications standard.
The multiple stream baseband processing module 306 may calculate or gather at least one signal metric, such as but not limited to, the mean, the total energy, the average power, the mean square, the instantaneous power, the root mean square, the variance, the norm, and/or any other suitable signal metric to provide some examples, of at least one digital communication signal 350.1 through 350.N. The multiple stream baseband processing module 306 may generate a single stream selection signal 354 based upon the at least one signal metric to be used by the single stream baseband processing module 308 N to select one of the digital communication signals 350.1 through 350.N and/or one of the encoded multiple stream communication signals 352.1 through 352.N. The multiple stream baseband processing module 306 may generate a radio adjustment signal 356 to adjust a gain of the radio receiver 204 based on the at least one signal metric. Further discussion of multiple stream baseband processing module 306 is disclosed in U.S. patent application Ser. No. ______ (SKGF Ref No. 2875.1600001), entitled “Carrier Selection for Multiple Antennas,” filed on ______, which is incorporated by reference in its entirety.
The single stream baseband processing module 308 produces the decoded communications signal 254.2 based on the digital communication signals 350.1 through 350.N, the encoded multiple stream communication signals 352.1 through 352.N, and/or the single stream selection signal 354. More specifically, the single stream baseband processing module 308 selects one of the digital communication signals 350.1 through 350.N or one of the encoded multiple stream communication signals 352.1 through 352.N based upon the single stream selection signal 354 to produce an encoded single stream communication signal. The single stream baseband processing module 308 may include, without limitation, the detection of the presence of the single stream communications signal from the encoded single stream communications signal and/or decode the single stream communications signal in accordance with the single stream communications standard to provide some examples. Further discussion of the single stream baseband processing module 308 is disclosed in U.S. patent application Ser. No. ______ (SKGF Ref No. 2875.1600001), entitled “Carrier Selection for Multiple Antennas,” filed on ______, which is incorporated by reference in its entirety.

Exemplary Radio Receiver

FIG. 4 illustrates a block diagram of a radio receiver according to an exemplary embodiment of the present invention. A radio receiver 400 operates on the received communication signals 250.1 through 250.N as captured from a communication channel, such as the communication channel 104 to provide an example, by receiving antennas 202.1 through 202.N to produce downconverted communication signals 252.1 through 252.N. For example, the radio receiver 400 may downconvert the received communication signals 250.1 through 250.N to baseband or any suitable intermediate frequency (IF) to produce the downconverted communication signals 252.1 through 252.N. The radio receiver 400 may additionally perform functions such as, but not limited to, filtering, and/or automatic gain control (AGC). The radio receiver 400 may represent an exemplary embodiment of the radio receiver 204 as shown in FIG. 2.
The radio receiver 400 includes radio receiver chains 402.1 through 402.N, each radio receiver chain is configured to receive a corresponding received communications signal 250.1 through 250.N and to produce a corresponding downconverted communications signal 252.1 through 252.N. In an exemplary embodiment, each receiving antenna 202.1 through 202.N is coupled to a corresponding radio receiver chain 402.1 through 402.N. However, this example is not limiting, those skilled in the relevant art(s) will recognize that receiving antenna 202.1 through 202.N may be coupled to at least one corresponding radio receiver chain 402.1 through 402.N without departing from the spirit and scope of the present invention. The radio receiver chains 402.1 through 402.N operate in a substantially similar manner, thus only radio receiver chain 402.1 will be described in further detail.
The radio receiver chain 402.1 includes a low noise amplifier (LNA) 402.1, a mixer 406.1, a receiver filter 408.1, and a variable gain amplifier (VGA) 410.1. The LNA 404.1 receives the received communications signal 250.1 as captured from a communication channel, such as the communication channel 104 to provide an example, by the receiving antenna 202.1. The LNA 404.1 amplifies or attenuates the received communications signal 250.1 by a LNA gain, denoted as LNA, in FIG. 4, to produce an attenuated communications signal 450.1.
The mixer 406.1 downconverts the attenuated communications signal 450.1 to baseband or any suitable intermediate frequency (IF) to produce the downconverted communications signal 452.1 based on a local oscillator (LO) reference frequency 456.1. The local oscillator (LO) reference frequencies 456.1 through 456.N may be similar and/or dissimilar in frequency to each other. For example, all of the LO reference frequencies 456.1 through 456.N may be similar in frequency or at least one group of the LO reference frequencies 456.1 through 456.N may be similar in frequency. Those skilled in the relevant art(s) will recognize that the functionality of the LNA 404.1 and the mixer 406.1, as described above, may be implemented using a low-noise block (LNB) without departing from the spirit and scope of the present invention.
The receiver filter 408.1 produces a filtered communications signal 454.1 based on the downconverted communications signal 452.1. More specifically, the receiver filter 408.1 filters out of band noise and/or interference from the downconverted communications signal 452.1. The out of band noise and/or interference may result from, without limitation, noise and/or interference resulting from the communication channel 104, noise and/or interference resulting from the LNA 404.1 and/or the mixer 406.1, and/or noise and/or interference resulting from adjacent channels in the received communication signals 154.1 through 154.N and/or the received communication signals 164.1 through 164.N to provide some examples. The receiver filter 408.1 is described in further detail below in FIG. 6 through FIG. 11.
The VGA 410.1 amplifies or attenuates the filtered communications signal 454.1 by a VGA gain, denoted as VGA, in FIG. 4, to produce the downconverted communications signal 252.1. The VGA gain may be dynamically adjusted in response to a radio receiver gain control signal 458.1. The radio receiver gain control signals 458.1 through 458.N may be similar and/or dissimilar to each other. For example, all of the radio receiver gain control signals 458.1 through 458.N may be similar causing all of the VGAs 410.1 through 410.N to have a substantially similar gain or at least one radio receiver gain control signal 458.1 through 458.N may be similar causing at least one of the VGAs 410.1 through 410.N to have a substantially similar gain. The radio receiver gain control signals 458.1 through 458.N may represent an exemplary embodiment of the radio adjustment signal 356 as described in FIG. 3. The radio adjustment signal 356 may include a single radio adjustment signal 356 coupled to all of the radio receiver gain control signals 458.1 through 458.N or at least one radio adjustment signal 356 coupled to at least one radio receiver gain control signal 458.1 through 458.N.
From the discussion above, a communications transmitter, such as the communications transmitter 102 to provide an example, produces a transmitted communication signal, such as the transmitted communications signal 152 to provide an example, by encoding at least one information signal, such as the information signals 150.1 through 150.K to provide an example. The known single stream communications standard encodes the information signals into at least one formatted blocks of data or packets according to the known single stream communications standard.

Exemplary Communications Packets

FIG. 5A illustrates a single stream communications packet according to the known single stream communications standard. A single stream communications packet 500 may include at least one single stream signal field such as, but not limited to, a single stream preamble 502, a single stream signal field 506, and/or a single stream single stream information payload 508 to provide some examples. However, this example is not limiting, those skilled in the relevant art(s) will recognize that the single stream communications packet 500 may include a lesser number or a greater number of signal fields according to the single stream communications standard without departing from the spirit and scope of the present invention.
The single stream preamble 502 includes a single stream training sequence 504 and a single stream signal field 506. Typically, the single stream training sequence 504 is included at a start of the single stream communications packet 500 to provide time synchronization for the single stream baseband processing module 308 in accordance with the known single stream communications standard. The known single stream communications standard may provide for a short training sequence and/or a long training sequence. A communication receiver, such as the communications receiver 106 to provide an example, may use the short training sequence for, but not limited to, signal detection, automatic gain control, diversity selection, coarse frequency offset estimation and/or timing synchronization to provide some examples. Likewise, the communication receiver may use the long training sequence for, but not limited to, communication channel estimation and/or fine frequency offset estimation to provide some examples.
The single stream signal field 506 determines characteristics of the single stream information payload 508. The single stream signal field 506 may indicate the information relating to modulation of the single stream information payload 508. For example, the single stream signal field 506 may convey information about the type of modulation of the single stream information payload 508, a coding rate of the single stream information payload 508, a length of the single stream information payload 508, or any other suitable characteristic of the single stream information payload 508.
The communications transmitter may further encode the transmitted communications signal according to the known single stream communications standard for transmission to the communication receiver over a communications channel, such as the communications channel 104 to provide an example. For example, the known single stream communications standard, such as the IEEE 802.11a™ standard to provide an example, may orthogonal frequency division multiplex (OFDM) the transmitted communications signal for transmission to the communication receiver over the communications channel. However, this example is not limiting, those skilled in the relevant art(s) will recognize that the communications transmitter may encode the transmitted communications signal according to any suitable known single stream communication standard for transmission to the communication receiver over the communications channel without departing from the spirit and scope of the present invention. For example, those skilled in the relevant art(s) may encode the transmitted communications signal according to the IEEE 802.11b™ standard or the IEEE 802.11g™ standard differently in accordance with the teachings herein without departing from the spirit and scope of the present invention.
FIG. 5B illustrates a frequency domain representation of the single stream communications packet encoded in accordance with the IEEE 802.11a™ standard. Orthogonal frequency division multiplexing (OFDM) is a digital multi-carrier scheme that uses multiple orthogonal sub-carriers spaced apart at different frequencies. Each sub-carrier may be modulated using any one of a number of modulation schemes, such as binary phase-shift keying (BPSK), quadrature PSK (QPSK), 16-level quadrature amplitude modulation (16-QAM), or 64-level QAM (64-QAM) to provide some examples, at a low symbol rate.
The single stream communications packet 500 encoded in accordance with the IEEE 802.11a™ standard includes 52 sub-carriers, denoted as sub-carrier −26 through sub-carrier 26. The single stream communications packet 500 includes the single stream training sequence 504 and the single stream information payload 508. Those skilled in the relevant art(s) will recognize that magnitudes and/or frequency characteristics of the single stream training sequence 504, the single stream information payload 508, and the IEEE 802.11a™ standard sub-carriers as shown in FIG. 5B are for demonstrative purposes only. The IEEE 802.11a™ standard encodes the single stream training sequence 504 onto sub-carrier −24 through sub-carrier 24, denoted as a single stream training sequence bandwidth 552. On the other hand, the IEEE 802.1 1a™ standard encodes the single stream information payload 508 onto sub-carrier −26 through sub-carrier 26, denoted as a single stream information payload bandwidth 554 in accordance with the IEEE 802.11a™ standard. The single stream training sequence bandwidth 552 is substantially less than the single stream information payload bandwidth 554.
From the discussion above, a communications transmitter, such as the communications transmitter 102 to provide an example, produces a transmitted communication signal, such as the transmitted communications signal 162 to provide an example, by encoding at least one information signal, such as the information signals 160.1 through 160.K to provide an example. The known multiple stream communications standard encodes the information signals into at least one formatted blocks of data or packets according to the known multiple stream communications standard.
FIG. 6A illustrates a multiple stream communications packet according to the known multiple stream communications standard. A multiple stream communications packet 600 may include at least one multiple stream signal field such as, but not limited to, a multiple stream preamble 602, a multiple stream signal field 606, and/or a multiple stream information payload 608 to provide some examples. However, this example is not limiting, those skilled in the relevant art(s) will recognize that the multiple stream communications packet 600 may include a lesser number or a greater number of signal fields according to the multiple stream communications standard without departing from the spirit and scope of the present invention.
The multiple stream preamble 602 includes a multiple stream training sequence 604 and a multiple stream signal field 606. The multiple stream training sequence 604 may be included at a start of the multiple stream communications packet 600 to provide time synchronization for the multiple stream baseband processing module 306 in accordance with the known multiple stream communications standard. The known multiple stream communications standard may provide for a short training sequence and/or a long training sequence. A communication receiver, such as the communications receiver 106 to provide an example, may use the short training sequence for, but not limited to, signal detection, automatic gain control, diversity selection, coarse frequency offset estimation and/or timing synchronization to provide some examples. Likewise, the communication receiver may use the long training sequence for, but not limited to, communication channel estimation and/or fine frequency offset estimation to provide some examples.
The multiple stream signal field 606 determines characteristics of the multiple stream information payload 608. The multiple stream signal field 606 may indicate the information relating to modulation of the multiple stream information payload 608. For example, the multiple stream signal field 606 may convey information about the type of modulation of the multiple stream information payload 608, a coding rate of the multiple stream information payload 608, a length of the multiple stream information payload 608, or any other suitable characteristic of the multiple stream information payload 608.
The communications transmitter may further encode the transmitted communications signal according to the known multiple stream communications standard for transmission to the communication receiver over a communications channel, such as the communications channel 104 to provide an example. For example, the known multiple stream communications standard, such as the IEEE 802.11n™ standard to provide an example, may orthogonal frequency division multiplex (OFDM) the transmitted communications signal for transmission to the communication receiver over the communications channel. However, this example is not limiting, those skilled in the relevant art(s) will recognize that the communications transmitter may encode the transmitted communications signal according to any suitable known multiple stream communication standard for transmission to the communication receiver over the communications channel without departing from the spirit and scope of the present invention.
FIG. 6B illustrates a frequency domain representation of the multiple stream communications packet encoded in accordance with the IEEE 802.11n™ standard. The multiple stream communications packet 600 encoded in accordance with the IEEE 802.11n™ standard includes 56 sub-carriers, denoted as sub-carrier −28 through sub-carrier 28. The multiple stream communications packet 600 includes the multiple stream training sequence 604 and the multiple stream information payload 608. Those skilled in the relevant art(s) will recognize that magnitudes and/or frequency characteristics of the multiple stream training sequence 604, the multiple stream information payload 608, and the IEEE 802.11n™ standard sub-carriers as shown in FIG. 6B are for demonstrative purposes only. The IEEE 802.11n™ standard encodes the multiple stream training sequence 604 onto sub-carrier −24 through sub-carrier 24, denoted as a multiple stream training sequence bandwidth 652. On the other hand, the IEEE 802.11n™ standard through sub-carrier 28, denoted as a multiple stream information payload bandwidth 654 in accordance with the IEEE 802.11n™ standard. The multiple stream training sequence bandwidth 652 is substantially less than the multiple stream information payload bandwidth 654.

Exemplary Receiver Filters

FIG. 7A illustrates a receiver filter according to an exemplary embodiment of the present invention. A receiver filter 700 may represent an exemplary embodiment of frequency domain representation of the receiver filter 304 as discussed in FIG. 3 and/or the receiver filters 408.1 through 408.N as discussed in FIG. 4. The receiver filter 700 may be implemented using any suitable known filter topology that is capable of selecting among two or more receiver filter bandwidths. For example, the receiver filter 700 may be implemented as, but is not limited to, a digital filter with one or more selectable sets of filter coefficients or an analog filter with one or more selectable sets of passive elements such as capacitors or inductors to provide some examples.
The receiver filter 700 filters the single stream communications packet 500, as discussed in FIG. 5A and FIG. 5B, including at least one received single stream signal field such as the single stream training sequence 504 and/or the single stream information payload 508 to provide some examples and/or the multiple stream communications packet 600, as discussed in FIG. 6A and FIG. 6B, including at least one received multiple stream signal field such as the multiple stream training sequence 604 and/or the multiple stream information payload 608 to provide some examples, to produce a filtered stream communications packet 750.
The receiver filter 700 may include at least one receiver filter bandwidth for at least one single stream signal field and/or at least one multiple stream signal field. Alternatively, the receiver filter 700 may include a corresponding receiver filter bandwidth for more than one single stream signal field and/or at least one multiple stream signal field. FIG. 7B illustrates a frequency domain representation of the receiver filter according to an exemplary embodiment of the present invention. The frequency domain representation of the receiver filter 700 may represent an exemplary embodiment of a frequency domain representation of the receiver filter 304 as discussed in FIG. 3 and/or a frequency domain representation of at least one of the receiver filters 408.1 through 408.N as discussed in FIG. 4.
The receiver filter 700 may include a training sequence bandwidth 702, a single stream information payload bandwidth 704, and/or a multiple stream information payload bandwidth 706. However, this example is not limiting, those skilled in the relevant art(s) will recognize that the receiver filter 700 may include any suitable number of receiver filter bandwidths as provided by the known single stream communications standard and/or the known multiple stream communications standard without departing from the spirit and scope of the present invention. Those skilled in the relevant art(s) will recognize that magnitudes and/or frequency characteristics of the training sequence bandwidth 702, the single stream information payload bandwidth 704, and/or the multiple stream information payload bandwidth 706 as shown in FIG. 7B are for demonstrative purposes only.
The training sequence bandwidth 702 corresponds to the single stream training sequence bandwidth 552 and/or the multiple stream training sequence bandwidth 652. As a result, the receiver filter 700 may dynamically select the training sequence bandwidth 702 to filter the single stream training sequence 504 and/or the multiple stream training sequence 604. Alternatively, the receiver filter 700 may dynamically select the training sequence bandwidth 702 to filter the single stream preamble 502 in its entirety and/or the multiple stream preamble 602 in its entirety. Likewise, the single stream information payload bandwidth 704 corresponds to the single stream information payload bandwidth 554. As a result, the receiver filter 700 may dynamically select the single stream information payload bandwidth 704 to filter the single stream information payload 508. Similarly, the multiple stream information payload bandwidth 706 corresponds to the multiple stream information payload bandwidth 654. As a result, the receiver filter 700 may dynamically select the multiple stream information payload bandwidth 706 to filter the multiple stream information payload 608.
However, these examples are not limiting, the receiver filter 700 may select any one of the at least one receiver filter bandwidths for at least one single stream signal field and/or at least one multiple stream signal field without departing from the spirit and scope of the present invention. For example, the receiver filter 700 may dynamically select the training sequence bandwidth 702 to filter the single stream training sequence 504 and/or the multiple stream training sequence 604. The receiver filter 700 may dynamically select the single stream information payload bandwidth 554 to filter some of the single stream preamble 502 and/or the single stream information payload 508 and/or the receiver filter 700 may dynamically select the multiple stream information payload bandwidth 654 to filter some of the multiple stream preamble 602 and/or the multiple stream information payload 608.
A signal to noise ratio (SNR) of a communications signal, such as, but not limited to, at least one of the encoded multiple stream communication signals 352.1 through 352.N or at least one of the filtered communications signals 454.1 through 454.N to provide some examples, represents a ratio of a power of the communications signal in a spectral bandwidth to a power of noise and/or interference in the spectral bandwidth. The SNR of the communications signal may be expressed as:
$\begin{matrix} SNR = \frac{P_{SIGNAL}}{P_{NOISE}}, & (1) \end{matrix}$
where SNR represents the SNR of the communications signal, P_SIGNALrepresents the power of the communications signal in the spectral bandwidth, and P_NOISErepresents the power of noise and/or interference in the spectral bandwidth.
A conventional receiver filter typically includes a conventional receiver filter bandwidth having a single or individual receiver filter bandwidth approximating the multiple stream information payload bandwidth 654. More specifically, the conventional receiver filter bandwidth is the largest or greatest of the single stream training sequence bandwidth 552, the single stream information payload bandwidth 554, the multiple stream training sequence bandwidth 652, or the multiple stream information payload bandwidth 654. The conventional receiver filter filters the single stream communications packet 500 and/or the multiple stream communications packet 600 in their entirety using the conventional receiver filter bandwidth. In other words, the conventional receiver filter filters the single stream preamble 502, the single stream signal field 506, and/or the single stream single stream information payload 508 corresponding to the single stream communications packet 500 and/or the multiple stream preamble 602, the multiple stream signal field 606, and/or the multiple stream information payload 608 corresponding to the multiple stream communications packet 600 using one of the single stream training sequence bandwidth 552, the single stream information payload bandwidth 554, the multiple stream training sequence bandwidth 652, or the multiple stream information payload bandwidth 654 having the largest bandwidth. As a result, the SNR of the conventional receiver filter may be substantially less than the SNR of the receiver filter 700 for one or more signal fields. For example, the SNR of the single stream training sequence 504 and/or the multiple stream training sequence 604 for the conventional receiver filter including the bandwidth of the multiple stream information payload bandwidth 654 may be given as:
$\begin{matrix} SNR = \frac{P_{TRAINING}}{P_{CONVENTIONAL}}, & (2) \end{matrix}$
where SNR represents SNR ratio for the single stream training sequence 504 and/or the multiple stream training sequence 604, P_TRAININGrepresents a power of the single stream training sequence 504 and/or the multiple stream training sequence 604, and P_CONVENTIONALrepresents a power of a bandwidth of the conventional receiver filter, usually one of the single stream training sequence bandwidth 552, the single stream information payload bandwidth 554, the multiple stream training sequence bandwidth 652, or the multiple stream information payload bandwidth 654 having the largest bandwidth. For example, P_CONVENTIONALrepresents usually represents a power of the bandwidth the multiple stream information payload bandwidth 654 representing a bandwidth of the multiple stream single stream information payload 608. The spectral difference between the bandwidth of the conventional receiver filter and a bandwidth of the single stream training sequence 504 or a bandwidth of the multiple stream training sequence 604 represents a noise contribution to the SNR resulting from a substantial excess bandwidth in the conventional receiver filter. From the example above, the difference between P_TRAININGand P_CONVENTIONALrepresents the substantial excess bandwidth in the conventional receiver filter that does not contain any substantial power of the signal of interest, namely the single stream training sequence bandwidth 552 or the multiple stream training sequence bandwidth 652.
From the discussion above, the receiver filter 700 may dynamically select among one or more bandwidths based upon the one signal field to substantially increase the SNR as compared to the conventional receiver filter. The one or more dynamically selectable bandwidths more closely approximate a signal of interest when compared to the conventional receiver filter. For example, the SNR of the single stream training sequence 504 and/or the multiple stream training sequence 604 for the receiver filter 700 may be given as:
$\begin{matrix} SNR = \frac{P_{TRAINING}}{P_{RECEIVER}}, & (3) \end{matrix}$
where SNR represents SNR ratio for the single stream training sequence 504 and/or the multiple stream training sequence 604, P_TRAININGrepresents a power of the single stream training sequence 504 and/or the multiple stream training sequence 604, and P_RECEIVERrepresents a power of a bandwidth of the receiver filter 700. A difference between P_TRAININGand P_RECEIVERis substantially less than or equal to the difference between P_TRAININGand P_CONVENTIONAL, as discussed above, resulting in substantially less excess bandwidth when compared to the conventional receiver filter, thereby increasing the SNR of the receiver filter 700.

Exemplary Operation of the Communications Environments

FIG. 8 is a flowchart 800 of exemplary operational steps of a communications environment according to an aspect of the present invention. The invention is not limited to this operational description. Rather, it will be apparent to persons skilled in the relevant art(s) from the teachings herein that other operational control flows are within the scope and spirit of the present invention. The following discussion describes the steps in FIG. 8.
At step 802, one or more communications signals, such as the transmitted communications signal 152 and/or the transmitted communications signal 162.1 through 162.I, are generated from one or more information signals as received from one or more transmitter user devices, such as the information signals 150.1 through 150.K and/or the information signals 160.1 through 160.K. More specifically, the one or more information signals are encoded according to a known single stream communications standard, such as, but not limited to, the IEEE 802.11a™ standard, the IEEE 802.11b™ standard, the IEEE 802.11g™ standard, and/or any other suitable single stream communications standard and/or a known multiple stream communications standard, such as, but not limited to, the IEEE 802.11n™ standard, and/or any other suitable multiple stream communications standard to produce the one or more communications signals.
At step 804, the one or more communications signals from step 802 are transmitted as a single stream communications signal according to the known single stream communications standard to produce the one or more communications signals from step 802 Alternatively, the one or more communications signals from step 802 are transmitted as a multiple stream communications signal according to the known multiple stream communications standard.
At step 806, the one or more communications signals from step 804 traverse through a communication channel, such as the communication channel 104. The communication channel may include, but is not limited to, a microwave radio link, a satellite channel, a fiber optic cable, a hybrid fiber optic cable system, or a copper cable to provide some examples. The communication channel contains a propagation medium that the one or more communications signals from step 804 pass through before reception. The propagation medium of the communication channel introduces interference and/or distortion into the communications signal. For example, noise such as, but not limited to, thermal noise, burst noise, impulse noise, interference, signal strength variations known as fading, phase shift variations, to provide some examples, may introduce interference and/or distortion into the communications signal. In addition, the propagation medium of the communication channel may cause the one or more communications signals to propagate onto multiple communication paths, reflecting from different objects, surface areas, surface boundaries, and interfaces in the communications environment. Potential causes of multipath propagation may include, but are not limited, to atmospheric ducting, ionospheric reflection and/or refraction, and/or reflection from terrestrial objects such as mountains and/or buildings to provide some examples.
At step 808, the one or more communications signals from step 806 are received. The one or more communications signals from step 806 are received as either a single stream communications signal and/or a multiple stream communications signal. The multiple communication paths traversed by the one or more communications signals from step 806 resulting from the multipath propagation introduced by the communication channel may be received. For example, the multiple communication paths of the one or more communications signals from step 806 transmitted as the single stream communications signal may be received as it traverses through the communication channel. Likewise, the multiple communication paths of the one or more communications signals from step 806 transmitted as the multiple stream communications signal may be received as it traverses through the communication channel.
At step 810, one or more information signals, such as the recovered information signals 156.1 through 156.K and/or the recovered information signals 166.1 through 166.K to provide some examples, are recovered from the one or more communications signals from step 808 to produce one or more recovered information signals. The one or more communications signals from step 808 are operated upon according to the known single stream communications standard and/or the known multiple stream communications standard to recover the one or more information signals.

Exemplary Operation of the Communications Receiver

FIG. 9 is a flowchart 900 of exemplary operational steps of a communications receiver according to an aspect of the present invention. FIG. 9 further defines steps 808 and 810 as shown in FIG. 8. The invention is not limited to this operational description. Rather, it will be apparent to persons skilled in the relevant art(s) from the teachings herein that other operational control flows are within the scope and spirit of the present invention. The following discussion describes the steps in FIG. 9. At step 902, one or more communications signals, such the received communications signals 154.1 through 154.N and/or the received communications signals 164.1 through 164.N to provide some examples, are received to produce one or more received communications signals, such as the received communications signals 250.1 through 250.N to provide some examples. More specifically, the one or more communications signals are received as they traverse through a communication channel, such as the communication channel 104. The one or more communications signals may include one or more single stream communications signals, one or more multiple stream communications signals, and/or any combination thereof.
At step 904, the one or more frames of one or more communications signals from step 902 are operated on to produce one or more downconverted communications signals, such as the downconverted communications signals 252.1 through 252.N to provide an example. For example, the one or more communications signals from step 902 may be downconverted to baseband or any suitable intermediate frequency (IF) to produce the downconverted communications signals. However, those skilled in the relevant art(s) will recognize that step 904 is optional, the operational control may flow directly from step 902 to step 906 for a baseband and/or a near baseband communication.
At step 906, the one or more communications signals from step 904 are decoded to produce one or more decoded communications signals, such as the decoded communications signals 254.1 through 254.M to provide an example. Alternatively, the one or more communications signals from step 902 may be directly decoded to produce the one or more decoded communications signals. More specifically, the one or more communications signals from step 902 and/or the one or more communications signals from step 904 are decoded to produce the one or more decoded communications signals according to the known single stream communications standard and/or the known multiple stream communications standard. If the one or more communications signals from step 902 and/or the one or more communications signals from step 904 includes the single stream communications signal, the one or more communications signals from step 902 and/or the one or more communications signals from step 904 are decoded according to the known single stream communications standard. If the one or more communications signals from step 902 and/or the one or more communications signals from step 904 includes the multiple stream communications signal, the one or more communications signals from step 902 and/or the one or more communications signals from step 904 are decoded according to the known multiple stream communications standard.
At step 908, one or more information signals, such as the recovered information signals 256.1 through 256.K to provide an example, are recovered by operating on the communications signal from step 906 according to the known single stream communications standard and/or the known multiple stream communications standard.

Exemplary Operation of the Receiver Filter

FIG. 10 is a flowchart 1000 of exemplary operational steps of the receiver filter according to an exemplary embodiment of the present invention. FIG. 10 further defines steps 904 and 906 as shown in FIG. 9. The invention is not limited to this operational description. Rather, it will be apparent to persons skilled in the relevant art(s) from the teachings herein that other operational control flows are within the scope and spirit of the present invention. The following discussion describes the steps in FIG. 9.
At step 1002, one or more communications signals, such as the digital communication signals 350.1 through 350.N and/or the downconverted communications signal 452.1 through 452.N to provide some examples, is received. The one or more communications signals may be encoded according to a known single stream communications standard and/or a known multiple stream communications standard. The known single stream communications standard and/or the known multiple stream communications standard encodes the one or more communications signals into at least one formatted block of data or packet to produce a single stream communications packet, such as the single stream communications packet 500, and/or a multiple stream communications packet, such as the multiple stream communications packet 600. The single stream communications packet and or the multiple stream communications packet includes at least one signal field such as, but not limited to, a multiple stream preamble, a multiple stream signal field, a multiple stream information payload, a single stream preamble, a single stream signal field, and/or a single stream single stream information payload to provide some examples.
At step 1004, the single stream preamble and/or the multiple stream preamble is filtered using a training sequence bandwidth, such as the training sequence bandwidth 702 and/or the training sequence bandwidth 1102 to provide some examples. The single stream preamble and/or the multiple stream preamble may be filtered in its entirety using the training sequence bandwidth. Alternatively, some of the single stream preamble, such as the single stream training sequence 504 to provide an example, and/or the multiple stream preamble, such as the multiple stream training sequence 604 to provide an example, may be filtered using training sequence bandwidth.
At step 1006, a determination is made as to whether the one or more communications signals includes the single stream communications packet and/or the multiple stream communications packet. More specifically, the single stream preamble and/or the multiple stream preamble, or the some of the single stream preamble and/or the multiple stream preamble, may be decoded according to the known single stream communications standard and/or the known multiple stream communications standard to determine whether the one or more communications signals includes the single stream communications packet and/or the multiple stream communications packet.
At step 1008, the single stream payload and/or the multiple stream payload is filtered using a single stream information payload bandwidth, such as the single stream information payload bandwidth 554, or a multiple stream information payload bandwidth, such as the multiple stream information payload bandwidth 654 based on the determination of step 1006. The single stream payload is filtered using the single stream information payload bandwidth when the one or more communications signals includes the single stream communications packet. Alternatively, some of the single stream preamble, such as the single stream signal field 506 to provide an example, and the single stream payload may be filtered using the single stream information payload bandwidth when the one or more communications signals includes the single stream communications packet. Likewise, the some of the multiple stream preamble, such as the multiple stream signal field 606 to provide an example, and the multiple stream payload may be filtered using the multiple stream information payload bandwidth when the one or more communications signals includes the multiple stream communications packet.

Conclusion

While various exemplary embodiments of the present invention have been described above, it should be understood that they have been presented by way of example and not limitation. It will be apparent to one skilled in the pertinent art that various changes in form and detail can be made therein without departing from the spirit and scope of the invention. Therefore, the present invention should only be defined in accordance with the following claims and their equivalents.

Claims

1. A method to filter a communications packet including one or more signal fields, comprising:

(A) receiving one or more communications signals, wherein the one or more communications signals includes a short training sequence and an information payload;

(B) filtering at least the short training sequence using a training sequence bandwidth;

(C) determining if the one or more communications signals includes at a single stream communications packet or a multiple stream communications packet;

(D) filtering at least the payload using a single stream information payload bandwidth when the one or more communications signals includes the single stream communications packet; and

(E) filtering at least the payload using a multiple stream information payload bandwidth when the one or more communications signals includes the multiple stream communications packet.

2. The method of claim 1, wherein the communications packet is encoded according to at least one known single stream communications standard or a known multiple stream communications standard.

3. The method of claim 2, wherein the known single stream communications standard includes at least one of: the Institute of Electrical and Electronics Engineers (IEEE) 802.11a™ standard, the IEEE 802.11b™ standard, and the IEEE 802.11g™ standard.

4. The method of claim 2, wherein the known multiple stream communications standard includes an IEEE 802.11n™ standard.

5. The method of claim 1, wherein step (B) comprises:

(B)(i) selecting the training sequence bandwidth from at least one of:

the training sequence bandwidth,

the single stream information payload bandwidth, and

the multiple stream information payload bandwidth.

6. The method of claim 5, wherein the training sequence bandwidth is substantially less than the single stream information payload bandwidth and the multiple stream information payload bandwidth.

7. The method of claim 1, wherein step (D) comprises:

(D)(i) selecting the single stream information payload bandwidth from at least one of:

the training sequence bandwidth,

the single stream information payload bandwidth, and

the multiple stream information payload bandwidth.

8. The method of claim 1, wherein step (E) comprises:

(D)(i) selecting the multiple stream information payload bandwidth from at least one of:

the training sequence bandwidth,

the single stream information payload bandwidth, and

the multiple stream information payload bandwidth.

9. The method of claim 1, wherein the one or more communications signals includes a preamble, step (B) further comprises:

(B)(i) filtering the preamble using the training sequence bandwidth.

10. The method of claim 9, wherein step (D) further comprises

(D) filtering the payload and at least some of the preamble using the single stream information payload bandwidth when the one or more communications signals includes the single stream communications packet.

11. The method of claim 9, wherein step (D) further comprises

(D) filtering the payload and at least some of the preamble using the multiple stream information payload bandwidth when the one or more communications signals includes the multiple stream communications packet.

12. A communications receiver configured to receive one or more communication signals, wherein the one or more communication signals includes a short training sequence and an information payload, comprising:

a receiver filter configured to filter at least the short training sequence using a training sequence bandwidth; and

a baseband processing module configured to determine if the one or more communications signals includes at a single stream communications packet or a multiple stream communications packet,

wherein the receiver filter filters at least the payload using a single stream information payload bandwidth when the one or more communications signals includes the single stream communications packet, and filters at least the payload using a multiple stream information payload bandwidth when the one or more communications signals includes the multiple stream communications packet.

13. The communications receiver of claim 12, wherein the baseband process module includes a multiple stream baseband processing module to processes the payload using a known multiple stream communications standard when the one or more communication signals includes the multiple stream communications signal.

14. The communications receiver of claim 13, wherein the known multiple stream communications standard includes an IEEE 802.11n™ standard.

15. The communications receiver of claim 12, wherein the baseband process module includes a single stream baseband processing module to processes the payload using a known single stream communications standard when the one or more communication signals includes the single stream communications signal.

16. The communications receiver of claim 15, wherein the known single stream communications standard includes at least one of: the Institute of Electrical and Electronics Engineers (IEEE) 802.11a™ standard, the IEEE 802.11b™ standard, and the IEEE 802.11g™ standard.

17. The communications receiver of claim 12, wherein the receiver filter selects the training sequence bandwidth from at least one of:

the training sequence bandwidth,

the single stream information payload bandwidth, and

the multiple stream information payload bandwidth.

18. The communications receiver of claim 12, wherein the receiver filter selects the single stream information payload bandwidth from at least one of:

the training sequence bandwidth,

the single stream information payload bandwidth, and

the multiple stream information payload bandwidth.

19. The communications receiver of claim 12, wherein the receiver filter selects the multiple stream information payload bandwidth from at least one of:

the training sequence bandwidth,

the single stream information payload bandwidth, and

the multiple stream information payload bandwidth.

20. The communications receiver of claim 12, wherein the one or more communications signals includes a preamble, and the receiver filter is further configured to filter the preamble using the training sequence bandwidth

21. The communications receiver of claim 20, wherein the receiver filter filters the payload and at least some of the preamble using the single stream information payload bandwidth when the one or more communications signals includes the single stream communications packet.

22. The communications receiver of claim 20, wherein the receiver filter filters the payload and at least some of the preamble using the multiple stream information payload bandwidth when the one or more communications signals includes the multiple stream communications packet.