U.S. patent application number 13/664013 was filed with the patent office on 2013-02-28 for system and method for carrying a wireless based signal over wiring.
The applicant listed for this patent is Yehuda Binder, Shlomo Butbul, Ami Hazani. Invention is credited to Yehuda Binder, Shlomo Butbul, Ami Hazani.
Application Number | 20130051404 13/664013 |
Document ID | / |
Family ID | 34960527 |
Filed Date | 2013-02-28 |
United States Patent
Application |
20130051404 |
Kind Code |
A1 |
Binder; Yehuda ; et
al. |
February 28, 2013 |
SYSTEM AND METHOD FOR CARRYING A WIRELESS BASED SIGNAL OVER
WIRING
Abstract
A device, network and method wherein a standard wireless modem
is coupled to wiring for carrying a wireless baseband signal that
may be OFDM based, and may be directly generated by the wireless IF
modem, or extracted from the modem RF signal. The wiring may be a
building utility wiring, such as telephone, AC power or CATV
wiring. The baseband signal is carried simultaneously with the
utility service signal over the utility wiring using Frequency
Division Multiplexing. The device may be enclosed with a data unit,
a standalone dedicated enclosure, within an outlet or as a plug-in
outlet adapter. Data units may couple the device by a wiring port
such as standard data connector, or via wireless connection. The
device may be locally powered or via a power signal carried over
the wiring. This abstract is not intended to limit or construe the
scope of the claims.
Inventors: |
Binder; Yehuda; (Hod
Hasharon, IL) ; Butbul; Shlomo; (Ra'anana, IL)
; Hazani; Ami; (Ra'anana, IL) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Binder; Yehuda
Butbul; Shlomo
Hazani; Ami |
Hod Hasharon
Ra'anana
Ra'anana |
|
IL
IL
IL |
|
|
Family ID: |
34960527 |
Appl. No.: |
13/664013 |
Filed: |
October 30, 2012 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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12944964 |
Nov 12, 2010 |
8325693 |
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13664013 |
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12129278 |
May 29, 2008 |
8325759 |
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12944964 |
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11066442 |
Feb 28, 2005 |
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12129278 |
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Current U.S.
Class: |
370/467 |
Current CPC
Class: |
H04L 5/06 20130101; H04L
5/14 20130101; H04L 27/2601 20130101 |
Class at
Publication: |
370/467 |
International
Class: |
H04L 12/46 20060101
H04L012/46 |
Foreign Application Data
Date |
Code |
Application Number |
May 6, 2004 |
IL |
161869 |
Claims
1. A device adapted to be connected to a network over LAN wiring in
a building, the LAN wiring concurrently carrying a LAN signal in a
LAN frequency band and a radio frequency signal in an intermediate
frequency band different from and non-interfering with, the LAN
frequency band, the device comprising: a first LAN connector
connectable to the LAN wiring; a high pass filter, coupled to the
first LAN connector, passing only signals in the intermediate
frequency band; an antenna; and a signal frequency converter
coupled to the high pass filter, the signal frequency converter
converting the radio frequency signal in the intermediate frequency
band received from the LAN wiring to a radio frequency band signal
for transmission through the antenna and converting a radio
frequency band signal received from the antenna to an intermediate
frequency band signal for transmission over the LAN wiring.
2. The device according to claim 1 further comprising a low pass
filter coupled to the first LAN connector, passing only signals in
the LAN frequency band to network devices connected to the a second
LAN connector.
3. The device according to claim 1 further comprising at least one
of a radio frequency filter and a Tx/Rx switch connected between
the antenna and the signal frequency converter.
4. (canceled)
5. The device according to claim 1 wherein the radio frequency band
signal is a cellular telephone signal selected from the group
including GSM, GPRS, 2.5G, 3G, UMTS, DCS, PCS, CDMA, WCDMA and
WiMAX.
6. (canceled)
7. The device according to claim 1 wherein the radio frequency band
signal is a wireless local area networking signal.
8. The device according to claim 1 wherein the radio frequency band
signal is a wireless wide area network signal.
9. The device according to claim 1 wherein the LAN wiring carries a
power signal and the device is powered by the power signal.
10.-31. (canceled)
32. A device adapted to be connected to a network over LAN wiring
in a building, the LAN wiring concurrently carrying a LAN signal in
a LAN frequency band and a radio frequency signal in an
intermediate frequency band different from and non-interfering
with, the LAN frequency band, the device comprising: a first LAN
connector connectable to the LAN wiring; a high pass filter,
coupled to the first LAN connector, passing only signals in the
intermediate frequency band; a processor; and a network interface
adapted for connecting the device to an external network, wherein
the processor converts a network signal received from the external
network to the radio frequency signal in the intermediate frequency
band for transmission over the LAN wiring and converts the radio
frequency signal in the intermediate frequency band received from
the LAN wiring to a network signal for transmission over the
external network.
33. The device according to claim 32 further comprising a low pass
filter connecting the first LAN connector to a second LAN
connector, the second LAN connector providing a data connection for
a network device.
34. The device according to claim 32 further comprising a Tx/Rx
switch connected between the high pass filter and the
processor.
35. The device according to claim 32 wherein the radio frequency
band signal is a cellular telephone signal selected from the group
including GSM, GPRS, 2.5G, 3G, UMTS, DCS, PCS, CDMA, WCDMA and
WiMAX.
36. (canceled)
37. The device according to claim 32 wherein the radio frequency
band signal is a wireless local area networking signal.
38. The device according to claim 32 wherein the radio frequency
band signal is a wireless wide area network signal.
39. The device according to claim 32 wherein the LAN wiring carries
a power signal and the device is powered by the power signal.
40. (canceled)
41. The device according to claim 32 further comprising a media
access control layer processor connected between the network
interface and the processor.
42. The device according to claim 32 further comprising an RF-IF
converter and a signal frequency converter connecting the processor
to the high pass filter, wherein the RF-IF converter converts
signals received from the processor from an intermediate frequency
band to the radio frequency band and signals received from the
signal frequency converter from the radio frequency band to the
intermediate frequency band and the signal frequency converter
converts signals received from the LAN wiring from an intermediate
frequency band to the radio frequency band and signals received
from the processor from the radio frequency band to the
intermediate frequency band.
43. The device according to claim 42 further comprising at least
one of a Tx/Rx switch and a radio frequency filter connected
between the RF-IF converter and the signal frequency converter.
44. (canceled)
45. The device according to claim 32 further comprising: an
antenna; a sharing device connecting the processor and the high
pass filter to the antenna; a line interface connecting the high
pass filter to the sharing device; and an RF-IF converter
connecting the sharing device to the antenna, where the RF-IF
converter converts the intermediate frequency band signals to the
radio frequency band signals and the radio frequency band signals
to the intermediate frequency band signals.
46. The device according to claim 45 further comprising at least
one of a Tx/Rx switch and a radio frequency filter connected
between the RF-IF converter and the antenna.
47. (canceled)
48. The device according to claim 32 further comprising: an
antenna; a sharing device connecting the processor and the high
pass filter to the antenna; a signal frequency converter connecting
the high pass filter to the sharing device; and an RF-IF converter
connecting the processor to the sharing device; wherein the RF-IF
converter converts signals received from the processor from an
intermediate frequency band to the radio frequency band and signals
received from the sharing device from the radio frequency band to
the intermediate frequency band and the signal frequency converter
converts signals received from the LAN wiring from an intermediate
frequency band to the radio frequency band and signals received
from the sharing device from the radio frequency band to the
intermediate frequency band.
49.-50. (canceled)
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation of U.S. patent
application Ser. No. 12/129,278 filed 29 May 2008, which is a
continuation of U.S. patent application Ser. No. 11/066,442 filed
28 Feb. 2005, claims any and all benefits of the prior filed
applications as provided by law and the contents of each of the
earlier filed applications are hereby incorporated by reference in
its entirety.
[0002] This application is related to U.S. application Ser. No.
11/329,270, filed on 11 Jan. 2006 and 12/038,435, filed on 27 Feb.
2008.
FIELD OF THE INVENTION
[0003] The present invention relates to the field of wired
communication, and, more specifically, to using wireless oriented
signals over a wired medium.
BACKGROUND OF THE INVENTION
[0004] Wired Home Networking.
[0005] Most existing offices and some of the newly built buildings
facilitate a data network structure based on dedicated wiring.
However, implementing such a network in existing buildings
typically requires installation of new wiring infrastructure. Such
installation of new wiring may be impractical, expensive and
problematic. As a result, many technologies (referred to as "no new
wires" technologies) have been proposed in order to facilitate a
LAN in a building without adding new wiring. Some of these
techniques use existing utility wiring installed primarily for
other purposes such as telephone, electricity, cable television
(CATV), and so forth. Such an approach offers the advantage of
being able to install such systems and networks without the
additional and often substantial cost of installing separate wiring
within the building.
[0006] The technical aspect for allowing the wiring to carry both
the service (such as telephony, electricity and CATV) and the data
communication signal commonly involves using FDM technique
(Frequency Division Multiplexing). In such configuration, the
service signal and the data communication signals are carried
across the respective utility wiring each using a distinct
frequency spectrum band. The concept of FDM is known in the art,
and provides means of splitting the bandwidth carried by a medium
such as wiring. In the case of a telephone wiring carrying both
telephony and data communication signals, the frequency spectrum is
split into a low-frequency band capable of carrying an analog
telephony signal and a high-frequency band capable of carrying data
communication or other signals.
[0007] A network in a house based on using powerline-based home
network is also known in the art. The medium for networking is the
in-house power lines, which is used for carrying both the mains
power and the data communication signals. A PLC (Power Line
Carrier) modem converts a data communication signal (such as
Ethernet IEEE802.3) to a signal which can be carried over the power
lines, without affecting and being affected by the power signal
available over those wires. A consortium named HomePlug Powerline
Alliance, Inc. of San Ramon, Calif. USA is active in standardizing
powerline technologies. A powerline communication system is
described in U.S. Pat. No. 6,243,571 to Bullock et al., which also
provides a comprehensive list of prior art publications referring
to powerline technology and application. An example of such PLC
modem housed as a snap-on module is HomePlug1.0 based
Ethernet-to-Powerline Bridge model DHP-100 from D-Link.RTM.
Systems, Inc. of Irvine, Calif., USA. Outlets with built in PLC
modems for use with combined data and power using powerlines are
described in US Patent Application 2003/0062990 to Schaeffer et al.
entitled `Powerline bridge apparatus`. Such power outlets are
available as part of PlugLAN.TM. by Asoka USA Corporation of San
Carlos, Calif. USA.
[0008] Similarly, carrying data over existing in home CATV coaxial
cabling is also known in the art, for example in US Patent
application 2002/0166124 to Gurantz et al. An example of home
networking over CATV coaxial cables using outlets is described in
US Patent application 2002/0194383 to Cohen et al. Such outlets are
available as part of HomeRAN.TM. system from TMT Ltd. of Jerusalem,
Israel.
[0009] Telephony Definitions and Background
[0010] The term "telephony" herein denotes in general any kind of
telephone service, including analog and digital service, such as
Integrated Services Digital Network (ISDN).
[0011] Analog telephony, popularly known as "Plain Old Telephone
Service" ("POTS") has been in existence for over 100 years, and is
well-designed and well-engineered for the transmission and
switching of voice signals in the 300-3400 Hz portion (or "voice
band" or "telephone band") of the audio spectrum. The familiar POTS
network supports real-time, low-latency, high-reliability,
moderate-fidelity voice telephony, and is capable of establishing a
session between two end-points, each using an analog telephone
set.
[0012] The terms "telephone", "telephone set", and "telephone
device" herein denote any apparatus, without limitation, which can
connect to a Public Switch Telephone Network ("PSTN"), including
apparatus for both analog and digital telephony, non-limiting
examples of which are analog telephones, digital telephones,
facsimile ("fax") machines, automatic telephone answering machines,
voice (a.k.a. dial-up) modems, and data modems.
[0013] The terms "data unit", "computer" and "personal computer"
("PC") are used herein interchangeably to include workstations,
Personal Digital Assistants (PDA) and other data terminal equipment
(DTE) with interfaces for connection to a local area network, as
well as any other functional unit of a data station that serves as
a data source or a data sink (or both).
[0014] In-home telephone service usually employs two or four wires,
to which telephone sets are connected via telephone outlets.
[0015] Home Networking Existing in-house Wiring.
[0016] Similarly to the powerlines and CATV cabling described
above, it is often desirable to use existing telephone wiring
simultaneously for both telephony and data networking. In this way,
establishing a new local area network in a home or other building
is simplified, because there is no need to install additional
wiring. Using FDM technique to carry video over active residential
telephone wiring is disclosed by U.S Pat. No. 5,010,399 to Goodman
et al. and U.S. Pat. No. 5,621,455 to Rogers et al.
[0017] Existing products for carrying data digitally over
residential telephone wiring concurrently with active telephone
service by using FDM commonly uses a technology known as HomePNA
(Home Phoneline Networking Alliance) whose phonelines interface has
been standardized as ITU-T (ITU Telecommunication Standardization
Sector) recommendation G.989.1. The HomePNA technology is described
in U.S. Pat. No. 6,069,899 to Foley, U.S. Pat. No. 5,896,443 to
Dichter, U.S. Patent application 2002/0019966 to Yagil et al., U.S.
Patent application 2003/0139151 to Lifshitz et al. and others. The
available bandwidth over the wiring is split into a low-frequency
band capable of carrying an analog telephony signal (POTS), and a
high-frequency band is allocated for carrying data communication
signals. In such FDM based configuration, telephony is not
affected, while a data communication capability is provided over
existing telephone wiring within a home.
[0018] Prior art technologies for using the in-place telephone
wiring for data networking are based on single carrier modulation
techniques, such as AM (Amplitude Modulation), FM (Frequency
Modulation) and PM (Phase Modulation), as well as bit encoding
techniques such as QAM (Quadrature Amplitude Modulation) and QPSK
(Quadrature Phase Shift Keying) and CCK (Complementary Code
Keying). Spread spectrum technologies, to include both DSSS (Direct
Sequence Spread Spectrum) and FHSS (Frequency Hopping Spread
Spectrum) are known in the art. Spread spectrum commonly employs
Multi-Carrier Modulation (MCM) such as OFDM (Orthogonal Frequency
Division Multiplexing). OFDM and other spread spectrum are commonly
used in wireless communication systems, and in particular in WLAN
networks. As explained in the document entitled "IEEE 802.11g
Offers Higher Data Rates and Longer Range" to Jim Zyren et al. by
Intersil which is incorporated herein by reference, multi-carrier
modulation (such as OFDM) is employed in such wireless systems in
order to overcome the signal impairment due to multipath. Since
OFDM as well as other spread spectrum technologies are considered
to be complex and expensive (requiring Digital Signal
Processors--DSP), and since telephone wiring is considered a better
communication medium wherein multipath is less considered as a
major impairment than it is in wireless networks, OFDM technique
(and any other spread spectrum or any multi-carrier modulation),
which is considered to be powerful and high performance, has not
been suggested as a dominant modulation for wired communication in
general and over telephone wiring in particular.
[0019] There is thus a widely recognized need for, and it would be
highly advantageous to have a method and system for using spread
spectrum modem technologies such as OFDM for wired applications,
such as over utility wiring, and in particular over telephone
wiring.
[0020] Wireless Home Networking.
[0021] A popular approach to home networking (as well as office and
enterprise environments) is communication via radio frequency (RF)
distribution system that transports RF signals throughout a
building to and from data devices. Commonly referred to as Wireless
Local Area Network (WLAN), such communication makes use of the
Industrial, Scientific and Medical (ISM) frequency spectrum, which
is unregulated and license free. In the US, three of the bands
within the ISM spectrum are the A band, 902-928 MHz; the B band,
2.4-2.484 GHz (a.k.a. 2.4 GHz); and the C band, 5.725-5.875 GHz
(a.k.a. 5 GHz). Overlapping and/or similar bands are used in
different regions such as Europe and Japan.
[0022] In order to allow interoperability between equipments
manufactured by different vendors, few WLAN standards have evolved,
as part of the Institute of Electrical and Electronic Engineers
(IEEE) 802.11 standard group, branded as WiFi Error! Hyperlink
reference not valid. the Wi-Fi Alliance of Austin, Tex., USA. IEEE
802.11b describes a communication using the 2.4 GHz frequency band
and supporting communication rate of 11 Mb/s, IEEE 802.11a uses the
5 GHz frequency band to carry 54 MB/s and IEEE 802.11g uses the 2.4
GHz band to support 54 Mb/s. This is described in an Intel White
Paper entitled "54 Mbps IEEE 802.11 Wireless LAN at 2.4 GHz", and a
chip-set is described in an Agere Systems White Paper entitled
"802.11 Wireless Chip Set Technology White Paper", both of these
documents being incorporated herein by reference.
[0023] A node/client with a WLAN interface is commonly referred to
as STA (Wireless Station/Wireless client). The STA functionality
may be embedded as part of the data unit, or alternatively may be a
dedicated unit, referred to as bridge, coupled to the data unit.
While STAs may communicate without any additional hardware (ad-hoc
mode), such network usually involves Wireless Access Point (a.k.a.
WAP or AP) as a mediation device. The WAP implements the Basic
Stations Set (BSS) and/or ad-hoc mode based on Independent BSS
(IBSS). STA, client, bridge and WAP will be collectively referred
to herein as WLAN unit.
[0024] Bandwidth allocation for IEEE802.11g wireless in the USA is
shown as graph 20 in FIG. 2, along the frequency axis 27. In order
to allow multiple communication sessions to take place
simultaneously, eleven overlapping channels are defined spaced 5
MHz apart, spanning from 2412 MHz as the center frequency for
channel number 1 (shown as 23), via channel 2 centered at 2417 MHz
(shown as 24) and 2457 MHz as the center frequency for channel
number 10 (shown as 25), up to channel 11 centered at 2462 MHz
(shown as 26). Each channel bandwidth is 22 MHz, symmetrically
(.+-.11 MHz) located around the center frequency.
[0025] WLAN unit block diagram 10 is shown in FIG. 1. For the sake
of simplicity, only IEEE802.11g will be described from now on. In
general, the wireless physical layer signal is handled in two
stages. In the transmission path, first the baseband signal (IF) is
generated based on the data to be transmitted, using 256 QAM
(Quadrature Amplitude Modulation) based OFDM (Orthogonal Frequency
Division Multiplexing) modulation technique, resulting in a 22 MHz
(single channel wide) frequency band signal. The signal is then up
converted to the 2.4 GHz (RF) and placed in the center frequency of
the required channel, and wirelessly transmitted via the antenna.
Similarly, the receiving path comprises a received channel in the
RF spectrum, down converted to the baseband (IF) from which the
data is then extracted.
[0026] The WLAN unit 10 connects to the wired medium via port 11,
supporting an IEEE802.3 10/100BaseT (Ethernet) interface. The
physical layer of this interface is handled by a 10/100BaseT PHY
function block 12, converting the incoming Manchester or MLT3
modulated signal (according to the 10BaseT or 100BaseTX coding,
respectively) into a serial digital stream. Similarly, a WLAN
outgoing digital data stream is modulated to the respective coded
signal and transmitted via the port 11, implementing full duplex
communication. The internal digital stream may be of proprietary
nature of any standard such as MII (Media Independent Interface).
Such MII to Ethernet PHY 12 (a.k.a. Ethernet physical layer or
Ethernet transceiver) can be implemented based on LAN83C180 10/100
Fast Ethernet PHY Transceiver available from SMSC--Standard
Microsystems Corporation of Hauppauge, N.Y. U.S.A. While this
function can be implemented by using a single dedicated component,
in many embodiments this function is integrated into single
component including other functions, such as handling higher
layers. The PHY block 12 also comprises the isolation magnetics,
balancing, surge protection and connector (commonly RJ-45) required
for proper and standard interface via port 11.
[0027] For the sake of simplicity, in the foregoing and subsequent
description only Ethernet 10/100BaseT interface will be described.
However, it will be appreciated that any wired interface, being
proprietary or standard, packet or synchronous, serial or parallel
may be equally used, such as IEEE1394, USB, PCI, PCMCIA or
IEEE1284. Furthermore, multiple such interfaces (being of the same
type or mixed) may also be used.
[0028] In the case wherein the WLAN unit is integrated and enclosed
within another unit (such as data unit, e.g. computer) and does not
support a dedicated and direct wired interface, the function of
block 12 may be omitted.
[0029] MAC (Media Access Control) and higher layers are handled in
function block 13, comprising two sub blocks, designated as
10/100BaseT MAC block 13a and IEEE802.11g MAC block 13b (typically,
the same MAC device is used for all IEEE802.11 variants, such as
a/b/g). The MAC block 13a handles the MAC layer according to
IEEE802.3 MAC associated with the wired port 11. Such a function
block 13a may be implemented using LAN91C111 10/100 Non-PCI
Ethernet Single Chip MAC+PHY available from SMSC--Standard
Microsystems Corporation of Hauppauge, N.Y. U.S.A, which includes
both the MAC 13a and the PHY 12 functionalities. Reference is made
to the manufacturer's data sheet: SMSC--Standard Microsystems
Corporation, LAN91C111 10/100 Non-PCI Ethernet Single Chip MAC+PHY,
Datasheet Rev. 15 (02-20-04), which is incorporated herein by
reference. Similarly, the MAC block 13b handles the MAC layer
according to IEEE802.11g MAC associated with the wireless port 22.
Such MAC 13b is designed to support multiple data rates, encryption
algorithms and is commonly based on an embedded processor and
various memories. Such a functional block 13b may be implemented
using WaveLAN.TM. WL60040 Multimode Wireless LAN media Access
Controller (MAC) from Agere Systems of Allentown, Pa. U.S.A., whose
a product brief is incorporated herein by reference, which is part
of a full chip-set as described in WaveLAN.TM. 802.11a/b/g Chip Set
document from Agere Systems of Allentown, Pa. U.S.A., which is
incorporated herein by reference. Reference is made to the
manufacturer's data sheet Agere Systems, WaveLAN.TM. WL60040.
Multimode Wireless LAN Media Access Controller (MAC), Product Brief
August 2003 PB03-164WLAN, which is incorporated herein by
reference. All the bridging required in order to connect the wired
IEEE802.3 MAC handled by block 13a to the wireless IEEE802.11g MAC
handled by block 13b is also included in functional block 13,
allowing for integrated and proper operation.
[0030] The data stream generated by the IEEE802.11g MAC 13b is
converted to an OFDM-based baseband signal (and vice versa) by the
baseband processor 18. In common applications, the baseband
processor 18 (a.k.a. wireless modem and IF transceiver) is
implemented by a transmitter/receiver 14 digitally processing the
data stream, and an analog unit (I-Q modulator) 15 generating the
actual signal. The communication channel in wireless environments
imposes various impairments such as attenuation, fading,
multi-path, interferences among others, and the transmitter may
process the data stream according to the following functions:
[0031] a. Packet framing, wherein the data from the MAC 13 is
adapted and organized as packets, wherein header, CRC, preamble,
control information and end-of-frame delimiter are added. [0032] b.
Scrambler. [0033] c. Convolution encoder (such as Viterbi encoder)
to allow better robustness against channel impairments such as
impulse and burst noise. [0034] d. Puncturer to reduce the required
data rate. [0035] e. Interleaver performing permutations on the
packet blocks (e.g. bytes) in order to better immune against error
bursts by spreading the information. [0036] f. IFFT modulator to
produce separate QAM (quadrature Amplitude Modulation)
constellation sub-carriers.
[0037] Using digital to analog conversion, the processed digital
from the transmitter 14 is used to generate the OFDM baseband
signal in the modulator 15. The received OFDM baseband signal from
functional block 16 is digitized by the modulator 15, processed by
the receiver 14, transferred to MAC 13 and PHY 12 to be conveyed
via port 11. Some implementations of WLAN chipsets provide the
actual baseband signal, while others provides orthogonal analog I/Q
modem signals which need to be further processed to provide the
actual real analog form IF (Intermediate Frequency) OFDM baseband
signal. In such a case, as known in the art, a Local Oscillator
(LO) determining the IF frequency is used to generate a sine wave
which is multiplied by the I signal, added to the Q signal
multiplied by 90 degrees shifted LO signal, to produce the real
analog IF baseband signal. Such function can be implemented based
on Maxim MAX2450 3V, Ultra-Low-Power Quadrature
Modulator/Demodulator from Maxim Integrated Products of Sunnyvale,
Calif. U.S.A, a data sheet of which is incorporated herein by
reference. The baseband processor block 18 may be implemented based
on WaveLAN.TM. WL64040 Multimode Wireless LAN Baseband from Agere
Systems of Allentown, Pa. U.S.A., whose product brief is
incorporated herein by reference. SA5250 Multi-Protocol Baseband
from Philips Semiconductors including both baseband processor 18
and MAC 13b functionalities may be alternatively used.
[0038] The RF-IF Converter functional block 16 shifts the IF OFDM
baseband signal from the IF band to the ISM RF band. For example,
an OFDM baseband signal symmetrically centered around 10 MHz and
required to use channel 2 centered at 2417 MHz, is required to be
frequency shifted by 2417-10=2407 MHz. Such frequency conversion
may use many methods known in the art. A direct modulation
transmitter/receiver may be used, such as WaveLAN.TM. WL54040
Dual-Band Wireless LAN Transceiver from Agere Systems of Allentown,
Pa. U.S.A., for directly converting the orthogonal I-Q analog
signal to the 2.4 GHz RF band. A product brief is incorporated
herein by reference. Alternatively, superheterodyne (dual
conversion, for example) architecture may be used, as described for
SA5251 Multiband RF Transceiver from Philips Semiconductors. The
converter 16 and the baseband processor 18 constitute the wireless
path physical layer processor 17.
[0039] A T/R switch 19 is used to connect the antenna 22 to the
transmitter path and disconnect the receiver path (to avoid
receiver saturation) only upon a control signal signaling
transmission state of the WLAN unit 10. PIN Diode switch based
design is commonly used, such as PIN Diode switch SWX-05 from
MCE--KDI Integrated Products of Whippany, N.J. U.S.A., whose data
sheet is incorporated herein by reference. The antenna 22 is
coupled via a RF filter 21 in order to ensure transmitting limited
to the defined band mask (removing unwanted residual signals), and
to filter out noise and out of band signal in the receiving mode.
Such RF filter 21 may use SAW (Surface Acoustic wave) technology,
such as 2441.8 MHz SAW Filter from SAWTEK (A TriQuint company) of
Orlando, Fla. U.S.A., whose data sheet is incorporated herein by
reference.
[0040] Actual implementation of the WLAN unit 10 may also involve
amplifiers, attenuators, limiters, AGC (Automatic Gain Control) and
similar circuits involved with signal level functions. For example,
a Low Noise Amplifier (LNA), such as MAX2644 2.4 GHz SiGe, High IP3
Low-Noise Amplifier is commonly connected in the receive path near
the antenna 22. Similarly, a Power Amplifier (PA) is used in the
transmit path, such as MAX2247 Power Amplifier for IEEE802.11g
WLAN. Both the LNA and the PA are available from Maxim Integrated
Products of Sunnyvale, Calif. U.S.A. For the sake of simplicity,
such functions are omitted in FIG. 1 as well as in the rest of this
document. Similarly, wherever either a transmitting or a receiving
path is described in this document, it should be understood that
the opposite path also exists for configuring the reciprocal
path.
[0041] Outlets
[0042] The term "outlet" herein denotes an electro-mechanical
device, which facilitates easy, rapid connection and disconnection
of external devices to and from wiring installed within a building.
An outlet commonly has a fixed connection to the wiring, and
permits the easy connection of external devices as desired,
commonly by means of an integrated connector in a faceplate. The
outlet is normally mechanically attached to, or mounted in, a wall
or similar surface. Non-limiting examples of common outlets
include: telephone outlets for connecting telephones and related
devices; CATV outlets for connecting television sets, VCR's, and
the like; outlets used as part of LAN wiring (a.k.a. structured
wiring) and electrical outlets for connecting power to electrical
appliances. The term "wall" herein denotes any interior or exterior
surface of a building, including, but not limited to, ceilings and
floors, in addition to vertical walls.
[0043] Wireless coverage.
[0044] Most existing wireless technologies such as IEEE802.11x
(e.g. IEEE802.11a/g/b), BlueTooth.TM., UWB (Ultra WideBand) and
others are limited to tens of meters in free line of sight
environment. In common building environments, wherein walls and
other obstacles are present, the range may be dramatically reduced.
As such, in most cases a single wireless unit (such as an access
point) cannot efficiently cover the whole premises. In order to
improve the coverage, multiple access points (or any other WLAN
units) are commonly used, distributed throughout the premises.
[0045] In order to allow the access points to interconnect in order
to form a single communication cluster in which all the WLAN units
can communicate with each other and/or with wired data units, a
wired backbone is commonly used, to which the access points are
connected. Such a network combining wired and wireless segments is
disclosed for example in U.S. Pat. No. 6,330,244 to Swartz et al.
Such a configuration is popular today in offices, businesses,
enterprises, industrial facilities and other premises having a
dedicated wiring network structure, commonly based on Category 5
cabling (a.k.a. structured wiring). The access points interface the
existing wiring based on local area network (LAN), commonly by a
standard data interface such as Ethernet based 10/100BaseT.
[0046] However, installing a dedicated network wiring
infrastructure in existing houses is not practical as explained
above. The prior art discloses using existing AC power wiring also
as the wired backbone for interconnecting WLAN units. Examples of
such prior art includes U.S. Pat. No. 6,535,110 to Arora et al.,
U.S. Pat. No. 6,492,897 to Mowery, Jr., U.S. Patent application
2003/0224728 to Heinonen et al., U.S. Pat. No. 6,653,932 to Beamish
et al. Using powerlines as a backbone for connecting WLAN units
involves several drawbacks. The type of wiring, noise and the
general hostile environment results in a poor and unreliable
communication medium, providing low data rates and requiring
complex and expensive modems. In addition, the connection of a WLAN
unit to the powerline requires both wireless and powerline modems
for handling the physical layer over the two media involved, as
well as a complex MAC (Media Access control) to bridge and handle
the two distinct protocols involved. As such, this solution is
complex, expensive and offers low reliability due to the amount of
hardware required.
[0047] There is thus a widely recognized need for, and it would be
highly advantageous to have a method and system for using wireless
modem technologies and components in a wired applications.
Furthermore, it would be highly advantageous to have a method and
system for cost effectively enlarging the coverage of a wireless
network by carrying a wireless signal over a wired medium without
converting to a dedicated wired modem signal.
SUMMARY OF THE INVENTION
[0048] It is therefore an object of the invention to provide a
method and system for using standard existing wireless components
for wired communication.
[0049] According to the invention, a standard wireless baseband
signal that is conducted by existing wireless components (widely
used for wireless transmission), is coupled and carried by a
wiring, as a substitute for a dedicated wiring modem. As such, a
network (such as local area network) can be configured over the
wiring, either in bus topology, point-to-point or any other
arbitrary network topology. The invention is based on a WLAN unit
design, comprising a wired data port and a wireless port (e.g.
antenna) and enabling a data unit connected to the wired data port
(either proprietary or standard) to wirelessly communicate with
other data unit.
[0050] In one aspect of the present invention, a device is based on
a WLAN data design. However, only the baseband signal is used, so
that the baseband to RF portion (hereinafter `RF portion`) of the
WLAN unit may be obviated. The baseband signal may be coupled to
the wiring via isolation, analog switching, driver and receiver,
filtering and impedance matching functionalities, allowing for
networking over the wiring with one or more similar devices coupled
thereto.
[0051] In another aspect of the present invention, the RF portion
of the WLAN unit is also used. In this case, an up/down converter
is connected to the RF port (instead of connecting antenna
thereto). The converter shifts the center frequency down to a band
usable over the wiring.
[0052] In another aspect of the present invention, the full
functionality of the WLAN unit is retained, including both the
antenna and the RF portion. A wiring port coupled either directly
to the baseband signal or to the RF signal via an up/down converter
is added. In this case, a three ports sharing device is formed,
having a wiring port, wireless (antenna) port and data unit port.
Data units connected to a network comprising such multiple devices
may be interconnected by the wired medium (via the wiring) or via
the air using the RF signals propagating through the air.
[0053] In another aspect of the present invention, the device
comprises only the RF portion of a WLAN unit (including antenna).
The antenna RF signal is frequency shifted by an up/down converter
to a frequency band usable by the wiring (e.g. baseband signal). A
similar device or a device according to any of the above
embodiments connected to the wiring may couple to the signal, and
use it for coupling to a data unit either directly or
wirelessly.
[0054] Any single pair wiring may be used as a medium for the
baseband signal. In another aspect of the present invention, the
wiring is utility wiring in a building, such as telephone, CATV or
AC power wiring. In the case wherein the utility wiring also
carries an active service signal (e.g. telephone, CATV or AC power
signal respectively), FDM technique is used, wherein the service
signal and the baseband signal are carried in distinct frequency
bands. In another aspect of the present invention, the device
further provides a service connector allowing a service unit to be
connected thereto. In any case of wiring carrying active service
signal, various filters are employed in order to isolate the
service signal from the baseband signal, to avoid any interference
between the two signals.
[0055] In another aspect of the present invention, the device may
be comprised in a data unit. Alternatively, the device may be
enclosed as a stand-alone dedicated unit. In another aspect of the
present invention, the device is comprised within a service outlet.
Alternatively, the device may be enclosed as outlet add-on
module.
[0056] The device may be locally powered by a dedicated connection
to a local power source (e.g. AC power, directly or via AC/DC
converter). Alternatively, the device is power fed from a power
signal carried over the wiring. In the latter case, a circuitry
isolating the power signal carried over the wiring is employed. In
another aspect of the present invention, the device is powered by a
data unit connected thereto.
[0057] In another aspect of the present invention, spread spectrum
(either DSSS or FHSS) techniques such as employing a multi-carrier
modulation (e.g. OFDM, DMT or CDMA) modem, which due to its
complexity is mainly used for wireless applications, may be used
over a wired medium such as utility wiring in a building (e.g.
telephone wiring).
[0058] It is understood that other embodiments of the present
invention will become readily apparent to those skilled in the art
from the following detailed description, wherein are shown and
described only embodiments of the invention by way of illustration.
As will be realized, the invention is capable of other and
different embodiments and its several details are capable of
modification in various other respects, all without departing from
the scope of the present invention as defined by the claims.
Accordingly, the drawings and detailed description are to be
regarded as illustrative in nature and not as restrictive.
BRIEF DESCRIPTION OF THE DRAWINGS
[0059] The invention is herein described, by way of non-limiting
example only, with reference to the accompanying drawings,
wherein:
[0060] FIG. 1 shows schematically a general functional block
diagram of a prior art WLAN unit.
[0061] FIG. 2 shows schematically the frequency spectrum allocation
of IEEE802.11g standard.
[0062] FIG. 3 shows schematically a general functional block
diagram of an exemplary OFDM modem according to the invention.
[0063] FIG. 4 shows schematically the frequency spectrum allocation
over the telephone wiring according to the invention.
[0064] FIG. 5 shows schematically a general functional block
diagram of an exemplary up/down converter according to the
invention.
[0065] FIG. 6 shows schematically a general functional block
diagram of an exemplary OFDM modem according to the invention.
[0066] FIG. 6a shows schematically a general functional block
diagram of an exemplary line interface according to the
invention.
[0067] FIG. 6b shows schematically a general functional block
diagram of an exemplary network according to the invention.
[0068] FIG. 7 shows schematically a general functional block
diagram of an exemplary network according to the invention.
[0069] FIG. 8 shows schematically a view of an exemplary telephone
outlet according to the invention.
[0070] FIG. 9 shows schematically a view of an exemplary telephone
module according to the invention.
[0071] FIG. 10 shows schematically a general functional block
diagram of an exemplary OFDM modem according to the invention.
[0072] FIG. 10a shows schematically a general functional block
diagram of an exemplary OFDM modem according to the invention.
[0073] FIG. 11 shows schematically a view of an exemplary telephone
module according to the invention.
[0074] FIG. 12 shows schematically a general functional block
diagram of an exemplary network according to the invention.
[0075] FIG. 13 shows schematically a general functional block
diagram of an exemplary OFDM modem according to the invention.
[0076] FIG. 14 shows schematically a general functional block
diagram of an exemplary network according to the invention.
[0077] FIG. 15 shows schematically a general functional block
diagram of an exemplary OFDM modem according to the invention.
[0078] FIG. 16 shows schematically a general functional block
diagram of an exemplary OFDM modem according to the invention.
[0079] FIG. 17 shows schematically a general functional block
diagram of an exemplary network according to the invention.
DESCRIPTION OF EXEMPLARY EMBODIMENTS OF THE INVENTION
[0080] The principles and operation of a network according to the
present invention may be understood with reference to the drawings
and the accompanying description wherein similar components
appearing in different figures are denoted by identical reference
numerals. The drawings and descriptions are conceptual only. In
actual practice, a single component can implement one or more
functions; alternatively, each function can be implemented by a
plurality of components and circuits. In the drawings and
descriptions, identical reference numerals indicate those
components that are common to different embodiments or
configurations.
[0081] A wireless based OFDM modem 30 adapted for operating over
telephone wiring according to one or more embodiments of the
present invention is described in FIG. 3. OFDM modem 30 is
primarily based on the design and components shown as WLAN unit 10
in FIG. 1. In contrast to WLAN unit 10, the RF signal is not
coupled to antenna 22, but rather connect to an up/down converter
31. The converter 31 shifts the ISM band baseband signal to a band
usable over telephone wiring in home/office or any other building.
Owing to FCC regulation in North America regarding radiated
electromagnetic emission, the usable frequency band is considered
to extend up to 30 MHz. Hence, a spectrum allocation for a baseband
signal occupying 22 MHz may be between 8 MHz and 30 MHz (centered
around 19 MHz), as shown in curve 43 being part of graph 40 in FIG.
4, illustrating the various power levels allocation along the
frequency axis 44. Such allocation allows for ADSL signal 42 using
the 100 KHz (or 25 KHz) to 1.1 MHz and the POTS signal curve 41.
ADSL is an acronym for Asymmetric Digital Subscriber Line uses
standard phone lines to deliver high-speed data communications both
upstream and downstream, using a part of a phone line's bandwidth
not used for voice so as to allow simultaneous voice and data
communication.
[0082] As a non-limiting example, in the case wherein the WLAN unit
30 is using channel 10 (shown as curve 25 in FIG. 2) centered
around 2457 MHz, the converter is required to shift the frequency
up or down by 2457-19=2438 MHz resulting in the frequency
allocation shown in graph 40.
[0083] In order to avoid interference to and from the other signals
(POTS 41 and ADSL 42) carried over the same telephone pair, a High
Pass Filter (HPF) 32 is connected between the converter 31 and the
telephone wiring connector 36. The telephone wiring connector 36 in
commonly a telephone standard RJ-11 plug used in North America,
allowing for coupling the OFDM modem 30 to the telephone pair. The
HPF 32 may use passive components implementing a Butterworth filter
scheme. In some cases, a telephone unit is required to share the
same telephone wiring connector 35. In such a case, a Low Pass
Filter (LPF) 34 is used to isolate the POTS frequency band,
allowing a telephone set to couple to the telephone connector 35
via a telephone jack (e.g. RJ-11 jack). Any common filter used to
isolate POTS and ADSL signals (a.k.a. micro-filter) may be used as
LPF 34, comprising discrete capacitors and inductors). Such
configuration of connecting modem and telephone via a set of LPF
and HPF units is known in the art and commonly used also in HomePNA
environment.
[0084] OFDM and other spread spectrum modulation techniques are
known to be powerful, robust and high-performance. Yet, their
implementation complexity and associated costs have militated
against their use in communication systems. Even the first WLAN
technologies introduced used single-carrier technologies, such as
IEEE802.11b using CCK. As such, the OFDM modem 30 shown in FIG. 3
may be used as a superior substitute to the prior art HomePNA based
phonelines communication. Since the powerful OFDM technology is
used, the modem performance is expected to exceed any available or
future HomePNA technology using single carrier modulation (such as
QAM) as known in the prior-art. Furthermore, since the modem
utilizes existing off-the-shelf wireless oriented components such
as the wireless MAC 13b, the baseband processor 18 and the RF-IF
converter 16, the required effort to develop a dedicated modem is
obviated. Furthermore, the rapid proliferation of the WLAN
solutions to the residential, office, enterprise and industrial
applications, a trend expected to even grow in the future,
indicates a high volume of WLAN components, resulting in easy
availability, low price and ensured interoperability.
[0085] Up/Down converter 31 used for shifting the frequency as
described above is well known in the art. Such converters are known
to use mixing and filtering techniques, and may use single or
multiple stages (Superheterodyne scheme) as well as Direct
Conversion (DC) architecture. A non-limiting example for Up/Down
Converter function block 37, shown in FIG. 3 to include the
functions of the converter unit 31, the RF filter 21 and TX/RX
Switch 19, is shown as block 50 in FIG. 5. Such a block 50 shifts
the frequency of the RF signal coupled to port 51 to a low
frequency (IF) signal in port 68. RF Signal received in port 51 is
shifted down by a down channel based on mixer 57a and Band Pass
Filter (BPF) 58a and is outputted at port 68. Similarly, an IF
signal received in port 68 is shifted to the RF band by the up
channel comprising mixer 57b and BPF 58b, and as RF signal
outputted via port 51. The RF port 51 is coupled to the HPF 32 of
the OFDM modem 30 and the IF port 68 is coupled to the RF-IF
converter 16 of the OFDM modem 30.
[0086] While transmitting to the telephone pair via connector 36, a
RF signal received in port 51 (from the RF-IF converter 16) is
first filtered by the BPF 52 to remove any unwanted signals
residing outside the frequency band of the RF channel (e.g. the ISM
RF channel band). Since the converter 50 allows conversion in only
one direction at a time, either up or down, ganged switches 56a and
56b are used, having a center pole marked as (1) and two throw
states marked as (2) and (3). When converting from RF to IF, both
switches 56a and 56b are in the (2) state, hence the down channel
is operative. Such a switch may be based on PIN diode as explained
above regarding switch 19. The RF signal from the RF port 51
couples to mixer 57a via BPF 52 and switch 56a. The mixer 57a
multiplies the local oscillator 54 sine wave signal provided to its
LO port via a splitter 55 by the RF signal coupled to its RF port
(using its non linear characteristics), yielding in its IF port a
signal having two main components, one around the sum of the
frequencies and one around their difference. The frequencies' sum
signal is then filtered out by the BPF 58a, and fed to the IF port
68 via the switch 56b. A driver 59 may also be included in order to
allow proper driving of the load connected to port 68. In a similar
way, when receiving from the telephone pair, an IF signal from port
68 (originated in the telephone pair, and coupled via connector 36
and HPF 32), is routed via the switch 56b (now in state (3)) to the
IF port of mixer 57b, via BPF 58b. A signal is also fed from the
local oscillator 54 via splitter 55 to the LO port of the mixer
57b, which outputs an RF signal to port 51 via the switch 56a (now
in state (3)) and BPF 52. A level detector (or comparator) 53 is
used to monitor the level of the revived RF signal, and accordingly
operate the switches 56a and 56b via control channels 69b and 69a
respectively.
[0087] The converter 50 has been described above as having
dedicated up and down channels. However, since only one channel is
used at a time and the two channels are not used simultaneously, a
single channel (mixer) may also be used, wherein an appropriate
switching mechanism is employed.
[0088] A level detector 53 may be designed based on LM311 Voltage
Comparator available from National Semiconductors headquartered in
Santa-Clara, Calif. U.S.A. The local oscillator 54 may be based on
quartz crystal oscillator, wherein the frequency is multiplied
using Phase Locked Loop (PLL) circuits, and may comprise T83027 PLL
Clock Generator IC with VCXO available from TLSI Incorporated of
Huntington, N.Y. U.S.A., whose data sheet is incorporated herein by
reference. A mixer 57 may be designed based on MAX9993 High
Linearity 1700 MHz Down-Conversion Mixer with LO Buffer/Switch
available from Maxim Integrated Products of Sunnyvale, Calif.
U.S.A, whose data sheet is incorporated herein by reference. It
should be noted that other techniques and methods to implement the
converter block 50 functionality are known in the art and may be
equally used. Typically, converter block 50 may connect to the
telephone wiring using line interface functionalities such as
isolation, impedance matching, driving/receiving and filtering, as
will be described below for line interface 76 shown in FIG. 6.
[0089] The OFDM modem 30 inherently employs double frequency
conversions: from IF to RF by converter 16 and back to low
frequency by converter 31. This redundancy may be obviated by
directly extracting the baseband signal without going through the
RF stage, as shown in OFDM modem functional block diagram 60
illustrated in FIG. 6, which may be used in one or more embodiments
of the present invention.
[0090] Similar to modem 30, modem 60 is based on WLAN unit 10
described in FIG. 1. However, the OFDM baseband signal generated by
the broadband processor 18 is not frequency shifted to RF, but
rather handled directly in the IF spectrum. In one non-limiting
example, the baseband processor 18 provides an orthogonal analog
I/Q signal pair. In this case, a line interface 76 using a
Quadrature Modulator/Demodulator 191 shown in FIG. 6a converts the
signals directly to a baseband analog signal centered around 19 MHz
(for example by using 19 MHz local oscillator) in the example of
spectrum allocation according to graph 40. In another example, an
analog signal centered around another frequency is output by the
WLAN components comprising baseband processor 18, and in such a
case a simple and single frequency conversion may be used in order
to center the signal around 19 MHz.
[0091] A functional block diagram of the line interface 76 is shown
in FIG. 6a. The line interface 76 couples to the I-Q modulator 15
in the baseband processor 18 via port 192. The I-Q signals are
converted into a single real signal centered around the 19 MHz
frequency (shifted from zero) by the Quadrature
Modulator/Demodulator 191, which may be based on Maxim MAX2450 3V,
Ultra-Low-Power Quadrature Modulator/Demodulator from Maxim
Integrated Products of Sunnyvale, Calif. U.S.A, whose data sheet
which is incorporated herein by reference. The
Modulator/Demodulator output impedance is 75 ohms terminated by a
resistor 190 (if required), and fed to a driver 186 via BPF 188a,
passing only the required band (e.g. band 43 in graph 40). An
analog switch 183 routes the transmitted signal to the telephone
wiring (via port 36 and HPF 32) via an isolation unit 182 and
through port 181. The isolation unit 182 is typically based on a
signal transformer 193, and serves to reduce common-mode noises so
as to provide a balanced signal, as well as meeting the required
safety and ESD requirements imposed by the UL in the U.S.A. and CE
in Europe.
[0092] Similarly, a signal received from the telephone wiring is
isolated by the isolation unit 182, and routed via the analog
switch 183 to an AGC 187. A 100 Ohm resistor 185 serves as a
termination, matching the telephone wiring characteristic impedance
to avoid reflection. After being filtered by a BPF 188b, the signal
is I-Q modulated by the modulator 191 and coupled to the baseband
processor 18.
[0093] A sample network 75 over a telephone line using OFDM modems
is shown in FIG. 6b. A telephone wiring infrastructure as commonly
exists in residences in North America is described, based on single
telephone pair 62 accessed via outlets 63. A daisy-chain
configuration is shown, wherein wiring segment 62d connects outlets
63d and 63c, wiring segment 62c connects outlets 63b and 63c and
wiring segment 62b connects outlets 63a and 63b. Wiring segment 62a
connects the `first` outlet 63a to the PSTN (Public Switched
Telephone Network) 61 via a junction box (not shown) and the
external wiring part known as `local loop` or `subscriber loop`. In
each outlet, a standard telephone RJ-11 jack is connected to the
wiring 62, allowing telephone units to be connected thereto, using
RJ-11 plug. Outlets 63a, 63b, 63c and 63d respectively comprise
jacks 64a, 64b, 64c and 64d. Other wiring topologies such as `star`
(a.k.a. `HomeRun`, `structured wiring`), tree and mixed topologies
are also available, and are also suitable.
[0094] OFDM Modems 30 and 60 may be connected to and networked over
the telephone wiring 62 by connecting to the respective RJ-11
telephone connector 64 in outlet 63, and via cable 74 to the OFDM
modem connector 36, marked as `wiring` connection. A network may
include only OFDM modems 30 as shown functionally in FIG. 3, or
only OFDM modems 60 as shown functionally in FIG. 6 or any
combination thereof. The network 75 is shown to include an OFDM
modem 30b connected by a cable 74d to outlet 63d, an OFDM modem 60a
connected by a cable 74b to outlet 63b and OFDM modem 30a connected
by a cable 74a to outlet 63a. In each case, connection to the
outlets is via the respective connectors 64d, 64b and 64a. Computer
66a is shown connected to the OFDM modem 30b via its `data` port
(representing port 33 in FIG. 3), and computer 66b is connected to
OFDM modem 60a via its `data` port (representing port 33 in FIG.
6). The computers 66 represent any data units, preferably connected
via a standard wired data interface. The modems 30a and 60a allow a
half duplex communication between the computers 66a and 66b over
the telephone wiring. Similarly, additional OFDM modem 30a may also
support an additional data unit through its `data` port.
[0095] Simultaneously with the data network formed over the
telephone line, the standard telephone service is also provided.
Telephone set 65a is connected to the wiring 62 (so as to connect
to the PSTN 61) via the `TEL.` Port (port 35 in FIG. 3). Similarly,
telephone sets 65c and 65d connect to the PSTN 61 (via the
respective outlets 63 and wiring 62) by connecting to OFDM modems
60a and 30a, respectively. Telephone set 65b is directly connected
to outlet 63c (via cable 74c and plug/jack 64c). In such a case,
the usage of LPF 34 (a.k.a. micro-filter) is recommended in order
to avoid interference to and from the other signals using the same
telephone wiring as a medium.
[0096] In order to enable the computers 66a and 66b to connect to
an external network (such as the Internet), a device connected to
the external network (either broadband or narrowband) is commonly
employed, non-limiting examples including a DOCSIS based cable
modem, an ADSL modem, wireless (such as WiMax) and others. Such a
device should be connected to the `data` port of any OFDM modem,
hence allowing sharing the external connection to data units
connected throughout the building. In one example, an ADSL modem 67
is used. The ADSL modem is shown to connect to the telephone outlet
63a via cable 74e for coupling to the ADSL signal 42 (depicted in
FIG. 4), and providing a standard data interface (e.g. USB,
10/100BaseT). This data interface in turn connects to the OFDM
modem 30a `data` port, thus allowing computers 66a and 66b to share
the ADSL connection via the formed network. The OFDM modem 30a is
likewise connected to the telephone outlet 63a via a cable 74a
(together with cable 74e).
[0097] While network 75 has been described with regard to `bus`
topology wherein all the modems are connected to the same medium
(telephone wiring 62), it is known that better communication
performance (e.g. data-rate) may be achieved in point-to-point
structure, wherein two modems are connected at the ends of a wiring
segment. Such configuration may exist in newly installed
infrastructures (e.g. structured wiring in a newly constructed
building) or in MDU (Multiple Dwelling Unit), MTU (Multiple Tenant
Unit) and MHU (Multiple Hospitality Unit). In all the above, the
wiring segments are in `star` topology, wherein each wiring segment
connects a remote site (e.g. apartment) to a center (e.g.
basement).
[0098] An application of OFDM modems to such topology is shown as a
non-limiting example as network 70 in FIG. 7. The infrastructure of
network 70 is described as comprising two wiring segments (each
comprising a single pair) 72a and 72b, respectively connected
between connection points 73a and 73b (e.g. in junction box) and
respective outlets 63a and 63b, allowing telephone connection via
the respective connectors 64a and 64b. In order to allow both
telephone and data signals over the same wire pair, OFDM modems
(either modem 30 or modem 60 types) are connected to each wiring
end. OFDM modem 60a connects to wiring segment 72a via outlet 63a,
communicating over the wiring segment 72a with OFDM modem 30a
connected to the other end of the wiring segment 72a via connection
point 73a. Telephone signals are carried over the lower band,
allowing telephone set 65a to connect to PSTN 61, simultaneously
with the OFDM signal carried over a distinct band and connecting
the computer 66a (representing any data unit) to the Internet 71
(via any connection such as ADSL DOCSIS cable modem or wireless).
Similarly, OFDM modem 30c connects to wiring segment 72b via outlet
63b, communi-cating over this pair with OFDM modem 30b connected to
the other end via connection point 73b. Telephone signals are
carried over the lower band, allowing telephone set 65b to connect
to PSTN 61, simultaneously with the OFDM signal carried over a
distinct band and connecting the computer 66b (representing any
data unit) to the Internet 71 (via any connection such as ADSL
DOCSIS cable modem or wireless).
[0099] Outlet Enclosed Modem.
[0100] Outlets in general (to include LAN structured wiring,
electrical power outlets, telephone outlets, and cable television
outlets) have traditionally evolved as passive devices being part
of the wiring system house infrastructure and solely serving the
purpose of providing access to the in-wall wiring. However, there
is a trend towards embedding active circuitry in the outlet in
order to use them as part of the home/office network, and typically
to provide a standard data communication interface. In most cases,
the circuits added serve the purpose of adding data interface
connectivity to the outlet, added to its basic passive connectivity
function.
[0101] An outlet supporting both telephony and data interfaces for
use with telephone wiring is disclosed in U.S. Pat. No. 6,549,616
entitled `Telephone outlet for implementing a local area network
over telephone lines and a local area network using such outlets`
to Binder. Such outlets are available as part of NetHome.TM. system
from SercoNet Inc. of Southborough, Mass. U.S.A.
[0102] Another telephone outlet is described in U.S. Pat. No.
6,216,160 to Dichter, entitled `Automatically configurable computer
network`. An example of home networking over CATV coaxial cables
using outlets is described in US Patent Application 2002/0194383 to
Cohen et al. entitled: `Cableran Networking over Coaxial Cables` to
Cohen et al. Such outlets are available as part of HomeRAN.TM.
system from TMT Ltd. of Jerusalem, Israel. Outlets for use in
conjunction with wiring carrying telephony, data and entertainment
signals are disclosed in US Patent Application 2003/0099228 to
Alcock entitled `Local area and multimedia network using radio
frequency and coaxial cable`. Outlets for use with combined data
and power using powerlines are described in US Patent Application
2003/0062990 to Schaeffer et al. entitled `Powerline bridge
apparatus`. Such power outlets are available as part of PlugLAN.TM.
by Asoka USA Corporation of San Carlos, Calif. USA.
[0103] While the active outlets have been described above with
regard to networks formed over wiring used for basic services (e.g.
telephone, CATV and power), it will be appreciated that the
invention can be equally applied to outlets used in networks using
dedicated wiring. In such a case, the outlet circuitry is used to
provide additional interfaces to an outlet, beyond the basic
service of single data connectivity interface. As a non-limiting
example, it may be used to provide multiple data interfaces wherein
the wiring supports single such data connection. An example of such
outlet is the Network Jack.TM. product family manufactured by
3Com.TM. of Santa-Clara, Calif., U.S.A. In addition, such outlets
are described in U.S. Pat. No. 6,108,331 to Thompson entitled
`Single Medium Wiring Scheme for Multiple Signal Distribution in
Building and Access Port Therefor` as well as U.S. Patent
Application 2003/0112965 Published Jun. 19, 2003 to McNamara et al.
entitled `Active Wall Outlet`.
[0104] While the outlets described above use active circuitry for
splitting the data and service signals, passive implementations are
also available. An example of such passive outlet is disclosed in
WO 02/25920 to Binder entitled `Telephone communication system and
method over local area network wiring`. Such outlets are available
as part of the etherSPLIT.TM. system from QLynk Communication Inc.
of College Station, Tex. USA.
[0105] As known in the art, from the data communication (high
frequency band) point of view, the cables 74 connected to the
outlets 63 in system 75 are known as `taps`. Cable 74c, terminated
in the LPF 34 is considered an `open tap` or `bridged tap`. The
same goes for cable 74e, terminating the ADSL band, but open for
higher frequencies. Cable 74b (as a non-limiting example) is
considered a `terminated tap`, since appropriate termination is
expected to be part of the OFDM modem 60a. Taps in general and
non-terminated taps in particular, are considered a major
impairment in any wired communication system. Reflections are
generated at the tap points and at the ends of open taps, resulting
in a `notch` pattern in the appropriate frequency. Such
characteristics render part of the spectrum non-usable. As such,
taps results in lower communication performance, and it is
therefore desirable to eliminate taps as much as practical.
[0106] Wireless system in general, and WLAN systems in particular
are associated with mobile and handheld devices such as PDA
(Personal Digital Assistant), cellular phone, remote-controller and
laptop computers. Being mobile and man-carried, the space and
weight of the wireless components is critical. As such, a lot of
resources are allocated to integration and miniaturization efforts
in order to make the wireless components as small as possible.
Vendors are increasingly focusing on integrating more and more
functions into a minimum set of chips and peripherals. Hence, the
small dimension featured by the wireless components makes them well
suitable to be housed within small enclosures such as outlets.
[0107] In one or more embodiments of the present invention, the
OFDM modem (partially or completely) is integrated into a telephone
outlet. In addition to providing all the advantages described in
the aforementioned prior art, such configuration eliminates the tap
related impairments, thus improving the communication performance.
As a non-limiting example, in the case the OFDM modem functionality
is integrated into outlet 63d, the cable 74d is effectively zero in
length, hence effectively eliminating the tap existence.
[0108] A pictorial view of such outlet integrating OFDM modem
functionality is shown as outlet 80 in FIG. 8. The telephone wiring
connector 36 is in the back of the outlet (facing the wall), for
connecting to the wiring in the common way of connecting wiring to
a telephone outlet. The outlet 80 front (facing the room) comprises
connector 33, shown as RJ-45 for 10/100BaseT interface. A telephone
connector 35a is shown as standard telephone connector RJ-11 jack.
A second connector 35b may also be used for allowing connection to
multiple telephone sets. The outlet 80 also comprises indicators
81a and 81b (LEDs) that may be used to indicate proper operation
such as power availability, communication status (such as LINK
signal in Ethernet systems), communication performance and
others.
[0109] The above-described outlet 80 is a complete and
self-contained device. As such, it can be easily installed in new
houses instead of regular passive simple outlets. However, such
solutions are not appropriate in the case of retrofitting existing
wiring systems. In most cases, any such modification will require
dismantling the existing outlets and installing the new ones having
the improved features. Such activity is cumbersome, expensive and
will often require professional skill. Furthermore, owing to safety
aspects involved while handling hazardous voltages (such as in the
powerlines and telephone lines), local regulations may require only
certified personnel to handle the wiring, making it expensive and
militating against a do-it-yourself approach.
[0110] Furthermore, as technology and circumstances change in time,
a need to upgrade, modify or change the outlet functionalities,
features and characteristics may arise. For example, the data
interface may need to be upgraded to interconnect with new
standards. In another example, the circuitry may need to be
upgraded to support higher bandwidth. Similarly, management and
Quality of Service (QoS) functionalities may need to be either
introduced or upgraded. In yet another example, additional
functionalities and interfaces may need to be added. Using complete
self-contained outlets as a substitute to the existing ones also
introduces the disadvantages described above.
[0111] One approach to adding functionality to existing outlets is
by using a plug-in module. Such plug-in modules for use with
powerline communication are described in US Patent Application
2002/0039388 to Smart et al. entitled `High data-rate powerline
network system and method`, US Patent Application 2002/0060617 to
Walbeck et al. entitled `Modular power line network adaptor` and
also in US Patent Application 2003/0062990 to Schaeffer, JR et al.
entitled Towerline bridge apparatus'. Such a module using
HomePlug.TM. technology are available from multiple sources such as
part of PlugLink.TM. products by Asoka USA Corporation of San
Carlos, Calif., USA. However, such plug-in modules are known only
with regards to power outlets, and are not available for telephone
or CATV outlets.
[0112] A plug-in module according to one or more embodiments of the
present invention is shown as module 90 in FIG. 9. The module 90 is
based on the outlet 80 described above.
[0113] However, in contrast to being an outlet, the module 90 has
an RJ-11 plug that plugs in the RJ-11 jack 93 of the telephone
outlet 91, the latter thus not requiring replacement or
modification. In order to allow mechanical securing of the
connection, the module 90 comprises two sliding sides 94a and 94b,
which are latched and pressed against the outlet 91 surfaces 92a
and 92b respectively. In this way, the module 90 is both
electrically connected to the wiring and mechanically attached to
outlet 91, while not requiring any specific skills or tools. The
POTS service is fully retained through the telephone connectors 35a
and 35b.
[0114] Wireless Port.
[0115] Both OFDM modems 30 and 60 described above offer two wired
ports, namely the data unit port 33 and the telephone wiring port
36, and function to convert signals between those ports. Adding a
wireless port will enable the OFDM modems also to network with data
units over a non-wired medium.
[0116] Such an OFDM modem 100 comprising an antenna 22 as a
wireless port is shown in FIG. 10. Generally, such a modem 100 can
be considered as a combination of a WLAN unit 10 and OFDM modem 30
respectively as described above in relation to FIGS. 1 and 3. Modem
100 is shown to include the full WLAN unit 10 functions, and as
such may function as WLAN unit 10. However, the RF signal is
coupled in between the RF-IF converter 16 and TX/RX Switch 19 by a
sharing device 101. The RF signal is thus also coupled to the
telephone wiring connector 36 via the Up/Down Converter 31 and the
HPF 32, similar to the description above relating to OFDM modem 30.
Similarly, a telephone set may be coupled via connector 35 and LPF
34.
[0117] The sharing device 101 is a three ports device and functions
to share the three RF signals, such that an RF signal received in
any one of the ports is replicated and shared by the other two
ports. One RF signal relates to the wireless radio communication
via the antenna 22, a second signal relates to the telephone wiring
carried signal via connector 36 and the third RF signal is
associated with the data port 33.
[0118] In such a configuration, the OFDM modem 100 communicates via
three ports: Wireless port via antenna 22, wired data unit port via
connector 33 and wired telephone wiring connector 36. A data packet
(such as Ethernet packet) received from the data unit connected via
port 33 will be converted to an OFDM RF signal at the RF-IF
Converter 16 port, and then fed via sharing device 101 to both the
telephone wiring after being down converted to a baseband signal by
the Up/Down Converter 31 and through HPF 32 (as described above for
modem 30), and in parallel (via sharing device 101) to the antenna
22 to be transmitted over the air. Similarly, an OFDM RF signal
received in the antenna 22 is fed via the sharing device 101 to
both the telephone wiring port 36 in analog baseband form and data
unit port 33 as digital packets. Baseband signals received via the
telephone wiring port will be converted to RF and then transmitted
to the air by the antenna 22 in parallel to being down frequency
converted and encoded into a packet in digital form in port 33. In
some cases, an RF signal may be received from both the antenna 22
and the telephone wiring (via port 36). Since wireless systems are
able to handle the through-air multi-path phenomenon, the signal
received via the telephone wiring channel should be appreciated as
another signal path, hence being handled by the baseband processor
18.
[0119] The three ports modem 100 is shown to share the three RF
signals by sharing device 101. In one or more embodiments of the
present invention, the sharing function is performed in the
baseband (or IF) frequency spectrum. Such a modem 105 is shown in
FIG. 10a. Similar to modem 100, three ports are supported, two
wired and one wireless. However, in contrast to modem 100, the
sharing device 106 shares three baseband signals: an antenna 22
coupled signal, via the RF-IF Converter 16, telephone wiring signal
via line interface 76 and data unit related signal via the baseband
processor 18. One advantage of such configuration is the use of a
single Up/Down Converter 16, rather than the two converters (16 and
31) used in modem 100 configuration.
[0120] Similar to the above discussion relating to OFDM modems 30
and 60, wireless-port equipped modems 100 and 105 may be equally
enclosed within a telephone outlet or snap-on module. Such a
snap-on module 110 attached to a telephone outlet 91 is shown in
FIG. 11. Module 110 is similar to module 90 shown in FIG. 9, but in
contrast attaches to the outlet using screws 111a and 111b rather
than by snap-fit connection. It should be noted that other
mechanical attachment means could be equally employed. In addition
to the wired ports shown for module 90, an antenna 22 is shown,
serving as additional over-the-air wireless port.
[0121] A network 120 utilizing a wireless port equipped OFDM modem
100 is shown in FIG. 12. OFDM modem 105 may be equally employed.
The network 120 is based on network 75 shown in FIG. 6b, wherein
OFDM modem 100a substitutes OFDM modem 30b, hence introducing a
wireless port 22a to the network. Computer 66a and telephone unit
65a connect to the OFDM modem 100a in a similar manner as before.
The additional port 22a allows for a laptop computer 66c to be
connected to the wireless bridge 121a comprising an antenna 22b.
Similarly, the wireless client functionality 121a may be built in
the computer 66c. A wireless link according to standard IEEE802.11g
is established between the bridge 121a and the modem 100a, hence
enabling the computer 66c to network with the other data units
connected to the telephone wiring 62, as well as to computer
66a.
[0122] While a single modem 100 or 105 is part of network 120, it
should be appreciated that multiple such modems may be used, each
covering a different area in the premises, hence enlarging the
actual wireless coverage. Furthermore, such network 120 offers the
user the flexibility of adding data units either through wiring (by
connecting to the data ports of the OFDM modems) or wirelessly (via
the wireless port).
[0123] In some cases, only wireless ports may be required, thus
tethered data unit connection may be obviated. According to one or
more embodiments of the present invention, a wireless adaptor 130
supporting only wireless port is shown in FIG. 13. The data unit
port 33 associated functions described for modem 100 in FIG. 10
(such as baseband processor 18, MAC layer processor 13 and PHY 12)
are omitted. The receiving path comprises the antenna 22, RF Filter
21 and TX/RX Switch 19. The received RF signal is then frequency
down shifted by Up/Down converter 31, and fed to the telephone
wiring via connector 36 and HPF 32. Similarly, any OFDM signal
carried by the telephone wiring is received and up converted to RF,
and then feeds the antenna 22. A telephone set may be connected to
the telephone wiring via connector 35 and LPF 34.
[0124] A network 140 employing the wireless adaptor 130 is shown in
FIG. 14. Wireless adaptors 130a and 13b are respectively connected
to outlets 63d and 63b, and respectively employ antennas 22a and
22c. Computer 66c is wirelessly coupled to the telephone wiring 62
via the wireless bridge 121a and antenna 22b, communicating with
adaptor 130a via its antenna 22a. Similarly, computer 66d is
wirelessly coupled to the telephone wiring 62 via the wireless
bridge 121b and antenna 22d, communicating with adaptor 130b via
its antenna 22c. In this configuration, the computers 66c and 66d
communicate over the telephone wiring 62 via the respective
adaptors 130. In such a system, the telephone wiring 62 and the
adaptors 130 serve as a repeater, thus allowing communication
between units, which cannot directly wirelessly communicate. The
lower frequency band of the wiring is used simultaneously to carry
telephone signals between the PSTN 61 and the telephones 65a, 65b,
65c and 65d. Telephone sets 65a and 65c respectively connect via
adaptors 130a and 130b. Telephone sets 65b and 65d connect to the
wiring 62 via LPFs 34a and 34b, respectively.
[0125] Antennas 22b and 22d may be sufficiently close to enable
direct wireless communication between bridges 121a and 121b. In
such case, in addition to the path (or multiple paths) formed
through the air, a telephone wiring path is added. As a
non-limiting example, bridge 22d may receive signals transmitted by
bridge 121a via the air. In addition, the transmitted signal is
received by adaptor 130a (via antenna 22a), and converted to
baseband and carried over the telephone wiring segments 62d and
62c. The signal is then extracted by adaptor 130b, up frequency
shifted and transmitted through the air via antenna 22c to the
bridge 121b, hence forming an additional path. Since most wireless
technologies and IEEE802.11g in particular are well equipped to
handle multi-path, this phenomenon is not expected to degrade the
communication performance.
[0126] While the invention has been described with regard to `bus`
topology telephone wiring, it will be appreciated that
wireless-port equipped modems and adaptors may equally be used in
point to point topology, `star` topology or any combination
thereof.
[0127] While the invention has been described with regard to a
single specific channel frequency shifted to a specific band for
use over the telephone wiring, it will be appreciated that the
invention equally applies to any channel that can be used (as shown
in graph 20) and may be located at any usable frequency band over
the telephone wiring (not limited to the example shown as curve 43
of graph 40). Furthermore, several products are currently available
using multiple channels in order to improve data rate performance,
as well as using other techniques to improve throughput such as
compression. Such techniques are sometimes known as `Turbo-G`,
`Dynamic Turbo`, `Super G` and other brands. Such a solution may be
equally employed in one or more embodiments of the invention, using
larger baseband signal bandwidth. Exemplary techniques to improve
effective data rate are described in Atheros Communication White
Paper entitled "Super G Maximizing Wireless Performance", which is
incorporated herein by reference.
[0128] While the invention has been described with regard to modems
and adaptors supporting telephone port 35, it will be appreciated
that the invention equally applies to the case wherein the
telephone wiring is not carrying a telephone (POTS) signal. In such
a case, telephone connector 35, LPF 34 may be omitted, and HPF 32
may be omitted and bypassed. Furthermore, such configuration may
apply to any type of wiring dedicated for carrying the baseband
signal, not limited to telephone wiring of any kind.
[0129] In one or more embodiments according to the present
invention, other utility wiring (not limited to telephone oriented
wiring) is used, carrying a service signal. For example, powerlines
may be used to carry both the AC power signal and the OFDM signal
according to one or more embodiments according to the present
invention. In such a case, the HPF 32 should be substituted with
HPF filtering out the low frequency band (i.e. 60 Hz in North
America and 50 Hz in Europe) carrying the AC signal and its
associated noises. Similarly, in the case wherein the modem is
required also to provide AC power connection, the telephone
connector 35 should be substituted with a two or three prongs power
jack suitable for connecting powered appliances, and the
telephone-oriented LPF 34 should be substituted by a LPF passing
the 50/60 Hz AC signal. Furthermore, similar to the above
discussion about housing the modem within a telephone outlet and
telephone outlet snap-on module, the powerline OFDM modem may be
equally enclosed within an AC power outlet and snap-on module
respectively, with the warranted modifications.
[0130] In one or more embodiments according to the present
invention, the OFDM baseband signal is carried over CATV cabling,
carrying a CATV service signal. In one or more embodiments, the
baseband signal may be employed over a band not used for carrying
CATV signals (e.g. over 750 MHz in some implementations). The CATV
analog video channels are usually carried each occupying a 6 MHz
wide band. In such a case, an allocation of four adjacent channels
will result in a total bandwidth of 6*4=24 MHz, which may contain
the 22 MHz wide OFDM baseband signal. In such case, the Up/Down
Converter 31 used should shift the band to the allocated bandwidth,
for example by tuning the local oscillator 54 frequency to the
required value. Similarly, The HPF 32 should be substituted with a
BPF passing the allocated 24 MHz, and the LPF 34 should be
substituted with a BSP (Band Stop Filter) blocking the OFDM signal
and passing the CATV channels, to be coupled to via RF connector
(BNC or F-Type) substituting for the telephone connector 35.
[0131] A non-limiting example of generalizing OFDM modem 30 to be
used with any type of utility wiring is shown as modem 150 in FIG.
15. Connector 151 is connectable to appropriate utility wiring, and
represents a dedicated specific applicable connector, such as
telephone connector 36 (e.g. RJ-11 plug) in the case where the
utility wiring is telephone wiring, or an RF connector in the case
of CATV cabling and AC power plug in the case of powerlines.
Similarly, a service connector 152 represents the appropriate
service signal connector such as telephone connector 35, RF
connector and AC power jack when used with telephone, CATV and AC
power wiring, respectively. Service/Data Splitter/Combiner 153
functions to pass the service signal to the service connector 152,
to couple the OFDM baseband signal to the Up/Down Converter block
37 and to avoid interference between both signals. In the case of
telephony, the functionality of the Splitter/Combiner 153 is
provided by the LPF 34 and HPF 32. Similarly, LPF and HPF are used
in powerline applications, for coupling/stopping the AC power
signal. For use over CATV wiring, BPF (Band Pass Filter) and BSP
(Band Stop Filter) are used as described above.
[0132] Powering.
[0133] In most of the embodiments according to the present
invention, the OFDM modems (or wireless adaptor) include active
components (such as Up/Down converter 31), and as such need to be
powered. Three non-limiting powering schemes are described
hereinafter including local feeding, power over wiring and via the
interface module. The powering schemes apply to the modem/adaptor
being a stand-alone enclosure, housed within an outlet, enclosed
within a snap-on outlet module or as part of a data unit.
[0134] Local Feeding.
[0135] In this implementation the module is connected to an
external power source for feeding its active components. A common
small AC/DC converter may be connected to the modem/adaptor via a
dedicated power connection.
[0136] A power adaptor may be used in the modem/adaptor, for
adapting the external power to the internal needs. Such an adaptor
may include voltage conversion (such as DC to DC converter) in
order to adapt to specific voltages required, protection circuits
(such as fuse or current limiting), regulation and noise
filtration, as well as other functionality as known in the art.
[0137] Power Over Wiring.
[0138] In one or more embodiments according to the present
invention, the OFDM modem (or the wireless adaptor) is fed by power
carried over the wiring to which the module is connected. The power
may be carried over separated conductors. In this case, the same
wiring connector (such as 36 or 151) may be used to connect to the
power carrying conductors using separated pins. Alternatively, an
additional power dedicated connector may be used.
[0139] In one or more preferred embodiments, the power is carried
simultaneously over the wiring carrying the data network signals
and/or the basic service signal. The implementation of such a
mechanism is trivial when the basic service is AC power. In such a
case the power is extracted from the AC power signal carried,
commonly via AC/DC converter and LPF filter.
[0140] Similarly, a recent technique known as Power over Ethernet
(PoE) (a.k.a. Power over LAN) and standardized under IEEE802.3af,
also explained in U.S. Pat. No. 6,473,609 to Lehr et al. titled:
"Structure Cabling System", describes a method to carry power over
LAN wiring, using the phantom mechanism. Such technology, as well
as others, may be used to provide power to any of the
modems/adaptors described above, in the case where appropriate
cabling (such as CAT. 5) is used as the wired medium. As a
non-limiting example, in the case of using a different spectrum for
the power signal, a filter should be used. In the case of phantom
type of feeding, two transformers are required as known in the
art.
[0141] Recent techniques developed allow for carrying
simultaneously power and basic service (and data) over the same
wiring infrastructure. U.S. patent publication 2002/0003873 to
Rabenko et al. titled: "System and method for providing power over
a home phone line network" teaches carrying AC power over telephone
wiring carrying both telephony and data, by using a part of the
spectrum not used by the other signals. Such a technique may be
used for powering a modem or adaptor according to the current
invention. As a non-limiting example, AC power using a sine wave
power signal of 50 KHz may be used. As shown in graph 40, a 50 KHz
signal is in a non-allocated frequency band, and hence may be used
for power distribution with minimum or no interference to the other
signals carried over the same telephone wire pair.
[0142] In most prior-art systems involving carrying a power over a
non-power dedicated wiring (e.g. powerlines), the amount of power
that can be carried is limited either due to safety regulations and
limitations, ensuring minimum interference with the other signals
carried over the same wires or due to the power dissipation in the
wires. For example, power carried over telephone lines may not
exceed 60VDC due to safety limitations, and power carried over
coaxial wiring (e.g. CATV) may degrade its signal carrying
characteristics.
[0143] Wireless system in general, and WLAN systems in particular
are associated with mobile and handheld devices such as PDA
(Personal Digital Assistant), cellular phone, remote-controller and
laptop computers. Being battery operated, the power consumption of
the wireless components is critical. As such, a lot of resources
are allocated to make the wireless components consume very low
power, and the power consumption of any wireless components is
considered as one of its main features. This approach is described
for example in Texas Instruments White Paper entitled "Low Power
Advantage of 802.11a/g vs. 802.11b" which is incorporated herein by
reference. Hence, the low power feature of the wireless components
makes them well suitable to be used in any power over wiring
scheme, and also in any non-local feeding scenarios.
[0144] An additional advantage of carrying power over the same
wires carrying the OFDM signal relates to the superior
characteristics of the OFDM signal. Known single carrier
modulations use the whole spectrum for the whole data rates (single
`bin` approach), and as such are greatly susceptible to both white
noise and single frequency noise. In contrast, OFDM uses multiple
`bins`, each carrying part of the data, and hence is less impaired
by either white or narrowband noise. Power supplies are known to be
noisy, and in particular at specific frequencies, such as harmonies
of the PWM frequency (in the case of PWM based supply).
Furthermore, the wires connecting the wired medium to the power
supply and to the loads also serve as antennas and receive noise
from the environment. Since the OFDM is much more robust, the
effects described are less severe, allowing better performance, and
obviating the need for complex and expensive filters.
[0145] Furthermore, since the networks described above are used to
serve wireless clients (STAs) which are battery operated and thus
are operative even in the case of power outage, carrying power over
the wiring allows for continuing network operation in such a case.
The power is typically sourced from a central back-up power source
(e.g. UPS--Uninterruptible Power Supply), and allows continuous
operation of the network even in the case of power outage via the
wiring medium.
[0146] A non-limiting example of an OFDM modem 160 capable of being
power fed via the telephone wiring is shown in FIG. 16. OFDM modem
160 includes modem 30 (shown functionally in FIG. 3) and added
power extraction and feeding functionalities. OFDM modem 160
connects to the telephone wiring via telephone connector 36, in a
way similar to modem 30. A BPF 162, optimized to pass only the 50
KHz power signal, extracts the power signal and feeds AC/DC Power
Supply 161, which converts to various DC levels usually required by
the OFDM modem 30, such as 5 and 3.3 VDC. The non-power related
signals (telephony, ADSL and OFDM baseband) are passed through BSF
(Band Stop Filter) 163 (which may implement 50 KHz notch filter,
for example) and to the wiring port of OFDM modem 30. The data and
telephone ports of the OFDM modem 30 shown as 33 and 35 in FIG. 3
are represented as modem 160 data port 164 and telephone port 165,
respectively. Hence, OFDM modem 160 implements all OFDM modem 30
functions, added to the capability of being powered by a power
signal carried over the telephone wiring.
[0147] The BPF 162 and BSF 163 constitute the power/signal
splitter/combiner 166. In the case wherein the power is carried in
any other way, this function block 166 should be accordingly
modified to split/combine the power and other signals carried over
the wiring.
[0148] A network 170 employing AC power over telephone wiring is
shown in FIG. 17, based on network 75 described above with
reference to FIG. 6b. OFDM modems 30b and 60a of network 75 are
respectively substituted with telephone wiring AC powered modems
160b and 160a, including the same functionalities added to the
capability of being powered via the telephone lines. The 50 KHz
power signal is fed into the wiring via the 50 KHz AC power supply
171, coupled to the telephone wiring 62 via connector 64c of outlet
63c, through a BPF 162 to avoid interference with the other signals
carried over the same wiring 62. OFDM modem 30a is used connected
to outlet 63a, hence using local powering.
[0149] Powering Via Connected Appliance.
[0150] As explained above, several data interface standards also
carry power over the interface. As a non-limiting example, in the
case where the module is connected to USB host unit, the USB
interface may feed the module. The same applies when the data port
33 is an Ethernet port implementing PoE technology as described
above.
[0151] While the invention has been described with regard to a
single power source, it will be appreciated that the invention
equally applies to the case wherein multiple power sources are used
either for redundancy or load sharing.
[0152] General.
[0153] While the invention has been described with regard to the
configuration wherein OFDM signal is carried over telephone wiring
(or any other utility or dedicated wiring LAN), it will be
appreciated that the invention equally applies to any other spread
spectrum signaling (using either DSSS or FHSS). As a non-limiting
example, any multi-carrier modulation technique may be used such as
DMT (Discrete MultiTone) and CDMA (Code Division Multiple Access).
The term `OFDM modem` used herein is to be considered as an example
only, and not as limited to solely using OFDM based signal.
[0154] While the invention has been exampled above with regard to
using standard IEEE 802.11g technology, signals and components, it
will be appreciated that the invention equally applies to any other
wireless based technology, using either single or multi carrier
signals for implementing either spread spectrum or narrowband,
using either unlicensed bands (such as ISM) or licensed spectrum.
Such technology may be part of the IEEE 802.11 (such as IEEE
802.11b or IEEE 802.11a), ETSI HiperLAN/2 or any technology used
for WLAN, home networking or PAN (Personal Area Network). One
non-limiting example is using IEEE 802.11b based on CCK
(Complementary Code Keying). Other non-limiting examples are
BlueTooth.TM., ZigBee, UWB and HomeRF.TM.. Furthermore, WAN (Wide
Area Network) and other wireless technologies may be equally used,
such as cellular technologies (e.g. GSM, GPRS, 2.5G, 3G, UMTS, DCS,
PCS and CDMA) and Local Loop oriented technologies (WLL--Wireless
Local Loop) such as WiMax, WCDMA and other Fixed Wireless
technologies, including microwave based. Similarly, satellite based
technologies and components may be equally used. While the
technologies mentioned above are all standards-based, proprietary
and non-standards technologies may be equally used according to
present invention. Furthermore, the invention may equally apply to
using technologies and components used in non-radio based
through-the-air wireless systems such light (e.g. infrared) or
audio (e.g. ultrasonic) based communication systems.
[0155] While the invention has been described with regard to the
configuration wherein a single wireless oriented signal is carried
over the wiring medium (such as utility or dedicated wiring LAN),
it will be appreciated that the invention equally applies to the
case wherein multiple such signal are carried using FDM. For
example, additional IEEE802.11g signal may be added to graph 40,
occupying the frequency band of 32-54 Mb/s, hence not overlapping
the signals shown. Furthermore, different such signals may be
combined, and thus not limited to the same wireless oriented
signal.
[0156] While the invention has been described with regard to
networks using the same wireless technology (such as IEEE802.11g)
by all modems connected to the wired medium, it will be appreciated
that the invention equally applies to other embodiments wherein
different but interoperable signals are employed.
[0157] While the invention has been described with regard to
embodiments using a complete wireless solution based on existing
components, including wireless MAC 13b, baseband processor 18 and
converter 16, it will be appreciated that the invention equally
applies to other embodiments wherein one or more of theses
components are used. As a non-limiting example, the MAC 13b may be
substituted with a wired-dedicated MAC, still employing all
physical layer components. Similarly, other physical layer
components may be used, still using the powerful wireless MAC 13b.
Furthermore, while the wireless signal, either as baseband, IF or
RF form, has been described as only being frequency shifted,
additional processing may also apply to the standard wireless
signals and components, such as amplitude/level handling such as
amplification and attenuation and frequency handling such as
filtering. Such processing may be warranted in order to better
adapt to the wired medium, improve reliability or reduce costs.
[0158] While the invention has been described with regard to
wireless signals and systems carrying digital data, it will be
appreciated that the invention equally applies to other embodiments
wherein the wireless signals (and system) are used to carry analog
signals. One non-limiting example involves cordless telephony.
Cordless telephones are known to carry telephone (and control)
signals over the air using ISM bands. Applying the invention allows
for carrying the signals over any wired medium in general and over
a utility wiring in particular. In the case of carrying the signals
over telephone wiring, the above advantages are apparent, such as
enlarging the coverage. Furthermore, such configuration may allow
carrying multiple telephone signals over a single telephone
pair.
[0159] Those of skill in the art will understand that the various
illustrative logical blocks, modules and circuits described in
connection with the embodiments disclosed herein may be implemented
in any number of ways including electronic hardware, computer
software, or combinations of both. The various illustrative
components, blocks, modules and circuits have been described
generally in terms of their functionality. Whether the
functionality is implemented as hardware or software depends upon
the particular application and design constraints imposed on the
overall system Skilled artisans recognize the interchangeability of
hardware and software under these circumstances, and how best to
implement the described functionality for each particular
application.
[0160] Although exemplary embodiments of the present invention have
been described, this should not be construed to limit the scope of
the appended claims. Those skilled in the art will understand that
modifications may be made to the described embodiments. Moreover,
to those skilled in the various arts, the invention itself herein
will suggest solutions to other tasks and adaptations for other
applications. It is therefore desired that the present embodiments
be considered in all respects as illustrative and not restrictive,
reference being made to the appended claims rather than the
foregoing description to indicate the scope of the invention.
PUBLIC NOTICE REGARDING THE SCOPE OF THE INVENTION AND CLAIMS
[0161] While the invention has been described in terms of preferred
embodiments and generally associated methods, the inventor
contemplates that alterations and permutations of the preferred
embodiments and methods will become apparent to those skilled in
the art upon a reading of the specification and a study of the
drawings.
[0162] Accordingly, neither the above description of preferred
exemplary embodiments nor the abstract defines or constrains the
invention. Rather, the issued claims variously define the
invention. Each variation of the invention is limited only by the
recited limitations of its respective claim, and equivalents
thereof, without limitation by other terms not present in the
claim. In addition, aspects of the invention are particularly
pointed out in the claims using terminology that the inventor
regards as having its broadest reasonable interpretation; more
specific interpretations of 35 U.S.C. section.112 (6) are only
intended in those instances where the term "means" is actually
recited. The words "comprising," "including," and "having" are
intended as open-ended terminology, with the same meaning as if the
phrase "at least" were appended after each instance thereof.
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