U.S. patent application number 10/100229 was filed with the patent office on 2002-09-19 for techniques for inductive communication systems.
This patent application is currently assigned to Aura Communications, Inc.. Invention is credited to LaFranchise, Jeffrey R., Marshall, Charles M., Palermo, Vincent, Voegelin, Stephen A., White, Timothy E..
Application Number | 20020132585 10/100229 |
Document ID | / |
Family ID | 27533093 |
Filed Date | 2002-09-19 |
United States Patent
Application |
20020132585 |
Kind Code |
A1 |
Palermo, Vincent ; et
al. |
September 19, 2002 |
Techniques for inductive communication systems
Abstract
Contents of one or more received messages can be analyzed to
determine whether a transceiver device generating the inductive
field has already been programmed with a unique communication code.
If not, bidirectional communications can be established to program
the transceiver device with a unique communication code over an
inductive link. Orientation or position of a transceiver device can
be used to initiate a process for programming a communication code.
Generally, the communication code can define a unique relationship
between two or more transceiver devices.
Inventors: |
Palermo, Vincent; (Westford,
MA) ; Marshall, Charles M.; (North Andover, MA)
; White, Timothy E.; (Acton, MA) ; Voegelin,
Stephen A.; (Reading, MA) ; LaFranchise, Jeffrey
R.; (Newburyport, MA) |
Correspondence
Address: |
HAMILTON, BROOK, SMITH & REYNOLDS, P.C.
530 VIRGINIA ROAD
P.O. BOX 9133
CONCORD
MA
01742-9133
US
|
Assignee: |
Aura Communications, Inc.
Wilmington
MA
|
Family ID: |
27533093 |
Appl. No.: |
10/100229 |
Filed: |
March 15, 2002 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10100229 |
Mar 15, 2002 |
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10004989 |
Dec 3, 2001 |
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10100229 |
Mar 15, 2002 |
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09942372 |
Aug 29, 2001 |
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60301529 |
Jun 28, 2001 |
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60296229 |
Jun 6, 2001 |
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60276398 |
Mar 16, 2001 |
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Current U.S.
Class: |
455/41.1 ;
455/73 |
Current CPC
Class: |
H04M 1/727 20130101;
H04B 7/02 20130101; H04B 7/022 20130101; H04B 5/06 20130101; H04R
2420/07 20130101; H04M 1/6066 20130101; H04M 1/737 20130101; H04B
5/02 20130101 |
Class at
Publication: |
455/41 ; 455/568;
455/73 |
International
Class: |
H04B 001/38 |
Claims
What is claimed is:
1. A method of communicating in an inductive communication system
including multiple transceiver devices, the method comprising:
establishing an exclusive communication relationship between the
devices by: at one of the devices, initiating an initialization
process in which the devices communicate with each other; from the
strength of communication signals, assuring that the devices are in
a close physical proximity which is closer than used for normal
communications; and establishing a communication code transferred
between the devices; and conducting normal communications between
the devices using the communication code to maintain an exclusive
communication relationship between the devices.
2. A method as in claim 1, wherein the initialization process is
initiated by receipt of a message from a paging transceiver
device.
3. A method as in claim 2, wherein the message form the paging
transceiver device is initiated at least in part by sensing a
predetermined condition caused by a user.
4. A method as in claim 1, wherein the initialization process is
enabled at least in part based on a detected orientation of a
transceiver device.
5. A method as in claim 1, wherein the communication code
identifies a specific transceiver device and also identifies a type
of transceiver device.
6. A method as in claim 1, wherein the communication code supports
exclusive communications between a first transceiver device coupled
to a cell phone and a second transceiver device coupled to a
headset worn by a user.
7. A method as in claim 1 further comprising: storing a
communication code at each of two communicating devices to support
future exclusive communications between the two or more
devices.
8. A method as in claim 1, wherein the initialization process is
initiated by sensing whether a received signal is above a
threshold.
9. A method as in claim 1, wherein the communication code is at
least partially derived form a randomly generated number.
10. A method as in claim 1 further comprising: sensing a position
of the device as a part of the initialization process.
11. A method of communicating in an inductive communication system,
the method comprising: receiving a message from a transceiver
device generating an inductive field; based upon contents of the
received message, determining whether the transceiver device has
been programmed with a unique communication code that is used to
support exclusive communications when communicating with at least
one other transceiver device; and if the transceiver device
generating the inductive field has not been programmed with a
unique communication code, establishing bidirectional
communications with the transceiver device to program it with a
unique communication code.
12. A method as in claim 11, wherein the step of determining
whether the transceiver device has been programmed with a unique
communication code includes detecting whether a valid communication
code is received in a paging message generated by the transceiver
device.
13. A method as in claim 11 further comprising: sensing that a
predetermined condition has been met before programming the
transceiver device with the communication code.
14. A method as in claim 13, wherein the condition is a
predetermined protocol indicating a user's desire to initialize a
remote transceiver device for further communications with a base
transceiver device.
15. A method as in claim 11 further comprising: detecting that the
transceiver device generating the inductive field is in closer
proximity to a particular reference transceiver device than is
necessary to support communications; and initializing the
transceiver device with a unique communication code.
16. A method as in claim 15, wherein the transceiver device
generating the inductive field is positioned at particular angular
orientation relative to the reference transceiver device before it
is programmed with a unique communication code.
17. A method as in claim 11 further comprising: transmitting
messages from the transceiver device, the messages including the
communication code to identify an origin of each message.
18. A method as in claim 11, wherein the communication code
includes information identifying a type of the transceiver device
generating an inductive field.
19. A method as in claim 11 further comprising: generating a
communication code at a base transceiver that communicates with
multiple remote transceiver devices; and transmitting the
communication code from the base transceiver to program one of the
remote transceiver devices with the communication code.
20. An inductive communication system including multiple
transceiver devices, the system comprising: means for establishing
an exclusive communication relationship between the devices by: at
one of the devices, supplying means for initiating an
initialization process in which the devices communicate with each
other; from the strength of communication signals, sensing that the
devices are in close physical proximity to communicate; and
providing a means for establishing a communication code transferred
between the devices; and means for conducting normal communications
between the devices using the communication code to maintain an
exclusive communication relationship between the devices.
21. An inductive communication system comprising: a first
transceiver device that initiates communication by generating a
communication signal over an inductive field; a second transceiver
device that receives the communication signal and, based on a
measured characteristic of the inductive field, the transceiver
devices establishing a communication code that is to be transferred
between the devices to maintain an exclusive communication
relationship.
22. A system as in claim 21, wherein communication is initiated by
receipt of a message from a paging transceiver device.
23. A system as in claim 22, wherein the message from the paging
transceiver device is initiated at least in part by sensing a
predetermined condition.
24. A system as in claim 2 1, wherein communication is initiated at
least in part based on a detected orientation of the first
transceiver device.
25. A system as in claim 21, wherein the communication code
identifies a specific transceiver device and also identifies a type
of transceiver device.
26. A system as in claim 21, wherein the communication code
supports exclusive communications between the second transceiver
device coupled to a cell phone and the first transceiver device
coupled to a headset worn by a user.
27. A system as in claim 21 further comprising: a memory device in
each transceiver to store a communication code identifying a
relationship between the first and second transceiver devices.
28. A system as in claim 21, wherein establishing a communication
code is initiated by sensing whether a received signal is above a
threshold.
29. A system as in claim 21, wherein the communication code is at
least partially derived from a randomly generated number.
30. A system as in claim 21 further comprising: multiple
transducers in a transceiver device to sense its orientation before
initiating communication and an initialization process to program a
code.
31. A system as in claim 21, wherein the measured characteristic is
a strength of the inductive field.
32. A method of supporting inductive communications among multiple
transceivers, the method comprising: sharing a wireless bandwidth
to support bidirectional communications between pairs selected from
at least three transceivers, a transceiver pair being assigned use
of one or more time slots to communicate within a communication
cycle; disposing at least two transducer elements in at least one
transceiver to support communications between the transceivers at
any angular orientation relative to each other within a range of
distance; for each pair of transceivers communicating with each
other, comparing link qualities of communications between different
transmit-receive transducer element pairs of communicating
transceivers; and selecting transmit-receive pairs of transducer
elements to support further communications in respective time slots
between pairs of transceivers based on detected link quality.
33. A method as in claim 32 further comprising: transmitting a
signal from a single transceiver of the at least three
transceivers; and simultaneously receiving the transmitted signal
at each of multiple transceivers to determine link quality.
34. A method as in claim 32, wherein link qualities are compared by
determining which of multiple transducer elements in a transceiver
device receives a strongest signal from a transmitting
transceiver.
35. A method as in claim 32 further comprising: transmitting a
message from at least one of the transceivers to indicate which of
multiple transducer elements supports a strongest received signal
at the remote transceiver.
36. A method as in claim 34, wherein the strongest signal is
determined by comparing amplitudes of a received signal.
37. A method as in claim 32, wherein the at least three
transceivers includes a base transceiver and at least two remote
transceivers with which the base transceiver communicates.
38. A method as in claim 37, wherein the base transceiver includes
multiple transducers and the remote transceivers each include a
single transducer to support inductive communications.
39. A method as in claim 38 further comprising: generating a signal
from a selected transducer in the base transceiver; and
simultaneously receiving the signal on at least two remote
transceivers to compare link qualities of different transducer
element pairs.
40. A method as in claim 32 further comprising: allocating at least
a portion of the shared wireless bandwidth to receive paging
signals from other transceivers.
41. A method as in claim 40, wherein at least one of the other
transceivers generating paging signals attempts to initiate an
initialization process to establish a communication code for
exclusive communications with a base transceiver.
42. A method as in claim 32, wherein a base transceiver includes
one or more transducers and at least two remote transceivers each
include two or more transducers at unique orientations with respect
to each other to support communication with the base
transceiver.
43. A system supporting inductive communications among multiple
transceivers, the system comprising: at least three transceivers
sharing a wireless bandwidth that supports bidirectional
communications between pairs selected from the at least three
transceivers, a transceiver pair being assigned use of one or more
time slots to communicate within a communication cycle; at least
two transducer elements disposed in at least one transceiver to
support communications between the transceivers at any angular
orientation relative to each other within a range of distance; a
comparator to compare link qualities of communications between
different transmit-receive transducer elements in transceivers
communicating with each other; and a controller to select which of
multiple potential transmit-receive transducer elements is used to
support further communications in respective time slots between
pairs of transceivers based on detected link quality.
44. A system as in claim 43, wherein a signal is transmitted from a
single transceiver of the at least three transceivers and is
simultaneously received at each of multiple transceivers to
determine link quality.
45. A system as in claim 43, wherein the comparator determines
which of multiple transducer elements in a transceiver device
receives a strongest signal from a transmitting transceiver.
46. A system as in claim 43, wherein a message is transmitted from
at least one of the transceivers to indicate which of multiple
transducer elements supports a strongest received signal at the
remote transceiver.
47. A system as in claim 45, wherein the strongest signal is
determined by comparing amplitudes of received signals.
48. A system as in claim 43, wherein the at least three
transceivers includes a base transceiver and at least two remote
transceivers with which the base transceiver communicates.
49. A system as in claim 48, wherein the base transceiver includes
multiple transducers and the remote transceivers each include a
single transducer to support inductive communications.
50. A system as in claim 49, wherein a signal is generated from a
selected transducer in the base transceiver and is simultaneously
received on at least two remote transceivers to compare link
qualities of different transducer element pairs.
51. A system as in claim 43, wherein at least at least a portion of
the shared wireless bandwidth is allocated for receiving paging
signals from other transceivers.
52. A system as in claim 51, wherein at least one of the other
transceivers generating paging signals attempts to initiate an
initialization process to establish a communication code for
exclusive communications with a base transceiver.
53. A system as in claim 43, wherein a base transceiver includes
one or more transducers and at least two remote transceivers each
include two or more transducers at unique orientations with respect
to each other to support communication with the base
transceiver.
54. A system as in claim 43, wherein bidirectional communications
between a pair of transceivers is supported by a selected pair of
transmit-receive transducers, each transceiver of the pair of
transceivers including one transducer of the transmit-receive pair
of transducers.
Description
RELATED APPLICATION(S)
[0001] This application is a continuation-in-part of U.S.
Application No. 10/004,989 (attorney docket no. 3058.1008-004)
filed on Dec. 3, 2001, and U.S. application Ser. No. 09/942,372
(attorney docket no. 3058.1008-001) filed on Aug. 29, 2001, and
claims the benefit of U.S. Provisional Application No. 60/301,529
(attorney docket no. 3058.1009-000) filed on Jun. 28, 2001, U.S.
Provisional Application No. 60/296,229 (attorney docket no.
3058.1008-000) filed on Jun. 6, 2001, and U.S. Provisional
Application No. 60/276,398 (attorney docket no. 3058.1007-000)
filed on Mar. 16, 2001. The entire teachings of the above
application(s) are incorporated herein by reference.
BACKGROUND OF THE INVENTION
[0002] Transducers have been incorporated in transceivers to
transmit and receive inductive fields. In a typical application,
each of two transceiver devices supporting bidirectional
communication includes two specifically tuned transducers, one of
which is tuned for transmitting while the other is tuned for
receiving.
[0003] Interference can occur among transceiver devices when a
common carrier frequency is used by the transceivers to
simultaneously transmit data information. In this instance, it is
likely that an additional transceiver device within communication
range can "eavesdrop" and receive information originally intended
for another transceiver. This can be annoying or even detrimental
if the communication was intended to be confidential.
[0004] Unlike RF (Radio Frequency) antennas, inductive transducers
couple to each other via magnetic flux. Thus, unique problems arise
when multiple transceiver devices attempt to share an available
bandwidth to communicate with each other.
SUMMARY OF THE INVENTION
[0005] The present invention is directed towards an inductive
communication system in which messages are received at a
transceiver device over an inductive field.
[0006] Contents of one or more received messages can be analyzed to
determine whether a transceiver device generating the inductive
field has already been programmed with a unique communication code.
If not, bidirectional communications can be established to program
the transceiver device with a unique communication code over an
inductive link. Typically, the communication code is a sequence of
bits identifying a relationship between two or more transceivers
for exclusive communications.
[0007] A communication code can be a unique identifier that is
transmitted in messages between transceivers so that the recipient
can identify a source of the message. If a received message
includes an unexpected or unknown communication code, the message
can be ignored.
[0008] An activation protocol such as orientation or position of a
transceiver can cause one or multiple transceivers to be
initialized with a communication code. For example, to initialize a
pair of transceivers with a code, the transceiver devices can be
moved in close proximity to each other. Proximity of a transceiver
can be detected by sensing the strength of a received signal or
orientation of an inductive field.
[0009] Following detection of a predetermined activating condition,
a communication code can be generated and assigned for future use
by the transceivers. As mentioned, the transceivers can maintain an
exclusive communication relationship based on use of the
communication code.
[0010] In one application, a button is pressed indicating that a
transceiver device is to be initialized with a code. If a
predetermined sequence of events such as proper orientation or
proximity of the transceiver device is detected within a time
window, an initialization process to program a code is
initiated.
[0011] Another method to initiate the initialization process of
establishing a communication code includes detecting a paging
message. For example, a paging message received from a transceiver
device can indicate a desire by a user to establish a communication
code. A paging message can also indicate a desire by a user to
establish an exclusive communication link using the programmed
code.
[0012] A paging message can include a data field including the
communication code so that a transceiver receiving the message can
determine whether communications have been established with the
transceiver device in the past. If the communication code received
at a transceiver is a value unbeknownst to a monitoring transceiver
device, a new communication code for communicating can be
established. On the other hand, if the paging message includes a
code recognized by the receiving transceiver device, a
communication link can be established based on the code.
[0013] Using the communication code, a transceiver can determine
the type of transceiver device and its functionality. For example,
the code can identify whether a newly linking transceiver device is
a mouse or a keyboard device. As discussed, the initialization
process to establish a code can be initiated at least in part by
sensing a predetermined condition caused by a user. For example, a
user can press a button on a transceiver device to activate an
initialization process. Also, the user can move a transceiver
device closer in proximity than is required for normal
communications to initiate the initialization process. In general,
a proximity of a transceiver device can be sensed based on the
strength of a received signal. If the received signal is above a
threshold value, it can be determined that the transceiver device
is so close in proximity that such a condition is an indication
that a user desires to program a transceiver with communication
code.
[0014] An orientation of the transceiver device can be detected
based on an axis of a received inductive field to determine whether
a user desires to initiate programming of a communication code.
Proximity of a transceiver device as well as orientation can be
monitored to determine that a transceiver device should be
initialized.
[0015] After programming, a communication code can be stored to
support future exclusive communications. More specifically, a base
transceiver and remote transceiver can both store a communication
code in non-volatile memory. A transceiver can store different
communication codes for each of multiple transceiver devices with
which it can communicate.
[0016] When creating a new link, each device can determine based on
use of a communication code whether the devices have communicated
with each other in the past. If so, the initialization process of
programming a communication code can be skipped and the
transceivers can communicate almost immediately using a code.
[0017] A communication code can be derived at least in part based
on a randomly generated number. Thus, two different random
transceivers are unlikely to be programmed with the same code. In a
multi-point communication system, all or a portion of bits in the
communication code can be common to multiple transceiver, thereby
enabling multiple transceivers to communicate using a single,
shared communication code. Use of such a code can be advantageous
when a transceiver broadcasts to multiple transceivers
simultaneously.
[0018] As discussed, a portion of the code can identify a type of
communication device to which the transceiver is coupled. In this
way, a communication code is unique yet it also includes
information identifying a type of transceiver. A format of data to
be transmitted between devices can be determined based on a
code.
[0019] In one instance, a base transceiver device is used in a
cellular phone and a remote transceiver device is used in to a
headset including a speaker and a microphone. Based on use of a
communication code and bidirectional communications between the
transceiver devices, a user can communicate over an exclusive
inductive link between the cell phone and headset. A user wearing
the headset can therefore communicate with a remote party through a
phone link supported by the cell phone. The transceiver devices can
include multiple transducers so that continuous communication
between the headset and cell phone can be maintained regardless of
the orientation and position of the transceiver devices.
[0020] Another aspect of the present invention is directed towards
a system and method supporting inductive communications among
multiple transceivers in a multi-point communication system. In an
illustrative embodiment, bidirectional communications are supported
between pairs of transceivers selected from at least three
transceivers. Each pair of communicating transceivers can be
assigned one or more time slots in which to communicate. At least
one transceiver can include multiple transducer elements that are
selectively activated to support communications between the
transceivers regardless of their orientation relative to each
other. A transceiver can be incorporated in many types of devices
including computer equipment, games, mobile phones, Personal
Digital Assistants (PDA), or headsets.
[0021] A comparator can be used to compare link qualities of
communications of different transmit-receive transducer elements of
the pairs of transceivers communicating with each other. Based on
detected link quality, a controller can select which of multiple
potential transmit-receive transducer elements of a transceiver
pair will be used to support further communications. Consequently,
multiple transceivers can communicate with each other over selected
transducer elements.
[0022] In one application, at least one pair of transceivers
includes multiple transducers to support communication at any
angular orientation. For example, a first transceiver including
three orthogonal transducers can communicate with a second
transceiver including at least one transducer. Each combination of
transmit-receive pairs of transducers between the transceivers can
be compared to determine which provides an acceptable link quality.
As mentioned, a controller can select which set of transducers
between a pair of transceivers is used to support future
communications based on detected link quality. A set of
transceivers can include a transducer in each transceiver, multiple
transducers in one transceiver and a single transducer in another
transceiver, or multiple transducers in each transceiver.
[0023] During operation, a signal can be transmitted from one
transceiver to multiple transceivers. Each of multiple transceivers
can simultaneously receive the transmitted signal to determine link
quality for a potential future link between transceivers. Since
multiple transceivers detect link quality simultaneously, less
bandwidth is necessary to determine signal quality of multiple
links than when the process is performed individually for each
transceiver at different times.
[0024] Link qualities can be determined by comparing which of
multiple transducer elements in a transceiver device produces a
strongest signal in a receiving transceiver. A message can be sent
from the receiving transceiver indicating which of multiple
transducer elements in a transmitting device produces a strongest
signal. Typically, the strongest signal is determined based on
which transducer element receives the largest amplitude of a
received signal such as a voltage signal corresponding to strength
of a received inductive field. Link qualities can also be
determined by comparing which of multiple transducer elements in a
receiving device produces a strongest signal from a transmitting
transceiver.
[0025] In one application, link quality can be determined by
identifying how many bits in transmitted signal are properly
received at a transceiver.
[0026] A set of multiple transceivers in a communication system can
include a base transceiver and at least two remote transceivers
with which the base transceiver communicates. The base transceiver
can include multiple orthogonal transducers and each of the remote
transceivers can include as few as a single transducer. Based on
this topology, each transceiver can be positioned at any angular
orientation relative to the others, yet communication can be
continuously maintained via a selected pair of transmit-receive
transducers in each base-remote transceiver pair. Communications
also can be supported by activating more than two transducers to
transmit or receive an inductive field.
[0027] Each of multiple remote transceivers communicating with a
base transceiver can include multiple orthogonal transducer
elements, while the base transceiver includes one transducer
element. One of the multiple transducers in a remote transceiver
can be selected to transmit and receive messages from the base
transceiver including only one transducer.
[0028] As previously discussed, wireless bandwidth can be shared
among the multiple transceivers without interfering with each other
using time slots and, optionally, communication codes. At least a
portion of the wireless bandwidth can be allocated for receiving
paging signals from other transceiver devices trying to establish a
communication link. Consequently, paging transceivers can share a
wireless bandwidth with other transceivers already communicating
with each other.
[0029] As mentioned, a group of transceivers communicating with
each other can utilize communication codes to support exclusive
communications. A new transceiver not yet initialized with a
communication code can initiate a programming routine in which a
communication code is assigned for communications. To establish a
new communication code or relationship between transceiver devices,
a transceiver can send paging signals to a base transceiver that,
in response to an activation sequence, generates a unique
communication code for bidirectional communications. Typically, a
communication code is transmitted in each message so that a
receiving transceiver can identify that the message is generated
from a particular device.
BRIEF DESCRIPTION OF THE DRAWINGS
[0030] The foregoing and other objects, features and advantages of
the invention will be apparent from the following more particular
description of preferred embodiments of the invention, as
illustrated in the accompanying drawings in which like reference
characters refer to the same parts throughout the different views.
The drawings are not necessarily to scale, emphasis instead being
placed upon illustrating the principles of the invention.
[0031] FIG. 1 is a pictorial diagram of a wireless communication
system according to certain principles of the present
invention.
[0032] FIG. 2 is a block diagram of transceiver devices and
corresponding circuit components according to certain principles of
the present invention.
[0033] FIG. 3 is a block diagram of a hub topology in which a base
transceiver communicates with multiple remote transceiver devices
according to certain principles of the present invention.
[0034] FIG. 4 is a timing diagram illustrating a bandwidth
partitioned into time slots according to certain principles of the
present invention.
[0035] FIG. 5 is flow chart illustrating a method to establish
communication and program a transceiver device with a communication
code according to certain principles of the present invention.
[0036] FIG. 6 is a flow chart illustrating a method of activating
an initialization process to program a transceiver device with a
communication code according to certain principles of the present
invention.
[0037] FIGS. 7A and 7B are state diagrams illustrating transceiver
modes of operation according to certain principles of the present
invention.
[0038] FIG. 8 is a timing diagram of a remote transceiver device
paging a base transceiver to establish communications according to
certain principles of the present invention.
[0039] FIGS. 9A and 9B are state diagrams illustrating transceiver
modes according to certain principles of the present invention.
[0040] FIG. 10 is a timing diagram illustrating how multiple
transceiver devices share bandwidth according to certain principles
of the present invention.
[0041] FIG. 11 is a timing diagram illustrating how multiple
transceiver devices share bandwidth according to certain principles
of the present invention.
[0042] FIG. 12 is a timing diagram illustrating how bandwidth can
be dynamically allocated to a new remote transceiver according to
certain principles of the present invention.
[0043] FIG. 13 is a timing diagram illustrating a method of
implementing diversity checks according to certain principles of
the present invention.
[0044] FIG. 14 is a block diagram illustrating how multiple
transceiver devices can communicate with each other over a shared
inductive bandwidth according to certain principles of the present
invention.
[0045] FIG. 15 is a timing diagram illustrating time slot
assignment of multiple pairs of communicating transceiver devices
according to certain principles of the present invention.
[0046] FIG. 16 is a block diagram of multiple transceivers and
corresponding transducer elements according to certain principles
of the present invention.
[0047] FIG. 17 is a block diagram illustrating a method of
implementing diversity checks according to certain principles of
the present invention.
DETAILED DESCRIPTION OF THE INVENTION
[0048] A description of preferred embodiments of the invention
follows.
[0049] FIG. 1 is a pictorial diagram of a wireless communication
system according to certain principles of the present invention. As
shown, wireless communication system 100 includes cellular phone
device 130 and headset 110. Generally, headset 110 is worn by a
user to communicate with a remote party over one or multiple
wireless links. For example, inductive link 122 supports
communications between a user wearing headset 110 and cell phone
130. Radio Frequency (RF) link 127 supports communications between
cell phone 130 and cellular base station 125. Base station 125 is
coupled to network 129 such as a PSTN (Public Switching Telephone
Network).
[0050] Instead of holding cell phone 130 to one's ear as is
ordinarily done to communicate over a telephone with a remote
party, a user wearing headset 110 can communicate with the party
using headset 110. For example, a user can speak into microphone
112 to convey a voice signal to a remote party through inductive
link 122 and RF link 127. In a reverse direction, voice signals
generated by a remote user at the other end of phone 130 are
conveyed through RF link 127 and inactive link 122 to headset 110.
The voice signal received at headset 110 are generated over speaker
180.
[0051] Speech generated by a user is detected by microphone 112 and
modulated onto an inductive carrier frequency of inductive link
122. The inductive signal including voice information transmitted
from headset 110 is received and demodulated at base transceiver
120. Base transceiver 120 converts the voice signal into a protocol
accepted by cell phone device 130. Cell phone 130 receiving the
voice signal transmits it over wireless link 127 using standard
techniques such as those based on use of CDMA (Code Division
Multiple Access) technology.
[0052] In a reverse direction, signals generated by the remote
party at the other end of phone 130 are communicated through base
station 125. The signals are formatted for transmission over radio
link 127 to cell phone 130 using standard protocols. The signal
received at phone 130 is then reformatted into an appropriate
protocol for reception at base transceiver 120 that processes the
signal and re-generates the information over inductive link 122 to
headset 110. Accordingly, a sound output that is otherwise
generated at cell phone 130 is instead generated at speaker 180 for
a user wearing headset 110.
[0053] While wearing headset 110, a user can communicate hands-free
without otherwise being entangled in wires connecting cell phone
130 and headset 110. According to one aspect of the present
invention, inductive coupling techniques are used to minimize the
size and therefore the burden of wearing or using headset 110.
[0054] In one application, headset 110 communicates with base
transceiver 120 up to several meters away. Thus, cell phone 130 can
be held at a distance from user or, at a minimum, away from the
user's head.
[0055] Although communication system 100 is directed towards a
wireless headset device, it should be noted that a combination of
base transceiver 120 and remote transceiver 116 can be used in
other wireless applications as well. For example, base transceiver
120 can be coupled to a wired-telephone device so that a user can
communicate hands-free while wearing headset 110 in an office
setting or the like. Additionally, the transceivers can be used in
other short range applications where the use of inductive
technology for wireless voice or data transmissions is
appropriate.
[0056] Base transceiver 120 can include electronic components
housed in a rigid body made from plastic or other durable material.
In one application, base transceiver 120 is removably attached to
cell phone 130. Alternatively, base transceiver 120 is coupled to
cell phone 120 using a cable wire through a 2.5 mm jack or other
suitable phone connector. In yet another application, base
transceiver 120 is integrated into cell phone 130 so that it does
not protrude from the end of cell phone 130.
[0057] While in an operational state, communication system 100 can
utilize TDD (Time Division Duplexed) techniques to communicate.
More specifically, a usable bandwidth at a chosen carrier frequency
such as 12 MHz can be partitioned into time slots shared by two or
more communicating transceivers. An advantage of using inductive
technology is the reduced interference among multiple users that
share use of a common carrier frequency. Typically, inductive
communication signals are very difficult to detect at distance
greater than several meters away, so the effects of an inductive
field generated by one remote user can be negligible to another
remote user. However, techniques discussed in this specification
can be used to reduce interference with users within close range of
each other.
[0058] FIG. 2 is a block diagram illustrating electronic circuitry
supporting inductive communications according to certain principles
of the present invention. As shown, base transceiver 120 can
include three orthogonally disposed transducer elements, each of
which can be dynamically tuned for transmitting and receiving
information over inductive link 122. Remote transceiver 116 can
include a single transducer element 166 for transmitting and
receiving information over inductive link 122. Based on this
topology, base transceiver 120 and remote transceiver 116 can
maintain continuous communication regardless of their orientation
relative to each other.
[0059] Although base transceiver 120 is shown including three
transducer elements, namely, x-transducer 136, y-transducer 137 and
z-transducer 138, the number of transducers used in an application
can vary. For example, base transceiver 120 can include as few as
only a single transducer or as many transducers that fit in a
transceiver device. Similarly, remote transceiver 116 can include
any number of transducers such as three orthogonal transducers to
support bidirectional communications with base transceiver 120.
[0060] Typically, an appropriate number of transducers are employed
in each transceiver device so that base transceiver 120 and remote
transceiver 116 can communicate with each other regardless of their
orientation or position using inductive fields. In certain
applications, fewer transducers are necessary in a transceiver
because it is known that certain orientations of the transceivers
relative to each other are not possible or alternative transducer
configurations produce the required magnetic field for
communication.
[0061] Either transceiver device can be fixed so that its
orientation does not vary with respect to a complementary
transceiver. However, in the application as mentioned in FIG. 1, an
orientation of either transceiver device can vary. For example, a
user carrying phone 130 in his pocket while walking can enjoy
continuous connectivity with phone 130 over headset 110. In this
case, both transceiver devices are subject to random orientation
and position.
[0062] As shown in FIG. 2, base transceiver 120 can include
controller 115 such as an ASIC (Application Specific Integrated
Circuit), which is electrically connected to tuner circuit 130 via
transmit lines 132, receiver lines 133, and switch control lines
134. Tuner circuit 130 is connected to a set of three orthogonal
transducers, including x-transducer 136, y-transducer 137, and
z-transducer 138. In general, tuner circuit 130 can select a
transducer element and adjust its characteristics for transmitting
and receiving inductive signals.
[0063] Base transceiver 120 can be also electrically and logically
connected to base crystal 129, memory 125 such as EEPROM, audio
line 135, audio/data line in 140, control/status line 141, and
power source 190.
[0064] Remote transceiver 116 can include controller 145, which is
electrically connected to tuner circuit 160 via remote lines 162,
receive lines 163, and switch control lines 164. Remote transceiver
110 can also include remote crystal 150 frequency source, memory
155 such as EEPROM, audio/data line out 170, audio/data line in
165, and volume control line 185. In a voice application as
mentioned, headset 110 includes microphone 175 and speaker 180.
Power source 195 can be used to power circuitry in remote
transceiver 116.
[0065] In one application, controller 115 and controller 145
utilize Time Division Duplexing (TDD) and Gaussian Minimum Shift
Keying (GMSK) to transmit and receive data information.
[0066] If used, custom-designed CMOS (Complementary Metal Oxide
Semiconductor) chips support full duplex transmission of audio and
data. Other circuit technologies can be used but may not
necessarily provide the low power and design advantages that CMOS
semiconductor chips provide.
[0067] Typically, crystal 129 and crystal 150 are 9.8 MHz frequency
sources. Other suitable crystals can be used depending on the
application.
[0068] Memory 125 and memory 155 can be EEPROM (Electrically
Erasable Programmable Read Only Memory). Each memory device can
include grounding pins that identify the "personality" of a
transceiver device (e.g., a mouse, a keyboard, or gaming joystick,
Personal Digital Assistant, stereo, global positioning system,
radio, MP3 player). Accordingly, the grounding pins can be used to
select specific software functions for use in a particular
transceiver device.
[0069] X-transducer 136, y-transducer 137, z-transducer 138, and
single transducer 166 can be transducer coils having a ferrite
core. Microphone 175 can be a miniature microphone such as
Panasonic part number WM-66DC103. Typically, power source 190 and
power source 195 are rechargeable button cells such as NiMH 40
mA-Hr units.
[0070] In a phone application as discussed in FIG. 1, controller
115 receives audio or data information via input audio/data line
140, converts the received information from analog to digital for
processing (if it is analog audio), and drives the information to
impedance tuning circuit 130 that drives x-transducer 136, base
y-transducer 137, and base z-transducer 138 for transmission. The
transducers generate a magnetic induction field 122, such that
remote headset unit 110 receives the transmitted signals.
Transmitted signals on inductive field 122 are received by remote
unit transducer 166. The signals are sent to controller 145 and are
converted to a digital protocol for processing. Raw digital data is
then converted to an analog signal to drive speaker 180. The
process may also be reversed such that remote headset unit 110
sends signals to base transceiver 120.
[0071] Logic within controller 115 and controller 145 controls base
and remote switch lines 134 and 164 in order to operate tuner
circuits 130 and 160 that are used to adjust characteristics of the
transducers. Base and remote transmit lines 132 and 162, and base
and remote receive lines 133 and 163 assist in operating base unit
105 and remote unit 1110 in either transmit or receive mode. Base
and remote transmit lines 132 and 162 support the operation of base
unit 105 and remote unit 110 at maximum power and low impedance for
transmitting; while base and remote receive lines 133 and 163
support a parallel tuned network for receiving.
[0072] In one application, power source 190 and power source 195
are battery devices. In other applications, base power source 190
and second power source 195 can be supplied through an automobile
cigarette lighter, or may be directly supplied via wall
current.
[0073] Base and remote control/status lines 141 and 185, can be
used to "wake up" the devices from a very low-power operating mode.
In another example, base and remote control/status lines 141 and
185 can be used to instruct controller 115 and controller 145 to
"page" the other device to "wake-up" a link. Instructions for
controlling these communications can be stored in memory 125 and
155.
[0074] FIG. 3 is a block diagram of a point-to-multi-point
inductive communication system according to certain principles of
the present invention. As shown, base transceiver 120 can maintain
communication with one or multiple remote transceivers 116-1, 116-2
. . . 116-n over respective inductive links 122-1, 122-2, . . .
122-n. As discussed, each transceiver can include as few as a
single transducer element or multiple orthogonal transducer
elements. Briefly, FIG. 14 is a block diagram of yet another
topology in which multiple transceivers communicate with each
other. This will be discussed in more detail later in this
specification.
[0075] FIG. 4 is a timing diagram of a time-slotted inductive
communication system according to certain principles of the present
invention. Each frame 462 includes field A and field B for
transmitting and receiving data in respective time slots or data
fields. Although diagram 400 depicts an approximate ratio of 50%
transmitting to 50% receiving between transceivers, apportionment
of a bandwidth and use of particular data fields can vary depending
on the application.
[0076] Both field A and field B are broken down into four transmit
time slots 405 and four receive time slots 410 that alternate in a
time sequence. An additional time slot can be used for link
management. For example, a time slot such as diversity slot 492 in
field A and B can be allocated for diversity checks, which are
noted as TX-A and TX-B.
[0077] A diversity check is used to test whether other uniquely
oriented transducer devices support more efficient communications.
More specifically, a diversity time slot 492 can be used by base
transceiver 120 or remote transceiver 116 to monitor a quality of a
received signal transmitted on a different transducer axis. If one
transducer coil provides better coupling, e.g., greater detected
signal strength at a receiver, future bit information can be
transmitted or received on that transducer coil.
[0078] It should be noted that there are a number of ways to
implement diversity checks. For example, in one application, a
transceiver device can potentially include three orthogonal
transducers, namely, x-transducer 136, y-transducer 137 and
z-transducer 138. Each of the three axes of the individual
transducers can be tested to determine whether a link between a
single transducer and either x, y or z is more optimal. More
specifically, a signal can be transmitted to transducers x, y and
z. It can be determined which of the three axes is optimal for
transmitting based on a comparison of which transducer receives a
strongest received signal. This is one possible method of
performing a diversity check.
[0079] Additional axes can be tested in addition to those of each
transducer device x, y and z. For example, multiple transducers can
be simultaneously selected to transmit or receive an inductive
field. Thus, combinations of additional axes produced by
simultaneously activating transducers x-y, transducers y-z, and
transducers x-z can be tested using additional diversity checks.
Also, all three transducers can be activated simultaneously to
produce yet another axis on which to perform a diversity check.
[0080] A preferred combination of transceivers can be calculated
based upon results from the individually energized transducers. For
example, if equal signal strength is received on all three
transducers during diversity checks, it can be assumed that the
preferred axis can be achieved by selecting all three transducers
to transmit or receive an inductive field.
[0081] It should be noted that FIG. 4 is a timing diagram with
respect to a first transceiver. A complementary timing diagram for
the another transceiver communicating with the first transceiver
would have opposite time slots for receiving and transmitting data
information in data fields 405 and 410. In other words, while one
transceiver transmits, another transceiver receives.
[0082] Using an appropriate carrier frequency of 13.56 MHz, 296
data bits of information can be transmitted or received in a time
slot or 4,896 bits (24 milliseconds) can be transmitted in frame
462.
[0083] Each transmit time slot 405 and receive time slot 410 can be
used to transmit or receive 296 bits of information. A majority of
the 296 bits in each slot can be used to transmit or receive data
information. The other bits in a time slot can be used for command,
control, or error correction/detection.
[0084] Guard bits 420 (16 bits) and 460 generally serve as a buffer
zone between time slots. Typically, use of guard bits 420 allows
transients as a result of transmissions in a last slot to diminish
before data processing begins on data transmitted in a new time
slot.
[0085] Preamble bits 425 (24 bits) can be a predetermined bit
sequence of alternating ones and zeros. This sequence of bits can
be used to adjust timing and synchronize transceivers.
[0086] Synchronization bits 430 (16 bits) can be a coded sequence
of predetermined random bits that are used to synchronize a
receiver with a transmitting transceiver and indicate start of
data. When the received sequence of bits match the sequence in the
receiving transceiver, the devices are synchronized with respect to
the start of further transmissions.
[0087] An FEC (Forward Error Correction) code is optionally
included in a time slot to ensure that bit information is properly
received in a time slot.
[0088] LDATA bits 440 are generally used to maintain a link by
controlling gain, transmission power, frequency channel management,
diversity, device unique identifier or communication codes. These
bits can be command bits that identify a specific command to be
executed by a remote transceiver device. For example, a change in
the remote unit transmitter power level can be controlled via a
command. In the case of a change in the remote unit's transmitter
power, these bits would specify the level.
[0089] A list of commands that can be sent between transceivers
includes commands for: controlling gain of signals, changing
transmit power level, selecting transducers, selecting magnetic
field direction, changing communication codes, requesting bandwidth
changes, changing bandwidth allocation among multiple devices,
changing the length of transmit and receive time slots, changing
communication frequency, allocating communication time slots among
multiple devices, and changing operating parameters of controller
130 and controller 145.
[0090] Commands can also be used to control one transceiver
remotely from another transceiver. In one embodiment, volume
control buttons of phone 130 may be used to control volume of
speaker 180 in headset 110 by transmitting commands in slot 440.
Similarly, one transceiver may be powered off by another
transceiver on remaining battery power in transceiver may be
monitored by a display in another transceiver. Thus headset 110 can
be made "switchless" so that all functions, such as volume control
and operating power level are controlled by phone 130.
Functionality of a "switchless" headset can be further enhanced if
field orientation and field strength are also used to control the
functions of the headset.
[0091] In one embodiment, LDATA bits 440 are subdivided as follows:
an FEC (Forward Error Correction) code of 6 bits to ensure that bit
information is correctly received in a time slot; a slot ID of 2
bits which identifies which of the four transmit/received pairs in
a frame is currently being transmitted; a command name of 8 bits
that identifies the specific command being transmitted between
transceivers; and command data of 16 bits that contains data
specific to the command. Use of a slot ID can be advantageous since
it enables the slots to be randomized within the frame and then
sorted into proper order at the receiving unit, thereby minimizing
the impact on audio quality of missing or corrupted data.
[0092] The LDATA command name and command data may also include the
exclusive communication code as an alternative embodiment of a
dedicated communication code 470. In this alternative embodiment,
the communication code is transmitted in slots whenever commands
are not required, and thus the communication code would fill
otherwise "empty" command and data bits. This is advantageous in
that it requires less bandwidth whereas a separate bit allocation
470 ensures that every slot has the communication code.
[0093] Communication code 470 can be a 16-bit code that uniquely
mates a base transceiver and one or more other transceiver devices.
This code can be an at least partially random code that is passed
from base transceiver 120 to remote transceiver 116 upon
initialization. Code 470 can also be programmed during
manufacturing. If a code received in this data field is not
recognized by a receiving transceiver device, following data
information can be ignored. Consequently, communication code 470
can be used to support exclusive communications with one or
multiple other transceiver devices.
[0094] In one embodiment, a 16-bit code includes a 10-bit random
number that is unique to all devices in a multi-point communication
system, a 3-bit number unique to each transceiver device in a
multipoint system (optionally set to a null value when broadcasting
to all transceiver in a multi-point system), and a 3-bit unique to
a type of device. In another application, the code can be a 16-bit
value for each exclusive device and thus a unique code is stored
for each device.
[0095] Each transmit time slot 410 and receive time slot 405 can
include a field 450 that is used to transmit or receive payload
data. These bits can include CVSD encoded audio data. Since one
side of the system transmits only half the time, enough data must
be in this 192 bit interval so that the user will not perceive an
interruption in the audio.
[0096] As mentioned, diversity check slot 492 enables the base unit
to assess whether the current transducer selected for transmitting
and receiving is acceptable. Generally, base transceiver 120
monitors the received signal quality on a different transducer
axis. Based on a link quality, such as received power, received
noise, or bit error rate, a transceiver can determine whether to
continue using a current transducer to transmit or receive or to
switch to use of another transducer.
[0097] FIG. 5 is a flowchart illustrating a method of communicating
according to certain principles of the present invention.
Generally, flowchart 500 is a technique for establishing an
exclusive or at least partially exclusive relationship between
multiple transceivers based on use of a communication code 470.
[0098] More specifically, base transceiver 120 can determine
whether a message received from a remote transceiver 116 includes a
valid communication code 470 indicating that the transceivers have
been initialized for communications. Use of a communication code
470 ensures that data messages generated for an exclusive
communication between base transceiver 120 and remote transceiver
116 are not accidentally or intentionally picked up by another user
transmitting and receiving over the same carrier frequency. Thus, a
phone call supported by headset 110 can be secure so that
eavesdroppers do not listen in on a private call.
[0099] Flowchart 500 describes two methods to link a remote
transceiver 116 to a base transceiver 120 for private bidirectional
communications. If base transceiver 120 and remote transceiver 116
have not yet been initialized with each other, the transceivers can
be initialized with a communication code 470. After a transceiver
has been initialized or if the transceivers have already been
initialized with a communication code 470, flowchart 500
illustrates a method of establishing bidirectional communications
between transceivers.
[0100] In step 510, power is applied to headset 110. Headset 110 is
moved within detectable range of base transceiver 120 in cell phone
130. This is typically less than 2 meters.
[0101] Depending on recent use, base transceiver 120 coupled to
cell phone 130 can be set to a sleep mode to conserve battery
power. While in the sleep mode, base transceiver 120 intermittently
listens for paging signals from remote transceiver 116 coupled to
headset 110.
[0102] After applying power to headset 110 in step 510, remote
transceiver 116 enters a sleep mode in which remote transceiver 116
is dormant. Generally, minimal circuitry is powered to reduce power
consumption, yet selected circuitry in headset 110 remains powered
to enable the device to turn on quickly if an activation signal is
received. For example, features of a transceiver can be shut down
except the clock and microprocessor, which can run at a reduced
duty cycle. At predetermined time intervals, each transceiver can
"wake up" to check for an activation signal, such as user input or
receipt of a paging signal from another device. If no activity is
detected a transceiver remains in a low power or sleep mode.
[0103] In step 520, remote transceiver detects whether an
activation condition has occurred. One such activation may be
detection of throwing a switch or turning a volume control on
headset 110. The activation signal can vary depending on the
application.
[0104] If no activation signal is detected in step 520, remote
transceiver 116 remains in the sleep mode. However, when an
activation signal is detected in step 520, process flow continues
at step 522, which causes the remote transceiver to enter a paging
mode.
[0105] While in the paging mode, remote transceiver 116 of headset
110 transmits a repetitive stream of data information to base
transceiver 120. A protocol for transmitting the data was
previously discussed in FIG. 4. Generally, the remote transceiver
116 generates a data sequence and listens during interleaved time
slots for acknowledgment messages from base transceiver 120.
[0106] A paging signal can include a unique sequence of bits so
that a receiving transceiver can identify it as a paging signal. If
a link is not established within a predetermined time frame, the
system reverts to a power saving "low-power" mode.
[0107] FIG. 8 is a timing diagram more particularly illustrating
transmission of a paging signal by remote transceiver 116 while it
is in the paging mode. Multiple messages can be transmitted in a
sequence of frames.
[0108] While in the sleep mode, base transceiver 120 attempts to
detect paging signals on each of three transducer elements during
different time intervals. Based on orientation, it is possible that
one or even two of the transducers in base transceiver 120 can not
detect the paging signal generated by remote transceiver 116. To
account for this condition, base transceiver 120 intermittently
listens on each of different transducer elements during different
time durations to detect paging signals from remote transceiver
116. At least one transducer in base transceiver will be able to
detect a paging signal.
[0109] The process of receiving a signal on different transducers
can be achieved by including a multiplexer circuit in base
transceiver 120 so that a corresponding receiver can be selectively
coupled to each of different transducers at different times. A use
of a multiplexer circuit can reduce the number of receivers in a
transceiver device.
[0110] While in the sleep mode, base transceiver 120 does not
necessarily transmit information as shown in the timing diagram of
FIG. 4. Rather, base transceiver 120 occasionally listens for
paging signals transmitted by a remote transceiver 116. A sequence
of bits in a paging message such as preamble bits 425 and sync bits
430 can be used to synchronize base transceiver 120 and remote
transceiver 116.
[0111] Since base transceiver 120 and remote transceiver 116 can
initially be out of phase with each other prior to establishing a
formal two-way communication link, remote transceiver 116 can shift
the phase of the paging signal so that it eventually can be
detected by a base transceiver 120 in the sleep mode. In one
application, remote transceiver 116 shifts the phase of its timing
by 180.degree. or some incremental amount after determining that no
signal was received within a time period. Thus, base transceiver
120 can eventually detect a transmitted paging signal if it is
within range of remote transceiver 116.
[0112] Based on this technique, if both transceivers are
transmitting and receiving at the same time, one transceiver can
shift the phase of its transmit and receive cycle relative to the
second device so that the transceiver devices can communicate.
[0113] Referring again to FIG. 5, if base transceiver 120 does not
respond to the presence of a paging signal transmitted by remote
transceiver 116 in step 524, process flow continues to step 526,
which determines whether a timeout has occurred. If base
transceiver 120 does not respond within a time period of several
seconds or other predetermined amount of time, it is presumed that
there is no base transceiver 120 with which to connect and remote
transceiver 116 is set to the sleep mode again in step 515.
[0114] In the event that remote transceiver 116 receives a response
from base transceiver 120 in step 524 as a result of transmitting a
paging signal, process flow continues at step 530. It is determined
in step 530 whether base transceiver 120 acknowledges that a valid
communication code 470 was transmitted by remote transceiver 116 in
a previous paging message. For example, if a communication code 470
was previously established for use between headset 110 and cell
phone 130, this code can be sent in paging signals from remote
transceiver 116. Thus, base transceiver 120 can determine, based
upon receipt of a paging signal and value of a communication code
470 in the paging message, whether remote transceiver 116 has been
initialized with a non-factory programmed communication code 470.
More specifically, a base transceiver 120 can determine whether it
previously communicated with remote transceiver 116 based on code
470. A factory programmed code can be unique such as all zeros so
that the base transceiver 120 can determine whether remote
transceiver 116 has ever been previously initialized.
Alternatively, a unique communication code for a "matched" headset
110 and base can be factory programmed prior to shipment.
[0115] If base transceiver 120 sends a message to remote
transceiver 116 that it did not receive a valid or recognized
communication code 470 in a received paging signal in step 530,
process flow continues at step 535 where the remote transceiver 116
checks and waits for a queue indicating a desire by a user to
initiate an initialization process for establishing a communication
code 470 between headset 110 and cell phone 130.
[0116] The queue for initiating the initialization process to
establish a communication code 470 can vary depending on the
application. For example, the method of queuing a remote
transceiver 116 can involve steps as shown in FIG. 6. In step 610,
base transceiver 120 and remote transceiver 116 can be moved in
close proximity to each other, typically less than a foot apart.
The proximity or changing proximity can be detected at base
transceiver 120 based upon received signal strength.
[0117] Additional or alternative activating steps can be used to
initiate the initialization process. For example, in step 620, a
volume control or other switch on headset 110 can be held down by a
user to initiate programing a communication code. An internal
electronic signal generated by depressing the switch can be
received at remote transceiver 116 can indicate a desire by a user
to initiate the programming of a code 470. Thereafter, in step 630,
the transceivers are optionally positioned or oriented by a user in
a predetermined position with respect to each other to complete an
activation process.
[0118] Base transceiver 120 can identify an orientation of a
received magnetic field using a set of transducers to determine
whether headset 110 and, more particularly, remote transceiver 116
is oriented in such a way as to indicate that a user would like to
initialize headset 110 and cell phone 130 with a communication code
470. Following detection of the appropriate activation routine,
bidirectional communications are established between transceivers
to program a new communication code 470.
[0119] Other activation protocols can be used to initiate
programming of a communication code 470. In one application, a
strength of an inductive field received at base transceiver 120 is
used to determine that a user has initiated the initialization
process. It is known that the strength of a received field is a
strong function of distance between transceiver devices.
Consequently, a transceiver device can detect whether a received
signal is above a threshold to determine that the devices are in
close proximity. By measuring a signal strength, and therefore
approximate distance, an additional constraint can be used to
determine a user's intent to program the devices with a
communication initialization code.
[0120] As mentioned, an orientation of a received inductive field
can be used to activate the initialization process. For example, an
inductive field can be received on each of multiple transducer in a
transceiver device to determine an orientation of the inductive
field and therefore remote transceiver 116. Based on measured
characteristics, an orientation of the device transmitting the
inductive field can be determined.
[0121] In yet another application, a changing orientation over time
of, for example, a remote transceiver device relative to another
sensing transceiver device can be used to activate an
initialization process. More specifically, a headset can be
successively and rapidly moved near and far relative to a base
transceiver to initiate the initialization process. Also, a headset
device can be rotated or moved in a circular fashion to initiate
the initialization process.
[0122] A combination of conditions can be a prerequisite to
activating the initialization function. For example, a user can
press a "program" button to enter a mode in which one or more
conditions must be satisfied within a time window for the two
devices to proceed programming a new communication code 470 as
previously described. Thus, causing an activating condition outside
the window during normal bidirectional communications will not
cause the transceiver device to become programmed with a new
communication code 470.
[0123] One method of determining proximity includes sensing a
strength of a received signal on each of multiple transducers in a
transceiver device. Similarly, proximity can be determined by
detecting a strength of signals on a single transducer received
from multiple transducers transmitting at different times.
[0124] Fewer transducers can be used if the orientation is
predictable relative to the direction of the field being sensed,
such as would be possible if a game controller was limited to only
one or two degrees of freedom of motion relative to a fixed field
generating transducer in a base device.
[0125] Range, R, (to a first approximation) is typically a function
of the magnetic field strength M that is measured by the field
sensing coils and varies in accordance with the following
proportional formula:
M={square root}{square root over
(a.sub.x.sup.2+a.sub.y.sup.2+a.sub.z.sup.- 2)}
R=K.multidot.{cube root}{square root over (M)}
[0126] where a is the amplitude of signals measured by the x, y and
z coils, respectively, and K is a proportionality constant. An
advantage of the applying the formula above for determining
distance between transceivers is that ranging is achieved based on
amplitude of a received signal rather than the phase of the signal
on each transducer. Phase relationships of a detected signal can
also be used to determine orientation of a transceiver device.
[0127] Based on characteristics of transceiver devices and the
equations above, an inductive field can be analyzed to determine
the position and orientation of a transceiver.
[0128] In one application during the initialization process, a
first device with more than one transducer can be restricted to use
less then the total number of transducers when communicating with a
second device. Thus, physical orientation can be a condition for
initializing two devices. For example, a remote unit such as a
headset 110 may have to both be in close proximity and oriented
with respect to phone 130 for the initialization process to be
initiated. In such an embodiment one transducer, for example,
X-transducer 136 in the base transceiver 120, can be exclusively
used for initialization, the signal strength on the x transducer
would have to exceed a threshold while the remaining transducers
would fall below a second threshold. More specifically, orientation
of a transceiver can be determined by detecting that the strength
of a received signal is above a threshold value for one transducer
axis while the strength of a received signal is below corresponding
thresholds for two other transducer axes.
[0129] One method of determining an orientation of transceivers is
based upon measuring a relative strength of received signals on
multiple predetermined axes. For example, a strength of received
signals on each of three orthogonal transducers x, y and z can be
used to identify a relative angular orientation of a
transceiver.
[0130] Assuming that a pair of transceivers communicating with each
other do not substantially change their orientation during a major
cycle, a proportion of signal strengths can be used define a vector
of a received inductive field. The vector can be used to
approximate a relative positioning of base transceiver 120 with
respect to remote transceiver 116. For example, measurements of a
first sample reading on three orthogonal transducers can result in
a 0% received signal on transducer x, 0% received signal on
transducer y, and 100% received signal on transducer z. As
mentioned, the proportion of received signal strength identifies a
relative orientation of the transceiver at the time of the first
reading. At a later reading and after a change in orientation of
transceivers relative to each other, signal strengths can be
measured again. If the new readings result in a 100% received
signal on transducer x, 0% received signal on transducer y, and 0%
received signal on transducer z, it can be assumed that the
transceivers are now in a new relative orientation with respect to
each other. More specifically, based on the two readings of sample
data, it can be assumed that the relative angular orientation of
the transceivers relative to each other has changed by 90 degrees.
Consequently, an angular change in three dimensional space can be
estimated based on comparison of measured received signal values at
different times. A rate of change of orientation can be determined
by measuring the relative positions of a transceiver device at
different times.
[0131] In one application, an activation signal to answer a phone
call can be a motion of rotating headset 110 ninety degrees in less
than a 1 second time window. For example, a change in headset
orientation can be sensed at either base transceiver or remote
transceiver 116 using the technique as previously discussed. When a
proper predetermined motion is detected, a paging signal can be
generated by a sensing device to establish a communication link
between transceivers so that user can answer a call merely by
picking up headset 110 and placing it on his head. Hence, it is not
necessary to press a button to activate receiving a call.
[0132] Use of diversity circuits for magnetic induction
communication are discussed in greater detail in U.S. Pat. Nos.
5,777,438 and 5,912,925, issued to Aura Communication, the entire
teachings of which are incorporated herein by this reference.
[0133] Referring again to FIG. 5, if a queue such as one of the
above-mentioned activation protocols is not detected within a
timeout period in step 540, process flow continues at step 542 to
determine whether a timeout occurred. If so, remote transceiver 116
enters the sleep mode in step 515. If not, remote transceiver 116
continues in the paging mode in step 522.
[0134] If a queue is detected within a predetermined timeout period
in step 540, process flow continues at step 545 in which a
communication code 470 is established for exclusive communications
between headset 110 and cell phone 130. Typically, base transceiver
120 generates a unique communication code 470 and transmits it to
remote transceiver 116. Conversely, a remote transceiver 116 or a
combination of transceivers can generate communication code
470.
[0135] Both transceiver devices can store code 470 in non-volatile
memory for later retrieval. Additional bidirectional communications
can be used to confirm that a communication has been properly
established.
[0136] After establishing a communication code 470 in step 545,
process flow then continues at step 555 in which bidirectional
communications are supported between headset 110 and cell phone 130
using the new communication code 470.
[0137] If base transceiver 120 responds to remote transceiver 116
in step 530 indicating that a valid communication code 470 was
detected in a paging message, it is noted that the transceivers
have already been initialized for exclusive one-way or
bidirectional communications. Process flow would then also continue
at step 555.
[0138] After establishing a communication link between
transceivers, it is determined in step 560 whether an out-of-range
condition is detected during a conversation. For example,
communication between headset 110 and cell phone 130 may cease as a
result of separating the transceivers so far apart that
corresponding transmit signals can not be detected at either
transceiver device.
[0139] If the transceivers reestablish communication as a result of
moving the devices in range with each other again, it is determined
in step 570 whether the re-connection has occurred within a timeout
period. If so, process flow continues at step 555 to resume
previous communications. If not, headset 110 is set to the sleep
mode to conserve battery resources because it is assumed that the
previous link has terminated.
[0140] If no out of range condition is detected in step 560, it is
determined in step 565 whether a terminate command has been
received indicating a desire by a user to terminate the active link
between base transceiver 120 and remote transceiver 116. If not,
communications continue again in step 555. If so, remote
transceiver 116 and base transceiver 120 are set to sleep mode in
step 515 in order to conserve power. Terminate commands can be any
of the activating type of conditions as previously discussed. More
specifically, a terminate command can be detected by sensing a
proximity, orientation or motion of a transceiver device.
[0141] After a transceiver device is initialized to uniquely
associate it with another transceiver device, other devices can
ignore such communications. For example, consider that two cell
phone users each having corresponding headsets are in range of each
other. According to the principles of the present invention, the
first user can use his cell phone and headset without worrying
about the second user turning on his headset and eavesdropping on a
private communication because the communication code sent in each
message will not be known by the second user's headset or cell
phone.
[0142] Multiple devices for multi-point communication can be
initiated in a similar manner. For example, one base transceiver
can be initialized to two headsets via two different communication
codes. This enables a single headset to communicate with multiple
transceiver devices. More specifically, a headset can be programmed
to communicate with a wireless phone and, alternatively, a second
base transceiver coupled to a wired phone in a user's office.
Initialization can be required only once per
transceiver-to-transceiver relationship since the communication
code or communication codes can be stored in non-volatile
memory.
[0143] In one application, base transceiver 120 is held physically
close to remote transceiver 116 and a deliberate action, such as
holding a power on/off switch for an extended period of time, is
performed by a user to initiate the initialization process. This
activation routine can trigger firmware stored in memory 125 or
remote memory 155 to generate a communication code 470 that
uniquely identifies the base-remote transceiver relationship
110.
[0144] Portions of the communication code can identify different
aspects of a transceiver device. For example, a communication code
470 can identify a type of device (e.g., a type of headset, PDA,
joystick, mouse, keyboard . . . ), a version of operating firmware,
a master-slave relationship, number of transducers in a transceiver
device, or protocol for transmitting and receiving data.
[0145] Information transmitted in a data field transmitted from a
transceiver can be encrypted so that only a user programmed with a
proper communication code 470 can decode received data messages. In
this instance, a communication code is not sent in each message.
Rather, a communication link is established between transceiver
devices and each transceiver encrypts and decrypts the data based
upon a code known only to the transceiver device.
[0146] Once base transceiver 120 and remote transceiver 116 are
initialized to each other via code 470, both devices store the
unique paired device identifier code in nonvolatile memory until
erased by a second predetermined action. The protocol to erase or
reprogram a communication code can be similar to those previously
discussed to activate the initialization process.
[0147] It should be noted that orientation and proximity of two or
more transceiver devices can be used to control other aspects of
communication system 100. For example, if a headset "docking"
station (e.g., a station in which a headset can be secured to a
slot or hook in cell phone 130) is used to secure a headset 110 to
phone 130 when not in use, the orientation and proximity of headset
110 relative to the phone 130 can be used to identify that a phone
call has been terminated. More specifically, a user can complete a
call and move the headset in a specific predetermined relation to
cell phone 130 to terminate a call. Base transceiver 120 can detect
this motion as previously discussed and, in response, automatically
shut off power to the phone. Accordingly, a call may be terminated
more simply than is otherwise necessary using buttons or other
mechanical components.
[0148] Base station 120 can also monitor the movement of headset
110 to determine that a call is being initiated by a user removing
the headset from a resting position such as a docking station. In
other words, removing the headset from the docking station can
cause either or both the headset and base transceiver to become
powered and establish a communication link via paging signals.
Accordingly, fewer push buttons and control features are necessary
to activate a transceiver device. Also, the use of this contactless
activation method is simple to use because the headset 110 must be
detached from phone 130 to use anyway.
[0149] FIGS. 7A and 7B are state diagrams illustrating different
modes of an inductive communication system according to certain
principles of the present invention. As shown, remote transceiver
116 can communicate with base transceiver 120 to establish a
communication link as previously discussed in FIG. 5.
[0150] Initially, power is applied to headset 110 to enter the
sleep mode in state 710. Remote transceiver 116 then waits for an
input such as a "flash" condition in which a user activates the
headset for use. The activation can be motion, pressing a button,
or any activation as previously discussed. This causes headset 110
to enter the standby mode 715.
[0151] While in the standby mode 715, headset 110 and, more
specifically, remote transceiver 116 generates paging signals and
transmits them to base transceiver 120. Initially, base transceiver
120 is in standby mode 760 listening for paging signals. Upon
detection of a message from remote transceiver 116, transceiver 120
enters acquire mode 765.
[0152] While in paging mode 715, remote transceiver 116 will
retransmit a link request message until a response is received from
base transceiver 120. If no response is received within time out
period, remote transceiver 116 goes back into sleep mode 710. If a
response is received from base transceiver 120, remote transceiver
116 enters either initialize mode 720 or active link mode 725
depending on whether base transceiver 120 received a valid
communication code 470. If base transceiver 120 acknowledges
receipt of a paging message from remote transceiver 116, a
communication code is programmed in mode 720 if conditions are
detected to activate programming a communication code. After a new
code 470 is programmed, bidirectional communications are supported
while remote transceiver 116 is in active link mode 725.
[0153] Base transceiver 120 enters corresponding modes to
initialize a base-remote transceiver pair with communication code
470. For example, initialization mode 770 is used to link base
transceiver 120 and remote transceiver 116 to establish a code,
while active link mode 775 enables transceiver to communicate
information over an active link.
[0154] FIGS. 9A and 9B are state diagrams illustrating modes of an
inductive communication system according to certain principles of
the present invention. As shown, inductive communications system
900 is directed towards establishing a communication link between
cell phone 130 and headset 110. However, it should be noted that
such principles can be extended for use in other inductive wireless
communication applications as well.
[0155] Initially, both base transceiver 120 and remote transceiver
116 in headset 110 wait in sleep modes 960 and 910, respectively.
In addition to "ringing" a phone 130 to notify a user of incoming
call, an active call signal can be detected by base transceiver 120
monitoring new calls based on appropriate electronic signals in
cell phone 130. When a call is detected, base transceiver 120
enters paging mode 965. At this point, base transceiver 120 sends
out paging signals to remote transceiver 116 to establish an active
link.
[0156] In response to hearing ringing cell phone 130, a user
activates headset 110 based on an action such as pressing a button
or merely removing headset 110 from a docking station and
positioning it on his head. This activation signal can be detected
as previously discussed by remote transceiver 116 and causes remote
transceiver 116 to enter paging mode 915. At this point, both base
transceiver 120 and remote transceiver 116 are in paging mode
increasing chances that both devices will detect each others
presence to establish an active link. Recall that while in the
paging mode, both transceivers also listen for acknowledgment
messages from the other paging transceiver device.
[0157] If for some reason base transceiver 120 and remote
transceiver 116 can not establish a link within a timeout period,
both transceivers will enter a listen mode 920 and 970,
respectively, to conserve power.
[0158] On the other hand, when base transceiver 120 and remote
transceiver 116 acknowledge receipt of paging messages from each
other, base transceiver 120 and remote transceiver 116 enter active
link modes 980 and 930, respectively. In these states, base
transceiver 120 and remote transceiver 116 communicate with each
other by sharing a common bandwidth. If the transceivers
accidentally become out-of-range with each other, base transceiver
120 and remote transceiver 116 will enter out-of-range modes 985
and 935, respectively, until a link is reacquired or a timeout
occurs.
[0159] If a previous link is not reaquired within a timeout period,
both base transceiver 120 and remote transceiver 116 enter listen
modes 970 and 920, respectively. Both transceivers listen for
paging signals from the other transceiver device.
[0160] If lost, a user can reinitiate a link by activating headset
110. For example, a user can press a button on headset 110 causing
remote transceiver 116 to enter paging mode 915. When base
transceiver 120 receives a paging message from headset 110 (listen
mode 970), base transceiver 120 enters acquire mode 975. Messages
are then sent between transceivers to cause both transceivers to
again enter active link modes 980 and 930, respectively.
[0161] It should be noted that while base transceiver 120 and
remote transceiver 116 are in listen mode 970 and 920,
respectively, a user can optionally activate base transceiver 120
so that it enters paging mode 965. Upon receipt of a paging message
from base transceiver 120, remote transceiver 116 will enter
acquire mode 925 and eventually active link mode 930 if a base
acknowledge message is received.
[0162] FIG. 10 is a timing diagram illustrating allocation of
bandwidth to multiple transceiver devices communicating in an
inductive communication system according to certain principles of
the present invention. As shown, base transceiver 120 communicates
with each of multiple remote transceivers #1, #2 and #3 (116-1,
116-2, and 116-3) during allocated communication cycles.
[0163] One aspect of the present invention involves partitioning a
bandwidth so that multiple transceivers can communicate with base
transceiver 120. Base transceiver frames 610 illustrate time slots
in which data is either received from (denoted as R) or transmitted
to (denoted as T) a corresponding remote transceiver 116.
Communication cycles 612, 614 and 616 are used by respective remote
transceivers 116 to communicate with base transceiver 120.
[0164] During cycle 612, communications are supported between
remote transceiver #1 116-1 and base transceiver 120. In a first
part of cycle 612 denoted by T, remote transceiver #1 transmits
from a selected transducer (or axis as a result of transmitting on
multiple transducers) to base transceiver 120, which receives the
signal. In one application, base transceiver 120 receives on a
single selected transducer such as x-transducer 136, y-transducer
137 or z-transducer 138, depending on which transducer supported
the most robust communications as detected by prior
communications.
[0165] Base transceiver 120 can be notified by remote transceiver
#1 which transducer at base transceiver 120 resulted in a strongest
received signal from previous communications via a message to base
transceiver 120. Based upon receipt of this message, base
transceiver 120 can transmit and receive on the preferred
transducer or set of transducers.
[0166] During a second portion of cycle 612 denoted by T, base
transceiver 120 transmits to remote transceiver #1 over a selected
transducer while remote transceiver #1 receives the transmitted
data information in the same time slot. Consequently, a pair of
transducers, one disposed in base transceiver 120 and another
disposed in remote transceiver #1, can be used to support
communications between transceivers.
[0167] If an orientation of remote transceiver #1 changes with
respect to base transceiver 120, a different pair of transducers of
a transceiver pair can be selected for communications as a result
of diversity checks.
[0168] A last portion of cycle 612 (as well as a last portion of
cycle 614 and cycle 616) can be used to perform a diversity check
to occasionally check if another transducer or set of transducers
is more optimal for transmitting and receiving data than a
previously selected transducer or transducer for transmitting and
receiving data information.
[0169] In the timing diagram shown, a last portion of each cycle is
dedicated for use as a broadcast mode in which a selected
transducer (or combination of transducers) of base transceiver
device 120 transmits an inductive field that is received by each of
multiple remote transceivers. For example, in diversity check slot
658 of cycle 612, base transceiver 120 can generate a signal from
x-transducer 136. Each remote transceiver #1, #2 and #3 receives
the signal and detects a quality of the received signal.
[0170] In later time cycles 614 and 616, base transceiver 120
transmits on y-transducer 137 and z-transducer 138 in respective
diversity check slots 659 and 660. Again, remote transceivers #1,
#2 and #3 receive and detect a quality of received signal in each
diversity time slot. Each remote transceiver #1, #2, and #3 can
then compare link qualities of signals received over each of the
different combinations of transducer pairs to determine which
combination of selected transducers supports an acceptable link
quality. This method ensures that different transducers are at
least occasionally tested to determine whether they would otherwise
provide a higher quality or more robust communication link with a
corresponding transceiver. Thus, continuous coupling can be
maintained for multiple transceivers regardless of their
orientation.
[0171] After determining a preferred transducer or set of
transducers on which to transmit and receive, a message can be
generated by remote transceiver 116 to notify base transceiver 120
which transducer or transducers should be selected to transmit or
receive further information at least in the next communication
cycle.
[0172] Cycle 614 illustrates time slots supporting bidirectional
communications between base transceiver 120 and remote transceiver
#2. Similarly, cycle 616 illustrates time slots supporting
bidirectional communication between base transceiver 120 and remote
transceiver #3. As previously discussed for remote transceiver #1,
remote transceiver #2 and #3 can determine which transmit or
receive axis supported by base transceiver 120 should be selected
in corresponding cycles to communicate with a remote
transceiver.
[0173] Based on an orientation of each remote transceiver 116, a
single transceiver can communicate with multiple remote transceiver
regardless of their orientation. An advantage of this technique is
efficient use of bandwidth since a transmission from a transceiver
can be simultaneously received by multiple transceivers to
determine link quality for different links.
[0174] It should be noted that the duration of time slots is not
necessarily to scale as illustrated in FIG. 10. For example, as
shown, a diversity check slot can include around 2% of time in
cycle 612, while transmit and receive slots are partitioned to
approximately 49% each. This partitioning can vary depending on the
application.
[0175] In lieu of partitioning slots as shown in FIG. 10, each
cycle 612, 614, and 616 can include multiple interleaved
transmit-receive time slots as shown in field A or field B of FIG.
4. Consequently, a remote transceiver 116 can notify base
transceiver 120 early in a cycle which of multiple transducers
should be used for further communications. Such a message is
optionally incorporated in data field 440, reserved for link
control commands.
[0176] Although cycle 612, cycle 614 and cycle 616 illustrate that
base transceiver 120 receives in first part of cycle, a sequence of
which transceiver transmits or receives first can vary depending on
the application.
[0177] FIG. 11 is a timing diagram including a portion of bandwidth
allocated for paging signals according to certain principles of the
present invention. As shown, cycle 1105 is reserved for paging
transmissions from either remote transceiver 116 or base
transceiver 120. Consequently, base transceiver 120 can page other
transceivers and detect paging signals from other transceivers that
are not presently allocated bandwidth.
[0178] It should be noted that a paging signal can include a code
identifying a target transceiver in which it is trying to establish
a communication link. For example, a base transceiver can transmit
a paging signal including a communication code 470 of the
transceiver device with which it is attempting to establish
communications. Only the transceiver or transceivers having a code
will respond with an acknowledgment message.
[0179] In one application, timing diagram 1100 is fixed to support
a predetermined number of remote transceivers. As each new remote
transceiver 116 request assignment of time slot usage, they are
assigned use of cycle 612, cycle 614 or cycle 616 if they are not
in use. A single remote transceiver can be assigned any number of
minor cycles.
[0180] Before generating a paging signal as a result of being
activated by a user, a transceiver device can listen to other
transceiver transmissions to determine whether a link presently
exists between base transceiver 120 and a remote transceiver. If
so, a remote transceiver attempting to establish a communication
link can determine when cycle 1105 occurs in a major cycle.
Accordingly, a transceiver can identify when to transmit a paging
signal to base transceiver 120 for assignment of bandwidth.
[0181] Once a transceiver is assigned bandwidth such as cycle 612,
the new remote transceiver 116 can utilize diversity checks to
support more robust communications as previously discussed in FIG.
10.
[0182] FIG. 12 is a timing diagram illustrating dynamic bandwidth
allocation according to certain principles of the present
invention. Upon detection of a fourth remote transceiver 116
transmitting paging signals, an available bandwidth can be
reapportioned from that as shown in FIG. 11 to also include cycle
617 for supporting communication between remote transceiver #4 and
base transceiver 120.
[0183] A paging message can be transmitted in cycle 1105 indicating
that a remote transceiver desires allocation of bandwidth. Base
transceiver 120 can then determine whether to allocate bandwidth to
the link requesting transceiver.
[0184] Each remote transceiver 116 can be notified of an addition
or deletion of a cycle in timing diagram 1200. The message can be
broadcast from base transceiver 120 in cycle 1105 to all remote
transceivers indicating that a new timing diagram will be
implemented at the beginning of the next or following major cycle.
Consequently, a newly added user can communicate with base
transceiver 120 without interfering with other transceivers isnce a
number of minor cycles in a major cycle is reapportioned to
accommodate new or terminated transceivers. This technique ensures
that bandwidth is optimally utilized by multiple transceivers.
[0185] FIG. 13 is a timing diagram of communications between a base
transceiver and remote transceiver according to certain principles
of the present invention. As shown, base transceiver 120 transmits
and receives information to remote transceiver 116 during cycles
1305.
[0186] Between cycles 1305, a diversity check is performed. More
specifically, two other transducers not presently used to support
communications are activated in respective diversity slots 1320 and
1321 of a major cycle 1345 to determine whether orientation of a
transceiver has changed substantially to warrant on which new axis
the transceivers should transmit and receive.
[0187] Link qualities for communications between different
combinations of transducers are compared in timing diagram 1300.
Specifically, link qualities of communications in respective cycles
1305 and diversity slots 1320 and 1321 of a major cycle 1345 are
compared. A selection of transducers for transmitting and receiving
a data payload is derived as a result of comparing the link
qualities.
[0188] Crossover point 1350 illustrates a condition when transducer
z (as a result of changing orientation) provides a higher link
quality than previously used transducer x. As a result, future data
payload transmissions are supported on z-transducer 138 in
following cycles 1310. Diversity checks of x-transducer 136 and
y-transducer 137 are thereafter performed in time slots 1323 and
1320, respectively, for major cycle 1365.
[0189] FIG. 14 is a block diagram of a communication system
according to certain principles of the present invention. As shown,
multiple transceivers communicate with each other over multiple
inductive links 122.
[0190] More specifically, transceiver A can communicate with
transceiver B and transceiver C over inductive links 122-AB and
122-AC, respectively. Similarly, other transceivers can communicate
with each other over additional inductive links 122-BC and 122-BD.
A communication code 470 is optionally used to support exclusive
communications between transceivers.
[0191] As previously discussed, each transceiver can include one or
multiple transducers so that the transceivers can communicate with
each other regardless of their orientation with respect to each
other. Also, more than one remote transceiver can be allocated a
time slot for receiving data information. For example, a broadcast
message can be transmitted to multiple transceivers simultaneously.
This aspect of the present invention can be advantageous in audio
systems where a single transceiver broadcasts music to multiple
headsets. This technique is also applicable to the topology
illustrated in FIG. 3.
[0192] FIG. 15 is a timing diagram for supporting inductive
communications among multiple transceivers according to certain
principles of the present invention. As shown, different pairs of
transceivers are allocated use of a particular communication cycle
1520 to communicate with each other. As previously discussed for
FIG. 11, a minor cycle 1520 in a major cycle 1530 can be dedicated
for paging signals and initialization of transceivers.
[0193] Each cycle 1520 allocated for use by a pair of transceivers
for bidirectional communications can include a diversity check slot
1510. As previously discussed, diversity checks can be used to
determine which of multiple potential axes is optimal to transmit
or receive an inductive field. At a minimum, it can be determined
which of multiple transducers is optimal for transmitting and
receiving.
[0194] If a transceiver device includes multiple transducers, one
or more of the multiple transducers can be selected to generate an
inductive field on a particular axis. This adds another dimension
to the number of potential axes on which a transceiver can transmit
and receive. For example, both x-transducer 136 and y-transducer
can be simultaneously activated to generate an inductive field on
an axis between the two. This technique can be implemented in any
application discussed in this specification. Consequently, an
orientation of a transmitted or received inductive field is not
limited to axes of the individual transducers in a transceiver.
implementation of a diversity time slot can vary depending on the
application. In the application as shown in FIG. 15, diversity
check slot 1510 can be used to compare link qualities of different
transducer links prior to bidirectional transmissions from a pair
of transceivers in a given cycle 1520.
[0195] If both transceivers each include multiple transducers, a
single transducer in one transceiver of the transceivers can be
selected for transmitting and receiving. Each potential link
between the selected transducer and other transducers at another
transceiver can be tested using diversity checks to determine which
combination provides a better link quality.
[0196] FIG. 16 is a block diagram of a communication system
including multiple transceivers according to certain principles of
the present invention. As shown, each transceiver device includes
multiple transducer elements to receive and generate information
over inductive field 122. Since each transceiver includes multiple
transducers, a single transducer in one of the transceivers is
selected to communicate with the other transceiver. In the instance
shown, transducer x of transceiver A is selected for supporting
communications.
[0197] In an application utilizing communication codes, a
communication code 470 can include information identifying the
single "selected" transducer in a transceiver if there an excess
number of transducers in the transceiver device to communicate with
other transceiver devices.
[0198] FIG. 17 is a timing diagram illustrating a diversity check
according to certain principles of the present invention. To
identify a preferred link for communications between transceivers,
transceiver A transmits a coded signal from selected transducer x
during cycle 1710.
[0199] During cycle 1710, transceiver B receives the signal
transmitted from transceiver A and compares link qualities of the
corresponding received signal on transducer x, y and z of
transceiver B during respective time slots in timing diagram 1700.
Transceiver B compares link qualities to determine which transducer
receives a strongest signal.
[0200] A link comparison message 1730 is then generated by
transceiver B and is transmitted from transceiver B to transceiver
A indicating which transducer provides the best received signal
quality. Consequently, future communications following a diversity
check 15 10 in cycle 1520 of FIG. 15 can identify which axis to
transmit and receive data information.
[0201] While this invention has been particularly shown and
described with references to preferred embodiments thereof, it will
be understood by those skilled in the art that various changes in
form and details may be made therein without departing from the
scope of the invention encompassed by the appended claims.
* * * * *