Slotted synchronous frequency division multiplexing for multi-drop networks
View Patent ↗In a modulation system an efficient modulation at a master station and allows great flexibility in clients, from simple 2 bit/symbol single-channel modulation and demodulation to multi-channel multiple-bit modulation. The present invention also permits selection of the frequency band to use for transmission, thus dealing effectively with channel nulls and no channel equalization is required. The present invention is a useful technique for short-distance moderate-rate multi-drop networking, such as multi-channel home-telephone for Voice over IP(VoIP).
1. A method of communicating information within a local area network using a master station forming a residential gateway for transmitting and receiving information from a broad band network and distributing said information in the local area network to a number of slave transmitter/receivers comprising the steps of
a. dividing said information into mapping frames;
b. applying said mapping frames to a plurality of channels; said channels each allocated a complex transmit symbol
c. transmitting a signal characterized by the empirical relationship:
x
(
4
mK
+
n
)
=
∑
k
=
0
K
-
1
A
k
m
·
ⅇ
-
j
nk
π
K
+
∑
k
=
0
K
-
1
(
A
K
-
k
m
)
*
·
ⅇ
-
j
n
(
K
+
k
)
π
K
where A k m is the k-th symbol of the m-th mapping frame, where x( ) is a discrete-time transmit signal, n is an index from 0 to 4K, (A m K−k )* is a complex conjugate of a value of the (K−k)th symbol of the m-th mapping frame, k is a channel index, and K is a maximum number of symbols per mapping frame.
2. A method of communicating information within a local area network using a master station forming a residential gateway for transmitting and receiving information from a broad band network and distributing said information in the local area network to a number of slave transmitter/receivers comprising the steps of
a. dividing said information into mapping frames;
b. applying said mapping frames to a single channel allocated a complex transmit symbol
c. transmitting a signal characterized by the empirical relationship:
x
(
4
mK
+
n
)
=
A
k
m
·
ⅇ
-
j
nk
π
K
+
(
A
k
m
)
*
·
ⅇ
-
j
n
(
2
K
-
k
)
π
K
where A k m is the k-th symbol of the m-th mapping frame where x( ) is a discrete-time transmit signal, n is an index from 0 to 4K, (A m K−k )* is a complex conjugate of a value of the (K−k)th symbol of the m-th mapping frame, k is a channel index, and K is a maximum number of symbols per mapping frame.
3. A method of communicating information within a local area network using a master station forming a residential gateway for transmitting and receiving information from a broad band network and distributing said information in the local area network to a number of slave transmitter/receivers comprising the steps of
a. dividing said information into mapping frames;
b. applying said mapping frames to a single channel allocated a complex transmit symbol
c. transmitting a signal characterized by the empirical relationship:
x
(
4
mK
+
n
)
=
Re
[
A
k
m
ⅇ
-
j
nk
π
K
]
where A k m is the k-th symbol of the m-th mapping frame, where x( ) is a discrete-time transmit signal, n is an index from 0 to 4K, (A m K−k )* is a complex conjugate of a value of the (K−k)th symbol of the m-th mapping frame, k is a channel index, and K is a maximum number of symbols per mapping frame.
4. A method of communicating information as described in claim 3 comprising the further steps of:
a. receiving said transmitted signal and
b. demodulating said transmitted a signal according to the empirical relationship:
A
⋒
k
m
=
1
2
K
∑
n
=
0
2
K
-
1
x
⋒
(
(
4
m
+
1
)
K
+
n
)
·
ⅇ
j
nk
π
K
where  k m is an estimated of the k-th symbol of the m-th mapping frame, where {circumflex over (x)}( ) is a discrete-time receive signal.
5. A multi-drop network comprising:
a master transmitter and receiver for receiving a composite signal having multiple sets of information, said master transmitter and receiver providing primary modulation and demodulation of said composite signal and generating a plurality of signal receiver signals to be transmitted on plurality of separate communication channels; and
a plurality of single transmitter receivers each coupled to said master transmitter on a selected ones of said separate communication channels for receiving a selected ones of said single receiver signals;
wherein said master transmitter and receiver transmits said composite signal as data in the form of mapping frames and where each sub-channel is allocated a complex transmit symbol characterized by A k m denoting the k-th symbol of the m-th mapping frame and where the transmit signal is determined by the following empirical relationship:
x
(
4
mK
+
n
)
=
∑
k
=
0
K
-
1
A
k
m
·
ⅇ
-
j
nk
π
K
+
∑
k
=
0
K
-
1
(
A
K
-
k
m
)
*
·
ⅇ
-
j
n
(
K
+
k
)
π
K
where x( ) is a discrete-time transmit signal, n is an index from 0 to 4K, (A m K−k )* is a complex conjugate of a value of the (K−k)th symbol of the m-th mapping frame, k is a channel index, and K is a maximum number of symbols per mapping frame.
6. A multi-drop network as described in claim 5 wherein said master transmitter further comprises:
a. a synchronous modulator using inverse FFT.
7. A multi-drop network as described in claim 5 wherein said master receiver further comprises:
a. a synchronous demodulator using FFT.
8. A multi-drop network comprising:
a master transmitter and receiver for receiving a composite signal having multiple sets of information, said master transmitter and receiver providing primary modulation and demodulation of said composite signal and generating a plurality of signal receiver signals to be transmitted on plurality of separate communication channels; and
a plurality of single transmitter receivers each coupled to said master transmitter on a selected ones of said separate communication channels for receiving a selected ones of said single receiver signals;
wherein said master transmitter and receiver receives said composite signal as data in the form of mapping frames and where a single sub-channel is allocated a complex transmit symbol characterized by A k m denoting the k-th symbol of the m-th mapping frame and where the transmit signal is determined by the following empirical relationship:
x
(
4
mK
+
n
)
=
∑
k
=
0
K
-
1
A
k
m
·
ⅇ
-
j
nk
π
K
+
∑
k
=
0
K
-
1
(
A
K
-
k
m
)
*
·
ⅇ
-
j
n
(
K
+
k
)
π
K
where x( ) is a discrete-time transmit signal, n is an index from 0 to 4K, (A m K−k )* is a complex conjugate of a value of the (K−k)th symbol of the m-th mapping frame, k is a channel index, and K is a maximum number of symbols per mapping frame.
9. A multi-drop network comprising:
a master transmitter and receiver for receiving a composite signal having multiple sets of information, said master transmitter and receiver providing primary modulation and demodulation of said composite signal and generating a plurality of signal receiver signals to be transmitted on plurality of separate communication channels; and
a plurality of single transmitter receivers each coupled to said master transmitter on a selected ones of said separate communication channels for receiving a selected ones of said single receiver signals;
wherein said master transmitter and receiver receives said composite signal as data in the form of mapping frames and where a single sub-channel is allocated a complex transmit symbol characterized by A k m denoting the K-th symbol of the m-th mapping frame and where the transmit signal is determined by the following empirical relationship:
x
(
4
mK
+
n
)
=
Re
[
A
k
m
ⅇ
-
j
nk
π
K
]
where A k m is the k-th symbol of the m-th mapping frame, where x( ) is a discrete-time transmit signal, n is an index from 0 to 4K, (A m K−k )* is a complex conjugate of a value of the (K−k)th symbol of the m-th mapping frame, k is a channel index, and K is a maximum number of symbols per mapping frame.
10. A multi-drop network comprising:
a master transmitter and receiver for receiving a composite signal having multiple sets of information, said master transmitter and receiver providing primary modulation and demodulation of said composite signal and generating a plurality of signal receiver signals to be transmitted on plurality of separate communication channels; and
a plurality of single transmitter receivers each coupled to said master transmitter on a selected ones of said separate communication channels for receiving a selected ones of said single receiver signals;
wherein said single transmitter and receiver receives said composite signal as data in the form of mapping frames where a complex transmit symbol characterized by  k m denoting an estimate of the K-th symbol of the m-th mapping frame and where the received signal is recovered by the following empirical relationship:
A
⋒
k
m
=
1
2
K
∑
n
=
0
2
K
-
1
x
⋒
(
(
4
m
+
1
)
K
+
n
)
·
ⅇ
j
nk
π
K
where {circumflex over (x)}( ) is a discrete-time receive signal, n is an index from 0 to 4K, k is a channel index, and K is a maximum number of symbols per mapping frame.