US20020101913A1 - Dynamic adaptive modulation negotiation for point-to-point terrestrial links - Google Patents
Dynamic adaptive modulation negotiation for point-to-point terrestrial links Download PDFInfo
- Publication number
- US20020101913A1 US20020101913A1 US09/967,479 US96747901A US2002101913A1 US 20020101913 A1 US20020101913 A1 US 20020101913A1 US 96747901 A US96747901 A US 96747901A US 2002101913 A1 US2002101913 A1 US 2002101913A1
- Authority
- US
- United States
- Prior art keywords
- wireless modem
- receiver
- signal
- transmitter
- link
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
Links
- 230000003044 adaptive effect Effects 0.000 title description 4
- 238000000034 method Methods 0.000 claims abstract description 7
- 230000008569 process Effects 0.000 claims description 2
- 238000012937 correction Methods 0.000 abstract description 36
- 230000015556 catabolic process Effects 0.000 abstract description 22
- 238000006731 degradation reaction Methods 0.000 abstract description 22
- 230000007613 environmental effect Effects 0.000 abstract description 19
- 230000005540 biological transmission Effects 0.000 abstract description 13
- 230000008859 change Effects 0.000 description 34
- 238000011084 recovery Methods 0.000 description 16
- 238000010586 diagram Methods 0.000 description 13
- 239000000872 buffer Substances 0.000 description 9
- 230000003247 decreasing effect Effects 0.000 description 9
- 230000007423 decrease Effects 0.000 description 8
- 230000004044 response Effects 0.000 description 8
- 238000005070 sampling Methods 0.000 description 8
- 230000007704 transition Effects 0.000 description 8
- 230000000694 effects Effects 0.000 description 5
- 230000000593 degrading effect Effects 0.000 description 3
- 230000009471 action Effects 0.000 description 2
- 230000001419 dependent effect Effects 0.000 description 2
- 238000012546 transfer Methods 0.000 description 2
- 230000001052 transient effect Effects 0.000 description 2
- 230000006872 improvement Effects 0.000 description 1
- 230000000977 initiatory effect Effects 0.000 description 1
- 230000003993 interaction Effects 0.000 description 1
- 230000028161 membrane depolarization Effects 0.000 description 1
- 238000012360 testing method Methods 0.000 description 1
Images
Classifications
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L1/00—Arrangements for detecting or preventing errors in the information received
- H04L1/0001—Systems modifying transmission characteristics according to link quality, e.g. power backoff
- H04L1/0015—Systems modifying transmission characteristics according to link quality, e.g. power backoff characterised by the adaptation strategy
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B17/00—Monitoring; Testing
- H04B17/30—Monitoring; Testing of propagation channels
- H04B17/309—Measuring or estimating channel quality parameters
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L1/00—Arrangements for detecting or preventing errors in the information received
- H04L1/0001—Systems modifying transmission characteristics according to link quality, e.g. power backoff
- H04L1/0002—Systems modifying transmission characteristics according to link quality, e.g. power backoff by adapting the transmission rate
- H04L1/0003—Systems modifying transmission characteristics according to link quality, e.g. power backoff by adapting the transmission rate by switching between different modulation schemes
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L1/00—Arrangements for detecting or preventing errors in the information received
- H04L1/0001—Systems modifying transmission characteristics according to link quality, e.g. power backoff
- H04L1/0009—Systems modifying transmission characteristics according to link quality, e.g. power backoff by adapting the channel coding
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L5/00—Arrangements affording multiple use of the transmission path
- H04L5/14—Two-way operation using the same type of signal, i.e. duplex
- H04L5/16—Half-duplex systems; Simplex/duplex switching; Transmission of break signals non-automatically inverting the direction of transmission
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L1/00—Arrangements for detecting or preventing errors in the information received
- H04L1/0001—Systems modifying transmission characteristics according to link quality, e.g. power backoff
- H04L1/0023—Systems modifying transmission characteristics according to link quality, e.g. power backoff characterised by the signalling
- H04L1/0025—Transmission of mode-switching indication
Definitions
- the present invention relates to a wireless modem, and more particularly, the present invention relates to a wireless modem that improves link characteristics between modems during periods of reduced environmental degradation of the link, and method therefor.
- channel capacity is primarily dependent upon signal-to-noise ratio, or “SNR”.
- SNR signal-to-noise ratio
- the channel capacity decreases, causing a link formed between the transmitter and the receiver to be degraded, corrupting the transfer rate of the corresponding carrier signal.
- the SNR increases, the channel capacity increases, resulting in improved transfer rate of the carrier signal.
- the level of the effects of these interactions between the carrier signal and the rainfall depend on both the number of raindrops encountered by the carrier signal, and the distribution of the size and shapes of the raindrops, both of which depend on the rate of the rainfall.
- a raindrop is substantial enough in size to degrade the link during periods of moderate to intense rainfall.
- the wireless broadband link is a terrestrial link, the entire link may be covered in rain, depending on the size of the associated storm, and therefore substantially the entire link is degraded.
- FIG. 1 is a graphical representation of a relationship between the SNR and rainfall over time.
- Environmental degradation of a signal that occurs, for example, during an intense snowfall in January is indicated by a downward extending spike 20 a .
- environmental degradation of the signal that occurs during intense rainfall in June and July is indicated by downward extending spikes 20 b - d
- environmental degradation of the signal that occurs during an intense snow storm in December is indicated by a downward extending spike 20 e .
- degradation of a carrier signal due to intense snow or rainfall might only occur less than one percent of the time in a given year, for a link to be reliable it must be engineered to always operate throughout the year at an SNR corresponding to the periods of intense snow or rainfall. Accordingly, the link must be engineered to always operate at the lowest SNR, indicated by a horizontal line 22 .
- Objects of the invention are achieved by a wireless modem that includes a controller that samples a number of parameters of a wireless terrestrial signal and a data adjusting unit that adjusts data throughput responsive to the parameters.
- a device for transmitting a signal to a remote device and receiving a signal transmitted from the remote device that includes a transmitting unit that generates the signal transmitted to the remote device, and a receiving unit that receives the signal transmitted from the remote device and outputs remote modulation variation information included in the received signal.
- the receiving device also generates link quality information corresponding to the received signal, and a control unit generates a modulation change command packet instructing the remote device to change to a quadrature amplitude modulation index corresponding to the link quality information.
- the control unit variably controls the generation of the signal by the transmitter according to the remote modulation variation information output from the receiving unit.
- the link quality information corresponds to environmental degradation of the signal.
- the quadrature amplitude modulation index is increased in response to the link quality information indicating reduced degradation of the link, and decreased in response to the link quality information indicating degradation of the link.
- a wireless modem for transmitting a signal to a remote device and receiving a signal transmitted by the remote device that includes a forward error correction encoder unit that inserts error correction information to the signal transmitted by the wireless modem and outputs a corresponding encoded signal.
- a modulation unit variably modulates the encoded signal and outputs a modulated signal having a corresponding quadrature amplitude modulation index to the remote device.
- a demodulating unit demodulates the signal transmitted by the remote device and outputs a corresponding demodulated signal
- a control unit generates a modulation change command packet instructing the remote device to change quadrature amplitude modulation index corresponding to link quality information generated by the demodulating unit and the forward error correction decoder unit, and variably controls the inserted forward error correction information and the quadrature amplitude modulation index based on remote modulation variation information included in the signal received from the remote device.
- FIG. 1 is a graphical representation of a relationship between signal-to-noise ratio of a signal and rainfall over time.
- FIG. 2 is a schematic diagram illustrating interconnections for dynamic adaptive modulation negotiations between wireless modems according to the present invention.
- FIG. 3 is a block diagram of a transmitter according to the present invention that is included in the wireless modems of FIG. 2.
- FIG. 4 is a block diagram of a receiver according to the present invention that is included in the wireless modems of FIG. 2.
- FIG. 5 is a receiver state transition diagram illustrating negotiation for point-to-point links that occurs on a receiver side according to the present invention.
- FIG. 6 is a transmitter state transition diagram illustrating negotiation for point-to-point links that occurs on a transmitter side according to the present invention.
- FIG. 2 is a schematic diagram illustrating interconnections for dynamic adaptive modulation negotiations between wireless modems, according to the present invention.
- a first wireless modem 26 transmits a signal to a second wireless modem 28 , and receives a signal transmitted from the second wireless modem 28
- the second wireless modem 28 correspondingly transmits a signal to the first wireless modem 26 , and receives a signal transmitted from the first wireless modem 26 .
- the first wireless modem 26 includes a transmitter 30 that transmits the signal to the second wireless modem 28 , a receiver 32 that receives the signal transmitted from the second wireless modem 28 , and a microprocessor, microcontroller or controller 34 that receives parameters from the receiver 32 related to link quality of the signal, such as SNR, bit error rate, etc., which will be described below.
- the transmitter 30 includes an output buffer 31 that buffers data to be transmitted just prior to the transmission.
- the second wireless modem 28 includes a transmitter 36 that transmits a signal to the first wireless modem 26 , a receiver 38 that receives the signal transmitted from the first wireless modem 26 , and a microprocessor, microcontroller or controller 40 that receives parameters from the receiver 38 related to link quality of the signal, such as SNR, bit error rate, and so forth, as described below.
- the transmitter 36 includes an output buffer 31 that buffers data to be transmitted just prior to the transmission.
- the transmitter 36 , receiver 38 , and controller 40 of the second wireless modem 28 are the same as the transmitter 30 , receiver 32 , and controller 34 of the first wireless modem 26 .
- a signal transmitted from the transmitter 30 of the first wireless modem 26 is received by the receiver 38 of the second wireless modem 28 .
- Information about the signal is output by the receiver 38 to the controller 40 and is processed by the controller 40 to control the transmitter 36 and receiver 38 of the second wireless modem 28 .
- a signal transmitted by the transmitter 36 of the second wireless modem 28 is received by the receiver 32 of the first wireless modem 26 .
- Information about the signal is output by the receiver 32 to the controller 34 and is processed by the controller 34 to control the transmitter 30 and receiver 32 of the first wireless modem 26 .
- a feedback loop is formed between the controller 34 of the first wireless modem 26 and the controller 40 of the second wireless modem 28 .
- FIG. 3 is a block diagram of the transmitters 30 , 36 according to the present invention.
- a signal from a data source network 42 of any type, such as a LAN, the Internet, telephony, video, etc. is received by a forward error correction unit 44 , such as described, for example, in the 1960 article entitled “Polynomial Codes Over Certain Finite Fields”, by I. S. Reed and G. Solomon incorporated by reference herein.
- the forward error correction unit 44 under control of the controller 34 , 40 , inserts error correction information into the signal and outputs a corresponding encoded signal.
- the amount of error correction can be variably controlled by the controller 34 , 40 . For example, the amount of channel capacity typically used for error correction is varied from one to ten percent.
- the encoded signal output by the forward error correction unit 44 is input to a variable level quadrature amplitude modulation, or QAM modulation unit 46 , such as, for example, a BCM3033 available from Broadcom Corporation.
- QAM modulation unit 46 under control of the controller 34 , 40 varies a modulation index of the signal and outputs a modulated signal.
- the modulated signal output by the QAM modulation unit 46 is received by a conventional RF millimeter wave upconverter and transmitter 48 .
- Both the amount of error correction performed by the forward error correction unit 44 and the variation in the modulation index performed by the QAM modulation unit 46 is controlled based on feedback FB received, respectively, by the controllers 34 , 40 from the receivers 32 , 38 of the corresponding wireless modems 26 and 28 , as will be described in detail below.
- the modulated signal received by the upconverter and transmitter 48 of the first wireless modem 26 is then transmitted through an antenna 50 of the transmitter 30 and received by the receiver 38 of the second wireless modem 28 .
- the modulated signal received by the upconverter and transmitter 48 of the second wireless modem 28 is transmitted through an antenna 50 of the transmitter 36 of the second wireless modem 28 and received by the receiver 32 of the first wireless modem 26 .
- the controller 34 , 40 outputs a modulation index change command packet requesting the modulation index to be changed to the forward error correction encoder 44 of the respective receiver 32 , 38 , as will be described below.
- FIG. 4 is a block diagram of the receivers 32 , 38 according to the present invention.
- the receiver 32 of the first wireless modem 26 receives the signal transmitted from the transmitter 36 of the second wireless modem 28
- the receiver 38 of the second wireless modem 28 receives the signal transmitted from the transmitter 30 of the first wireless modem 26
- each receiver 32 , 38 essentially performs the reverse process described previously with respect to the transmitters 30 , 36 .
- the signal transmitted from the antenna 50 of the corresponding transmitter 30 , 36 is received by a conventional RF millimeter wave down converter 54 of the respective receiver 32 , 38 through a corresponding antenna 52 .
- the RF millimeter wave down converter 54 down converts the received signal and outputs a corresponding down converted signal to a variable level QAM demodulator unit 56 , such as, for example, a BCM 3118 available from Broadcom Corporation.
- the QAM demodulator unit 56 demodulates the down converted signal received from the RF millimeter wave down converter 54 and outputs a corresponding demodulated signal to a forward error correction decoder 58 , as described by I. S. Reed and G.
- the forward error correction decoder 58 decodes the demodulated signal received from the QAM demodulator unit 56 and outputs a decoded signal to a data destination 60 .
- the QAM demodulator unit 56 also provides parameters related to the link quality of the signal, such as SNR, etc., to the controller 34 .
- the forward error correction decoder 58 provides link quality parameters of the signal related to bit error rate (BER) to the controller 34 .
- BER bit error rate
- the controller 40 of the second wireless modem 28 determines an appropriate modulation index and encoding of the signal. This determined level of modulation and encoding is then included as a modulation index change command packet in the signal transmitted by the transmitter 36 of the second wireless modem 28 to the receiver 32 of the first wireless modem 26 .
- the controller 34 of the first wireless modem 26 receives the modulation index change command packet from the output of the forward error correction decoder 58 of the receiver 32 of the first wireless modem 26 .
- the determined modulation index and encoding is fed back to the controller 34 of the first wireless modem 26 , which then controls the QAM modulator 46 of the transmitter 30 of the first wireless modem 26 to change the level of modulation and/or encoding in the transmitter 30 , accordingly.
- the controller 34 of the first wireless modem 26 determines an appropriate modulation index and encoding of the signal. This determined level of modulation and encoding is then included as a modulation index change command packet in the signal transmitted by the transmitter 30 of the first wireless modem 26 to the receiver 38 of the second wireless modem 28 .
- the controller 40 of the second wireless modem 28 receives the modulation index change command packet from the output of the forward error correction decoder 58 of the receiver 38 of the second wireless modem 28 .
- the determined modulation index and encoding is fed back to the controller 40 of the second wireless modem 28 , which then controls the QAM modulator 46 of the transmitter 36 of the second wireless modem 28 the data to change the level of modulation and/or encoding in the transmitter 36 , accordingly.
- the command packet can also be used to change the demodulation and decoding in the receiver, although such is not necessary as will be understood from the discussion of FIG. 5.
- the wireless modem according to the present invention actively detects SNR and BER, and variably increases or decreases the modulation index and/or level of encoding based on the detected SNR and BER.
- the modulation index can be increased from QPSK, which gives 2 bits per symbol, to 16 QAM that gives 4 bits per symbol, 32 QAM that gives 5 bits per symbol, or 64 QAM that gives 6 bits per symbol, or decreased from any one modulation index to another modulation index.
- the percentage of the link used for error correction can be increased as the link degrades and decreased as the link improves.
- the forward encoding of the forward error correction unit 44 is used to enable the transition between the decreases or increases in the modulation index to take place in a more controlled, smooth manner.
- the level of encoding can be increased, for example, from two to three bits of encoding used for error correction. This maintains the modulation index but decreases the bit throughput rate because of the increased encoding while maintaining link availability.
- the modulation index can be switched (lowered) and the encoding level decreased.
- the reverse can also be accomplished where the encoding is decreased as the signal quality improves until the minimum encoding is used, at which time the modulation index can be increased, thereby increasing the throughput in a smoother fashion.
- the present invention achieves a more robust link having a variable lower throughput during periods of increased environmental degradation, and a variable greater throughput during periods of less environmental degradation.
- the present invention provides improved link characteristics between modems by varying the modulation index and/or encoding in response to changes in link quality as a result of environmental degradation or other non-transient man-made interference sources of the link.
- FIG. 5 is a receiver state transition diagram illustrating the negotiation for point-to-point links that occurs on a receiver side of the signal when the modulation index and/or encoding is adjusted, according to the present invention.
- FIG. 6 is a receiver state transition diagram illustrating the negotiation for point-to-point links that occurs on a transmitter side of the signal, according to the present invention.
- the receiver 38 of the second wireless modem 28 receives a signal from the transmitter 30 of the first wireless modem 26 through the antenna 52 .
- the QAM demodulator unit 56 receives and demodulates the signal and outputs the SNR, etc. to the controller 40
- the forward error correction decoder 58 receives and decodes the demodulated signal and outputs the corresponding bit error rate to the controller 40 to enable the controller 40 to determine whether the modulation index, or QAM index, should be increased or decreased.
- the determination of whether to increase or decrease the QAM index is dependent upon and varies according to field tests corresponding to a particular application.
- typical SNR threshold values associated with each QAM index for determining upgrade QAM index eligibility have been determined to be a minimum SNR of 12.0 for QPSK, 18.0 for 16 QAM, 24.0 for 32 QAM, and 26.0 for 64 QAM.
- Minimum SNR values for 128 QAM and 256 QAM have been determined to be 27.0 and 28.0, respectively.
- synchronization when the wireless modems 26 and 28 are initially turned on, synchronization (“sync”) has not been achieved. Packets advertising the ability of each of the wireless modems to support a certain version of a protocol, which is typically automatic for standard link establishment, are transmitted at the lowest modulation index between the wireless modems 26 and 28 . Therefore, when initially powered on, the second wireless modem 28 is in a recovery state 62 , as illustrated in FIG. 5, and the state machine of the receiver 38 is not automatically initialized until sync is acquired and the packet is received from the first wireless modem 26 specifying the version of protocol that the first wireless modem 26 supports.
- the first wireless modem 26 when initially powered on, the first wireless modem 26 is in the recovery state 62 and the state machine of the receiver 32 is not automatically initialized until sync is acquired and the packet is received from the second wireless modem 28 specifying the version of protocol that the second wireless modem 28 supports.
- the state machines in the wireless modems 26 and 28 are initialized and the corresponding transmitters 30 , 36 are transmitting using the same QAM index.
- the respective receivers 32 , 38 move from the recovery state 62 to a stable state 64 .
- the receivers 32 , 38 continuously sample the line quality of the signal to determine whether to upgrade or downgrade the modulation index and/or encoding.
- the controller 40 of the second wireless modem 28 receives the SNR parametric output by the QAM demodulator unit 56 of the receiver 38 in addition to the bit error rate parametric output by the forward error correction decoder 58 of the receiver 38 and, on the basis of the received parameters, determines that the line quality has not decreased as a result of environmental degradation.
- the controller 40 makes such a determination by comparing the difference in the current SNR to a previous SNR average, or to a SNR threshold, and determining that the link quality is clean, i.e. that there is a +q event.
- the controller 40 generates corresponding feedback information in the form of a modulation index change command packet specifying an increased QAM index to which the receiver 38 intends to move.
- the receiver 38 of the second wireless modem 28 then moves from the stable state 64 to an upgrade state 66 . While in the upgrade state 66 , the second wireless modem 28 continues to receive and transmit data at the initial QAM index so that data transmission is not effected by the transmission of the modulation index change command packet.
- the controller 40 outputs the modulation index change command packet to the forward error correction encoder 44 of the transmitter 36 of the second wireless modem 28 which then transmits the modulation index change command packet to the receiver 32 of the first wireless modem 26 .
- the controller 34 of the first wireless modem 26 receives the modulation index change command packet after it is forward error correction decoded by the forward error correction decoder 58 of the first wireless modem 26 .
- the transmitter 30 of the first wireless modem 26 stops placing data in the output buffer 31 , and data that remains to be transmitted in the output buffer 31 of the transmitter 30 is transmitted.
- the first wireless modem 26 then flushes out the output buffer 31 of the transmitter 30 and as soon as the last data element is sent, the controller 34 controls the QAM modulator 46 of the first wireless modem 26 to upgrade it's modulation index to correspond to the increased QAM index, and then resumes transmitting data.
- the resumed data transmission initially includes empty frames for a certain period of time, such as 20 ms, for example.
- the controller 40 controls the QAM demodulator of the receiver 38 to upgrade the modulation index to correspond to the upgraded QAM index requested in the modulation index change command packet, and the receiver 38 of the second wireless modem 28 moves to an upgrade wait state 68 . Since the first wireless modem 26 is already transmitting empty frames at the upgraded QAM index, a sync event occurs. Once this sync event occurs, the receiver 38 moves from the upgrade wait state 68 to the stable state 64 and continues sampling the line quality.
- the sync loss event does not occur, i.e., the modulation index is not upgraded by the QAM demodulator 56 of the second wireless modem 28 and therefore the link between the first wireless modem 26 and the second wireless modem 28 is not momentarily lost, after a preferably one second timeout event occurs, and the receiver 38 of the second wireless modem 28 moves from the upgrade state 66 to the stable state 64 and resumes sampling the line quality. During this time, neither the first wireless modem or the second wireless modem 28 stop receiving or transmitting data, and therefore no loss in data transmission has resulted.
- the receiver 38 When the receiver 38 is in the upgrade state 66 , achieves the sync loss event and moves to the upgrade wait state 68 to wait for receipt of the empty frames from the transmitter 30 of the first wireless modem 26 , if the receiver 38 does not receive the empty frames while in the upgrade wait state 68 , or the empty frames are received in a degraded condition, a no sync event occurs.
- the receiver 38 instructs the controller 40 of the second wireless modem 28 to generate a modulation index change command packet specifying the previous modulation index, and the receiver 38 moves from the upgrade wait state 68 to a downgrade wait state 70 after changing to the previous modulation index.
- the controller 40 generates and outputs the modulation index change command packet to the forward error correction encoder 44 of the transmitter 36 of the second wireless modem 28 and the modulation index change command packet is transmitted to the receiver 32 of the first wireless modem 26 .
- the controller 34 of the first wireless modem 26 receives the modulation index change command packet after it is forward error correction decoded by the forward error correction decoder 58 of the first wireless modem 26 . If the modulation index change command packet is received by the receiver 32 of the first wireless modem 26 , the transmitter 30 of the first wireless modem 26 ensures that the output buffer 31 is flushed out, changes it's modulation index accordingly, and then transmits data including the empty frames as described above.
- the receiver 38 of the second wireless modem 28 moves from the upgrade wait state 68 to the downgrade wait state 70 as described above, and a sync event does not occur, meaning that the transmitter 30 of the first wireless modem 26 is not transmitting at the previous modulation index after preferably one second, a no sync event occurs and the receiver 38 of the second wireless modem 28 moves to the recovery state 62 .
- the receiver 38 of the second wireless modem 28 instructs the controller 40 of the second wireless modem 28 to generate a modulation index change command packet specifying the lowest QAM index and to immediately change the receiver 38 to the lowest QAM index without waiting for a response from the first wireless modem.
- the receiver 32 of the first wireless modem 26 which is in the stable state 64 , experiences a sync loss event, since the line goes down momentarily, and therefore immediately goes to the recovery state 62 and the transmitter 30 and receiver 32 of the first wireless modem 26 are reset, as described above.
- the effect of resetting the transmitter 36 and receiver 38 of the second wireless modem 28 when a no sync event occurs while in the recovery state 62 is that the transmitter 30 and receiver 32 of the first wireless modem 26 are reset as well, so that both wireless modems 26 , 28 are at the lowest available QAM index and attempting to attain sync, similar to when the wireless modems 26 , 28 are powered on, as described above.
- the controller 40 of the second wireless modem 28 determines that the line quality is degrading as a result of environmental degradation of the link, a ⁇ q event occurs.
- the controller 40 generates corresponding feedback information in the form of a modulation index change command packet specifying a decreased QAM index to which the receiver 38 intends to move and the receiver 38 moves from the stable state 64 to a downgrade state 72 .
- the controller 40 outputs the modulation index change command packet to the forward error correction encoder 44 of the transmitter 36 and the modulation index change command packet is transmitted to the receiver 32 of the first wireless modem 26 .
- the controller 34 of the first wireless modem 26 receives the modulation index change command packet after it is forward error correction decoded by the forward error correction decoder 58 of the first wireless modem 26 .
- the second wireless modem 28 While in the downgrade state 72 , continues to receive and transmit data at the initial QAM index so that data transmission is not effected by the transmission of the modulation index change command packet.
- the transmitter 30 of the first wireless modem 26 stops sending data, flushes out the output buffer 31 of the transmitter 30 , and as soon as the last data element is sent, the controller 34 controls the QAM modulator 46 of the first wireless modem 26 to downgrade it's modulation index to correspond to the decreased QAM index, and then resumes transmitting data, beginning with empty frames.
- the controller 40 controls the QAM demodulator of the receiver 38 to downgrade the modulation index of the receiver 38 to correspond to the downgrade QAM index requested in the modulation index change command packet, and the receiver 38 of the second wireless modem 28 moves from the downgrade state 72 to the downgrade wait state 70 . Since the first wireless modem 26 is already transmitting empty frames at the downgraded QAM index, a sync event occurs. Once this sync event occurs, the receiver 38 moves from the downgrade wait state 70 to the stable state 64 and continues sampling the line quality.
- the receiver 38 While the receiver 38 is in the downgrade state 72 , if the sync loss event does not occur, i.e., the modulation index is not upgraded by the QAM modulator 46 of the first wireless modem 26 and therefore the link between the first wireless modem 26 and the second wireless modem 28 is not momentarily lost, a timeout event occurs, and the receiver 38 of the second wireless modem 28 moves from the upgrade state 66 to the stable state 64 and resumes sampling the line quality. During this time, neither the first wireless modem or the second wireless modem 28 stop receiving or transmitting data, and therefore no loss in data transmission has resulted.
- the state transition of the receiver 38 is the same as in the ease when the receiver 38 moves from the upgrade wait state 68 to the downgrade wait state 70 after a no sync event occurs while in the upgrade wait state 68 , described above, and therefore the repeated description will be omitted.
- the receiver 38 takes the same action as described above; that is, the receiver 38 and transmitter 36 are reset (reconfigured) which in turn resets the remote modem 26 to do the same. This way, in the recovery state both modems constantly try to achieve sync at the lowest QAM level.
- the state diagram for the transmitter 30 includes a stable state 74 and a recovery state 76 .
- the transmitter 30 is therefore in the stable state 74 and continuously transmits data at the particular QAM index determined by the protocol during initialization.
- the transmitter 30 remains at that particular QAM index until the above-described feedback information is received from the second wireless modem 28 requesting the first wireless modem 26 to change QAM index.
- the transmitter 30 changes to a QAM index corresponding to the feedback information that in turn is related to whether the line quality is determined to be degrading ⁇ q, or clean +q, as described above.
- the transmitter 30 after changing the QAM index simply returns to the stable state where is ready to receive feedback information again.
- the transmitter 30 of the first wireless modem 26 is reset and configured to the lowest QAM index as a result of the receiver 38 of the second wireless modem 28 losing sync, the transmitter 30 moves to the recovery state 76 .
- the transmitter 30 receives feedback information requesting some QAM index, the transmitter moves to the stable state 74 and transmits data.
- the present invention enables wireless modems to make use of the increased SNR corresponding to the hashed region of the graph of FIG. 1 located between where the SNR can be tolerated, line 24 , and the engineered level of the SNR, line 20 .
- the modems of the present invention are able to successfully maintain a link in periods of environmental degradation, such as during periods of intense rainfall, while allowing the modems to operate with greater throughput during the time of the year when environmental degradation does not occur.
- the wireless modems 26 , 28 continue to transmit and receive data while the modulation negotiation takes place, negotiation of the signal received is performed transparent to the payload, thereby minimizing the impact of the negotiation on data transmitted along the carrier signal.
- the negotiation for point-to-point links of the present invention are described in terms of negotiating a modulation index, it is understood that the negotiation is not limited to modulation index, but could also involve other features of the transmitted data, such as bandwidth, Reed-Solomon correction bytes, carrier frequency, convolution code rate, antenna beam focus, and excess bandwidth, etc.
- the modulation negotiation has been described in relation to wireless communications, the modulation negotiation of the present invention could also applied in cable communications, and stratospheric links provided by high altitude aircraft and satellites.
Abstract
Description
- 1. Field of the Invention
- The present invention relates to a wireless modem, and more particularly, the present invention relates to a wireless modem that improves link characteristics between modems during periods of reduced environmental degradation of the link, and method therefor.
- 2. Description of the Related Art
- Although there are several link dependencies that must necessarily be taken into consideration during the transmission of a carrier signal from a wireless transmitter to a wireless receiver, channel capacity is primarily dependent upon signal-to-noise ratio, or “SNR”. Typically, as the SNR decreases, the channel capacity decreases, causing a link formed between the transmitter and the receiver to be degraded, corrupting the transfer rate of the corresponding carrier signal. On the other hand, as the SNR increases, the channel capacity increases, resulting in improved transfer rate of the carrier signal.
- At the same time, while there are several factors that have a tendency to cause the SNR to decrease, environmental degradation, such as rain, snow, fog, and other non-transient man-made interference sources tend to be major factors causing a decrease in SNR. For example, individual raindrops absorb/scatter energy from radio waves and a certain amount of energy in the waves is scattered away from the propagation path. Rain attenuation and depolarization of a transmitted carrier signal particularly occurs during periods of intense rainfall, causing the SNR to degrade.
- The level of the effects of these interactions between the carrier signal and the rainfall depend on both the number of raindrops encountered by the carrier signal, and the distribution of the size and shapes of the raindrops, both of which depend on the rate of the rainfall. In a wireless modem operating over a carrier at millimeter wave frequencies, where the wavelength of the carrier is close to the size of a raindrop, or on the order of a couple of millimeters, a raindrop is substantial enough in size to degrade the link during periods of moderate to intense rainfall. When the wireless broadband link is a terrestrial link, the entire link may be covered in rain, depending on the size of the associated storm, and therefore substantially the entire link is degraded.
- As a result, in order to insure successful data transmission along a link when implementing wireless broadband links in the wireless modem, it is important that the links be engineered to operate during the period of the year in which the rainfall is the most intense. Therefore, since the most intense rainfall occurs typically during less than one percent of a given year, additional capacity of the carrier is available for more than ninety-nine percent of the time and cannot be used.
- FIG. 1 is a graphical representation of a relationship between the SNR and rainfall over time. Environmental degradation of a signal that occurs, for example, during an intense snowfall in January is indicated by a downward extending
spike 20 a. In addition, environmental degradation of the signal that occurs during intense rainfall in June and July is indicated by downward extendingspikes 20 b-d, and environmental degradation of the signal that occurs during an intense snow storm in December is indicated by a downward extendingspike 20 e. Although degradation of a carrier signal due to intense snow or rainfall might only occur less than one percent of the time in a given year, for a link to be reliable it must be engineered to always operate throughout the year at an SNR corresponding to the periods of intense snow or rainfall. Accordingly, the link must be engineered to always operate at the lowest SNR, indicated by ahorizontal line 22. - During the remaining ninety-nine percent of the year, when environmental degradation is no longer a factor, and therefore when the SNR that can be tolerated is greatest, indicated by a
line 24, additional or excess capacity is available that cannot be used. This excess capacity is illustrated by a hashed region located between where the SNR can be tolerated,line 24, and the engineered level of the SNR, line 20. Therefore, the excess capacity is wasted ninety-nine percent of the time during the year, resulting in reduced throughput. - It is an object of the present invention to provide a wireless modem and method therefor that transmits a signal having a greater throughput during periods when there are no effects on the carrier signal resulting from environmental degradation of a terrestrial link.
- It is a further object of the present invention to provide a wireless modem and method therefor that negotiates modulation of a carrier signal along a link in response to changes in effects of environmental degradation on the link.
- It is a still further object of the present invention to provide a wireless modem and method therefor that negotiates modulation of a carrier signal along a link in response to changes in effects of environmental degradation on the link, while minimizing the impact of the negotiation on data transmitted along the carrier signal.
- Objects of the invention are achieved by a wireless modem that includes a controller that samples a number of parameters of a wireless terrestrial signal and a data adjusting unit that adjusts data throughput responsive to the parameters.
- Further objects of the invention are achieved by a device for transmitting a signal to a remote device and receiving a signal transmitted from the remote device that includes a transmitting unit that generates the signal transmitted to the remote device, and a receiving unit that receives the signal transmitted from the remote device and outputs remote modulation variation information included in the received signal. The receiving device also generates link quality information corresponding to the received signal, and a control unit generates a modulation change command packet instructing the remote device to change to a quadrature amplitude modulation index corresponding to the link quality information. The control unit variably controls the generation of the signal by the transmitter according to the remote modulation variation information output from the receiving unit.
- According to the present invention, the link quality information corresponds to environmental degradation of the signal. The quadrature amplitude modulation index is increased in response to the link quality information indicating reduced degradation of the link, and decreased in response to the link quality information indicating degradation of the link.
- Further objects of the invention are achieved by a wireless modem for transmitting a signal to a remote device and receiving a signal transmitted by the remote device that includes a forward error correction encoder unit that inserts error correction information to the signal transmitted by the wireless modem and outputs a corresponding encoded signal. A modulation unit variably modulates the encoded signal and outputs a modulated signal having a corresponding quadrature amplitude modulation index to the remote device. A demodulating unit demodulates the signal transmitted by the remote device and outputs a corresponding demodulated signal, and a control unit generates a modulation change command packet instructing the remote device to change quadrature amplitude modulation index corresponding to link quality information generated by the demodulating unit and the forward error correction decoder unit, and variably controls the inserted forward error correction information and the quadrature amplitude modulation index based on remote modulation variation information included in the signal received from the remote device.
- These and other objects and advantages of the invention will become apparent and more readily appreciated from the following description of the preferred embodiments, taken in conjunction with the accompanying drawings of which:
- FIG. 1 is a graphical representation of a relationship between signal-to-noise ratio of a signal and rainfall over time.
- FIG. 2 is a schematic diagram illustrating interconnections for dynamic adaptive modulation negotiations between wireless modems according to the present invention.
- FIG. 3 is a block diagram of a transmitter according to the present invention that is included in the wireless modems of FIG. 2.
- FIG. 4 is a block diagram of a receiver according to the present invention that is included in the wireless modems of FIG. 2.
- FIG. 5 is a receiver state transition diagram illustrating negotiation for point-to-point links that occurs on a receiver side according to the present invention.
- FIG. 6 is a transmitter state transition diagram illustrating negotiation for point-to-point links that occurs on a transmitter side according to the present invention.
- Reference will now be made in detail to the preferred embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to like elements throughout.
- FIG. 2 is a schematic diagram illustrating interconnections for dynamic adaptive modulation negotiations between wireless modems, according to the present invention. As illustrated in FIG. 2, a first
wireless modem 26 transmits a signal to a secondwireless modem 28, and receives a signal transmitted from the secondwireless modem 28, and the secondwireless modem 28 correspondingly transmits a signal to the firstwireless modem 26, and receives a signal transmitted from the firstwireless modem 26. - The first
wireless modem 26 includes atransmitter 30 that transmits the signal to the secondwireless modem 28, areceiver 32 that receives the signal transmitted from the secondwireless modem 28, and a microprocessor, microcontroller orcontroller 34 that receives parameters from thereceiver 32 related to link quality of the signal, such as SNR, bit error rate, etc., which will be described below. Thetransmitter 30 includes anoutput buffer 31 that buffers data to be transmitted just prior to the transmission. - Similarly, the second
wireless modem 28 includes atransmitter 36 that transmits a signal to the firstwireless modem 26, areceiver 38 that receives the signal transmitted from the firstwireless modem 26, and a microprocessor, microcontroller orcontroller 40 that receives parameters from thereceiver 38 related to link quality of the signal, such as SNR, bit error rate, and so forth, as described below. Thetransmitter 36 includes anoutput buffer 31 that buffers data to be transmitted just prior to the transmission. - The
transmitter 36,receiver 38, andcontroller 40 of the secondwireless modem 28 are the same as thetransmitter 30,receiver 32, andcontroller 34 of the firstwireless modem 26. - As illustrated in FIG. 2, a signal transmitted from the
transmitter 30 of the firstwireless modem 26 is received by thereceiver 38 of the secondwireless modem 28. Information about the signal is output by thereceiver 38 to thecontroller 40 and is processed by thecontroller 40 to control thetransmitter 36 andreceiver 38 of the secondwireless modem 28. In the same way, a signal transmitted by thetransmitter 36 of the secondwireless modem 28 is received by thereceiver 32 of the firstwireless modem 26. Information about the signal is output by thereceiver 32 to thecontroller 34 and is processed by thecontroller 34 to control thetransmitter 30 andreceiver 32 of the firstwireless modem 26. In this way, a feedback loop is formed between thecontroller 34 of the firstwireless modem 26 and thecontroller 40 of the secondwireless modem 28. - FIG. 3 is a block diagram of the
transmitters respective transmitter wireless modems data source network 42 of any type, such as a LAN, the Internet, telephony, video, etc., is received by a forwarderror correction unit 44, such as described, for example, in the 1960 article entitled “Polynomial Codes Over Certain Finite Fields”, by I. S. Reed and G. Solomon incorporated by reference herein. The forwarderror correction unit 44, under control of thecontroller controller - The encoded signal output by the forward
error correction unit 44 is input to a variable level quadrature amplitude modulation, orQAM modulation unit 46, such as, for example, a BCM3033 available from Broadcom Corporation. TheQAM modulation unit 46, under control of thecontroller QAM modulation unit 46 is received by a conventional RF millimeter wave upconverter andtransmitter 48. Both the amount of error correction performed by the forwarderror correction unit 44 and the variation in the modulation index performed by theQAM modulation unit 46 is controlled based on feedback FB received, respectively, by thecontrollers receivers corresponding wireless modems - The modulated signal received by the upconverter and
transmitter 48 of thefirst wireless modem 26, for example, is then transmitted through anantenna 50 of thetransmitter 30 and received by thereceiver 38 of thesecond wireless modem 28. In the same way, the modulated signal received by the upconverter andtransmitter 48 of thesecond wireless modem 28 is transmitted through anantenna 50 of thetransmitter 36 of thesecond wireless modem 28 and received by thereceiver 32 of thefirst wireless modem 26. - The
controller error correction encoder 44 of therespective receiver - FIG. 4 is a block diagram of the
receivers receiver 32 of thefirst wireless modem 26 receives the signal transmitted from thetransmitter 36 of thesecond wireless modem 28, and thereceiver 38 of thesecond wireless modem 28 receives the signal transmitted from thetransmitter 30 of thefirst wireless modem 26, and eachreceiver transmitters - In particular, as illustrated in FIG. 4, the signal transmitted from the
antenna 50 of the correspondingtransmitter converter 54 of therespective receiver antenna 52. The RF millimeter wave downconverter 54 down converts the received signal and outputs a corresponding down converted signal to a variable levelQAM demodulator unit 56, such as, for example, a BCM 3118 available from Broadcom Corporation. TheQAM demodulator unit 56 demodulates the down converted signal received from the RF millimeter wave downconverter 54 and outputs a corresponding demodulated signal to a forwarderror correction decoder 58, as described by I. S. Reed and G. Solomon in the 1960 article entitled “Polynomial Codes Over Certain Finite Fields”. The forwarderror correction decoder 58 decodes the demodulated signal received from theQAM demodulator unit 56 and outputs a decoded signal to adata destination 60. - The
QAM demodulator unit 56 also provides parameters related to the link quality of the signal, such as SNR, etc., to thecontroller 34. In addition, the forwarderror correction decoder 58 provides link quality parameters of the signal related to bit error rate (BER) to thecontroller 34. Based upon the value of these link quality related parameters, thecontroller 40 of thesecond wireless modem 28, for example, determines an appropriate modulation index and encoding of the signal. This determined level of modulation and encoding is then included as a modulation index change command packet in the signal transmitted by thetransmitter 36 of thesecond wireless modem 28 to thereceiver 32 of thefirst wireless modem 26. Thecontroller 34 of thefirst wireless modem 26 receives the modulation index change command packet from the output of the forwarderror correction decoder 58 of thereceiver 32 of thefirst wireless modem 26. As a result, the determined modulation index and encoding is fed back to thecontroller 34 of thefirst wireless modem 26, which then controls theQAM modulator 46 of thetransmitter 30 of thefirst wireless modem 26 to change the level of modulation and/or encoding in thetransmitter 30, accordingly. - In the same way, the
controller 34 of thefirst wireless modem 26 determines an appropriate modulation index and encoding of the signal. This determined level of modulation and encoding is then included as a modulation index change command packet in the signal transmitted by thetransmitter 30 of thefirst wireless modem 26 to thereceiver 38 of thesecond wireless modem 28. Thecontroller 40 of thesecond wireless modem 28 receives the modulation index change command packet from the output of the forwarderror correction decoder 58 of thereceiver 38 of thesecond wireless modem 28. As a result, the determined modulation index and encoding is fed back to thecontroller 40 of thesecond wireless modem 28, which then controls theQAM modulator 46 of thetransmitter 36 of thesecond wireless modem 28 the data to change the level of modulation and/or encoding in thetransmitter 36, accordingly. The command packet can also be used to change the demodulation and decoding in the receiver, although such is not necessary as will be understood from the discussion of FIG. 5. - In this way, the wireless modem according to the present invention actively detects SNR and BER, and variably increases or decreases the modulation index and/or level of encoding based on the detected SNR and BER. For example, depending on whether environmental degradation is a factor, the modulation index can be increased from QPSK, which gives 2 bits per symbol, to 16 QAM that gives 4 bits per symbol, 32 QAM that gives 5 bits per symbol, or 64 QAM that gives 6 bits per symbol, or decreased from any one modulation index to another modulation index. Likewise, the percentage of the link used for error correction can be increased as the link degrades and decreased as the link improves.
- There are discrete steps between the modulation indexes, and therefore the forward encoding of the forward
error correction unit 44 is used to enable the transition between the decreases or increases in the modulation index to take place in a more controlled, smooth manner. For example, when the signal is degrading and a switch to a lower modulation index should be considered, rather than making the switch to a lower modulation index, the level of encoding can be increased, for example, from two to three bits of encoding used for error correction. This maintains the modulation index but decreases the bit throughput rate because of the increased encoding while maintaining link availability. When the maximum level of encoding is reached and further improvement in signal quality is necessary, the modulation index can be switched (lowered) and the encoding level decreased. - The reverse can also be accomplished where the encoding is decreased as the signal quality improves until the minimum encoding is used, at which time the modulation index can be increased, thereby increasing the throughput in a smoother fashion. As a result, the present invention achieves a more robust link having a variable lower throughput during periods of increased environmental degradation, and a variable greater throughput during periods of less environmental degradation. As a result, the present invention provides improved link characteristics between modems by varying the modulation index and/or encoding in response to changes in link quality as a result of environmental degradation or other non-transient man-made interference sources of the link.
- FIG. 5 is a receiver state transition diagram illustrating the negotiation for point-to-point links that occurs on a receiver side of the signal when the modulation index and/or encoding is adjusted, according to the present invention. FIG. 6 is a receiver state transition diagram illustrating the negotiation for point-to-point links that occurs on a transmitter side of the signal, according to the present invention.
- In the description of the quadrature amplitude modulation negotiation for point-to-point links, according to the present invention, described in reference to FIGS. 5 and 6 below, it is assumed for the sake of simplicity that the receiver state transition diagram illustrated in FIG. 5 corresponds to the
receiver 38 of thesecond wireless modem 28, and the transmitter state transition diagram illustrated in FIG. 6 corresponds to thetransmitter 30 of thefirst wireless modem 26. At the same time, it is understood that therespective transmitters second wireless modems respective receivers second wireless modems - According to the present invention, the
receiver 38 of thesecond wireless modem 28 receives a signal from thetransmitter 30 of thefirst wireless modem 26 through theantenna 52. TheQAM demodulator unit 56 receives and demodulates the signal and outputs the SNR, etc. to thecontroller 40, and the forwarderror correction decoder 58 receives and decodes the demodulated signal and outputs the corresponding bit error rate to thecontroller 40 to enable thecontroller 40 to determine whether the modulation index, or QAM index, should be increased or decreased. The determination of whether to increase or decrease the QAM index is dependent upon and varies according to field tests corresponding to a particular application. For example, typical SNR threshold values associated with each QAM index for determining upgrade QAM index eligibility have been determined to be a minimum SNR of 12.0 for QPSK, 18.0 for 16 QAM, 24.0 for 32 QAM, and 26.0 for 64 QAM. Minimum SNR values for 128 QAM and 256 QAM have been determined to be 27.0 and 28.0, respectively. - According to a preferred embodiment of the present invention, when the
wireless modems wireless modems second wireless modem 28 is in arecovery state 62, as illustrated in FIG. 5, and the state machine of thereceiver 38 is not automatically initialized until sync is acquired and the packet is received from thefirst wireless modem 26 specifying the version of protocol that thefirst wireless modem 26 supports. In the same way, when initially powered on, thefirst wireless modem 26 is in therecovery state 62 and the state machine of thereceiver 32 is not automatically initialized until sync is acquired and the packet is received from thesecond wireless modem 28 specifying the version of protocol that thesecond wireless modem 28 supports. Once this information is exchanged, the state machines in thewireless modems transmitters - As illustrated in FIG. 5, once the
wireless modems respective receivers recovery state 62 to astable state 64. When in thestable state 64, thereceivers controller 40 of thesecond wireless modem 28 receives the SNR parametric output by theQAM demodulator unit 56 of thereceiver 38 in addition to the bit error rate parametric output by the forwarderror correction decoder 58 of thereceiver 38 and, on the basis of the received parameters, determines that the line quality has not decreased as a result of environmental degradation. Thecontroller 40 makes such a determination by comparing the difference in the current SNR to a previous SNR average, or to a SNR threshold, and determining that the link quality is clean, i.e. that there is a +q event. - Once a +q event is achieved when the
receiver 38 is in thestable state 64, thecontroller 40 generates corresponding feedback information in the form of a modulation index change command packet specifying an increased QAM index to which thereceiver 38 intends to move. Thereceiver 38 of thesecond wireless modem 28 then moves from thestable state 64 to anupgrade state 66. While in theupgrade state 66, thesecond wireless modem 28 continues to receive and transmit data at the initial QAM index so that data transmission is not effected by the transmission of the modulation index change command packet. - The
controller 40 outputs the modulation index change command packet to the forwarderror correction encoder 44 of thetransmitter 36 of thesecond wireless modem 28 which then transmits the modulation index change command packet to thereceiver 32 of thefirst wireless modem 26. Thecontroller 34 of thefirst wireless modem 26 receives the modulation index change command packet after it is forward error correction decoded by the forwarderror correction decoder 58 of thefirst wireless modem 26. - If the modulation index change command packet is received by the
receiver 32 of thefirst wireless modem 26, thetransmitter 30 of thefirst wireless modem 26 stops placing data in theoutput buffer 31, and data that remains to be transmitted in theoutput buffer 31 of thetransmitter 30 is transmitted. Thefirst wireless modem 26 then flushes out theoutput buffer 31 of thetransmitter 30 and as soon as the last data element is sent, thecontroller 34 controls theQAM modulator 46 of thefirst wireless modem 26 to upgrade it's modulation index to correspond to the increased QAM index, and then resumes transmitting data. When data transmission by thefirst wireless modem 26 is resumed, the resumed data transmission initially includes empty frames for a certain period of time, such as 20 ms, for example. - When the modulation index is upgraded by the
QAM modulator 46 of thefirst wireless modem 26, the link between thefirst wireless modem 26 and thesecond wireless modem 28 is momentarily lost, resulting in a sync loss event. As soon as the sync loss event occurs, thecontroller 40 controls the QAM demodulator of thereceiver 38 to upgrade the modulation index to correspond to the upgraded QAM index requested in the modulation index change command packet, and thereceiver 38 of thesecond wireless modem 28 moves to anupgrade wait state 68. Since thefirst wireless modem 26 is already transmitting empty frames at the upgraded QAM index, a sync event occurs. Once this sync event occurs, thereceiver 38 moves from theupgrade wait state 68 to thestable state 64 and continues sampling the line quality. - If, while in the
upgrade state 66, the sync loss event does not occur, i.e., the modulation index is not upgraded by theQAM demodulator 56 of thesecond wireless modem 28 and therefore the link between thefirst wireless modem 26 and thesecond wireless modem 28 is not momentarily lost, after a preferably one second timeout event occurs, and thereceiver 38 of thesecond wireless modem 28 moves from theupgrade state 66 to thestable state 64 and resumes sampling the line quality. During this time, neither the first wireless modem or thesecond wireless modem 28 stop receiving or transmitting data, and therefore no loss in data transmission has resulted. - When the
receiver 38 is in theupgrade state 66, achieves the sync loss event and moves to theupgrade wait state 68 to wait for receipt of the empty frames from thetransmitter 30 of thefirst wireless modem 26, if thereceiver 38 does not receive the empty frames while in theupgrade wait state 68, or the empty frames are received in a degraded condition, a no sync event occurs. - In response to the no sync event that occurs while the
receiver 38 is in theupgrade wait state 68, thereceiver 38 instructs thecontroller 40 of thesecond wireless modem 28 to generate a modulation index change command packet specifying the previous modulation index, and thereceiver 38 moves from theupgrade wait state 68 to adowngrade wait state 70 after changing to the previous modulation index. As described above, thecontroller 40 generates and outputs the modulation index change command packet to the forwarderror correction encoder 44 of thetransmitter 36 of thesecond wireless modem 28 and the modulation index change command packet is transmitted to thereceiver 32 of thefirst wireless modem 26. Thecontroller 34 of thefirst wireless modem 26 receives the modulation index change command packet after it is forward error correction decoded by the forwarderror correction decoder 58 of thefirst wireless modem 26. If the modulation index change command packet is received by thereceiver 32 of thefirst wireless modem 26, thetransmitter 30 of thefirst wireless modem 26 ensures that theoutput buffer 31 is flushed out, changes it's modulation index accordingly, and then transmits data including the empty frames as described above. - If a sync event occurs after the
receiver 38 of thesecond wireless modem 28 moves to thedowngrade wait state 70, meaning that thetransmitter 30 of thefirst wireless modem 26 is now transmitting at the previous modulation index, thereceiver 38 moves to thestable state 64 and continues sampling the line quality. - If the
receiver 38 of thesecond wireless modem 28 moves from theupgrade wait state 68 to thedowngrade wait state 70 as described above, and a sync event does not occur, meaning that thetransmitter 30 of thefirst wireless modem 26 is not transmitting at the previous modulation index after preferably one second, a no sync event occurs and thereceiver 38 of thesecond wireless modem 28 moves to therecovery state 62. In therecovery state 62, thereceiver 38 of thesecond wireless modem 28 instructs thecontroller 40 of thesecond wireless modem 28 to generate a modulation index change command packet specifying the lowest QAM index and to immediately change thereceiver 38 to the lowest QAM index without waiting for a response from the first wireless modem. - If a sync event occurs after the
receiver 38 of thesecond wireless modem 28 moves from thedowngrade wait state 70 to therecovery state 62, meaning that thetransmitter 30 of thefirst wireless modem 26 is transmitting at the lowest QAM index, thereceiver 38 moves from therecovery state 62 to thestable state 64 and continues sampling the line quality. On the other hand, if a no sync event occurs after thereceiver 38 of thesecond wireless modem 28 moves from thedowngrade wait state 70 to therecovery state 62, meaning that thetransmitter 30 of thefirst wireless modem 26 is not transmitting at the lowest QAM index, both thetransmitter 36 and thereceiver 38 of thesecond wireless modem 28 are reset or initialized. - When the
transmitter 36 of thesecond wireless modem 28 is reset, thereceiver 32 of thefirst wireless modem 26, which is in thestable state 64, experiences a sync loss event, since the line goes down momentarily, and therefore immediately goes to therecovery state 62 and thetransmitter 30 andreceiver 32 of thefirst wireless modem 26 are reset, as described above. As a result, the effect of resetting thetransmitter 36 andreceiver 38 of thesecond wireless modem 28 when a no sync event occurs while in therecovery state 62 is that thetransmitter 30 andreceiver 32 of thefirst wireless modem 26 are reset as well, so that bothwireless modems wireless modems - If, on the other hand, while sampling the line quality in the
stable state 62 by comparing the difference in the current SNR output by theQAM demodulator unit 56 of thereceiver 38 to a previous SNR average, or to a SNR threshold, thecontroller 40 of thesecond wireless modem 28 determines that the line quality is degrading as a result of environmental degradation of the link, a −q event occurs. In response to the −q event that occurs while thereceiver 38 is in thestable state 64, thecontroller 40 generates corresponding feedback information in the form of a modulation index change command packet specifying a decreased QAM index to which thereceiver 38 intends to move and thereceiver 38 moves from thestable state 64 to adowngrade state 72. Thecontroller 40 outputs the modulation index change command packet to the forwarderror correction encoder 44 of thetransmitter 36 and the modulation index change command packet is transmitted to thereceiver 32 of thefirst wireless modem 26. Thecontroller 34 of thefirst wireless modem 26 receives the modulation index change command packet after it is forward error correction decoded by the forwarderror correction decoder 58 of thefirst wireless modem 26. While in thedowngrade state 72, thesecond wireless modem 28 continues to receive and transmit data at the initial QAM index so that data transmission is not effected by the transmission of the modulation index change command packet. - In the same way as in the
upgrade state 66 described above, when the modulation index change command packet is received by thereceiver 32 of thefirst wireless modem 26 after a −q event occurs while thereceiver 38 is in thestable state 64, thetransmitter 30 of thefirst wireless modem 26 stops sending data, flushes out theoutput buffer 31 of thetransmitter 30, and as soon as the last data element is sent, thecontroller 34 controls theQAM modulator 46 of thefirst wireless modem 26 to downgrade it's modulation index to correspond to the decreased QAM index, and then resumes transmitting data, beginning with empty frames. - When the modulation index is downgraded by the
QAM modulator 46 of thefirst wireless modem 26, the link between thefirst wireless modem 26 and thesecond wireless modem 28 is momentarily lost, resulting in a sync loss event. As soon as the sync loss event occurs, thecontroller 40 controls the QAM demodulator of thereceiver 38 to downgrade the modulation index of thereceiver 38 to correspond to the downgrade QAM index requested in the modulation index change command packet, and thereceiver 38 of thesecond wireless modem 28 moves from thedowngrade state 72 to thedowngrade wait state 70. Since thefirst wireless modem 26 is already transmitting empty frames at the downgraded QAM index, a sync event occurs. Once this sync event occurs, thereceiver 38 moves from thedowngrade wait state 70 to thestable state 64 and continues sampling the line quality. - While the
receiver 38 is in thedowngrade state 72, if the sync loss event does not occur, i.e., the modulation index is not upgraded by theQAM modulator 46 of thefirst wireless modem 26 and therefore the link between thefirst wireless modem 26 and thesecond wireless modem 28 is not momentarily lost, a timeout event occurs, and thereceiver 38 of thesecond wireless modem 28 moves from theupgrade state 66 to thestable state 64 and resumes sampling the line quality. During this time, neither the first wireless modem or thesecond wireless modem 28 stop receiving or transmitting data, and therefore no loss in data transmission has resulted. - Once the sync loss event occurs and the
receiver 38 of thesecond wireless modem 28 moves from thedowngrade state 72 to thedowngrade wait state 70, the state transition of thereceiver 38 is the same as in the ease when thereceiver 38 moves from theupgrade wait state 68 to thedowngrade wait state 70 after a no sync event occurs while in theupgrade wait state 68, described above, and therefore the repeated description will be omitted. - Finally, while sampling the line quality in the
stable state 64, if thereceiver 38 no longer detects the signal, or loses sync, without initiating the loss of sync, such as during a loss of sync resulting from an event outside protocol, a sync loss event occurs. Once this sync loss event occurs, thereceiver 38 moves directly from thestable state 64 to therecovery state 62. While such an occurrence would be rare, once thereceiver 38 is in therecovery state 62 as a result of an event outside protocol, thereceiver 38 commands thecontroller 40 to reset both thereceiver 38 and thetransmitter 36. This action forces the link between the transmitter and the receiver to momentarily go down, which communicates the controller to reconfigure the transmitter and receiver to be at the minimum QAM index, as described above. - If at recovery state the no sync event is received, the
receiver 38 takes the same action as described above; that is, thereceiver 38 andtransmitter 36 are reset (reconfigured) which in turn resets theremote modem 26 to do the same. This way, in the recovery state both modems constantly try to achieve sync at the lowest QAM level. - As illustrated in FIG. 6, the state diagram for the
transmitter 30 includes astable state 74 and arecovery state 76. Once initialization of the wireless modems is performed as described above, and thetransmitter 30 is therefore in thestable state 74 and continuously transmits data at the particular QAM index determined by the protocol during initialization. Thetransmitter 30 remains at that particular QAM index until the above-described feedback information is received from thesecond wireless modem 28 requesting thefirst wireless modem 26 to change QAM index. Upon receipt of the feedback information, thetransmitter 30 changes to a QAM index corresponding to the feedback information that in turn is related to whether the line quality is determined to be degrading −q, or clean +q, as described above. Thetransmitter 30 after changing the QAM index simply returns to the stable state where is ready to receive feedback information again. When thetransmitter 30 of thefirst wireless modem 26 is reset and configured to the lowest QAM index as a result of thereceiver 38 of thesecond wireless modem 28 losing sync, thetransmitter 30 moves to therecovery state 76. Once thetransmitter 30 receives feedback information requesting some QAM index, the transmitter moves to thestable state 74 and transmits data. - By using the dynamic adaptive modulation negotiation according to the present invention described above, the present invention enables wireless modems to make use of the increased SNR corresponding to the hashed region of the graph of FIG. 1 located between where the SNR can be tolerated,
line 24, and the engineered level of the SNR, line 20. As a result, the modems of the present invention are able to successfully maintain a link in periods of environmental degradation, such as during periods of intense rainfall, while allowing the modems to operate with greater throughput during the time of the year when environmental degradation does not occur. In addition, since thewireless modems - It will be understood that while the embodiment of the present invention is described in association with modems operating at millimeter wave frequencies, the present invention could also apply to modems operating at lower frequencies.
- While the negotiation for point-to-point links of the present invention are described in terms of negotiating a modulation index, it is understood that the negotiation is not limited to modulation index, but could also involve other features of the transmitted data, such as bandwidth, Reed-Solomon correction bytes, carrier frequency, convolution code rate, antenna beam focus, and excess bandwidth, etc. In addition, while the modulation negotiation has been described in relation to wireless communications, the modulation negotiation of the present invention could also applied in cable communications, and stratospheric links provided by high altitude aircraft and satellites.
- Although a few preferred embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that changes may be made in these embodiments without departing from the principles and spirit of the invention, the scope of which is defined in the claims and their equivalents.
Claims (1)
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US09/967,479 US20020101913A1 (en) | 1999-07-28 | 2001-09-28 | Dynamic adaptive modulation negotiation for point-to-point terrestrial links |
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US09/362,043 US6330278B1 (en) | 1999-07-28 | 1999-07-28 | Dynamic adaptive modulation negotiation for point-to-point terrestrial links |
US09/967,479 US20020101913A1 (en) | 1999-07-28 | 2001-09-28 | Dynamic adaptive modulation negotiation for point-to-point terrestrial links |
Related Parent Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US09/362,043 Continuation US6330278B1 (en) | 1999-07-28 | 1999-07-28 | Dynamic adaptive modulation negotiation for point-to-point terrestrial links |
Publications (1)
Publication Number | Publication Date |
---|---|
US20020101913A1 true US20020101913A1 (en) | 2002-08-01 |
Family
ID=23424459
Family Applications (2)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US09/362,043 Expired - Fee Related US6330278B1 (en) | 1999-07-28 | 1999-07-28 | Dynamic adaptive modulation negotiation for point-to-point terrestrial links |
US09/967,479 Abandoned US20020101913A1 (en) | 1999-07-28 | 2001-09-28 | Dynamic adaptive modulation negotiation for point-to-point terrestrial links |
Family Applications Before (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US09/362,043 Expired - Fee Related US6330278B1 (en) | 1999-07-28 | 1999-07-28 | Dynamic adaptive modulation negotiation for point-to-point terrestrial links |
Country Status (5)
Country | Link |
---|---|
US (2) | US6330278B1 (en) |
EP (1) | EP1205034A1 (en) |
CN (1) | CN1382325A (en) |
AU (1) | AU6239900A (en) |
WO (1) | WO2001010048A1 (en) |
Cited By (14)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP1406405A1 (en) * | 2002-10-04 | 2004-04-07 | Alcatel | System and method for adaptive modulation based on channel estimates and capacity requirements |
US20060023747A1 (en) * | 2004-07-27 | 2006-02-02 | Eitan Koren | Method and apparatus for session layer framing to enable interoperability between packet-switched systems |
US20060023654A1 (en) * | 2004-07-27 | 2006-02-02 | Eitan Koren | Method and apparatus for enabling interoperability between packet-switched systems |
US20060090011A1 (en) * | 2004-10-26 | 2006-04-27 | Canon Kabushiki Kaisha | Communication system and control method thereof |
US20060133409A1 (en) * | 2004-12-22 | 2006-06-22 | Rajat Prakash | Connection setup using flexible protocol configuration |
US20060150055A1 (en) * | 2005-01-06 | 2006-07-06 | Terayon Communication Systems, Inc. | Adaptive information delivery system using FEC feedback |
US20060171477A1 (en) * | 2005-02-03 | 2006-08-03 | Juan-Antonio Carballo | Digital transmission circuit and method providing selectable power consumption via single-ended or differential operation |
US20060221847A1 (en) * | 2005-03-29 | 2006-10-05 | Dacosta Behram M | Method and apparatus for selecting transmission modulation rates in wireless devices for A/V streaming applications |
US20080117994A1 (en) * | 2006-11-17 | 2008-05-22 | Intersil Americas Inc. | Use of differential pair as single-ended data paths to transport low speed data |
US7567513B2 (en) | 2005-06-10 | 2009-07-28 | Samsung Electronics Co., Ltd. | Method of controlling transmission rate by using error correction packets and communication apparatus using the same |
WO2013056136A1 (en) * | 2011-10-14 | 2013-04-18 | Qualcomm Incorporated | Interference mitigation techniques for air to ground systems |
US8494063B1 (en) * | 2001-09-25 | 2013-07-23 | Netgear, Inc. | System and method for stacking receiver channels for increased system through-put in an RF data transmission system |
US8676192B2 (en) | 2011-02-09 | 2014-03-18 | Qualcomm Incorporated | High data rate aircraft to ground communication antenna system |
WO2014039722A3 (en) * | 2012-09-07 | 2014-06-26 | Qualcomm Incorporated | Selecting a modulation and coding scheme for beamformed communication |
Families Citing this family (34)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US6690884B1 (en) * | 1999-02-19 | 2004-02-10 | Corvis Corporation | Optical transmission systems including error correction and protection apparatuses and methods |
US6330278B1 (en) * | 1999-07-28 | 2001-12-11 | Integrity Broadband Networks, Inc. | Dynamic adaptive modulation negotiation for point-to-point terrestrial links |
US6804211B1 (en) | 1999-08-03 | 2004-10-12 | Wi-Lan Inc. | Frame structure for an adaptive modulation wireless communication system |
US6731688B1 (en) * | 1999-12-13 | 2004-05-04 | Intel Corporation | Speed signaling for data communications |
US6816505B1 (en) * | 2000-02-09 | 2004-11-09 | Marvell International Ltd. | Chip-to-chip interface for 1000 BASE T gigabit physical layer device |
US6760882B1 (en) * | 2000-09-19 | 2004-07-06 | Intel Corporation | Mode selection for data transmission in wireless communication channels based on statistical parameters |
US6802035B2 (en) * | 2000-09-19 | 2004-10-05 | Intel Corporation | System and method of dynamically optimizing a transmission mode of wirelessly transmitted information |
GB2367447B (en) * | 2000-09-27 | 2003-11-05 | Airspan Networks Inc | Transfer of data in a telecommunications system |
WO2002041520A2 (en) * | 2000-11-15 | 2002-05-23 | Ensemble Communications, Inc. | Improved frame structure for a communication system using adaptive modulation |
US7477702B2 (en) * | 2000-11-30 | 2009-01-13 | Nokia Mobile Phones Limited | Apparatus, and associated method, for selecting a switching threshold for a transmitter utilizing adaptive modulation techniques |
EP1244227B1 (en) | 2001-03-22 | 2005-07-20 | Siemens Mobile Communications S.p.A. | Automatic method for power control and phy mode switching control in adaptive phy mode systems |
EP1248396A1 (en) * | 2001-04-02 | 2002-10-09 | Alcatel | Method and receiver for evaluating a radio link quality in a wireless communication network |
US7584498B2 (en) * | 2001-04-23 | 2009-09-01 | Thomson Licensing | Method and apparatus for enhanced cable modem operation |
US7577100B2 (en) * | 2001-07-27 | 2009-08-18 | Stephen Pollmann | System and method for measuring signal to noise values in an adaptive wireless communication system |
JP3943877B2 (en) * | 2001-08-17 | 2007-07-11 | 富士通株式会社 | Positioning control apparatus and method |
US7277492B2 (en) * | 2001-08-28 | 2007-10-02 | Sony Corporation | Transmission apparatus, transmission control method, reception apparatus, and reception control method |
WO2003026189A1 (en) * | 2001-09-20 | 2003-03-27 | Itt Manufacturing Enterprises, Inc. | Methods and apparatus for satellite link throughput adaptation |
ATE320115T1 (en) | 2001-12-05 | 2006-03-15 | Siemens Mobile Comm Spa | OPTIMAL HYSTERESIS BASED ON TWO DIFFERENT PARAMETERS FOR TRANSMIT POWER CONTROL AND FOR PHY MODE SWITCHING CONTROL IN ADAPTIVE PHY MODE SYSTEMS |
JP3963737B2 (en) | 2002-02-28 | 2007-08-22 | 松下電器産業株式会社 | Multi-carrier signal generation method, radio transmission apparatus, and radio reception apparatus |
US7308611B2 (en) * | 2002-10-11 | 2007-12-11 | Agilent Technologies, Inc. | Intelligent power cycling of a wireless modem |
US7020484B2 (en) * | 2002-10-29 | 2006-03-28 | Qualcomm Incorporated | Controlling multiple modems in a wireless terminal using energy-per-bit determinations |
US7016697B2 (en) * | 2002-10-29 | 2006-03-21 | Qualcomm Incorporated | Controlling multiple modems in a wireless terminal using dynamically varying modem transmit power limits |
US7408892B2 (en) * | 2003-01-28 | 2008-08-05 | Broadcom Corporation | Upstream adaptive modulation in DOCSIS based applications |
US7178051B2 (en) * | 2003-02-27 | 2007-02-13 | Sun Microsystems, Inc. | Method for synchronous support of fault-tolerant and adaptive communication |
CN1864409A (en) * | 2003-10-16 | 2006-11-15 | 日本电气株式会社 | Medium signal transmission method, reception method, transmission/reception method, and device |
JP4423292B2 (en) * | 2004-07-12 | 2010-03-03 | 富士通株式会社 | Radio bearer control method and radio base station |
FR2903257A1 (en) * | 2006-06-30 | 2008-01-04 | Thomson Licensing Sas | COMMUNICATION METHOD ADAPTED FOR TRANSMITTING DATA PACKETS |
US8208873B2 (en) * | 2006-11-10 | 2012-06-26 | Powerwave Cognition, Inc. | Method and apparatus for adjusting waveform parameters for an adaptive air interface waveform |
CN101478366B (en) * | 2008-11-10 | 2011-09-14 | 华为技术有限公司 | Adaptive modulation method, station and communication system |
US8972825B2 (en) * | 2009-03-30 | 2015-03-03 | Telefonaktiebolaget L M Ericsson (Publ) | Channel estimation in adaptive modulation systems |
US9191863B2 (en) * | 2010-01-05 | 2015-11-17 | Nec Corporation | Bandwidth guaranteed system, radio node device and bandwidth guaranteeing method |
US8837564B2 (en) * | 2011-10-14 | 2014-09-16 | Broadcom Corporation | Multi gigabit modem for mmWave point to point links |
US10038497B2 (en) * | 2013-12-18 | 2018-07-31 | Northrup Grumman Systems Corporation | Optical transceiver with variable data rate and sensitivity control |
JP6454397B1 (en) * | 2017-12-20 | 2019-01-16 | Nttエレクトロニクス株式会社 | Error correction apparatus, error correction method, and optical communication system |
Citations (10)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US5321725A (en) * | 1991-07-26 | 1994-06-14 | General Instrument Corporation | Method and apparatus for communicating digital information such as compressed video using treillis coded QAM |
US5475711A (en) * | 1992-10-30 | 1995-12-12 | At&T Corp. | System for channel capacity modulation |
US5590405A (en) * | 1993-10-29 | 1996-12-31 | Lucent Technologies Inc. | Communication technique employing variable information transmission |
US5640684A (en) * | 1994-08-08 | 1997-06-17 | Nippondenso Co., Ltd. | Radio data communication system comprising a common base radio station and handy radio terminals |
US5828677A (en) * | 1996-03-20 | 1998-10-27 | Lucent Technologies Inc. | Adaptive hybrid ARQ coding schemes for slow fading channels in mobile radio systems |
US5852631A (en) * | 1996-06-21 | 1998-12-22 | Paradyne Corporation | System and method for establishing link layer parameters based on physical layer modulation |
US5914959A (en) * | 1996-10-31 | 1999-06-22 | Glenayre Electronics, Inc. | Digital communications system having an automatically selectable transmission rate |
US5940439A (en) * | 1997-02-26 | 1999-08-17 | Motorola Inc. | Method and apparatus for adaptive rate communication system |
US5982813A (en) * | 1996-09-30 | 1999-11-09 | Amsc Subsidiary Corporation | Demand-based power and data rate adjustments to a transmitter to optimize channel capacity and power usage with respect to data transmission traffic over a fixed-bandwidth channel |
US6330278B1 (en) * | 1999-07-28 | 2001-12-11 | Integrity Broadband Networks, Inc. | Dynamic adaptive modulation negotiation for point-to-point terrestrial links |
-
1999
- 1999-07-28 US US09/362,043 patent/US6330278B1/en not_active Expired - Fee Related
-
2000
- 2000-07-28 AU AU62399/00A patent/AU6239900A/en not_active Abandoned
- 2000-07-28 EP EP00948983A patent/EP1205034A1/en not_active Withdrawn
- 2000-07-28 CN CN00813536.3A patent/CN1382325A/en active Pending
- 2000-07-28 WO PCT/US2000/020552 patent/WO2001010048A1/en not_active Application Discontinuation
-
2001
- 2001-09-28 US US09/967,479 patent/US20020101913A1/en not_active Abandoned
Patent Citations (10)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US5321725A (en) * | 1991-07-26 | 1994-06-14 | General Instrument Corporation | Method and apparatus for communicating digital information such as compressed video using treillis coded QAM |
US5475711A (en) * | 1992-10-30 | 1995-12-12 | At&T Corp. | System for channel capacity modulation |
US5590405A (en) * | 1993-10-29 | 1996-12-31 | Lucent Technologies Inc. | Communication technique employing variable information transmission |
US5640684A (en) * | 1994-08-08 | 1997-06-17 | Nippondenso Co., Ltd. | Radio data communication system comprising a common base radio station and handy radio terminals |
US5828677A (en) * | 1996-03-20 | 1998-10-27 | Lucent Technologies Inc. | Adaptive hybrid ARQ coding schemes for slow fading channels in mobile radio systems |
US5852631A (en) * | 1996-06-21 | 1998-12-22 | Paradyne Corporation | System and method for establishing link layer parameters based on physical layer modulation |
US5982813A (en) * | 1996-09-30 | 1999-11-09 | Amsc Subsidiary Corporation | Demand-based power and data rate adjustments to a transmitter to optimize channel capacity and power usage with respect to data transmission traffic over a fixed-bandwidth channel |
US5914959A (en) * | 1996-10-31 | 1999-06-22 | Glenayre Electronics, Inc. | Digital communications system having an automatically selectable transmission rate |
US5940439A (en) * | 1997-02-26 | 1999-08-17 | Motorola Inc. | Method and apparatus for adaptive rate communication system |
US6330278B1 (en) * | 1999-07-28 | 2001-12-11 | Integrity Broadband Networks, Inc. | Dynamic adaptive modulation negotiation for point-to-point terrestrial links |
Cited By (28)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US8494063B1 (en) * | 2001-09-25 | 2013-07-23 | Netgear, Inc. | System and method for stacking receiver channels for increased system through-put in an RF data transmission system |
US9730192B1 (en) | 2001-09-25 | 2017-08-08 | Netgear, Inc. | System and method for stacking receiver channels for increased system through-put in an RF data transmission system |
US10070423B2 (en) | 2001-09-25 | 2018-09-04 | Netgear, Inc. | System and method for stacking receiver channels for increased system through-put in an RF data transmission system |
EP1406405A1 (en) * | 2002-10-04 | 2004-04-07 | Alcatel | System and method for adaptive modulation based on channel estimates and capacity requirements |
US20060023747A1 (en) * | 2004-07-27 | 2006-02-02 | Eitan Koren | Method and apparatus for session layer framing to enable interoperability between packet-switched systems |
US20060023654A1 (en) * | 2004-07-27 | 2006-02-02 | Eitan Koren | Method and apparatus for enabling interoperability between packet-switched systems |
US8249102B2 (en) * | 2004-07-27 | 2012-08-21 | Motorola Solutions, Inc. | Method and apparatus for session layer framing to enable interoperability between packet-switched systems |
US20060090011A1 (en) * | 2004-10-26 | 2006-04-27 | Canon Kabushiki Kaisha | Communication system and control method thereof |
US7970163B2 (en) * | 2004-10-26 | 2011-06-28 | Canon Kabushiki Kaisha | Communication system and control method thereof |
US20060133409A1 (en) * | 2004-12-22 | 2006-06-22 | Rajat Prakash | Connection setup using flexible protocol configuration |
US7990998B2 (en) * | 2004-12-22 | 2011-08-02 | Qualcomm Incorporated | Connection setup using flexible protocol configuration |
WO2006074408A3 (en) * | 2005-01-06 | 2007-09-13 | Terayon Comm Systems Inc | Adaptive information delivery system using fec feedback |
US20060150055A1 (en) * | 2005-01-06 | 2006-07-06 | Terayon Communication Systems, Inc. | Adaptive information delivery system using FEC feedback |
US20060171477A1 (en) * | 2005-02-03 | 2006-08-03 | Juan-Antonio Carballo | Digital transmission circuit and method providing selectable power consumption via single-ended or differential operation |
US7522670B2 (en) * | 2005-02-03 | 2009-04-21 | International Business Machines Corporation | Digital transmission circuit and method providing selectable power consumption via single-ended or differential operation |
US20060221847A1 (en) * | 2005-03-29 | 2006-10-05 | Dacosta Behram M | Method and apparatus for selecting transmission modulation rates in wireless devices for A/V streaming applications |
US7567513B2 (en) | 2005-06-10 | 2009-07-28 | Samsung Electronics Co., Ltd. | Method of controlling transmission rate by using error correction packets and communication apparatus using the same |
US8175173B2 (en) * | 2006-11-17 | 2012-05-08 | Intersil Americas Inc. | Methods and systems for transmitting signals differentially and single-endedly across a pair of wires |
US20110194595A1 (en) * | 2006-11-17 | 2011-08-11 | Intersil Americas Inc. | Methods and systems for transmitting signals differentialy and single-endedly across a pair of wires |
US7953162B2 (en) * | 2006-11-17 | 2011-05-31 | Intersil Americas Inc. | Use of differential pair as single-ended data paths to transport low speed data |
US20080117994A1 (en) * | 2006-11-17 | 2008-05-22 | Intersil Americas Inc. | Use of differential pair as single-ended data paths to transport low speed data |
US8676192B2 (en) | 2011-02-09 | 2014-03-18 | Qualcomm Incorporated | High data rate aircraft to ground communication antenna system |
US9295006B2 (en) | 2011-02-09 | 2016-03-22 | Qualcomm Incorporated | Real-time calibration of an air to ground communication system |
US9848391B2 (en) | 2011-02-09 | 2017-12-19 | Qualcomm Incorporated | High data rate aircraft to ground communication antenna system |
WO2013056136A1 (en) * | 2011-10-14 | 2013-04-18 | Qualcomm Incorporated | Interference mitigation techniques for air to ground systems |
US9319172B2 (en) | 2011-10-14 | 2016-04-19 | Qualcomm Incorporated | Interference mitigation techniques for air to ground systems |
WO2014039722A3 (en) * | 2012-09-07 | 2014-06-26 | Qualcomm Incorporated | Selecting a modulation and coding scheme for beamformed communication |
US9306640B2 (en) | 2012-09-07 | 2016-04-05 | Qualcomm Incorporated | Selecting a modulation and coding scheme for beamformed communication |
Also Published As
Publication number | Publication date |
---|---|
US6330278B1 (en) | 2001-12-11 |
EP1205034A1 (en) | 2002-05-15 |
WO2001010048A1 (en) | 2001-02-08 |
CN1382325A (en) | 2002-11-27 |
AU6239900A (en) | 2001-02-19 |
Similar Documents
Publication | Publication Date | Title |
---|---|---|
US6330278B1 (en) | Dynamic adaptive modulation negotiation for point-to-point terrestrial links | |
US6262994B1 (en) | Arrangement for the optimization of the data transmission via a bi-directional radio channel | |
US7072662B2 (en) | Data communication quality control system, transmitter system and receiver | |
US7043210B2 (en) | Adaptive coding and modulation | |
EP1435146A1 (en) | Adaptive point-to-point microwave radio system | |
KR20040039305A (en) | Asymmetric adaptive modulation in a wireless communication system | |
KR101026595B1 (en) | Wireless communication system, and demodulation method and data rate control method therefor | |
CA3048188C (en) | Filtering code blocks to maintain high throughput thru a forward error correction decoder | |
US6625776B1 (en) | Adaptive coding scheme for a processing communications satellite | |
CN102714633B (en) | Method for transmission and reception of traffic packets, device and system | |
JP2006211719A (en) | Control of transmission power in radio system | |
US9276636B2 (en) | Adaptive modulation system and method to minimize energy consumption | |
US9781489B2 (en) | Digital video broadcasting—terrestrial (DVB-T) system and modulation method thereof | |
US7469124B1 (en) | Rate adaptive satellite communications | |
US8744503B2 (en) | Wireless communication device, wireless communication system, and wireless communication method | |
JP2014230098A (en) | Communication device and control method thereof | |
KR20130021022A (en) | Apparatus and method for simulcast transmitting/receiving based on adaptive coding modulation | |
KR100418196B1 (en) | Adaptive transmission method in wireless communication system and device thereof | |
US6577847B2 (en) | Satellite communication system with multiple variable data rate carrier | |
CN106878577B (en) | Cable modem online control method and device | |
US20220131635A1 (en) | System and method for optimizing throughput of communication link | |
Celandroni et al. | Goodput optimisation of long-lived TCP connections in a rain-faded satellite channel | |
KR20000033357A (en) | Radio communication transmitting/receiving apparatus varying channel codec according to communication channel feature and method thereof | |
JP3941518B2 (en) | COMMUNICATION CONTROL METHOD, WIRELESS COMMUNICATION SYSTEM, AND WIRELESS COMMUNICATION DEVICE | |
CN102611649A (en) | LDPC (Low Density Parity Check) code self-adaptive demodulation coding device |
Legal Events
Date | Code | Title | Description |
---|---|---|---|
AS | Assignment |
Owner name: REMEC, INC., CALIFORNIA Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:SPIKE BROADBAND SYSTEMS, INC.;REEL/FRAME:012721/0628 Effective date: 20020107 |
|
AS | Assignment |
Owner name: SILICON VALLEY BANK, CALIFORNIA Free format text: SECURITY AGREEMENT;ASSIGNORS:REMEC, INC.;REMEC MICROWAVE, INC.;REEL/FRAME:014699/0119 Effective date: 20010816 |
|
AS | Assignment |
Owner name: SILICON VALLEY BANK, CALIFORNIA Free format text: SECURITY INTEREST;ASSIGNORS:REMEC, INC.;REMEC MICROWAVE, INC.;REEL/FRAME:015918/0671 Effective date: 20030211 |
|
AS | Assignment |
Owner name: AXXCELERA BROADBAND WIRELESS, INC., CALIFORNIA Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:REMEC., INC.;REEL/FRAME:016522/0658 Effective date: 20040510 |
|
STCB | Information on status: application discontinuation |
Free format text: ABANDONED -- FAILURE TO RESPOND TO AN OFFICE ACTION |
|
AS | Assignment |
Owner name: REMEC, INC., CALIFORNIA Free format text: RELEASE;ASSIGNOR:SILICON VALLEY BANK;REEL/FRAME:022421/0928 Effective date: 20090316 Owner name: REMEC MICROWAVE, INC., CALIFORNIA Free format text: RELEASE;ASSIGNOR:SILICON VALLEY BANK;REEL/FRAME:022421/0928 Effective date: 20090316 Owner name: REMEC, INC./REMEC MICROWAVE, INC., CALIFORNIA Free format text: RELEASE;ASSIGNOR:SILICON VALLEY BANK;REEL/FRAME:022418/0238 Effective date: 20090316 |