Classifications

• • 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
  • H04L5/02—Channels characterised by the type of signal
  • H04L5/023—Multiplexing of multicarrier modulation signals

Definitions

• the present invention relates generally to a system and method for digital communications, and more particularly to a system and method for providing multiple access in a multi-band, orthogonal frequency division multiplexed (multi-band-OFDM) digital communications system.
• multi-band-OFDM orthogonal frequency division multiplexed
• One way to help reduce the probability of transmission collisions is to divide the available bandwidth in the communications channel into multiple transmission bands and then assign certain communications devices to the various transmission bands, wherein the communications devices can only transmit within their assigned transmission bands. By assigning communications devices to different transmission bands, the probability of collisions with other transmissions can be reduced. If the number of transmission bands is equal to or greater than the number of communications devices, then the probability of collisions can be reduced to zero.
• Another way to help reduce the probability of transmission collisions is to allocate access to the communications channel based upon time, wherein a communications device can transmit only if it is within its transmission time window. Once again, the probability of collisions can be reduced to zero if only one communications device is assigned to a transmission time window.
• One disadvantage of the prior art is that if the available bandwidth is divided into a large number of transmission bands, then the total amount of bandwidth available to a single communications device can be a small fraction of the total bandwidth. If only a small number of communications devices are transmitting, then the bandwidth utilization can be small, resulting in the waste of a significant amount of the available bandwidth.
• a second disadvantage of the prior art is that unless properly allocated, the transmission time windows can be allocated to communications devices with nothing to transmit, while communications devices with a need to transmit may not receive enough transmission time windows to achieve adequate data throughput. Once again, this can lead to inefficient use of the available transmission bandwidth.
• Another disadvantage of the prior art is that should an adaptive technique be applied to either the transmission bands or the transmission time windows, to increase bandwidth utilization, for example, then considerable resources may be needed to fairly and effectively distribute available bandwidth. This may require the use of a dedicated bandwidth server (or processor), which can increase the costs of the communications system.
• a method for receiving a preamble includes receiving a current preamble that can be used for channel estimation.
• the current preamble is used for the estimation of channels present in both enhanced and legacy time-interleaved, orthogonal frequency division multiplexed communications systems.
• a header that contains physical layer parameters and media access control layer information is received.
• a channel estimation extension used for channel estimation.
• the channel estimated by the channel estimation extension are only present in the enhanced time-frequency interleaved, orthogonal frequency division multiplexed communications system.
• Other embodiments of the invention provide other features.
• An advantage of a preferred embodiment of the present invention is that the multiple access communications system can accommodate known sources of interferers and frequency bands that should be avoided, to mitigate interference from and to these known trouble spots.
• Figures la and lb are coverage maps of multiple piconets operating within close proximity of one another;
• Figure 2 is a diagram of a frequency allocation for a wireless communications system
• Figures 3a and 3b are diagrams of time-frequency interleaving sequences of length three and six, according to a preferred embodiment of the present invention.
• Figures 4a through 4c are diagrams of possible transmission collisions between transmission sequences, according to a preferred embodiment of the present invention.
• Figure 5 is a diagram of a frequency allocation for a wireless communications system, wherein a portion of the frequency is occupied by a known interferer, according to a preferred embodiment of the present invention
• Figure 6 is a diagram of a transmission sequence in an enhanced multi-band-OFDM wireless communications system with additional transmissions bands containing an enhanced preamble to support the additional transmission bands, according to a preferred embodiment of the present invention
• Figure 7 is a diagram of a transmission sequence in an enhanced multi-band-OFDM wireless communications system with additional transmissions bands containing an enhanced preamble to support the additional transmission bands, according to a preferred embodiment of the present invention
• Figure 8 is a diagram of time-frequency interleaving sequences of length six for a communications system with six transmission bands, according to a preferred embodiment of the present invention.
• Figures 9a and 9b are diagrams of time-frequency interleaving sequences of length six for a communications system using three transmission bands, according to a preferred embodiment of the present invention.
• Figure 10 is a diagram of a frequency allocation chart for a multi-band-OFDM wireless communications system, according to a preferred embodiment of the present invention.
• Figure 11 is a diagram of a frequency allocation chart for a multi-band-OFDM wireless communications system, wherein sets of two transmission bands have been bonded into one transmission band, according to a preferred embodiment of the present invention
• Figure 12 is a diagram of a frequency allocation chart for a multi-band-OFDM wireless communications system, wherein sets of three transmission bands have been bonded into one transmission band, according to a preferred embodiment of the present invention
• Figure 13 is a diagram of a frequency allocation chart for a multi-band-OFDM wireless communications system, wherein some transmission bands have been bonded and some have not been bonded, according to a preferred embodiment of the present invention
• Figure 14 is a flow diagram of an algorithm for use in configuring transmission bands for a multi-band-OFDM wireless communications system, according to a preferred embodiment of the present invention
• Figure 15 is a flow diagram of an algorithm for use in bonding transmission bands for a multi-band-OFDM wireless communications system, according to a preferred embodiment of the present invention.
• Figure 16 is a diagram of a wireless communications system containing both legacy and enhanced communications devices, according to a preferred embodiment of the present invention.
• the present invention will be described with respect to preferred embodiments in a specific context, namely a multi-band, orthogonal frequency division multiplexed (multi-band- OFDM) wireless communications system, such as one that is adherent to IEEE 802.15.3a technical specifications.
• IEEE 802.15.3a technical requirements can be found in a document entitled "TG3a Technical Requirements," published 12/27/2002, which is herein incorporated by reference.
• the invention may also be applied, however, to other communications systems, namely those that make use of a partitioning of available bandwidth into transmission bands and those that operate in areas with known sources of interference and frequency bands that need to be avoided.
• the IEEE 802.15.3a technical requirements has specified a set of performance criteria, such as bit rate, effective operating range, power consumption, and so forth, for wireless devices. For example, a bit rate of at least 110 Mb/s at 10 meters is required. The technical requirements also specify that the communications system must be able to coexist with other wireless devices that may be in close proximity. [0035] With reference now to Figures la and lb, there are shown diagrams illustrating a coverage map (100 ( Figure la) and 150 ( Figure lb)) of multiple piconets operating within close proximity of one another.
• the coverage map 100 illustrates three piconets (piconet A 105, piconet B 110, and piconet C 115) operating in close proximity, so close that portions of their coverage areas overlap.
• the coverage map 150 illustrates four piconets (piconets A through C and piconet D 155), wherein the piconets' coverage areas overlap.
• transmissions from a transmitter in one piconet can collide with transmissions from a transmitter in another piconet.
• a transmitter (not shown) in piconet A 105 may have its transmissions collide with transmissions from a transmitter (not shown) in piconet C 115.
• the frequency allocation 200 is for a wireless communications system that operates within a frequency band of 3.168 GHz to 4.752 GHz, wherein the frequency band has been divided into three transmission bands: a first transmission band 205 with a center frequency at 3.432 GHz, a second transmission band 210 with a center frequency at 3.960 GHz, and a third transmission band 215 with a center frequency at 4.488 GHz.
• the wireless communications system may be able to support three piconets, which can be simultaneously transmitting, without collision. If more than three piconets are to be supported, then there may be transmission collisions, since there will be at least one transmission band wherein more than one piconet that may be transmitting. [0038] However, rather than assigning a piconet to transmit only within a certain transmission band, which can result in a waste of bandwidth allocated to the transmission band if the piconet is not transmitting, it may be possible to specify an order of usage of the transmission bands that can be used by a piconet. The order of usage, which may be referred to as a transmission sequence, can specify a sequence of transmission bands that the piconet should use when transmitting.
• the piconet transmits during a certain time interval, then it should use a transmission band specified for use during that time interval, and if it has something to transmit during the subsequent interval, then it should use a transmission band specified for the subsequent interval.
• the use of the transmission sequence can result in a relatively low probability of transmission collisions combined with usage of the entire bandwidth of the communications system.
• FIGs 3a and 3b there are shown diagrams illustrating time- frequency interleaving sequences (TFIS) of length three ( Figure 3a) and six (Figure 3b) for a multi-band OFDM wireless communications system with three transmission bands, according to a preferred embodiment of the present invention.
• TFIS time- frequency interleaving sequences
• Figure 3a time- frequency interleaving sequences
• Figure 3b six
• FIG. 3a For discussion purposes, let the three transmission bands be referred to by their numerical identifiers: "1,” "2,” and "3.” Then, for transmission sequences of length three, there may be two transmission sequences that can be shown to be optimal.
• a first transmission sequence 305 can be specified as [1 2 3] and a second transmission sequence 310 can be specified as [1 3 2].
• the first transmission sequence 305 and the second transmission sequence 310 are considered to be optimal because if they are used to specify transmissions for two asynchronous piconets with overlapping coverage areas, then there may be a guarantee of only a single collision over any three transmissions. For example, if piconet A transmits using the first transmission sequence 305 and piconet B transmits using the second transmission sequence 310 and both start transmissions at the same time, then only their initial transmissions will collide, with the two subsequent transmissions being carried on different transmission bands and hence no collisions will occur.
• Figure 3b illustrates four transmission sequences of length six. These four length six sequences (a first sequence 355, a second sequence 360, a third sequence 365, and a fourth sequence 370) can be used to permit up to four asynchronous piconets with overlapping coverage areas share three transmission bands. Note that the four length six sequences are what can be considered near-optimal. They are near-optimal in that certain pairs of the sequences are pairwise optimal, but not every pair of the sequences are pairwise optimal. One way to find transmission sequences is via simulation.
• Figure 4a displays two transmission sequences: the first transmission sequence 305 being [1 2 3] and the second transmission sequence 310 being [1 3 2] as shown in Figure 3 a. If two asynchronous piconets were to use the two transmission sequences as shown, then a transmission collision 405 may occur during a first specified transmission time when both asynchronous piconets transmit on transmission band #1. Note that the subsequent transmission times may not result in transmission collisions since different transmission bands are being used.
• the shifted version 410 may represent a transmission sequence used by an asynchronous piconet with a different transmission time clock. If two asynchronous piconets were to use the two transmission sequences as shown, then a transmission collision 415 may occur during a third specified transmission time when both asynchronous piconets transmit on transmission band #3.
• the shifted version 420 may represent a transmission sequence used by an asynchronous piconet with a different transmission time clock. If two asynchronous piconets were to use the two transmission sequences as shown, then a transmission collision 425 may occur during a second specified transmission time when both asynchronous piconets transmit on transmission band #2.
• a similar set of diagrams can be used to show potential transmission collisions for the length six sequences (the first sequence 355, the second sequence 360, the third sequence 365, and the fourth sequence 370) displayed in Figure 3b.
• the partitioning of available transmission bandwidth into a plurality of transmission bands has been shown to enable the sharing of the transmission bandwidth by multiple asynchronous (uncoordinated) piconets.
• the transmission bands can also be used to avoid interference from other electronic devices and noise and interfering with other electronic devices. Avoiding interference from and interfering with other electronic devices may be accomplished by not using (and listening to) transmission bands that occupy the same frequency bands as those used by the electronic devices as long as these electronic devices (and their frequency bands) are known before hand.
• FIG. 5 there is shown a diagram illustrating a frequency allocation 500 for a wireless communications system, wherein a portion of the frequency is occupied by a known interferer, according to a preferred embodiment of the present invention.
• a communications system that is compliant must be able to accept interference from and not cause undo interference to other electronic devices operating nearby.
• a frequency band that is seeing a great deal of interest is the Unified National Information Infrastructure (UNIT) band, located at 5.15 to 5.825 GHz.
• the UNII band has been used for wireless computer networking, cordless telephones, and other unlicensed devices in countries such as the United States and Japan.
• One way to not cause interference to and receive interference from electronic devices operating at a frequency range may be to exclude the frequency range from any transmissions. By preventing transmissions from using the excluded frequency range (such as the UNII band), electronic devices operating in the excluded frequency range will not be interfered with and the communications system will not receive interference from the electronic devices since the communications system will not be expecting transmissions from the excluded frequency range.
• the excluded frequency range such as the UNII band
• Figure 5 displays the frequency allocation 500 for a communications system, wherein the frequency allocation 500 features six transmission bands: the first transmission band 205 with a center frequency at 3.432 GHz, the second transmission band 210 with a center frequency at 3.960 GHz, the third "transmission band 215 with a center frequency at 4.488 GHz, a fourth transmission band 510 with a center frequency at 6.336 GHz, a fifth transmission band 515 with a center frequency at 6.864 GHz, and a sixth transmission band 520 with a center frequency at 7.392 GHz.
• the first, second, and third transmission bands (205, 210, and 215) may be similar to the transmission bands displayed in the frequency allocation 200 ( Figure 2).
• the first, second, and third transmission bands may be below a frequency band 505 that can be representative of the UNII frequency band, while the fourth, fifth, and sixth transmission bands (510, 515, and 520) may be above the frequency band 505.
• the location (center frequencies) of transmission bands may be different. For example, there may be a desire for only four transmission bands or there may be multiple frequency bands to avoid, both of which can change the frequency allocation.
• the number of piconets to support as well as the amount of spectrum available, it may be possible to add additional transmission bands or it may not be possible to have all six transmission bands as shown.
• the allocation of the spectrum may be dependent upon factors such as the number of piconets to support, the presence of known interferers, the amount of spectrum available, and so forth. '
• the center frequencies of each of the transmission bands can be generated. Starting with a frequency of 8448 MHz, the continued division by a factor of two (2) can result in frequencies of 4224 MHz, 2112 MHz, 1056 MHz, 528 MHz, and 264 MHz. Note that for a different frequency allocation, a different starting frequency and division factor may be needed. Then, using the generated frequencies, the center frequencies of the transmission bands can be generated as follows (note that it can be possible to express the center frequencies as a sum (and difference) of powers of two (2) factors of the smallest generated frequency, 264
• each transmission band's center frequency may be expressed as a sum (and/or difference) of powers of two factors of the smallest generated frequency
• a single circuit may be used to generate the center frequency for both the lower three transmission bands (the first, second, and third transmission bands 205, 210, and 215) and the upper three transmission bands (the fourth, fifth, and sixth transmission bands 510, 515, and 520). Since a single circuit can be used to generate all of the center frequencies, the generation of the center frequencies can be simplified and may be more efficient, when compared to techniques that may require multiple center frequency generating circuits. Note that should additional transmission bands (above the sixth transmission band 520) be desired, the same technique can be used to generate their center frequencies.
• a preamble sequence can be used for packet detection, frame synchronization, frequency offset estimation, channel estimation, and so forth. Therefore, when additional transmission bands are added to a multi- band-OFDM wireless communications system, the preamble sequence should be modified in such a way that the previous uses of the preamble sequence (such as packet detection, frame synchronization, frequency offset estimation, and channel estimation) can be used in the additional transmission bands.
• the modified preamble sequence should be able to be used in both existing and enhanced multi-band-OFDM wireless communications systems without modification.
• FIG. 6 there is shown a space-time diagram illustrating a transmission sequence 600 in an enhanced multi-band-OFDM wireless communications system with additional transmissions bands containing an enhanced preamble to support the additional transmission bands, according to a preferred embodiment of the present invention.
• a first approach to extending a preamble sequence for an enhanced multi-band-OFDM wireless communications system can be to maintain an existing preamble sequence 630 and then after the existing preamble sequence 630, adding a channel estimation extension 645, which can be used to estimate the channel response on the additional transmission bands.
• the transmission sequence 600 displays the transmissions for a multi-band-OFDM wireless communications system with six transmission bands (such as transmission band #1 605, band #2 610, band #4 615, and band #5 620).
• the transmission sequence 600 displays the existing preamble 630, which can comprise a current preamble 635 and a PLCP header 640.
• the existing preamble 630 can be compatible in multi-band-OFDM wireless communications systems without the additional transmissions bands (i.e., a legacy multi-band- OFDM wireless communications system), therefore, transmissions in the existing preamble 630 are contained in the existing transmission bands (transmissions bands #1 605, #2 610, and #3).
• the channel estimation extension 645 can contain transmissions on the additional transmission bands '(transmission bands #4 615, #5 620, and #6) and these transmissions can be used to compute estimations of the additional transmission bands.
• a payload 650 contains data and control transmissions using the various transmission bands.
• An advantage of adding the channel estimation extension 645 at the end of the existing preamble 630 may be that existing devices (commonly referred to as legacy devices), i.e., devices that only communication using transmission bands #1, #2, and #3, can always decode the existing preamble 630 (the current preamble 635 and the PLCP header 640) and can be able to configure their network allocation vector (NAV) appropriately.
• An additional advantage of adding the channel estimation extension 645 at the end of the existing preamble 630 can be that a device can use the PLCP header 640 to signal the presence of the channel estimation extension 645 and whether or not the payload 650 will be using the additional transmission channels.
• FIG. 7 there is shown a space-time diagram illustrating a transmission sequence 700 for use in an enhanced multi-band-OFDM wireless communications system with additional transmissions bands containing an enhanced preamble to support the additional transmission bands, according to a preferred embodiment of the present invention.
• a second approach to extending a preamble sequence for an enhanced multi-band-OFDM wireless communications system can be to insert a channel estimation extension 705 in between the current preamble 635 and the PLCP header 640. As previously, the channel estimation extension 705 can be used to estimate the channel response on the additional transmission bands.
• the transmission sequence 700 displays the transmissions for a multi-band-OFDM wireless communications system with six transmission bands (numbered #1 through #6).
• the transmission sequence 700 displays the current preamble 635 and the PLCP header 640 with the channel estimation extension 705 positioned in between the two.
• An advantage of inserting the channel estimation extension 705 in between the current preamble 635 and the PLCP header 640 can be that it fits more naturally with the frequency division multiple access (FDMA) technique, i.e., the preamble (comprising the current preamble 635, the channel estimation extension 705, and the PLCP header 640) can be readily scaled to a single channel.
• FDMA frequency division multiple access
• FIG 8 there is shown a diagram illustrating time-frequency interleaving sequences (TFIS) of length six for a communications system with six transmission bands, according to a preferred embodiment of the present invention.
• TFIS time-frequency interleaving sequences
• a first transmission sequence 805 can be specified as [1 2 3 4 5 6]
• a second transmission sequence 810 can be specified as [1 4 6 2 3 5]
• a third transmission sequence 815 can be specified as [1 3 2 6 5 4]
• a fourth transmission sequence 820 can be specified as [1 42 5 6 3].
• the four transmission sequences shown in Figure 8 can permit the sharing of six transmission bands by four transmitters with near optimal performance. Note that transmission sequences of different length can be specified, some of which may be optimal.
• FIGS. 9a and 9b there are shown diagrams illustrating time- frequency interleaving sequences of length six for a communications system using three transmission bands, according to a preferred embodiment of the present invention.
• a single transmitter may be allowed to transmit on all of the available transmission bands (such as shown in the TFIS shown in Figure 8).
• each transmitter is limited to three transmission bands, then four transmitters can share each group of three transmission bands (using the TFIS shown in Figure 3b, for example) for a total of eight transmitters in the wireless communications system.
• Figure 9a displays two transmission sequences of length six using three transmission bands, a first transmission sequence 905 can be specified as [4 5 6 4 5 6] and a second transmission sequence 910 can be specified as [4 6 5 4 6 5].
• Figure 9b displays two transmission sequences of length six using three transmission bands, wherein the transmission bands are different from those shown in Figure 9a.
• the transmission sequences shown in Figure 9b may be a first transmission sequence 955 that can be specified as [1 2 3 1 2 3] and a second transmission sequence 960 that can be specified as [1 3 2 1 3 2].
• each transmission band may have a fixed bandwidth. Furthermore, in a multi-band-OFDM wireless communications system, the available bandwidth can be allocated to provide a desired transmission range, at the expense of data rate. Therefore, for a given application, the bandwidth afforded by a transmitter's allocated transmission band may not be able to provide a desired data rate or transmission range. In a lightly used wireless communications system, it may be possible to increase the data rate and/or transmission range at a cost of reducing the number of available transmission bands (and hence reducing the total number of transmitters that can be supported).
• the frequency allocation chart 1000 may illustrate one possible transmission band allocation for a multi-band-OFDM wireless communications system.
• the 12 transmission bands can be partitioned into groups of three, for example, group #1 1005 can be made up of transmission bands #1, #2, and #3, while group #2 1010 can be made up of transmission bands #4, #5, and #6, and so forth.
• each transmission band can have a bandwidth of 528 MHz, which when using OFDM with no coding and no spreading, a maximum bit rate of 640 Mbps may be possible.
• FDM frequency-division multiplexing
• An advantage in the use of TFI-OFDM over the FDM- OFDM may be an increase in range and robustness to multipath.
• the maximum bit rate remains at 640 Mbps.
• the frequency allocation chart 1000 displayed in Figure 10 is but one way to allocate the available spectrum. Other spectrum allocations may be possible, with a larger (or smaller) number of transmission bands, with a larger (or smaller) number of transmission bands per group, with (or without) frequency bands set aside for known interferers, and so forth.
• FIG. 11 there is shown a diagram illustrating a frequency allocation chart 1100 for a multi-band-OFDM wireless communications system, wherein sets of two transmission bands have been bonded into one transmission band, according to a preferred embodiment of the present invention.
• the frequency allocation chart 1100 may illustrate one possible transmission band allocation for a multi-band-OFDM wireless communications system, wherein single transmission bands, such as transmission band #1 1107 may be made from bonding two smaller transmission bands.
• the frequency allocation chart 1100 may represent a multi-band-OFDM wireless communications system made from a multi-band-OFDM wireless communications system whose frequency allocation may have been shown in Figure 10.
• each transmission band may have a bandwidth of 1056 MHz and when using OFDM with no coding and no spreading, a maximum bit rate of 1280 Mbps may be possible.
• the transmission bands may be partitioned into groups of three, such as group #1 1105 that can be made up of transmission bands #1, #2, and #3. Note that since each transmission band is made up of two smaller transmission bands, the total number of transmission bands available in the multi-band-OFDM wireless communications system is smaller than the total number of transmission bands available in the multi-band-OFDM wireless communications system shown in Figure 10. Furthermore, Figure 11 displays one possible spectrum allocation and there may be other possible spectrum allocations.
• a TFI-OFDM wireless communications system with the frequency allocation chart 1100 makes use of the four time-frequency interleaved sequences of length six displayed in Figure 3b, then it may be able to support up to eight piconets, wherein each piconet can transmit at up to twice the bit rate of piconets using unbonded transmission bands. Alternatively, the piconets can take advantage of the greater bandwidth to achieve greater operating range.
• FIG. 12 there is shown a diagram illustrating a frequency allocation chart 1200 for a multi-band-OFDM wireless communications system, wherein sets of three transmission bands have been bonded into one transmission band, according to a preferred embodiment of the present invention.
• the frequency allocation chart 1200 may illustrate one possible transmission band allocation for a multi-band-OFDM wireless communications system, wherein single transmission bands, such as transmission band #1 1207 may be made from bonding three smaller transmission bands.
• the frequency allocation chart 1200 may represent a multi-band-OFDM wireless communications system made from a multi-band-OFDM wireless communications system whose frequency allocation may have been shown in Figure 10.
• each transmission band may have a bandwidth of 1584 MHz and when using OFDM with no coding and no spreading, a maximum bit rate of 1920 Mbps may be possible.
• the transmission bands may be partitioned into groups of three, such as group #1 1105 that can be made up of transmission bands #1, #2, and #3. Note that since each transmission band is made up of three smaller transmission bands, the total number of transmission bands available in the multi-band-OFDM wireless communications system is smaller than the total number of transmission bands available in the multi-band-OFDM wireless communications system shown in Figure 10. Furthermore, Figure 11 displays one possible spectrum allocation and that there may be other possible spectrum allocations.
• group #1 1205 may include transmission bands #1 and #2 and group #2 1210 may include transmission bands #3 and #4.
• TFIS sequences of length four may be used.
• group #1 1205 may use TFIS sequences [1 1 2 2] and [1 2 1 2] and group #2 1210 may use TFIS sequences of [3 3 44] and [3 4 3 4].
• the transmission bands may make use of FDM-OFDM while others use TFI-OFDM.
• the operating mode can be provided to the receivers during the configuration of the transmission bands, such as prior to commencement of transmissions or during startup.
• FIG. 13 there is shown a diagram illustrating a frequency allocation chart 1300 for a multi-band-OFDM wireless communications system, wherein some transmission bands have been bonded and some have not been bonded, according to a preferred embodiment of the present invention.
• Figures 10, 11, and 12 displayed frequency allocation charts 1000, 1100, and 1200 for wireless communications systems wherein the transmission bands are homogeneous in nature, i.e., each transmission band is equal in size to every other transmission band in the wireless communications system.
• the transmission bands may vary in size.
• the frequency allocation chart 1300 displays a spectrum allocation for a multi-band- OFDM wireless communications wherein the transmission bands can vary in bandwidth.
• transmission bands in group #1 1305, such as transmission band #1 1307 can be constructed by bonding two transmission bands together, while transmission bands in group #2 1310, such as transmission band #4 1312 may have the bandwidth of a single transmission band.
• the spectrum allocation shown in Figure 13 may be one of many different possible configurations, and that the frequency allocation chart 1300 should not be construed as limiting the spirit of the present invention.
• the spectrum allocation may be static or dynamic in nature.
• the transmission bands may be allocated during an initial power-on sequence and may be set to provide a specific data rate or range performance requirement.
• the performance requirement may also specify a certain performance level under the presence of a specified amount of interference.
• the data rate and/or range performance requirement may be programmed into a controller that may be responsible for coordinating communications in a multi-band-OFDM wireless communications system during the configuration of the controller.
• the performance requirement may also be in hardware, software, or in a firmware upgrade.
• the performance requirement may be specified by a regulatory body (such as the Federal Communications Commission in the United States), an application using the multi-band-OFDM wireless communications system, a compliance and interoperability body (such as WiMedia, a compliance body to ensure interoperability for personal-area wireless devices or similarly, the Multi-band OFDM Alliance), or a manufacturer of the multi-band-OFDM communications systems.
• a regulatory body such as the Federal Communications Commission in the United States
• an application using the multi-band-OFDM wireless communications system such as WiMedia, a compliance body to ensure interoperability for personal-area wireless devices or similarly, the Multi-band OFDM Alliance
• WiMedia a compliance and interoperability body to ensure interoperability for personal-area wireless devices or similarly, the Multi-band OFDM Alliance
• the controller may be placed into a special configuration mode wherein the data rate and/or range performance requirements may be specified. Once the data rate and/or range performance requirements may be specified, the multi- band-OFDM wireless communications system may be reset in order to reconfigure the transmission bands.
• the spectrum allocation may be dynamic in nature, wherein the transmission bands can change based upon the needs of communicating devices in the multi- band-OFDM wireless communications network.
• the algorithm 1400 may execute on a processing element, a controller, a general purpose central processing unit, a custom design application specific integrated circuit, or so forth, of a controller that may be responsible for coordinating communications in the multi-band-OFDM wireless communications system.
• the controller can often be referred to as a piconet coordinator or an access point.
• the controller can execute the algorithm 1400 during a power-up sequence, after a reboot, or after the execution of a specific operation to initialize the reconfiguration of the transmission bands.
• the controller can begin by retrieving performance requirements for the multi-band- OFDM wireless communications system from memory (block 1405).
• the performance requirements may specify a desired data rate and/or range performance requirements.
• the controller can determine the size (bandwidth) of the transmission bands (block 1410). If the performance requirements are low, then the size of the transmission bands can be low, while if the performance requirements are high, then the size of the transmission bands can be high.
• the controller can configure the transmission bands (block 1415). After configuration (block 1415), the controller can initialize the communications (block 1420). Initialization may entail the controller providing the configuration of the transmission bands to the transmitters and receivers in the multi-band-OFDM wireless communications system. After initialization, the controller can complete the execution of the algorithm 1400.
• the algorithm 1500 may execute on a processing element, a controller, a general purpose central processing unit, a custom design application specific integrated circuit, or so forth, of a controller that may be responsible for coordinating communications in the multi-band-OFDM wireless communications system.
• the controller can execute the algorithm 1400 when there is a need for additional data rate or range than what is currently available.
• a dynamic spectrum allocation algorithm can offer the ability to change the transmission bands based upon the demands of the communicating devices (transmitters and receivers) in the multi-band-OFDM wireless communications network. This ability can help improve the ability of the multi-band-OFDM wireless communications network to meet the performance requirements of the communications devices.
• the communicating device may transmit the request to the controller.
• the controller can begin the execution of the algorithm 1500 when it receives a request(s) from communicating devices for more data rate and/or range performance (block 1505). If no requests are received or if the request can be met without channel bonding (blocks 1505 and 1510), then the algorithm 1500 can terminate. The controller can then determine the needed bandwidth to support the requested data rate and/or range performance (block 1515). Based on the needed and available bandwidth, the controller can bond together transmission bands and allocate them to the communicating device making the request (block 1520). Note that not shown may be additional operations that may be taken by the controller to free sufficient bandwidth in order to bond adjacent transmission bands. For example, the controller may need to move allocated transmission bands in order to have a sufficient number of adjacent transmission bands to bond together. This can be referred to as compacting the transmission spectrum. Compacting algorithms are considered to be well understood by those of ordinary skill in the art of the present invention and will not be discussed herein.
• the controller can monitor the communications to determine if the desired data rate and/or range performance is met (block 1525). If the desired data rate and/or range performance is met, then the algorithm 1500 can terminate. If the desired data rate and/or range performance is not met, then the controller can check if there is additional bandwidth available (block 1530). Once again, the controller may be required to perform a compaction of the transmission spectrum to find additional bandwidth. If there is no additional bandwidth, then the desired data rate and/or range performance cannot be met (block 1535) and the algorithm can terminate. If there is additional bandwidth, then the controller can bond additional transmission bands together (block 1540) and then return to block 1525 where it can monitor if the desired data rate and/or range performance requirements are being met.
• a performance requirement request from communicating requirement may typically be a request for additional fransmission bandwidth to support a higher data rate or a greater transmission range.
• communicating equipment may also release allocated bandwidth via a performance request. For example, after the communicating equipment has completed transmitting a large file, the communicating equipment can release the transmission bandwidth by requesting a smaller (or no) transmission bandwidth and then releasing the large transmission bandwidth previously allocated.
• the communicating devices may be used to perform the performance monitoring. Since the communicating devices are using the transmission bands, they may be able to monitor the data rates and range performance more readily than the controller. The communicating devices can then provide to the controller a request for additional bandwidth if the data rate and/or range performance are not being met.
• a piconet coordinator 1605 for an enhanced multi-band-OFDM wireless communications system may be able to operate with both enhanced communications devices 1610 and legacy communications devices 1615. If the piconet coordinator 1605 and the enhanced communications devices 1610 uses an enhanced preamble, such as those shown in Figures 6 and 7, and the legacy communications devices 1615 uses a legacy preamble, then the enhanced communications devices 1610 can make use of the additional fransmissions bands in addition to sharing the legacy transmissions bands with the legacy communications devices 1615.
• the enhanced communications devices 1610 may exclusively use the enhanced transmissions bands to help alleviate congestion of the legacy transmissions bands. Note that the fransmissions between the enhanced communications devices 1610 and the piconet coordinator 1605 may take place over bonded transmission bands.

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