the present invention is a novel and useful apparatus for and method of reducing the backoff required for ofdm based transmitters . in wireless communication links using ofdm schemes , a large backoff is required to maintain acceptable spectral mask and a good evm . the reduced backoff mechanism is operative to reduce the backoff required while meeting spectral mask and evm requirements imposed by wireless standards , for example . reducing the required backoff thus permits both higher wireless range and reduced power consumption thus significantly improving battery life . although the mechanism of the present invention can be used in numerous types of communication systems , to aid in illustrating the principles of the present invention , the description of the reduced backoff mechanism is provided in the context of an ofdm based communication device . the reduced backoff mechanism of the present invention can be incorporated in a communication device such a multimedia player , cellular phone , pda , etc . although the invention is described in the context of a cellular phone , it is appreciated that the invention is not limited to the example applications presented , but that one skilled in the art can apply the principles of the invention to other communication systems as well ( both wireless and wired ) without departing from the scope of the invention . note that throughout this document , the term communications device is defined as any apparatus or mechanism adapted to transmit , receive or transmit and receive data through a medium . the term communications transceiver or communications device is defined as any apparatus or mechanism adapted to transmit and receive data through a medium . the communications device or communications transceiver may be adapted to communicate over any suitable medium , including wireless or wired media . examples of wireless media include rf , infrared , optical , microwave , uwb , bluetooth , wimax , wimedia , wifi , or any other broadband medium , etc . examples of wired media include twisted pair , coaxial , optical fiber , any wired interface ( e . g ., usb , firewire , ethernet , etc .). the term ethernet network is defined as a network compatible with any of the ieee 802 . 3 ethernet standards , including but not limited to 10base - t , 100base - t or 1000base - t over shielded or unshielded twisted pair wiring . the terms communications channel , link and cable are used interchangeably . the term multimedia player or device is defined as any apparatus having a display screen and user input means that is capable of playing audio ( e . g ., mp3 , wma , etc . ), video ( avi , mpg , wmv , etc .) and / or pictures ( jpg , bmp , etc .). the user input means is typically formed of one or more manually operated switches , buttons , wheels or other user input means . examples of multimedia devices include pocket sized personal digital assistants ( pdas ), personal media player / recorders , cellular telephones , handheld devices , and the like . some portions of the detailed descriptions which follow are presented in terms of procedures , logic blocks , processing , steps , and other symbolic representations of operations on data bits within a computer memory . these descriptions and representations are the means used by those skilled in the data processing arts to most effectively convey the substance of their work to others skilled in the art . a procedure , logic block , process , etc ., is generally conceived to be a self - consistent sequence of steps or instructions leading to a desired result . the steps require physical manipulations of physical quantities . usually , though not necessarily , these quantities take the form of electrical or magnetic signals capable of being stored , transferred , combined , compared and otherwise manipulated in a computer system . it has proven convenient at times , principally for reasons of common usage , to refer to these signals as bits , bytes , words , values , elements , symbols , characters , terms , numbers , or the like . it should be born in mind that all of the above and similar terms are to be associated with the appropriate physical quantities they represent and are merely convenient labels applied to these quantities . unless specifically stated otherwise as apparent from the following discussions , it is appreciated that throughout the present invention , discussions utilizing terms such as ‘ processing ,’ ‘ computing ,’ ‘ calculating ,’ ‘ determining ,’ ‘ displaying ’ or the like , refer to the action and processes of a computer system , or similar electronic computing device , that manipulates and transforms data represented as physical ( electronic ) quantities within the computer system &# 39 ; s registers and memories into other data similarly represented as physical quantities within the computer system memories or registers or other such information storage , transmission or display devices . the invention can take the form of an entirely hardware embodiment , an entirely software embodiment or an embodiment containing a combination of hardware and software elements . in one embodiment , a portion of the mechanism of the invention is implemented in software , which includes but is not limited to firmware , resident software , object code , assembly code , microcode , etc . furthermore , the invention can take the form of a computer program product accessible from a computer - usable or computer - readable medium providing program code for use by or in connection with a computer or any instruction execution system . for the purposes of this description , a computer - usable or computer readable medium is any apparatus that can contain , store , communicate , propagate , or transport the program for use by or in connection with the instruction execution system , apparatus , or device , e . g ., floppy disks , removable hard drives , computer files comprising source code or object code , flash semiconductor memory ( usb flash drives , etc . ), rom , eprom , or other semiconductor memory devices . a block diagram illustrating an example communication device in more detail is shown in fig3 . the communication device may comprise any suitable wired or wireless device such as multimedia player , mobile device , cellular phone , pda , bluetooth device , etc . for illustration purposes only , the communication device is shown as a cellular phone . note that this example is not intended to limit the scope of the invention as the reduced backoff mechanism of the present invention can be implemented in a wide variety of communication devices . the cellular phone , generally referenced 70 , comprises a baseband processor or cpu 71 having analog and digital portions . the basic cellular link is provided by the rf transceiver 94 and related one or more antennas 96 , 98 . a plurality of antennas is used to provide antenna diversity which yields improved radio performance . the cell phone also comprises internal ram and rom memory 110 , flash memory 112 and external memory 114 . several user interface devices include microphone 84 , speaker 82 and associated audio codec 80 , a keypad for entering dialing digits 86 , vibrator 88 for alerting a user , camera and related circuitry 100 , a tv tuner 102 and associated antenna 104 , display 106 and associated display controller 108 and gps receiver and associated antenna 92 . a usb interface connection 78 provides a serial link to a user &# 39 ; s pc or other device . an fm receiver 72 and antenna 74 provide the user the ability to listen to fm broadcasts . wlan radio and interface 76 and antenna 77 provide wireless connectivity when in a hot spot or within the range of an ad hoc , infrastructure or mesh based wireless lan network . bluetooth radio and interface 73 and antenna 75 provide bluetooth wireless connectivity when within the range of a bluetooth wireless network . ultra wideband ( uwb ) radio and interface 83 and antenna 81 provide uwb wireless connectivity when within the range of a uwb wireless network . similarly , wimax radio and interface 123 and antenna 125 provide wimax wireless connectivity when within the range of a wimax wireless network . sim card 116 provides the interface to a user &# 39 ; s sim card for storing user data such as address book entries , etc . the cellular phone also comprises a reduced backoff block 128 adapted to implement the reduced backoff mechanism of the present invention as described in more detail infra . in operation , the reduced backoff block 128 may be implemented as hardware , software executed as a task on the baseband processor 71 or a combination of hardware and software . implemented as a software task , the program code operative to implement the link establishment mechanism of the present invention is stored in one or more memories 110 , 112 or 114 . portable power is provided by the battery 124 coupled to battery management circuitry 122 . external power is provided via usb power 118 or an ac / dc adapter 120 connected to the battery management circuitry which is operative to manage the charging and discharging of the battery 124 . a block diagram illustrating an example transmitter incorporating the reduced backoff mechanism of the present invention is shown in fig4 . the transmitter , generally referenced 130 , comprises a controller 132 , data buffer 134 , encryption block 136 , scrambler 138 , tx phy 140 , gain multiplier 150 , rf switch 151 , rf tx ( including power amplifier ) 152 , antenna 154 , peak to average calculator 156 , find min block 158 , am to am table 160 , buffer / register 162 , rx phy 164 , evm calculator 168 and spectral mask calculator 170 . the tx phy 140 comprises fec 142 , interleaver 144 , mapper 146 and inverse fast frequency transform ( ifft ) 148 . the rx phy 164 comprises fft block 166 . in accordance with the present invention , for each packet to be transmitted , a search is performed on all possible scrambler sequences or encryption - sequences ( i . e . initial value sequences ) to find the sequence that would produce the lowest papr and thus would result in the lowest backoff value for the transmission of that particular packet . note that there is no need to change both the encryption sequence and the scrambler sequence but rather only one of them . therefore , if a particular implementation does deploy encryption for a specific link than the method is operate to select the optimum scrambler sequence . in the event encryption is used , the mechanism is operative to select the optimum encryption sequence while the scrambler sequence is held fixed to a particular value . in an alternative embodiment , both the encryption and scrambler sequences may be selected in sequential fashion using the mechanism of the present invention . throughout this document , references to the scrambler sequence are intended to refer to either or both the scrambler sequence or the encryption sequence . as an aid to understanding the present invention , the description is provided in context of a search for a scrambler sequence . it is appreciated , however , that a search for the encryption sequence is contemplated as well . in mechanism of the invention is operative to search different scrambler sequences ( and / or different encryption sequences ) for the best combination that allows the particular transmitted packet to pass any spectral mask and evm requirements associated with a reduced backoff power amplifier . the search is performed by examining all ( or a portion thereof ) of the possible scrambler / encryption sequence hypotheses . note that in most ofdm standards , the receiver is informed of the scrambler seed as well as the encryption seed used in the transmitter by way of dedicated fields in the packet header . in order to optimize the performance of the transmitter , once the mechanism of the invention finds the optimum scrambler sequence , a search is performed for the maximum signal gain that still allows the transmission packet to meet the spectral mask and evm requirements . after finding the scrambler sequence ( and / or encryption sequence ) and the maximum gain value , the transmitter phy and the rf transmit circuit are activated and the packet is transmitted using the selected scrambler / encryption sequence . the invention provides two efficient ways to implement the mechanism described supra . the first method involves a two stage scanning scheme whereby the best scrambler sequence is found first , followed by the optimum gain setting . the second method performs a two dimensional search to find the best scrambler sequence and gain setting simultaneously . both these methods are described in more detail infra . a flow diagram illustrating a first reduced backoff method of the present invention is shown in fig5 a , 5 b and 5 c . the method of the invention is intended to be executed as software / firmware running on the controller 132 comprising any suitable processor or other hardware platform computing device . alternatively , it can be implemented in hardware using the equivalent circuitry or a combination of hardware and software / firmware . regardless of the implementation , the mechanism uses the tx phy circuit to calculate what the transmitter output would be during a normal transmit operation . in accordance with the invention , during the search for the minimum backoff , the tx phy circuit is configured such that the output thereof is not actually sent to the rf tx circuit and transmitted over the antenna . rf switch 151 is controlled by the controller 132 and is configured such that the transmitter output is not broadcast but rather input to the peak - to - average calculator 156 and am to am table 160 instead . after the scrambler sequence and encryption sequence ( depending on the implementation ) are determined , the transmitter output is output to the rf tx and the antenna 154 . in general , the method is implemented in two stages . first , all possible scrambler sequence candidate hypotheses are scanned until the lowest peak - to - average response is found . then , after finding the best scrambler sequence , the maximum gain of the signal that still meets the spectral mask and evm requirements is found . the following operations are repeated in order to find the best scrambler sequence that yields the lowest peak - to - average result : ( 1 ) calculate the signal to be transmitted using the ofdm tx circuit chain ( usually implemented in hardware ) and ( 2 ) calculate the peak - to - average of the generated packet . after the optimum scrambler sequence is found , the following steps are performed to find the maximum gain that still ensures meeting the evm and spectral mask : ( 1 ) multiply the tx phy output signal by the current gain candidate ; ( 2 ) pass the gain adjusted signal through generalized am to am model of the pa ; ( 3 ) store the output samples and than read them into the existing ifft receiver to demodulate the received symbols ; ( 4 ) measure the evm of the rx phy output and make sure that the desired specification is not violated ; and ( 5 ) perform an fft on the rx phy output and measure the spectral mask to verify that it is not violated . the above four stages are repeated until the spectral mask and evm is below an acceptable value ( which is typically defined by the system specification ). note that the method is performed for each packet to be transmitted supplied by the data buffer 143 ). with reference to fig4 and 5 , first , any required variables are initialized ( step 180 ). the scrambler is sequence is set to the next scrambler sequence candidate 134 as supplied by the controller ( step 182 ). the tx signal that would have normally been transmitted is then determined by passing the output of the scrambler 138 through the tx phy circuit 140 ( step 184 ). the transmitter output is input to the peak - to - average calculator 156 which is operative to calculate the peak - to - average value of the transmitter output ( step 186 ). the calculated peak - to - average value is then compared to the current value of the minimum peak - to - average variable ( step 188 ). if it is smaller , then a new minimum has been found and the minimum peak - to - average value is set to the peak - to - average value just calculated ( step 190 ). the next scrambler sequence is then determined ( step 192 ) and the method returns to step 182 if the scrambler sequence scan is not yet complete ( step 194 ). note that the invention contemplates searching ( i . e . scanning ) through all possible scrambler ( or encryption ) sequences or , alternatively , searching through a subset of the possible sequences as described in more detail infra . note that if the encryption block 136 is present , the search is performed for the encryption sequence 137 rather than the scrambler sequence 139 and the scrambler sequence is fixed once determined . once all the scrambler sequence candidates have been tested , the scan is complete ( step 194 ) and the scrambler 138 is configured with the scrambler sequence that yields minimum peak - to - average value ( step 196 ). after the best scrambler sequence has been found , the maximum gain that still ensures meeting the evm and spectral mask is then found . first , the gain value is initialized to a minimum value ( step 197 ). the next gain value 141 supplied by the controller is used to configure the multiplier 150 ( step 198 ). the output of the tx phy previously calculated is multiplied by the candidate gain value via multiplier 150 ( step 200 ). the signal output of the multiplier is then passed through the am to am table 160 which comprises a model of the power amplifier used in the rf tx circuit 152 ( step 202 ). the output of the am to am table is stored in memory such as buffer / register 162 ( step 204 ). the buffer contents are then passed through the rx phy circuit 164 which is operative to perform a fft 166 on the signal so as to demodulate the received symbol ( step 206 ). the evm is then calculated via evm calculator circuit 168 to ensure the evm of the signal is within specification ( step 208 ). the spectral mask is then measured and verified that it is within specification ( step 210 ). if the evm and the spectral mask are not within specification ( step 212 ), the scan is considered complete and the scrambler sequence and the gain selected are used for the actual transmission of the packet ( step 222 ). the switch 151 is now configured to output of the tx phy signal to the rf tx 152 and antenna 154 . if the evm and the spectral mask are within specification ( step 212 ), than the gain value is increased and this new increased gain value is used and the evm and spectral mask are checked again . specifically , it is checked whether the current gain candidate is greater than a running maximum gain variable ( step 214 ). if is it , the maximum gain variable is set equal tot the current gain setting ( step 216 ). the next gain candidate is determined ( step 218 ) and the method continues with step 198 to consider other gain candidates . a flow diagram illustrating a second reduced backoff method of the present invention is shown in fig6 . this method is based on a single stage approach that employs a two dimensional search to find the best scrambler sequence and the maximal gain setting . in general , the search is performed by repeating the following steps for each of the checked scrambler - seed value : ( 1 ) setting a certain examined scrambler sequence ; ( 2 ) transmitting the generated bit stream through the existing ofdm tx phy hardware ; ( 3 ) scanning to find the maximum gain value that still meets the spectral mask and evm , wherein the spectral mask and evm are calculated using the existing ifft mechanism in the rx phy circuit ; and ( 4 ) the best scrambler sequence is selected as the one that yields the maximum gain value that still enables the transmitter to meet the spectral mask and evm requirements . with reference to fig4 and 6 , first , any required variables are initialized ( step 230 ). the scrambler sequence is then configured with the next scrambler sequence candidate ( step 232 ). the bit stream generated by the scrambler is then input to the tx phy circuit ( step 234 ). the gain value is then scanned to find the local maximum gain value that meets the spectral mask and evm specifications ( step 236 ). if the local maximum gain determined is greater than the running maximum gain variable ( step 238 ), then the maximum gain variable is set to the local maximum gain value just found ( step 240 ). the next scrambler sequence is chosen ( step 242 ) and the method continues with step 232 if the scan is not complete ( step 244 ). thus , for each scrambler sequence candidate , the maximum gain setting that meets the spectral mask and evm requirements is found . this maximum gain setting is referred to as a ‘ local maximum gain ’. the maximum gain variable stores the running maximum of all local maximum gains found thus far . therefore , the scan is complete after all possible scrambler sequences have been tried ( step 244 ). the scrambler is then configured with the scrambler sequence that yields the maximum gain ( step 246 ). the scrambler sequence and the gain selected are used for actual transmission of the packet ( step 248 ). in accordance with the invention , it is possible to significantly reduce the size of the search space required to find an optimum scrambler sequence and gain value . as shown by the following simulation of an example 802 . 11g or 802 . 11a communication system , it is possible to achieve a significant reduction of the backoff using a greatly reduced search space . a diagram illustrating the cumulative distribution function of the mask margin is shown in fig7 . this graph illustrates the statistics of a short packet in terms of meeting the 802 . 11g spectral mask requirements . the probability of meeting a particular mask margin for values of backoff of 1 . 2 db , 3 db and 4 db are shown in curves 254 , 252 , 250 , respectively . for example , for a backoff of 4 db , a margin of 1 db is maintained approximately 99 . 9 % of the time . for a backoff of 1 . 2 db a margin of 0 db is maintained only 15 % of the time . this 15 % success rate for a very low backoff of 1 . 2 db translates to maintaining the margin every 6 . 6 packets , while the remainder of the time , the margin is not met . a diagram illustrating the cumulative distribution function of the number of hypotheses required to be scanned to meet the spectral mask requirements is shown in fig8 . this figure shows the actual statistics of the number of hypotheses ( i . e . packets with different scrambler sequences ) that would be required to be scanned in order to meet the spectral mask requirement . the probability of various time intervals for backoff values of 1 . 2 db , 3 db and 4 db is shown in curves 264 , 262 , 260 , respectively . as indicated in the figure , for example , about 20 scans ( i . e . iterations ), in which different scrambler or encryption sequence hypotheses are examined , are required in order to find a sequence ( s ) that pass the spectral mask with 90 % probability . this means that in the case of a 1 . 2 db backoff , approximately 20 hypotheses are required to be tested in order to meet the spectral mask requirement 90 % of the time . in one embodiment , the scrambler sequence candidate hypotheses to be tested , are chosen randomly from the entire set of possible candidates . other means of choosing the scrambler sequence candidate hypotheses are also contemplated by the present invention . it is noted that for typical wireless lan ( wlan ) applications , a total of sixteen gain values must be searched . considering that there are a maximum of 127 possible scrambler sequences , the total calculations required is 127 tx phy calculations x 16 fft and evm calculations . this introduces a significant computational load resulting in excessive delay ( i . e . increased latency ) and current consumption due to the long calculation times . using the simulation results described supra , however , the invention permits a reduction in the required calculations . in order to ensure a significant backoff reduction of 2 . 2 db , for example , on 90 % of the packets ( having a length of 2000 bits for the average voice packet ) only ten scrambler sequence hypotheses are required to be checked . therefore only ten fft , spectral mask and tx chain calculations are required to be performed . it is appreciated that this reduced number of calculations allows for a relatively simple implementation that results in low processing delay and current consumption . it is intended that the appended claims cover all such features and advantages of the invention that fall within the spirit and scope of the present invention . as numerous modifications and changes will readily occur to those skilled in the art , it is intended that the invention not be limited to the limited number of embodiments described herein . accordingly , it will be appreciated that all suitable variations , modifications and equivalents may be resorted to , falling within the spirit and scope of the present invention .