Telecommunications – Radiotelephone system – Programming control
Reexamination Certificate
1997-11-07
2001-02-06
Hunter, Daniel S. (Department: 2749)
Telecommunications
Radiotelephone system
Programming control
C455S425000, C455S434000, C455S553100, C370S200000
Reexamination Certificate
active
06185418
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to wireless communications systems and, more particularly, to a wireless communications system using adaptive reconfigurable communication techniques.
BACKGROUND OF THE INVENTION
Wireless communication systems are used for a variety of applications, such as identification, tracking, radar, data communications, voice communications, and video communications. In radio frequency (RF) digital radio systems, a terminal unit communicates with other terminal units using modulated radio signals. The terminal units include digital receivers which demodulate the incoming digitally modulated RF carrier to reproduce the data message being transmitted.
A software radio receiver system is a baseband receiver architecture and implementation in which all of the baseband receiver functions are performed digitally, typically utilizing a digital signal processor or a general purpose processor, in which the processor executes program instructions to perform the baseband processing functions. As such, software radio takes the received radio signal, typically after having been demodulated to an intermediate frequency (IF), and recovers the channel symbol bits. Current software radio technology is limited in terms of the channel symbol rates which can be digitally demodulated. A digital signal processor or general purpose processor is basically a serial computational device, thus limiting the processor's computational speed. Thus, wideband technology, such as code division multiple access (CDMA) systems with symbol rates near to or exceeding one megasymbol per second cannot currently be practically implemented in a traditional software radio approach. In summary, software radio techniques are limited due to the processing capabilities; they can either support narrowband technology, or must be coupled with other techniques in order to support wideband technology.
Current technology also supports multiple mode terminals. For example, cellular telephony supports dual or triple mode terminal units, where each mode communicates at a different frequency and utilizing a different protocol mode. As an example, a cellular telephone could support the analog advanced mobile phone system (AMPS) 30 kHz bandwidth air interface standard, and could also support a time division multiple access (TDMA) air interface standard based upon having multiple time slots within the same 30 kHz channel. However, in technology used to build dual-mode radio communication systems, the protocol mode is determined at call set-up time, and remains fixed for the duration of that call. Although some of the hardware can be reused between these modes, a dual-mode cellular telephone typically utilizes duplicative or redundant hardware, such as the RF and intermediate frequency (IF) filters, with the software digital receiver implementing the baseband or IF-to-baseband processing functions. As discussed above, software radios are limited to narrowband modulation processing (typically less than 100 ksamples/sec), with additional hardware needed to perform wideband modulation processing (typically greater than 100 ksamples/sec).
Beyond the current limitations of software radio technology, there are many impairments in the RF channel, such as shadowing due to the geographic terrain, Rayleigh fading due to the constructive and destructive addition of multipath signals, and interference from other radios, which disrupt the successful transfer of data between the terminal units and to reduce the throughput of the information being transferred. Additionally, these RF impairments are time varying. To overcome RF impairments, complex transmitter/receiver schemes and devices have been developed, such as convolutional coders and adaptive antenna arrays. These complex schemes are designed based upon the worst case RF impairments of the RF channel to achieve certain quality of service measures which can be measured by various parameters, such as bit error rate (BER), packet error rate and latency or delay in subsequently delivering information previously corrupted. These schemes reduce the information capacity of the communication system to counter the expected RF impairments. However, if an RF channel is in a relatively uncorrupted state and not suffering from any impairments, current schemes do not take advantage of the full information capacity of the available bandwidth because bandwidth is still being used to counter the RF impairments.
SUMMARY OF THE INVENTION
The present invention involves an adaptive digital radio communications architecture which can be reconfigured by reprogramming at least one programmable device, and thus more efficiently use the available bandwidth of a time-varying RF channel and/or to provide a flexible and adaptive digital communications system. In certain embodiments, the programmable device uses a Programmable Logic Device (PLD) to perform the digital communications processing functions of the transmitter or the receiver of a radio communications system. In this context, PLD is a general term representing a family of programmable logic devices; examples of this family are a Programmable Array Logic (PAL), a Complex PLD (CPLD), and a Field Programmable Gate Array (FPGA). The architecture is reconfigurable in the sense that any or all of the digital communications processing algorithms can be modified by reprogramming the PLD. The architecture of the digital communications system can be characterized by the following parameters; the channel symbol rate, the occupied bandwidth, the modulation technique, and the multiple access technique. A reconfiguration is a modification of the architecture of the digital communications system, and can occur by reprogramming the PLD through external control, for example in the event a radio communications base station wishes to change the radio architecture being used for a particular piece of radio spectrum. A reconfiguration can also occur, for example, by dynamically reprogramming the digital communications system depending upon time-varying radio channel conditions, such as the effect of the number of channel users, the offered load, quality of service measurements, or the characteristics of the desired application(s), including voice, data, video and/or tracking. Methods to measure the time varying radio channel conditions are disclosed, and further how those measurements can impact a reconfiguration. This invention discloses how the architecture for the digital communications system can be dynamically reprogrammed based upon current channel conditions and/or through external control.
REFERENCES:
patent: 4254504 (1981-03-01), Lewis et al.
patent: 4335426 (1982-06-01), Maxwell et al.
patent: 4525865 (1985-07-01), Mears
patent: 4843588 (1989-06-01), Flynn
patent: 4905305 (1990-02-01), Garner et al.
patent: 4926497 (1990-05-01), Shirley, Jr. et al.
patent: 4984295 (1991-01-01), Engstrom et al.
patent: 5019910 (1991-05-01), Filmer
patent: 5429820 (1995-07-01), Okada et al.
patent: 5485505 (1996-01-01), Norman et al.
patent: 5488356 (1996-01-01), Martinovich et al.
patent: 5655003 (1997-08-01), Erving et al.
patent: 5657487 (1997-08-01), Doner
patent: 5946634 (1999-08-01), Korpela
patent: 5960335 (1999-09-01), Umemoto et al.
patent: WO95/17077 (1995-06-01), None
patent: WO97/48188 (1997-12-01), None
“Model of Digital Communications System”, by John G. Proakis,Digital CommunicationsSecond Edition. pp. 64-67.
MacLellan John Austin
Shober R. Anthony
Wright Gregory Alan
Armstrong Darnell R.
Garceran Julio A.
Hunter Daniel S.
Lucent Technologies - Inc.
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