Pulse or digital communications – Receivers – Particular pulse demodulator or detector
Reexamination Certificate
1999-10-14
2004-08-31
Chin, Stephen (Department: 2634)
Pulse or digital communications
Receivers
Particular pulse demodulator or detector
C375S340000, C375S364000
Reexamination Certificate
active
06785350
ABSTRACT:
The present invention relates generally to a manner by which to detect a symbol sequence, such as a preamble portion of a data frame, generated during operation of the communication system. More particularly, the present invention relates to apparatus, and an associated method, by which phase calculations are performed to, at least in part, detect receipt at a receiving station of the symbol sequence. Greater detection reliability is provided through operation of an embodiment of the present invention as false, i.e., erroneous, symbol sequence detections are less likely to be made when phase calculations are used to detect the symbol sequence.
BACKGROUND OF THE INVENTION
Advancements in communication technologies have permitted the introduction, and popularization, of new types of communication systems. In various of such new types of communication systems, the rate of data transmission and the corresponding amount of data to be permitted to be communicated, has increased relative to existing types of communication systems.
New types of radio communication systems are exemplary of communication systems made possible as a result of advancements in communication technologies. Communication channels of a radio communication system are formed upon radio-links, thereby obviating the need for conventional wireline connections between sending and receiving stations operable therein. A radio communication system, therefore, inherently permits increased communication mobility in contrast to conventional wireline systems.
Bandwidth limitations sometimes limit the communication capacity of the communication system. That is to say, the bandwidth capacity of the communication channel, or channels, available to a communication system to communicate information between sending and receiving stations is sometimes limited. And, the limited capacity of the communication channel, or channels, limits increase of the communication capacity of the communication system. The communication capacity of a radio communication system is particularly susceptible to capacity limitations resulting from communication channel bandwidth limitations. Generally, a radio communication system is allocated a limited portion of the electromagnetic spectrum upon which to define communication channels. Communication capacity increase of a radio communication system is, therefore, sometimes limited by such allocation. Increase of the communication capacity of the radio communication system, therefore, is sometimes only possible if the efficiency by which the allocated spectrum is used is increased.
Digital communication techniques provide a manner by which the bandwidth efficiency of communications in the communication system may be increased. Because of the particular need in a radio communication system to efficiently utilize the spectrum allocated in such a system, the use of digital communication techniques is particularly advantageously implemented therein.
When digital communication techniques are used, information which is to be communicated is digitized. In one technique, the digitized information is formatted into packets, or frames, and the packets are communicated to effectuate the communication. Individual ones, or groups, of the packets of data can be communicated at discrete intervals, and, once communicated, concatenated together to recreate the informational content contained therein.
Because packets of data can be communicated at the discrete intervals, a communication channel need not be dedicated solely for the communication of packet data generated by one sending station to one receiving station as conventionally required in circuit-switched communications. Instead, a single channel can be shared amongst a plurality of different sending and receiving station-pairs. Because a single channel can be utilized to effectuate communications by the plurality of pairs of communication stations, improved communication capacity is possible.
Packet data communications are effectuated, for instance, in conventional LANs (local area networks). Wireless networks, operable in manners analogous to wired LANs, have also been developed and are utilized to communicate packets of data over a radio-link thereby to effectuate communications between a sending and receiving station.
For example, A High Performance Radio Local Area Network, type 2 (HIPERLAN/2) standard promulgated by the ETSI sets forth a standard for operation of a wireless LAN operable in the five GHz range. In this standard, a medium access control (MAC) frame structure is defined. The MAC frame structure consists of several kinds of transport channels that are used to deliver both control information and user data. In the system defined by the HIPERLAN/2 standard, as well as other wireless LANs, mobile stations are utilized by users of the network to effectuate telephonic communications. The telephonic communications include, for example, voice as well as data communications.
Data which is to be communicated is formatted into frames of data in which a frame is formed of a preamble portion and a payload portion. Frame-formatted data is transmitted, for instance, on the down-link transport channel. A mobile station tuned to a frequency channel must be able to detect the preamble portion of the frame so that the informational content of the frame, i.e., the payload portion, can be properly utilized.
In at least one existing manner proposed by which to detect the preamble portion, correlation calculations are performed by the mobile station. A ratio is formed of the calculated correlation value relative to average power levels. And, the ratio, so-formed, is compared with a threshold value. If the value of the ratio is greater than the threshold, a determination is made that the preamble portion of the frame is received, and following portions of the frame form the payload.
However, performing such calculations on other portions of the frame might also indicate that such other portions of the frame form the preamble portion. Therefore, the reliability of this existing manner by which to detect the preamble portion is deficient.
A manner by which more reliably to detect reception of a preamble portion of a frame of data would therefore be advantageous.
It is in light of this background information related to the communication of data that the significant improvements of the present invention have evolved.
SUMMARY OF THE INVENTION
The present invention, accordingly, advantageously provides apparatus, and an associated method, by which to detect, at a receiving station, reception of a selected symbol sequence, such as a preamble portion of a frame of data. Phase calculations are performed to detect, at least in part, the selected symbol sequence.
Operation of an embodiment of the present invention provides a manner by which to detect the selected symbol sequence with greater reliability than generally possible through the use of conventional detection techniques. Particularly when phase calculations, performed pursuant to the operation of an embodiment of the present invention, are used together with correlation and power level calculations, false, i.e., erroneous symbol sequence detections are less likely to be made, thereby resulting in improved performance of the receiving station at which an embodiment of the present invention is operable.
Also, ratio calculation of calculated correlation values relative to calculated power level values is a computationally-intensive procedure. Through operation of an embodiment of the present invention, such ratio calculation is performed only if the phase calculation indicates detection of the selected symbol sequence.
In one aspect of the present invention, a receiving station is tunable to receive frame-formatted data transmitted thereto upon a communication channel. Each frame of the frame-formatted data is formed of a preamble portion and a payload portion. The selected symbol sequence detected during operation of an embodiment of the present invention is the preamble portion of a frame of data. Phase calculations are
Kasslin Mika
Poulbere Vincent
Chin Stephen
Nokia Corporation
Yeh Edith
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