摘要:
A technique for filter-enhanced clock synchronization is disclosed. In one particular exemplary embodiment, the technique may be realized by/as a method for filter-enhanced clock synchronization. The method comprises subjecting a clock error signal to a first exponentially weighted moving average (EWMA) filter to generate a first output signal, where the first EWMA filter comprises a first gain element. And the method further comprises subjecting the first output signal to a second EWMA filter to generate a second output signal, where the second EWMA filter comprises a second gain element and the second EWMA filter is coupled with a feedback loop having a delay element and a summing junction.
摘要:
Techniques for time transfer via signal encoding are disclosed. In one particular exemplary embodiment, the techniques may be realized as a method for time transfer via signal encoding comprising generating a time service ordered-set for inclusion in a physical coding sublayer frame of a physical layer device, generating time service data for inclusion in the physical coding sublayer frame of the physical layer device, and transmitting the physical coding sublayer frame.
摘要:
A clock synchronization backup mechanism is disclosed for maintaining clock synchronization during periods of degraded synchronization. The clock synchronization backup mechanism includes a jitter buffer having a fill value at a given sample time which is compared with a threshold. When the jitter buffer fill value exceeds the threshold, a non-normal condition is registered and the local clock frequency is set to a combination of a long-term frequency setting plus a threshold sensitive frequency adjustment. The clock synchronization backup mechanism is particularly useful for overcoming residual errors accumulated due to temperature change, oscillator degradation, and a variety of other system perturbations problematical for clock synchronization mechanisms known in the art.
摘要:
Disclosed is a queue based multi-level Active Queue Management with drop precedence differentiation method and apparatus which uses queue size information for congestion control. The method provides for a lower complexity in parameter configuration and greater ease of configuration over a wide range of network conditions. A key advantage is a greater ability to maintain stabilized network queues, thereby minimizing the occurrences of queue overflows and underflows, and providing high system utilization.
摘要:
Techniques for time transfer via signal encoding are disclosed. In one particular exemplary embodiment, the techniques may be realized as a method for time transfer via signal encoding comprising generating a time service ordered-set for inclusion in a physical coding sublayer frame of a physical layer device, generating time service data for inclusion in the physical coding sublayer frame of the physical layer device, and transmitting the physical coding sublayer frame.
摘要:
This invention relates to methods and devices for channel identification. The invention is particularly concerned with techniques for non-line of sight channel identification. In embodiments of the invention the methods and devices are used for channel identification in wireless geolocation systems. Embodiments of the invention make use of an entropy estimation of the channel to distinguish channel conditions and in particular to identify line-of-sight and non-line-of-sight channels and which can be used to solve the NLOS problem of determining relative distances between transmitter and receiver. In particular embodiments an entropy estimation of the channel impulse response (CIR) is used to construct a robust entropy-based channel identification technique. As a result, more accurate localization in indoor and other multipath environments may be possible.
摘要:
A method and apparatus for locating in a list of pre-defined codes, a longest code matching a given code. The method and apparatus involve producing a search mask encoding at least one portion of said given code and comparing the search mask to a search key having a Prefix Node Bit Array (PNBA) in which a bit is set active in at least one of a plurality of bit positions corresponding to possible bit combinations of bits in a bit string having a length equal to or less than the longest predefined code in the plurality of pre-defined codes and arranged by the lengths of possible bit combinations and by numeric values of the bit combinations, to identify a common active bit position in the search key and the search mask corresponding to one of the pre-defined codes having a length greater than all others of said pre-defined codes which correspond to common active bit positions.
摘要:
This invention relates to methods and devices for clock synchronization. The invention makes particular use of IEEE 1588 with offset and skew correction. In embodiments of the invention, the IEEE 1588 Precision Time Protocol is used to exchange time stamps between a time server and a client from which the client can estimate the clock offset and skew. In embodiments of the invention a free running clock at the client is provided with an estimation technique based on the time stamps from the IEEE 1588 PTP message exchange between the server and client clocks. The offset and skew from the estimation process can be combined with the local free running clock to give a synchronized local clock which is an accurate image of the master clock.
摘要:
This invention relates to methods and devices for clock synchronization. The invention makes particular use of IEEE 1588 with offset and skew correction. In embodiments of the invention, the IEEE 1588 Precision Time Protocol is used to exchange time stamps between a time server and a client from which the client can estimate the clock offset and skew. In embodiments of the invention a free running clock at the client is provided with an estimation technique based on the time stamps from the IEEE 1588 PTP message exchange between the server and client clocks. The offset and skew from the estimation process can be combined with the local free running clock to give a synchronized local clock which is an accurate image of the master clock.
摘要:
This invention relates to methods and devices for entropy-based location fingerprinting, in particular for use over wireless local-area networks (WLANs). The invention has particular application in localization for indoor environments. In embodiments of the invention, an entropy-based fingerprint is determined at a number of predetermined locations within the desired area of localization during an off-line phase and subsequently used in an on-line mode to determine the location of a receiver. In particular embodiments, the fingerprint is a vector of entropy estimates of the channel transfer function (CTF) between a mobile terminal and all access points within coverage. The invention seeks to provide a fingerprinting localization solution that has a simplicity of structure, leading to advantages in storage and pattern recognition requirements, and robustness by proving a unique measure of information that is related to the channel experienced at the location of the mobile terminal.