摘要:
To mitigate the adverse affects of the load imbalance phenomenon prevalent in spread spectrum, multi-carrier wireless communication systems, the system beneficially employs the use of handoff as a means for balancing the call traffic (commonly referred to as "load") among a plurality of carriers within the communication system. The multi-carrier wireless communication system monitors a plurality of metrics corresponding to the loading of each of the plurality of carriers in the communication system and, based upon the metrics, will handoff call traffic to and between the plurality of carriers, thereby mitigating the adverse effects associated with the load imbalance, in accordance with the invention.
摘要:
An RF cellular communication system employing offset frame synchronization between cells, any cell being omni-directional or directional, such that a frame at one cell is offset by an integral number of frames from another cell; the system incorporating multiplexed speech transcoding of traffic channels from multiple cells while supporting stringent delay requirements. Offset frame synchronization for providing rapid mobile assisted handoff.
摘要:
A smart card (100) is equipped with an internal time-of-day clock and calendar (106). Between the smart card (100) and a subscriber unit (209, 300), into which it is inserted, there is a communication of the subscriber's identity and a negotiated agreement for how long the subscriber unit (209, 300) is to maintain the transferred identity. For that duration of time, the subscriber unit (209, 300) is enabled with the subscriber's identity, and the smart card is essentially "dumb," and therefore unusable until that duration has elapsed.
摘要:
A communication unit for use in a communication system is provided which includes a hopping mechanism which hops communication frames over a plurality of carrier frequencies according to a predetermined hopping pattern. At least one of the communication frames preferably includes a synchronization channel time slot having data bits from which the predetermined hopping pattern may be derived. In addition, a communication unit is provided which includes a signal acquisition mechanism for initially acquiring a predetermined hopping pattern that specifies the sequence over which hop frames are hopped over a plurality of carrier frequencies. Also, this communication unit includes a hopping mechanism for hopping receiving frequency according to the predetermined hopping pattern such that a control channel may be detected. In an alternative embodiment, either communication unit may derive the predetermined hopping pattern from detected global position satellite information.
摘要:
A method and apparatus is provided for creating a composite waveform. This composite waveform is created by coding a plurality of input digital information signals. Subsequently, the plurality of coded input digital information signals are communicated over a communication medium to a digital combiner. The digital combiner combines the plurality of coded input digital information signals. Finally, the digitally combined information signal is spectrally shaped to form a composite waveform. These composite waveform creation principals may be applied to digitally encoded voice subbands in a subband coding system as well as channel information in a direct sequence code division multiple access (DS-CDMA) communication system transmitter.
摘要:
A method and apparatus are provided for digitizing a wide frequency bandwidth signal (105). The digitizing is accomplished by separating the wide frequency bandwidth signal (105) into a plurality of narrow frequency bandwidth signals with a plurality of filters (110). Subsequently, a converter (120) generates digitized samples of the narrow frequency bandwidth signals. Finally, a composite digitized signal (160) is generated by a combiner (150) from the digitized samples which substantially represents the wide frequency bandwidth signal (105).
摘要:
A base-site (304) combines baseband frequency hopping and fast-synthesizer hopping to produce an economical frequency hopping communication system (300). The base-site (304) combines the fast-synthesizer frequency hopping capability of transmitters (307-309) with baseband frequency hopping to produce a frequency hopping communication system (300) which serves the same number of subscribers served by transmitters (208-213) in a purely baseband hopping communication system (200), but with fewer transmitters (307-309). The implementation of frequency-selective cavities (312-317) having very low loss eliminates the need for wideband hybrid combiners (112-114), which in turn eliminates transmitted-signal power loss experienced in a purely fast-synthesizer frequency hopping communication system (100).
摘要:
A method comprising distributing channel coding on either side of a limited capacity communication path by partially channel coding a signal at a first processing point and communicating the partially coded signal over the communication path to a second processing point. The partially coded signal comprises at least some but not all of the necessary coded bits. The channel coding algorithm is completed at the second processing point using the communicated partially coded signal thereby increasing throughput over the limited capacity path while minimizing added delays.
摘要:
A method is disclosed and apparatus is described whereby plain text is modified before it is input to a binary key generator (encryptor). According to the invention, a plain text bit may be modified by a current modifying bit, which in turn, is based on a prior modifying bit, a prior plain text bit, and a prior ciphered text bit. The only data path provided to the transmitter is the encrypted key generator cipher text output. As a result, the only feed-foward path of the plain text to the channel is through the key generator, and thus the fault-immune physical barrier between the plain text and the cipher information inherent with the key generator is maintained. The invention provides a way of utilizing conventional binary key generators to digitally encrypt for radio transmission multilevel sub-band coded speech.
摘要:
According to the invention, an information signal, such as a information signal, is sampled, quantized and processed digitally through an information encoder. Digitally processed samples produced by the encoder are modulated onto a communication channel to create channel symbols having a magnitude of modulation proportional to a characteristic of a respective digitally processed sample. Both a radio frequency (RF) transmission embodiment, and a wireline embodiment are provided. In a final aspect of the present invention, encryption is provided to ensure communication privacy.