Orthogonal code division multiple access waveform format for use in satellite based cellular telecommunications
First Claim
1. A system for providing a telecommunications link between earth stations and terminals via satellites, said system comprising:
- a satellite, said satellite maintaining forward and return communications channels over forward and return communications links, respectively, between an earth station and a plurality of terminals;
a plurality of terminals, said terminals utilizing orthogonal CDMA codes to maintain forward communications links synchronous with one another; and
an earth station, said earth station utilizing orthogonal CDMA codes to maintain return communications links from multiple terminals synchronous with one another, said earth station measuring and calculating chip timing error correction information for said return communications links based on a sync field in said communications links, and transmitting, to at least one terminal, said chip timing error correction information over a loop signaling channel, said at least one terminal updating chip timing error information using said chip timing error correction information received.
4 Assignments
0 Petitions
Accused Products
Abstract
A communications waveform format is provided for a satellite-based telecommunications system. The waveform format includes forward and return link waveforms between the satellite, earth stations and terminals. The forward and return links use orthogonal direct-sequence code division multiple access (ODS-CDMA) to minimize interference between users. The forward and return link spectrum may be divided into channels, the frequencies and spacing of which are adjustable to compensate for Doppler effects, thereby maintaining synchronization. The spectrum of the terminal links may be divided into multiple subbands (e.g., 38), each of which may support multiple (e.g., 80) ODS-CDM channels. The forward and return links support traffic channels (TCH), associated signaling channels (ASC), broadcast control channels (BCC), forward signaling channels (FSC) having paging slots (PAS) and channel allocation slots (CAS), call establishment channels (CEC), and loop signaling channels (LSC), a measurement reporting channel (MRC), and a return access channel (RAC). The RAC carries nonsynchronous spread spectrum pseudo-noise (PN) signal access bursts which are used by terminals to initially access the communications system.
-
Citations
40 Claims
-
1. A system for providing a telecommunications link between earth stations and terminals via satellites, said system comprising:
-
a satellite, said satellite maintaining forward and return communications channels over forward and return communications links, respectively, between an earth station and a plurality of terminals;
a plurality of terminals, said terminals utilizing orthogonal CDMA codes to maintain forward communications links synchronous with one another; and
an earth station, said earth station utilizing orthogonal CDMA codes to maintain return communications links from multiple terminals synchronous with one another, said earth station measuring and calculating chip timing error correction information for said return communications links based on a sync field in said communications links, and transmitting, to at least one terminal, said chip timing error correction information over a loop signaling channel, said at least one terminal updating chip timing error information using said chip timing error correction information received. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15)
-
-
16. A system for providing a telecommunications link between earth stations and terminals via satellites, said system comprising:
-
a satellite, said satellite maintaining forward and return communications channels over forward and return communications links, respectively, between an earth station and a plurality of terminals;
a plurality of terminals, said terminals utilizing orthogonal CDMA codes to maintain forward communications links synchronous with one another; and
an earth station, said earth station utilizing orthogonal CDMA codes to maintain return communications links from multiple terminals synchronous with one another, said earth station measuring and calculating power update informtion for said return communications links based on a code symbol error rate in said communications links, and transmitting, to at least one terminal, said calculated power update information over a loop signaling channel, said at least one terminal updating a power level using said power update information received. - View Dependent Claims (17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27)
-
-
28. A system for providing a telecommunications link between earth stations and terminals via satellites, said system comprising:
-
a satellite, said satellite maintaining forward and return communications channels over forward and return communications links respectively, between an earth station and a plurality of terminals;
a plurality of terminals, said terminals utilizing orthogonal CDMA codes to maintain forward communications links synchronous with one another; and
an earth station, said earth station utilizing orthogonal CDMA codes to maintain return communications links from multiple terminals synchronous with one another, said earth station measuring and calculating frequency offset error correction information for said return communications links based on a carrier tracking loop, and transmitting, to at least one terminal, said frequency offset error correction information over a loop signaling channel, said at least one terminal updating a frequency offset using said frequency offset error correction information received. - View Dependent Claims (29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40)
-
Specification