摘要:
More efficient utilization of available bandwidth is implemented in an OFDM wireless communication system. The partitions of bandwidth may be of different sizes and may be different from the original system design parameters. Basic system structure such as the number of tones used and the number of OFDM symbol times in a slot is maintained throughout the system. Bandwidth is varied by adjusting the inter-tone spacing or bandwidth associated with a single tone. As the inter-tone spacing is increased, the OFDM symbol transmission time is decreased following an inverse proportional relationship. A wireless communications device, during a first period of time transmits signals using a first uplink frequency band of a first number of uniformly distributed tones and during a second period of time transmits signals using a second uplink frequency band of a second number of uniformly distributed tones, the second number being the same as the first number, the second frequency band being wider than the first frequency band.
摘要:
Techniques for performing automatic gain control (AGC) at a receiver are described. The receiver may receive an OFDM-based symbol composed of a cyclic prefix and a useful portion. The receiver may scale the OFDM-based symbol with an initial receiver gain, adjust the initial receiver gain based on the cyclic prefix, apply the adjusted receiver gain prior to the useful portion, and process the useful portion to recover at least one signal sent by at least one transmitter. The receiver may select the initial receiver gain, e.g., based on a predicted received power level for the at least one transmitter, a pattern of different receiver gains, etc. The receiver may apply the initial receiver gain at the start of the OFDM-based symbol. The receiver may measure the power of a set of samples in the cyclic prefix and may adjust the receiver gain based on the measured power and a target power.
摘要:
A base station generates and transmits a multi-symbol beacon/timing synchronization signal. The multi-symbol beacon/timing synchronization signal includes: (i) an initial symbol including a body portion and a cyclic prefix, the cyclic prefix preceding the body portion and being generated from an end portion of the body portion and (ii) an extension symbol, which immediately follows the initial symbol. The extension symbol includes a first copy of the body portion beginning at the start of the extension symbol. The first copy of the body portion is immediately followed by a truncated portion, which is a copy of an initial portion of the body portion. The multi-symbol beacon/timing synchronization signal includes a single high power beacon tone, a plurality of low power tones comprising the synchronization signal, and a plurality of intentional Null tones. Each tone designation remains the same for both the initial symbol and the extension symbol.
摘要:
Scheduling of regular signal transmissions, e.g., between a plurality of wireless terminals and a base station in a cellular network in a manner designed to reduce or minimize recurring periodic interference encountered by individual wireless terminals from transmission in neighboring cells is described. Signal transmissions of wireless terminals in each cell are scheduled on a group slot basis. A group slot comprises a number of time slots. Each wireless terminal serviced by a particular base station is assigned a time slot in a group slot used by the particular base station. A given wireless terminal is assigned different time slots in successive group slots as specified by a hopping function. Adjacent, base stations e.g., base stations of physically neighboring or overlapping cells, use distinct, i.e., different, hopping functions for the scheduling purpose thereby avoiding correlation of slots between overlapping or adjacent cells during consecutive group slots.
摘要:
Techniques for performing automatic gain control (AGC) at a receiver are described. The receiver may receive an OFDM-based symbol composed of a cyclic prefix and a useful portion. The receiver may scale the OFDM-based symbol with an initial receiver gain, adjust the initial receiver gain based on the cyclic prefix, apply the adjusted receiver gain prior to the useful portion, and process the useful portion to recover at least one signal sent by at least one transmitter. The receiver may select the initial receiver gain, e.g., based on a predicted received power level for the at least one transmitter, a pattern of different receiver gains, etc. The receiver may apply the initial receiver gain at the start of the OFDM-based symbol. The receiver may measure the power of a set of samples in the cyclic prefix and may adjust the receiver gain based on the measured power and a target power.
摘要:
Improved beacon signaling methods are described. Beacon signals are transmitted on the same tone in at least two consecutive symbol periods facilitating accurate energy measurements over a symbol period even if timing synchronization with the transmitter is not maintained. A low power wideband signal is also combined with the beacon signal to facilitate channel estimation and other operations such as timing synchronization operations.
摘要:
Symbol timing synchronization in OFDM communication systems where multiple wireless terminals communicate with a single base station is described. Base station transmitter and receiver symbol timing is fixed. Each wireless terminal operates to independently adjust its transmitter timing. Transmitter timing synchronization at the wireless terminal is slaved to the terminal's receiver timing synchronization. Each wireless terminal first corrects its receiver symbol timing based on a signal received from the base station. The wireless terminal then adjusts its transmitter symbol timing as a function of its receiver symbol timing. When the receiver symbol timing is to be advanced or delayed by some amount, the transmitter symbol timing is also advanced or delayed, respectively, by the same, or substantially the same, amount. Symbol timing adjustment can be made by adding or deleting digital samples from the first or last symbol in a dwell.
摘要:
Methods and apparatus of efficient communication of resource allocation are described. A base station transmits a resource assignment message, e.g., a state transition message, to a wireless terminal including a first part, e.g., a base station assigned wireless terminal On state identifier, identifying a resource being assigned and a second part, e.g., an ON state mask, identifying a portion of the resource allocated to the wireless terminal. The same resource allocation message information also communicates one of a plurality of different modes of commanded On state operation. The resource allocation message structure supports flexible allocation of available resources facilitating a resource to be partitioned differently at different times accommodating current needs. A predetermined recurring channel structure and association of segments with particular mask bits, facilitates allocated control segments to be used unambiguously without the need to include an overhead wireless terminal identifier field with the control report bits being communicated.
摘要:
Wireless terminals and base stations support multiple modes of dedicated control channel operation wherein wireless terminals are allocated different amounts of dedicated uplink resources for reporting control information. A set of dedicated control channel segments is utilized by a wireless terminal to communicate uplink control information reports to its serving base station attachment point. Full tone and split-tone modes of dedicated control channel operation are supported. In full tone mode, a single wireless terminal is allocated each of the dedicated control channel segments associated with a single logical tone. In split tone mode, dedicated control channel segments associated with a single logical tone are allocated between different wireless terminals, with each of the multiple wireless terminals receiving a different non-overlapping subset of the dedicated control channel segments. Logical dedicated control channel tones can be dynamically reallocated for full-tone mode use or split tone mode use.
摘要:
Methods and apparatus for allocating tones for communications purposes in adjoining cells of an OFDM system are described. Tones used in each cell are allocated to tone hopping sequences according to a tone to tone hopping sequence allocation function. Different cells use different tone to tone hopping sequence allocation functions to minimize the number of collisions between hopping sequences of neighboring cells. Tone hopping sequence to communications channel allocation functions are used to allocate tone hopping sequences to communications channels. Communications channels are used by wireless terminals, e.g., mobile nodes, to transmit data. Over time, a wireless terminal uses the tones included in the tone hopping sequences corresponding to communications channels it is authorized to use. Accordingly, tones are assigned to communications devices by a multi-function, e.g., two level, mapping operation.