Method and system for multi-carrier packet communication with reduced overhead
A method and system for minimizing the control overhead in a multi-carrier wireless communication network that utilizes a time-frequency resource is disclosed. In some embodiments, one or more zones in the time-frequency resource are designated for particular applications, such as a zone dedicated for voice-over-IP (VoIP) applications. By grouping applications of a similar type together within a zone, a reduction in the number of bits necessary for mapping a packet stream to a portion of the time-frequency resource can be achieved. In some embodiments, modular coding schemes associated with the packet streams may be selected that further reduce the amount of necessary control information. In some embodiments, packets may be classified for transmission in accordance with application type, QoS parameters, and other properties. In some embodiments, improved control messages may be constructed to facilitate the control process and minimize associated overhead.
1. A communication method for a mobile device in an orthogonal frequency division multiple access (OFDMA) wireless packet system including a plurality of base stations and mobile devices in a plurality of geographic cells, each mobile device having an identifier that is assigned by the system, the method comprising:
receiving a signal over a time-frequency resource region contained in a plurality of frames, the signal carrying packets destined to a number of mobile devices with a plurality of modulation and coding schemes using an integer multiple of basic time-frequency resource units, wherein each frame is divided into a plurality of time slots, each time slot consists of a plurality of orthogonal frequency division multiplexing (OFDM) symbols, each OFDM symbol contains a plurality of frequency subcarriers, and the basic time-frequency resource unit contains a number of subcarriers in a number of OFDM symbols; and
identifying from the signal a plurality of packets that are destined to the mobile device using a time index or a frequency index of the time-frequency resource region in conjunction with the identifier assigned to the mobile device.
2. The method of claim 1 , wherein the integer multiple of basic time-frequency units is 1, 2, 4, or 8 basic time-frequency resource units.
3. The method of claim 1 , wherein the time-frequency resource region corresponds to a frame.
4. The method of claim 3 , wherein the time index of the time-frequency resource region corresponds to a frame number.
5. The method of claim 1 , wherein the identifier assigned to the mobile device contains 16 bits.
6. The method of claim 1 , wherein the identifier assigned to the mobile device is released after a period of time.
7. The method of claim 1 , wherein physical subcarrier and OFDM symbol indices of a time-frequency resource are mapped to logical indices so that the logical indices may be utilized by upper layer facilities in the mobile device.
8. The method of claim 7 , wherein contiguous physical indices are mapped to contiguous logical indices.
9. The method of claim 7 , wherein discontiguous physical indices are mapped to contiguous logical indices.
10. The method of claim 1 , wherein one of the plurality of packets destined to the mobile device is a control packet that carries a control message for the mobile device.
11. The method of claim 10 , wherein the control message comprises information on modulation and coding schemes or resource allocation.
12. The method of claim 10 , wherein the control packet uses a modulation and coding scheme the same as or one level lower than modulation and coding schemes used for other data packets that are destined to the mobile device.
13. A communication method for a base station in an orthogonal frequency division multiple access (OFDMA) wireless packet system including a plurality of base stations and mobile devices in a plurality of geographic cells, each mobile device having an identifier that is assigned by the system, the method comprising:
allocating a time-frequency resource region in a plurality of frames for carrying packets to a number of mobile devices with a plurality of modulation and coding schemes using an integer multiple of basic time-frequency resource units, wherein each frame is divided into a plurality of time slots, each time slot consists of a plurality of orthogonal frequency division multiplexing (OFDM) symbols, each OFDM symbol contains a plurality of frequency subcarriers, and the basic time-frequency resource unit contains a number of subcarriers in a number of OFDM symbols;
generating a plurality of packets for a mobile device in the system and scheduling transmission of the plurality of packets in the time-frequency resource region in a manner that allows the mobile device to recover the plurality of packets using a time index or a frequency index of the time-frequency resource region in conjunction with the identifier assigned to the mobile device; and
transmitting the plurality of packets to the mobile device.
14. The method of claim 13 , wherein the integer multiple of basic time-frequency units is 1, 2, 4, or 8 basic time-frequency resource units.
15. The method of claim 13 , wherein the time-frequency resource region corresponds to a frame.
16. The method of claim 15 , wherein the time index of the time-frequency resource region corresponds to a frame number.
17. The method of claim 13 , wherein the identifier assigned to the mobile device contains 16 bits.
18. The method of claim 13 , wherein the identifier assigned to the mobile device is released after a period of time.
19. The method of claim 13 , further comprising mapping logical indices of a time-frequency resource seen by upper layer facilities of the base station to physical subcarrier and OFDM symbol indices prior to transmitting the plurality of packets.
20. The method of claim 19 , wherein contiguous logical indices are mapped to contiguous physical indices.
21. The method of claim 19 , wherein contiguous logical indices are mapped to discontiguous physical indices.
22. The method of claim 13 , further comprising not using the same time-frequency resource region that is used by a base station in an adjacent cell.
23. In an orthogonal frequency division multiple access (OFDMA) wireless packet system including a plurality of base stations in a plurality of geographic cells, a mobile device having an identifier that is assigned by the system, the mobile device comprising:
a facility configured for receiving a signal over a time-frequency resource region contained in one or more frames, the signal carrying packets destined to a number of mobile devices with a plurality of modulation and coding schemes using an integer multiple of basic time-frequency resource units, wherein each frame is divided into a plurality of time slots, each time slot consists of a plurality of orthogonal frequency division multiplexing (OFDM) symbols, each OFDM symbol contains a plurality of frequency subcarriers, and the basic time-frequency resource unit contains a number of subcarriers in a number of OFDM symbols; and
a facility configured for identifying from the signal a plurality of packets that are destined to the mobile device using a time index or a frequency index of the time-frequency resource region in conjunction with the identifier assigned to the mobile device.
24. The mobile device of claim 23 , wherein the time-frequency resource region corresponds to a frame and the time index of the time-frequency resource region corresponds to a frame number.
25. The mobile device of claim 23 , wherein one of the plurality of packets destined to the mobile device is a control packet that carries a control message for the mobile device and the control message comprises information on modulation and coding schemes or resource allocation.
26. The mobile device of claim 23 , further comprising a facility for synchronization, a facility for fast Fourier transform, a facility for demodulation, a facility for channel estimation, and a facility for channel decoding.
27. A base station in an orthogonal frequency division multiple access (OFDMA) wireless packet system including a plurality of mobile devices in a plurality of geographic cells, each mobile device having an identifier that is assigned by the system, the base station comprising:
a facility configured for allocating a time-frequency resource region in one or more frames for carrying packets to a number of mobile devices with a plurality of modulation and coding schemes using an integer multiple of basic time-frequency resource units, wherein each frame is divided into a plurality of time slots, each time slot consists of a plurality of orthogonal frequency division multiplexing (OFDM) symbols, each OFDM symbol contains a plurality of frequency subcarriers, and the basic time-frequency resource unit contains a number of subcarriers in a number of OFDM symbols;
a facility configured for generating a plurality of packets for a mobile device in the system and scheduling transmission of the plurality of packets in the time-frequency resource region in a manner that allows the mobile device to recover the plurality of packets using a time index or a frequency index of the time-frequency resource region in conjunction with the identifier assigned to the mobile device; and
a transmitter configured for transmitting the plurality of packets to the mobile device.
28. The base station of claim 27 , wherein the time-frequency resource region corresponds to a frame and the time index of the time-frequency resource region corresponds to a frame number.
29. The base station of claim 27 , wherein one of the plurality of packets destined to the mobile device is a control packet that carries a control message for the mobile device and the control message comprises information on modulation and coding schemes or resource allocation.
30. The base station of claim 27 , further comprising a facility for channel encoding, a facility for modulation, and a facility for inverse fast Fourier transform.