Broadcast Multicast Mode
A broadcast/multicast transmission format includes a data portion and a cyclic prefix (CP) coupled to the traffic data portion. A method and system for providing broadcast/multicast transmissions with the application to communication systems that perform broadcast or multicast transmission is also disclosed. The addition of a pilot to the data portion of the transmissions is also disclosed.
This application claims priority to U.S. Provisional Application No. 60/579,957 filed Jun. 15, 2004, and entitled “CDMA with CP Based Enhanced Broadcast Multi-Cast Mode for HRPD,” by Anand G. Dabak et al; and to U.S. Provisional Patent Application No. 60/611,436, filed Sep. 20, 2004, entitled “A CDMA based enhanced broadcast multi-cast system with content-dependent data and pilot spreading for HRPD,” by Onggosanusi, et al; both provisional applications are incorporated by reference as if fully set forth herein.
FIELD OF THE INVENTIONThis invention relates in general to the field of communications and more specifically to a broadcast/multicast mode for use in communication systems.
BACKGROUND OF THE INVENTIONHigh rate packet data (HRPD) is also commonly referred to as 1×EV-DO which is a high-speed code division multiple access (CDMA) based wireless data technology. A comprehensive discussion of HRPD be found in the Telecommunications Industries Association's interim standard TIA/EIA/IS-856 entitled cdma2000 High Rate Packet Data Air Interface Specification, November 2000, which is incorporated herein by reference.
Referring now to
The broadcast/multicast data is broadcast to all system users and it is also possible the same information information is also transmitted from different cells/sectors in a communication system employing the format shown in
In highly frequency selective channels (example, a Pedestrian B channel), an equalizer can be employed as a substitute to a rake receiver in order to enhance performance. In this case, equalization is performed per sector prior to soft combining across the sectors. Most equalizers require a sufficiently high signal-to-noise ratio (SNR) training to achieve good performance in order to train its equalizer taps or perform channel estimation. Unfortunately, this is not possible since the SNR for the secondary sectors is very low due to interference from the stronger (primary) sectors. Also, due to sector-dependent data and pilot spreading it is not possible to achieve a one shot equalization of the total channel summed across all the sectors.
In the case of OFDM, since the exact same information is transmitted from the different cells/sectors (without the long code), the signals received from the different cells/sectors look like multi-path propagation delay. Hence, all the different multi-paths/signals can be efficiently combined at the receiver using fast Fourier transform (FFT) prior to performing frequency-domain equalization. This approach typically uses a cyclic prefix (CP) having a length that is larger than the expected propagation delay from the different base stations in the system. Hence, a very large CP (e.g., 80 samples requiring approximately 65 microseconds) is in employed with the transmission format of
As shown in
The current broadcast/multicast system (BCMS) applies sector-dependent long code spreading on the pilot and data fields which generates a few problems. One problem
In this description, we use an HRPD system to illustrate one embodiment of the broadcast multicast mode of the present invention. Note that the mode is applicable to any wireless standard and is not limited to HRPD systems.
In
In accordance with an embodiment of the invention, whenever identical broadcast/multicast data is being transmitted from different sectors/cells in a system, a CP is attached to the broadcast/multicast data, as shown in
Some advantages of using what will be referred to as a CDMA+CP based transmission as shown in
Using the CDMA+CP scheme of the present invention, different types of receivers can be employed since CDMA is used, for example, conventional rake receivers or equalizers can be used. If there is a need for a more advanced receiver that can efficiently combine the identical broadcast/multicast signals from the different cells/sectors, then a fast Fourier transform (FFT)/inverse fast Fourier (IFFT) receiver 600 as shown in
Referring now to
In another embodiment of the invention, pilot symbols are inserted into the data fields for the broadcast/multicast messages. The pilot symbols can be code-domain (CD) or time-domain (TD) multiplexed. The position of the pilot symbols in the code or in the time domain can be arbitrary or optimized based on different criteria. The addition of the pilot symbols can be in addition to the CP previously described or using the pilot symbols alone without using the CP. In
In
In
While the preferred embodiments of the invention have been illustrated and described, it will be clear that the invention is not so limited. Numerous modifications, changes, variations, substitutions and equivalents will occur to those skilled in the art without departing from the spirit and scope of the present invention as defined by the appended claims. The concept of CDMA+CP transmission with content dependent spreading for broadcast/multicast can be applied in other systems besides the 3GPP High Speed Downlink Packet Access (HSDPA) system that was discussed.
Claims
1-32. (canceled)
33. A method, comprising:
- receiving a broadcast/multicast transmission;
- extracting data fields from the received transmission;
- extracting a pilot signal from the data fields;
- performing channel estimation using the extracted pilot signal; and
- removing any cyclic prefix (CP) associated with the data fields.
34. A method as defined in claim 33, wherein the data fields each comprise a cyclic prefix appended to a data portion.
35. A method as defined in claim 33, wherein the data fields each comprise a cyclic prefix pre-pended to a data portion.
36. A method as defined in claim 34, wherein the data fields each comprise a cyclic prefix pre-pended to the data portion.
37. A method as defined in claim 33, wherein the data Melds each comprise a pilot symbol appended to a data portion.
38. A method as defined in claim 33, wherein the data fields each comprise a cyclic prefix pre-pended to a data portion.
39. A method as defined in claim 34, wherein the data fields each comprise a cyclic prefix pre-pended to the data portion.
40. A method as defined in claim 33, wherein the data fields in the received broadcast/multicast transmission were not transmitted using cell/sector specific long code spreading.
41. A method as defined in claim 33, wherein the data fields in the received broadcast/multicast transmission were transmitted using content-dependent long code spreading.
42. An apparatus, comprising:
- means for receiving a broadcast/multicast transmission;
- means for extracting data fields from the received transmission;
- means for extracting a pilot signal from the data fields;
- means for performing channel estimation using the extracted pilot signal; and
- means for removing any cyclic prefix (CP) associated with the data fields.
43. An apparatus, comprising:
- circuitry configured to receive a broadcast/multicast transmission;
- circuitry configured to extract data fields from the received transmission;
- circuitry configured to extract a pilot signal from the data fields;
- circuitry configured to perform channel estimation using the extracted pilot signal; and
- circuitry configured to remove any cyclic prefix (CP) associated with the data fields.
44. The apparatus of claim 43, wherein the data fields each comprise a cyclic prefix appended to a data portion.
45. The apparatus of claim 43, wherein the data fields each comprise a cyclic prefix prepended to a data portion.
46. The apparatus of 44, wherein the data fields each comprise a cyclic prefix pre-pended to the data portion.
47. The apparatus of claim 43, wherein the data fields each comprise a pilot symbol appended to a data portion.
48. The apparatus of claim 43, wherein the data fields each comprise a cyclic prefix pre-pended to a data portion.
49. The apparatus of claim 43, wherein the data fields each comprise a cyclic prefix pre-pended to the data portion.
50. The apparatus of claim 43, wherein the data fields in the received broadcast/multicast transmission were not transmitted using cell/sector specific long code spreading.
51. The apparatus of claim 43, wherein the data fields in the received broadcast/multicast transmission were transmitted using content-dependent long code spreading.
52. The apparatus of claim 43 wherein code division multiple access (CDMA) is used to implement a non-data portion of the received broadcast/multicast transmission and orthogonal frequency division access (OFDM) is used to implement a data portion of the received broadcast/multicast transmission.
Type: Application
Filed: Nov 17, 2016
Publication Date: Mar 9, 2017
Inventors: Anand G. Dabak (Plano, TX), Eko N. Onggosanusi (Allen, TX), Aris Papasakellariou (Houston, TX)
Application Number: 15/354,780