Multiplex communications – Communication over free space – Having a plurality of contiguous regions served by...
Reexamination Certificate
1999-04-22
2003-09-30
Bost, Dwayne (Department: 2681)
Multiplex communications
Communication over free space
Having a plurality of contiguous regions served by...
C370S342000, C370S468000
Reexamination Certificate
active
06628633
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to a communication method and system using code division multiple access (CDMA) and, in particular, to a CDMA communication method and a spread spectrum communication system adapted to a forward packet transmission.
In a packet transmission of a CDMA communication system, generally, a spreading code and a frequency band are reserved at a time when a packet to be transmitted occurs, communication is made using a reserved spreading code and a reserved frequency band, and the reserved spreading code and the reserved frequency band are released when the communication comes to end.
Such a technique is, for example, disclosed in Japanese Unexamined Patent Publication of Tokkai No. Hei 9-327,072 or JP-A 9-327,072 (which will be called a first publication). Specifically, the first publication discloses “CDMA COMMUNICATION METHOD AND SPREAD SPECTRUM COMMUNICATION SYSTEM” each of which is capable of enhancing the flexibility of communication service by processing information individually. A frequency band for a communication zone between a base station and a plurality of terminal apparatuses (mobile stations) are divided into a forward (downlink) band in a forward direction and a reverse (uplink) band in a reverse direction. In addition, a plurality of carrier frequencies are defined corresponding to a plurality of sub-frequency bands which has one of a plurality of kinds of bandwidths in both the frequency bands. A sub-frequency band having the bandwidth in matching with the information transmission speed is preliminarily assigned to each terminal apparatus. Each terminal apparatus spreads a spectrum of a reserved packet using a reservation channel spreading code to produce a spread spectrum reserved packet and then transmits the spread spectrum reserved packet by using a specific carrier frequency corresponding to the reverse sub-frequency band. After the base station spreads a spectrum of a reply packet using a reply channel spreading code to produce a spread spectrum reply packet, the base station transmits the spread spectrum reply packet by using a particular carrier frequency corresponding to the forward sub-frequency band. After each terminal apparatus spreads a spectrum of an information packet using a spreading code for an information transmission channel designated by the reply packet to produce a spread spectrum information signal, each terminal apparatus transmits the spread spectrum information signal by using a specific carrier frequency in the reverse direction.
In addition, in the CDMA communication system, control of transmission power is important. Accordingly, as regards a pair of reverse like (uplink) and forward link (downlink), power control information of a link for transmitting data is generally transmitted using a link in the opposite direction to the link for transmitting data.
However, problems arise in the above-mentioned first publication in the manner which will presently be described.
A first problem is that transmission rates for the reverse channel and the forward channel in pairs are basically equal to each other. In other words, the same bandwidth is assigned to both of the reverse channel and the forward channel. However, in a case, for example, of accessing data on the internet, data in the forward direction are overwhelmingly greater in comparison with data in the reverse direction, and it results in wasting capacity of the reverse channel in a case where the reverse channel and the forward channel are equal to each other. Inasmuch as unless channel is established, the number of terminal apparatuses enable to be simultaneously connected is restricted. In addition, it jams communications for other terminal apparatuses where the frequency band overlaps.
In addition, in Paper No. B-5-35 to “1997-nen Denshi Jôhô Tsushin Gakkai Sôgô Taikai Yokô (1997 National Convention Record of the Institute of Electronics, Information and Communication Engineers of Japan)” discloses a method of collectively transmitting data in the forward direction by using one channel. However, this method cannot be applied to the reverse direction.
A second problem is that time for reserving a channel is required.
In addition, various other publications, which may be related to this invention, are already known. By way of example, Japanese Unexamined Patent Publication of Tokkai No. Hei 7-312,783 or JP-A 7-312,783 (which will be called a second publication) discloses “CDMA COMMUNICATION METHOD AND ITS DEVICE” each of which is capable of attaining multiplex transmission from low speed data till high speed data such as image data without much increase in the scale of the circuit. In the second publication, a basic transmission rate adopts 32 kbps higher than a usually used transmission rate of 8 kbps, the information needing a rate equal to the basic transmission rate is sent as a frame structure without an idle inter-period, and the information needing a transmission rate of 16 kbps is sent in a communication channel of frames having an idle period. Furthermore, no information is sent in an idle period other than the communication channel. Thus, the information of other channel is received for an idle period. The information at a high speed such as information whose transmission speed is 128 kbps is sent by multiplexing four channels with different spreading codes.
In addition, Japanese Unexamined Patent Publication of Tokkai No. Hei 9-055,693 or JP-A 9-055,693 (which will be called a third publication) discloses “MOBILE COMMUNICATION SYSTEM AND MOBILE TERMINAL EQUIPMENT” each of which is capable of providing a mobile communication system in which the throughput deterioration is not in existence by a reservation control packet by sending a reservation packet in the CDMA (code division multiple access) system. In the third publication, mobile terminals having a transmission request send a reservation packet through a reserved channel by the CDMA system and a base station allocates a transmission channel and a time slot available for the mobile terminals of request sources by using a reply packet outputted through a reply channel. A short spreading code corresponding to a matched filter is applied to the reservation channel. When the reservation packet is sent by the CDMA system, even when a plurality of reservation packets are caused overlapping timewise, the base station extracts each packet independently when a timing differs and it is not required to retransmit the reservation packet due to collision.
Furthermore, Japanese Unexamined Patent Publication of Tokkai No. Hei 9-327,073 or JP-A 9-327,073 (which will be called a fourth publication) discloses “METHOD FOR ARRANGING AND TRANSMITTING PILOT CHANNEL IN CDMA MOBILE COMMUNICATION SYSTEM” each of which is capable of reducing the influence of a pilot channel on the spreading code shortage by time-dividing and multiplexing an outgoing radio channel into a plurality of time slots and assigning one of them as a pilot channel. The whole outgoing radio channels consisting of X spreading codes have frame configuration and one frame is divided into the plurality of time slots so as to be multiplexed by the division. Then, the specified time slot of the radio channel spread by the specified spreading code is assigned as the pilot channel. The other time slots and the spreading codes are used as the communication channel for communication with the mobile station. For example, time slot numbers
1
-
4
are given to the four time slots in the frame in order from an early one in terms of time, the time slot #1 of the radio channel where the spreading code is spread by one is assigned as the pilot channel and the other time slots and the spreading codes are assigned as the communication channel.
In addition, Japanese Unexamined Patent Publication of Tokkai No. Hei 10-013,337 or JP-A 10-013,337 (which will be called a fifth publication) discloses “RADIO COMMUNICATION SYSTEM ” which is capable of setting the transmission power of respective stations to a proper level when a base station and
Bost Dwayne
Dickstein Shapiro Morin & Oshinsky LLP.
NEC Corporation
Ramos-Feliciano Eliseo
LandOfFree
CDMA communication method adapted to forward packet... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with CDMA communication method adapted to forward packet..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and CDMA communication method adapted to forward packet... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3013377