Parallel hopping hybrid direct sequence/slow frequency hopping CDMA system

• US 6,215,810 B1
• Filed: 01/15/1999
• Issued: 04/10/2001
• Est. Priority Date: 01/20/1998
• Status: Expired due to Term

• Current Assignee: Samsung Electronics Co. Ltd.
• Original Assignee: Samsung Electronics Co. Ltd.
• Inventors: Park, Chan-bum
• Primary Examiner(s): Bocure, Tesfaldet
• Application Number:
  US09/232,739
• Time in Patent Office: 816 Days
• Field of Search: 375/132, 375/130, 375/131, 375/135, 375/146, 375/260, 370/342, 370/344
• US Class Current: 375/131
• CPC Class Codes: H04B 1/692 Hybrid techniques using combinations of two or more spread spectrum techniques
• CPC Class Codes: H04B 7/2621 using frequency division multiple access [FDMA] H04B7/2615 takes precedence

Abstract

A radio system is disclosed for supporting a greater number of users than can be supported in a conventional CDMA system that supports multiple users. The radio system is a hybrid system combining elements of conventional spread spectrum techniques. The system may be defined as a parallel hopping hybrid direct sequence (DS)/slow frequency hopping (SFH) code division multiple access (CDMA) system in combination with a DS/CDMA system, frequency hopping (FH)/CDMA system and a multi-carrier system.

Claims

1. A transmitter used in a parallel hopping hybrid direct sequence/slow frequency hopping code division multiple access system comprising:

(a) a data signal generating unit for generating a data signal to be transmitted;

(b) a spreader for multiplying said data signal by a pseudo-random (PN) sequence generating a spread spectrum signal;

(c) a plurality of frequency hopping multipliers for multiplying said spread spectrum signal by a unique carrier in a plurality of sub-bands;

(d) a plurality of gate function generators for selecting a subset of said plurality of sub-bands for transmission of said multiplied spread spectrum signals from each of said selected sub-bands;

(e) a combiner for combining said multiplied spread spectrum signals in those sub-bands selected by said plurality of gate functions; and

(f) a radio frequency (RF) transmitting unit for transmitting said combined multiplied spread spectrum signals via radio path.

2. The transmitter as set forth in claim 1, wherein the data signal b_k(t) is generated for each of k users, is multiplied by a spread signal, a_k(t) characterized as a rectangular pulse stream having a continuation time, T_c.

3. The transmitter as set forth in claim 2, wherein

a^l_k(t) has values of 1 or − 1 during a time interval of lT_c≦

t≦

(l+1) T_c, said a^l_k(t) being an amplitude of the lth pulse of the spread signal, a_K(t).

4. The transmitter as set forth in claim 1, wherein said plurality of frequency hopping multipliers multiplies a data signal carrier by a hopping frequency in each of said selected sub-bands.

5. The transmitter as set forth in claim 1, wherein said plurality of gate function generators arbitrarily generates one of an on and off signal, wherein said on signal permits transmission of with arbitrarily determining a sub-band so as to transmit only signals with the determined sub-band.

6. The transmitter as set forth in claim 1, wherein said gate function, w_k,m(t) arbitrarily generates one of an on and off signal during a frequency hopping time, jT_h≦

t≦

(j+1)T_h, in each of said plurality of sub-bands, where m and k correspond to an mth gate function generator of a kth user, and where t is time interval, j is a jth hopping, T_h is a frequency hopping time, M is the number of available sub-bands and Q is the number of sub-bands selected as hopping frequencies from the M available sub-bands.

7. The transmitter as set forth in claim 1, wherein a transmitted signal, s_k(t) transmitted for a kth user, is:

$s_k<br><br>\left(t\right)=\underset{m=1}{\overset{M}{\sum <br><br>}}<br><br>\text{\hspace{1em}<br><br>}<br><br>\sqrt{\frac{2<br><br>P_k}{Q}}<br><br>w_{k,m}<br><br>\left(t\right)<br><br>b_k<br><br>\left(t\right)<br><br>a_k<br><br>\left(t\right)<br><br>\cos <br><br>\left(2<br><br>{\mathrm{\pi <br><br>f}}_m<br><br>t+{\mathrm{\phi <br><br>}}_{k,m}\right)$

where M is the number of available sub-bands, Q is the number of sub-bands selected from the number of available sub-bands M, P_k is power at the transmitting unit for the kth user, b_k(t) is data signal to be transmitted for a kth user, a_k(t) is PN sequence being multiplied in the spreader for DS spread spectrum of the kth user, w_k,m(t) is a gate function being generated in the mth gate function generator of the kth user, f_m is the mth carrier being multiplied in the frequency hopping apparatus, and φ

_k,m is the mth phase component of the kth user.

8. The transmitter as set forth in claim 1, wherein said transmitter can support both cases where hopping frequency bands are overlapped and not, respectively.

9. The transmitter as set forth in claim 1, wherein said transmitter has a structure to reduce the influence of interference on other users in such a way that each user uses a frequency band, which is different each other.

10. The transmitter as set forth in claim 1, wherein said transmitter makes it possible to get an additional frequency diversity effect in time varying channel by hopping with changing the carrier being transmitted every hopping time.

11. A method for transmitting a signal in a parallel hopping hybrid direct sequence slow frequency hopping code division multiple access system, comprising the steps of:

separating a transmission frequency bandwidth into a plurality of sub-bands; and

selecting a subset of said plurality of sub-bands for transmitting a direct sequence spread spectrum signal in parallel using a plurality of gate function generators.