Wireless network system and communication method employing both contention mode and contention-free mode

• US 6,791,996 B1
• Filed: 09/20/2000
• Issued: 09/14/2004
• Est. Priority Date: 09/22/1999
• Status: Expired due to Term

• Current Assignee: Redwood Technologies, LLC (Dominion Harbor Enterprises, LLC)
• Original Assignee: Matsushita Electric Industrial Company Limited (Panasonic Holdings Corporation)
• Inventors: Doi, Hiroshi, Kobayashi, Hirokazu, Watanabe, Yoshinori
• Primary Examiner(s): TON, DANG T
• Application Number:
  US09/665,674
• Time in Patent Office: 1,455 Days
• Field of Search: 370/401, 370/311, 370/328, 370/350, 370/241, 370/252, 370/254, 370/232-235, 370/244, 370/250, 370/251, 370/351, 370/384, 370/347, 370/321, 370/332, 370/333, 370/334, 370/337, 370/442, 370/339, 370/341, 370/349, 370/414, 370/416, 370/418, 370/433, 370/441, 370/444, 370/445, 370/447, 370/448, 370/461, 370/462, 370/458
• US Class Current: 370/447
• CPC Class Codes: H04W 74/02 Hybrid access

Abstract

A network communication system is provided whereby communication stations can obtain priority for data transmission to communicate directly with each other in a contention-free mode communication period independently of a polling operation of the control station. The control station emits a series of beacons at equal intervals to initiate contention-free mode communication at the completion of a predetermined number of beacons. During the maximum contention-free mode communication period a contention-free communication operation is initiated, for allowing contention-free mode transmission, by a polling operation by the control station. A series of time-slots is imaginarily provided at equal intervals from the start of the contention-free period throughout the maximum contention-free period. A communication station conducts a call-connection procedure in order to obtain a priority for data transmission in a given set of time-slots.

Claims

1. A communication method in a wireless network system using both a contention mode communication period and a contention-free mode communication period determined by a polling operation of a control station as a communication protocol between communication stations controlled by the control station, said communication method comprising the steps of:

(a) providing time-slots in the contention-free mode communications period;

(b) employing one of the communication stations to establish a call-connection between itself and another one of the communication stations through executing a procedure of call-connection with the control station in order to communicate in the time-slots; and

(c) when the control station acknowledges that the call-connection is established, performing a packet communication operation involving transmitting packets between the one of the communication stations and the another one of the communication stations in the time-slots while bypassing the control station.

2. The communication method according to claim 1, further comprising the steps of:

(d) employing the control station to transmit a time-slot change instruction packet for directing change of a first time-slot where a first communication station of the communication stations establishes a call-connection to the first communication station; and

(e) employing the first communication station when receiving the time-slot change instruction packet to change the first time-slot according to information in the time-slot change instruction packet.

3. The communication method according to claim 2, further comprising the steps of:

(f) employing the control station to produce a call-connection table through monitoring the procedure of call-connection;

(g) employing the first communication station to transmit a time-slot change request packet to the control station for requesting change of the first time-slot;

(h) employing the control station when receiving the time-slot change request packet to access the call-connection table;

(i) employing the control station to examine from accessed information in the call-connection table whether or not a first call-connection requested by the first communication station is admitted for establishment;

(j) employing the control station when judging that the first call-connection is not admitted for establishment to transmit the time-slot change instruction packet to the first communication station; and

(k) employing the first communication station when receiving the time-slot change instruction packet to change the first time-slot.

4. The communication method according to claim 1, 2, or 3, wherein said step (b) comprises the sub-steps of:

(i) employing the communication station to transmit a test packet; and

(ii) employing the communication station to adjust transmission quality of the call-connection according to information in the test packet with an adjusting method.

5. The communication method according to claim 4, further comprising the steps of:

(l) employing one of the communication stations which receives the test packet to transmit a test response packet;

(m) applying a signal reception state data section to each of the test packet and the test response packet;

(n) employing the one of the communication stations to save data about signal reception state of the test packet and the test response packet respectively in the signal reception state data section; and

(o) employing the communication stations to adjust transmission quality according to the data about the signal reception state.

6. The communication method according to claim 5, wherein said step (n) comprises the sub-steps of:

(i) measuring at least one of an error rate in wireless signal reception and a level of the wireless signal reception; and

(ii) saving a resultant measurement as the data about the signal reception state in the signal reception state data section.

7. The communication method according to claim 5, wherein said step (o) comprises the sub-step of:

lowering wireless transmission power of the test packet to such a level that the data about the signal reception state stays above a threshold.

8. A communications method according to claim 5, wherein said step (o) comprises the sub-steps of:

(i) estimating a direction of signals from the data about the signal reception state when the test packet or the test response packet is received; and

(ii) controlling antenna directivity to correspond to the direction.

9. The communication method according to claim 8, wherein the antenna directivity is controlled with an adaptive array antenna.

10. The communication method according to claim 8, wherein the antenna directivity is controlled by switching between a non-directional antenna and a directional antenna.

11. The communication method according to claim 4, further comprising the steps of:

(n) when receiving no acknowledgment of reception of packet transmitted, employing an adjusting method comprising causing the communication station to transmit the test packet in the contention mode communication period;

(o) when the adjusting method of step (n) is employed, employing the communication station to transmit a time-slot change request packet to the control station; and

(p) when an adjusting method is employed which is different from the adjusting method of step (n), employing the communication station to adjust the transmission quality with another adjusting method.

12. A communication method in a wireless network system using both a contention mode communication period and a contention-free mode communication period determined by a polling operation of a control station as a communication protocol between communication stations controlled by the control station, said communication method comprising the steps of:

(a) providing time-slots in the contention-free mode communication period;

(b) employing one of the communication stations to request a call-connection by requesting allotment of a number of time-slots and an address of a leading time-slot through execution of a call-connection procedure with the control station; and

(c) when the control station acknowledges that a call-connection has been established, employing the one of the communication stations to perform a packet communication operation with another one of the communication stations in the time-slots beginning with the leading time-slot while bypassing the control station.

13. The communication method according to claim 12, further comprising the steps of:

(d) when the call-connection procedure of step (b) cannot be approved by the control station, employing the control station to transmit a time-slot change instruction packet to the one of the communication stations in order to effect a change to the requested leading time-slot or the number of time-slots; and

(e) employing the one of the communication stations to change the leading time-slot requested in step (b) according to information in the time-slot change instruction packet received from the control station.

14. The communication method according to claim 13, further comprising the steps of:

(f) employing the control station to maintain a call-connection table through monitoring the call-connection procedure of step (b);

(g) employing the one of the communication stations to transmit a time-slot change request packet to the control station to request a change of a leading time-slot;

(h) employing the control station to access the call-connection table upon receipt of the time-slot change request packet;

(i) employing the control station to examine from information accessed in the call-connection table whether or not the call-connection requested by the one of the communication stations can be established;

(j) employing the control station to transmit a time-slot change instruction packet to the one of the communication stations when the control station determines that the call-connection requested by the one of the communication stations cannot be established;

(k) employing the one of the communication stations to change the leading time-slot upon receipt of the time-slot change instruction packet from the control station.

15. The communication method according to claims 12, 13, or 14, wherein said step (b) further comprises the sub-steps of:

(i) employing one of the communication stations to transmit a test packet; and

(ii) employing one of the communication stations to adjust a transmission quality of a call-connection according to information received in the test packet.

16. The communication method according to claim 15, further comprising the steps of:

(l) employing one of the communication stations to transmit a test response packet in response to receipt of the test packet;

(m) providing a signal reception quality data section in each of the test packet and the test response packet;

(n) employing one of the communication stations to save data about signal reception quality of the test packet and the test response packet in the signal reception quality data section; and

(o) employing one of the communication stations and the control station to adjust transmission quality based on the saved data about signal reception quality.

17. The communication method according to claim 16, wherein said step (n) further comprises the sub-steps of:

(i) measuring the quality of a received signal as at least one of an error rate in the wireless signal reception and a level of the wireless signal reception; and

(ii) saving the measurement as the data about the signal reception quality in the signal reception quality data section.

18. The communication method according to claim 16, wherein said step (o) comprises the sub-step of:

lowering wireless transmission power of the test packet to a level to cause the data about the signal reception quality stays above a threshold.

19. The communication method according to claim 16, wherein step (o) further comprises the sub-steps of:

(i) estimating a direction of signals from the data about signal reception quality when the test packet or the test response packet is received; and

(ii) controlling antenna directivity to correspond to the estimated direction.

20. The communication method according to claim 19, wherein the controlling recited step (o)(ii) is controlled by an adaptive array antenna.

21. The communication method according to claim 19, wherein the controlling recited step (o)(ii) is controlled by switching between a non-directional antenna and a directional antenna.

22. The communication method according to claim 15, further comprising the steps of:

(p) adjusting the quality of a call-connection by an adjusting method comprising transmission of a test packet in a contention mode communication period when no acknowledgment of receipt of a transmitted packet is received by one of the communication stations;

(q) employing one of the communication stations to transmit a time-slot change request packet to the control station when the quality of a call-connection is adjusted by the adjusting method of step (p); and

(r) employing one of the communication stations to adjust the transmission quality using another adjusting method when the quality of a call-connection is not adjusted by the adjustment method of step (p).

23. A wireless communication system for allowing plural call-connections to be initiated at a same time-slot, said system including a communication station which comprises:

(a) means for gaining data about a wireless signal reception state;

(b) means for controlling a power level of signal transmission; and

(c) means for, upon receiving one of a test packet and a test response packet, providing in the one of the test packet and the test response packet data describing one of the state of a previous packet received at the communication station.

24. A system as in claim 23, wherein said state comprises one of a power level of the received wireless signal and a transmission error rate of the wireless signal.

25. A wireless network system comprising a control station and plural communication stations controlled by the control station, said system employing a communication procedure using both a contention mode communication period and a contention-free mode communication period determined by a polling operation of the control station as a communication protocol between the communication stations, the communication procedure comprising the operations of:

(a) providing time-slots in the contention-free mode communications period;

(b) employing one of the communication stations to establish a call-connection between itself and another one of the communication stations through executing a procedure of call-connection with the control station in order to communicate in the time-slots; and

(c) when the control station acknowledges that the call-connection is established, performing a packet communication operation involving transmitting packets between the one of the communication stations and the another one of the communication stations in the time-slots while bypassing the control station.

26. A wireless network system comprising a control station and plural communication stations controlled by the control station, said system employing a communication procedure using both a contention mode communication period and a contention-free mode communication period determined by a polling operation of the control station as a communication protocol between the communication stations, said communication procedure comprising the operations of:

(a) providing time-slots in the contention-free mode communication period;

(b) employing one of the communication stations to request a call-connection by requesting allotment of a number of time-slots and an address of a leading time-slot through execution of a call-connection procedure with the control station; and

(c) when said control station acknowledges that a call-connection has been established, employing the one of the communication stations to perform a packet communication operation with another one of the communication stations in the time-slots beginning with the leading time-slot while bypassing the control station.