Transmission range adjustment according to network conditions

• US 20080005351A1
• Filed: 06/28/2006
• Published: 01/03/2008
• Est. Priority Date: 06/28/2006
• Status: Active Grant

• Current Assignee: SAP SE
• Original Assignee: SAP AG (SAP SE)
• Inventors: Ploennigs, Joern, Neugebauer, Mario, Kabitzsch, Klaus
• Granted Patent: US 7,699,234 B2
• Time in Patent Office: Days
• US Class Current: 709/238
• CPC Class Codes: H04W 40/04 based on wireless node resources
• CPC Class Codes: H04W 40/08 based on transmission power
• CPC Class Codes: H04W 40/20 based on geographic position or location
• CPC Class Codes: Y02D 30/70 in wireless communication networks

Abstract

A method is disclosed for selecting between a multi-hop transmission route and a single-hop transmission route for transmitting data from a smart item in a network of smart items to a base station. The method includes receiving signals at the smart item from neighboring smart items in a vicinity of the smart item, measuring a density of neighboring smart items around the smart item based on information in the received signals, and parameterizing a loss of energy in a signal transmitted between a neighboring smart item and the smart item as a function of distance between the neighboring smart item and the smart item. The parameterization is based on information in the received signals. Based on the measured density and on the parameterization of the loss of energy, a multi-hop transmission route or a single-hop transmission route is selected for transmitting data from the smart item to the base station.

Claims

1. A method of selecting between a multi-hop transmission route and a single-hop transmission route for transmitting data from a smart item in a network of smart items to a base station, the method comprising:

receiving signals at the smart item from neighboring smart items in a vicinity of the smart item;

measuring a density of neighboring smart items around the smart item based on information in the received signals;

parameterizing a loss of energy in a signal transmitted between a neighboring smart item and the smart item as a function of distance between the neighboring smart item and the smart item, wherein the parameterization is based on information in the received signals; and

selecting, based on the measured density and on the parameterization of the loss of energy, a multi-hop transmission route or a single-hop transmission route for transmitting data from the smart item to the base station.

2. The method of claim 1, wherein measuring the density comprises receiving, at the smart item, information about the locations of the neighboring smart items.

3. The method of claim 1, wherein parameterizing the loss of energy comprises:

receiving information at the smart item about the locations of the neighboring smart items;

receiving, from each of the neighboring smart items at the smart item, a signal having a calibrated transmission power; and

measuring a power of each of the received signals;

comparing the calibrated transmission power to the measured received power for each of the signals to determine an amount of energy lost during transmission between each of the neighboring smart items and the smart item.

4. The method of claim 3, wherein parameterizing the loss of energy further comprises determining a parameter, α

, to relate a power of a signal received at the smart item, P_rec, to a power of the signal when transmitted from a neighboring smart item, P_trans, and a distance, r, between the smart item and the neighboring smart item through the relation, P_rec∝

P_trans/r^α

.

5. The method of claim 1, further comprising:

storing pre-determined parameters characterizing an approximate equivalence between energy costs associated with single-hop transmission and multi-hop transmission for a model of the network of smart items; and

selecting, based on the measured density, on the parameterization of the loss of energy, and on the pre-determined parameters, a multi-hop transmission route or a single-hop transmission route for transmitting data from the smart item to the base station.

6. The method of claim 1, further comprising:

storing pre-determined parameters characterizing an approximate equivalence between energy costs associated with single-hop transmission and multi-hop transmission for a plurality of models of the network of smart items; and

identifying pre-determined parameters characterizing an approximate equivalence between energy costs associated with single-hop transmission and multi-hop transmission for one of the plurality of models of the network of smart items; and

selecting, based on the measured density, on the parameterization of the loss of energy, and on the identified pre-determined parameters, a multi-hop transmission route or a single-hop transmission route for transmitting data from the smart item to the base station.

7. The method of claim 1, further comprising adjusting a transmission signal energy with which to transmit data from the smart item to the base station, wherein the transmission signal energy is adjusted to reduce an amount of energy expended during transmission of data from the smart item to the base station.

8. The method of claim 1, further comprising:

determining an amount of energy required to transmit a bit of data between the smart item and a neighboring smart item;

determining an amount of energy required to receive a bit of data at the smart item from a neighboring smart item;

selecting, based on the measured density, based on the parameterization of the loss of energy, based on the amount of energy required to transmit a bit of data, and based on the amount of energy required to receive a bit of data, a multi-hop transmission route or a single-hop transmission route for transmitting data from the smart item to the base station.

9. The method of claim 1, further comprising adjusting transmission signal powers of the smart item and of the neighboring smart items to ensure that each smart item in the network of smart items is connected to the base station.

10. The method of claim 1, wherein the multi-hop path between the smart item and the base station along different smart items in the network is selected according to a shortest-path-finding algorithm.

11. A smart item within a network of smart items, wherein the network includes a base station, the smart item comprising:

an antenna for receiving signals from neighboring smart items of the network located in a vicinity of the smart item; and

a monitoring service adapted for;

measuring a density of neighboring smart items around the smart item based on information in the received signals;

parameterizing a loss of energy in a signal transmitted between a neighboring smart item and the smart item as a function of distance between the neighboring smart item and the smart item, wherein the parameterization is based on information in the received signals; and

selecting, based on the measured density and on the parameterization of the loss of energy, a multi-hop transmission route or a single-hop transmission route for transmitting data from the smart item to the base station.

12. The smart item of claim 11, wherein the received signals comprise information about the locations of the neighboring smart items, and wherein measuring the density of neighboring smart items around the smart item is based at least in part on the information about the locations of the neighboring smart items.

13. The smart item of claim 11, wherein the signals received from neighboring smart items comprise information about the locations of the neighboring smart items and signals having a calibrated transmission power, and the monitoring service is further adapted for:

measuring a power of a signal received from each of the neighboring smart items; and

comparing the calibrated transmission power to the measured received power to determine an amount of energy lost during transmission between each of the neighboring smart items and the smart item.

14. The smart item of claim 13, wherein parameterizing the loss of energy further comprises determining a parameter, α

, to relate a power of a signal received at the smart item, P_rec, to a power of the signal when transmitted from a neighboring smart item, P_trans, and a distance, r, between the smart item and the neighboring smart item through the relation, P_rec∝

P_trans/r^α

.

15. The smart item of claim 11, further comprising:

a memory adapted for storing pre-determined parameters characterizing an approximate equivalence between energy costs associated with single-hop transmission and multi-hop transmission for a model of the network of smart items; and

wherein the monitoring service is further adapted for selecting, based on the measured density, on the parameterization of the loss of energy, and on the pre-determined parameters, a multi-hop transmission route or a single-hop transmission route for transmitting data from the smart item to the base station.

16. The smart item of claim 11, further comprising:

a memory adapted for storing pre-determined parameters characterizing an approximate equivalence between energy costs associated with single-hop transmission and multi-hop transmission for a plurality of models of the network of smart items; and

wherein the monitoring service is further adapted for;

identifying pre-determined parameters characterizing an approximate equivalence between energy costs associated with single-hop transmission and multi-hop transmission for one of the plurality of models of the network of smart items; and

selecting, based on the measured density, on the parameterization of the loss of energy, and on the identified pre-determined parameters, a multi-hop transmission route or a single-hop transmission route for transmitting data from the smart item to the base station.

17. The smart item of claim 11, wherein the monitoring service is further adapted for adjusting a transmission signal energy with which to transmit data from the smart item to the base station via intermediate nodes, wherein the transmission signal energy is adjusted to reduce an amount of energy expended during transmission of data from the smart item to the base station.

18. The smart item of claim 11, wherein smart item is an RFID device.

19. The smart item of claim 11, wherein the monitoring service is further adapted for adjusting a transmission signal powers of the smart item to ensure that the smart item in the network is connected to the base station.

20. The smart item of claim 11, wherein the multi-hop path between the smart item and the base station along different smart items in the network is selected according to a shortest-path-finding algorithm.